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BIOLOGY
•
•
Development of the concepts for origin of
life
...
o Francesco Redi – all life comes from an
egg
o Luise Pasteur – all life comes from preexisting life
o Oparin – components underwent series
of reactions becoming complex
molecules, which in water environment
formed aggregates leading to
evolutionary processes and first life
forms
o From molecules to monomers, from
monomers to polymers, from polymers
to aggregates, the first cells were
anaerobic
...
Parasites
and Hosts
...
o The parasite benefits at the expense of
the host
...
o Commensalisms – only one side has
benefits, the other is unaffected
o Symbiosis – two organism which can
not exist independently
o Mutualism – both partners benefit
o Parasitism – one partner uses the other
eating, living and causes medical
disorders to the partner
o Infection can be affected by direct or
indirect contact
o Transmission infection is by a vector, eg
mosquito
o Parasite activities – mechanical action
penetration, toxic action due to toxic
produced by parasite, nutritive
combination food
o Host – not passive – can respond to the
parasite by building membranes
capsules and immunological reaction
production of antibodies
•
Relationship between parasite and host
and its medical significance
o Commensalisms – only one side has
benefits, the other is unaffected
o Symbiosis – two organism which cannot
exist independently
o Mutualism – both partners benefit
o Parasitism – one partner uses the other
eating, living and causes medical
disorders to the partner
o Infection can be affected by direct or
indirect contact
o Transmission infection is by a vector, eg
mosquito
o Parasite activities – mechanical action
penetration, toxic action due to toxic
produced by parasite, nutritive
combination food
o Host not passive - can respond to the
parasite by building
membranes/capsules and
immunological reaction - production of
antibodies
o Mechanical influence of the parasite
upon the host – worm parasite and
arthropods (Ascari may cause
obstruction of liver ducts of intestines,
Larva of pork tapeworm in human eye –
blindness)
o Toxic influence of the parasite upon the
host – release secretion and excretions
of toxins (itching pimples on skin after
mosquito/insect bite)
o Nutritive influence of the parasite upon
the host – effect when parasite use for
food – blood, lymph, tissues or intestine
o Cell tissue influence of host upon
parasite – expressed by
inflammation/irritation – increase of
number of polynuclears, eosinophils
and monocytes in blood
o Humoral influence of host upon
parasite – formation of antibodies
against parasite antigens – formed by
plasmocytes – neutralization of parasite
toxins protect, specific cells work
against intercellular parasites, allergic
reaction
•
Taxonomy of Invertebrates
...
o Carlos Linnaeus, 1739 wrote ‘Systema
naturae’ – organization of plants and
animals
o Taxonomy levels – Kingdom, Phylum,
Class, Order, Family, Genus, Species
o Parasites are free living, single celled,
eukaryotic cells with cytoplasmic
membrane and cellular organelles
o Ectoparasite - lives on the outside
o Endoparasite – lives within the body of
the host
o Falcutative – can live independently
o Obligate – completely dependent on
host
o Incidental – lives in a host
o Temporary – free living during part of
his life
o Permanent – stays in host for its whole
life
o Pathogenic – causes injuries to host
o Pseudo – an artefact
o Coprozoic – foreign species that passes
through the alimentary tract without
any infection to host
o Kingdom Protista
phylum Sarcomatigophora,
subphylum Sarcodina (amoebas)
(/Mastigophora (Flagellate)
phylum Sporozoa (uses spores for
reproduction, plasmodium,
toxoplasma – causes malaria)
phylum ciliophoran (infosaria)
o
Kingdom Animalia
phylum Spongia (water fungi)/
Coelenterata (jellies)/ Ctenophora
(comb jellies)
phylum Platyhelmintes (flatworms),
class turbellaria (tassel
worms)/Trematoda
(flukes)/Cestoda (taenia), order
Pseudophyllidea (fish
taenia)/Cyclophyllidea (rest of
taenia phyla)
phylum Nemathelminthes
(roundworms), class Nematoda,
orders Triplonchida/ Ascaridida/
Oxyurida/ Strpngylida/ Spirurida/
Trichocephalus
phylum Annelida (earthworms),
class Hirundinea
phylum Arthropoda, class
Crustacea/Archnida
•
Characterization of Kingdom Protista,
Phylum Sacromastigophora, Subphylum
Sarcodina, Entamoeba Histolytica
...
o Leishmania and Trypanosoma are
transmitted by the bite of a blood
sucking insect
o They exist as amastigotes (rounded cells
without flagella) in vertebrates or
promastigotes, epimastigotes and
trypomastigotes (flagellated motile
forms) in invertebrates
...
Cell ruptures and merozoites are
released into the blood stream,
becomes trophozoites which invade red
blood cells where they divide until cell
bursts which releases trophozoites
Some turn into female and male
gametocytes which when fertilize, they
form an ookinete, this matures in the
guts of mosquito to oocyte which will
divide into sporozoite
Malaria causes periodic episodes of
chills and fever, related to the burst of
red blood cells which cause anaemia
and sticky red blood cells resulting in
haemorrhages and blocked blood
delivery to tissues, renal failure, lung
edema and coma, leading to death
Toxoplasma is infection in animals,
especially cats, the human gets exposed
to infection by eating undercooked
meat (raw pork) and food contaminated
with cat faeces
Toxoplasma Gondii undergoes sexual
division in the cat, excreted in faeces as
the infectious cyst
Immunocompromised patient or those
taking immuosuppresive drugs are
susceptible to growth of Toxoplasma
Gondii
Infection causes fever, enlargement of
lymph node, liver and spleen and brain
infection
Can also cause blindness, seizures and
mental retardation in pregnant women
Phylum Ciliophora – characterization
Balantidum Coli
...
Class Trematoda
...
o
o
o
o
Platyhelminthes are flat worms
Trematodes also called flukes, exist
within the human, flukes have snail
species, larva multiplies asexual,
between 1mm and 7cm big, leave
shaped and flat, have two suckers,
mouth opens into a muscular, pumping
pharynx connected via esophagus to
blind ending caeca
No anus, waste material through the
mouth, pair of ganglia in the head
region, generally lack sense organs
Cestodes known as tapeworms, live and
mate within the human digestive tract,
each tapeworms has both male and
female sex organs, larva lives in tissues
of vertebrates and invertebrates, the
scolex armed with suckers and hooks,
between 3mm and 10mm, gravid
proglottides containing fertilized eggs,
male reproduction organs in dorsal part
o
o
o
o
o
o
•
proglottides, female reproduction
organs lie towards ventral surface of
proglottides
Fasciola hepatica in common liver
fluke/sheep liver fluke, infects liver,
disease caused fascioliasis
Freshwater snail as an intermediate
host, minute cercariae emerge and
swim through pools of water in pasture
and encyst as mericerea on nearby
vegetation, parasite ingested by infinity
host eating uncooked foods like
watercress, contact with low pH in the
stomach and early immature juvenile
begins process of excyst
In duodenum larva breaks free of the
cysts and burrows through the
intestinal lining in to the peritoneal
cavity, once it finds liver parenchyma
then feeding starts which is the
pathogenic stage causing anemia,
matures into adult in bile duct and
produce eggs
Medical significance of fascioliasis
include anemia, weight loss, diarrhea,
liver fluke and diagnosed by yellow
brown eggs in faeces
Dicrocoelium Lanceatum, adult lives in
bile duct and eggs leave the body with
faeces which is eaten by snail, matures
to cercariae/sporocytes (cyst) and
leaves the snail, ant eats the cyst and
excyst to form mericarea, ant gets
eaten by adult and goes to bile duct and
liver and starts to produce eggs
Symptoms include anaemia and weight
loss
Class Cestoda (tapeworms)
...
o Tapeworms are flatworms and live in
the intestines of hosts, suck nutrients
digested by their host, tapeworms are
hermaphrodites
o Taenia Solium (pork Tapeworm), eating
raw or undercooked pork infects the
human, adult attaches to mucosa of
o
o
o
o
o
intestine via hooks on scolex, releases
eggs in human faeces, pig graze on
contaminated eggs
Eggs – larva – pig muscles – cyticercus
Cysticerci causes neurocysticercosis
Diagnosis of TS by examining faeces for
eggs and proglottids or biopsy to
identify cysts
Taenia Saginata (beef Tapeworm) same
lifestyle, but humans do not develop
cysterci when eggs injected, adult beef
tapeworm in intestinal mucosa
Patients may develop malnutrition and
weight loss and diagnosis by identifying
gravis proglottids and eggs in faeces
•
Echinococcus Granulosus (dog tapeworm)
characterization and medical significance
...
Class Nematoda
...
o Nematodes mature into adults in the
intestinal tract and larva forms,
digestive system openings at both ends
o Oral cavity is lined with cuticle,
digesting glands produce enzymes, no
stomach, absorbs nutrients through its
lining, expels waste through the anus
o Nervous system, ventral nerve largest,
dorsal nerve motor control, lateral
nerves sensory, ventral combines both
functions
o Enterobius Vermicularis, egg ingested,
pinworm matures in cecum and large
intestine, lays eggs though female
perianal area, causes itching, eggs on
hand, touching next person, infection
o
o
o
o
Diagnosis by placing tape on perianal
area to pick up eggs
Ascaris Lumbricoides, food
contaminated with eggs, larvae emerge
eggs in small intestine and penetrate
walls, travels in bloodstream to lungs
and coughed up and swallowed again,
mature to adult in small intestine, eggs
excreted in faeces
May develop abdominal cramps and
mass of worms can block intestine
Diagnosis by chest x-ray and high
eosinophil count in blood
o
o
pedipalps serves in locomotion and
reproductive functions
Scorpions – head and tail, abdomen of 7
segments, 4 pairs of legs, exoskeleton,
exoskeleton, tail 6 segments with a
sting of venomous glands, venom attack
and paralyse and kill prey
Spiders – fused segmented head,
jointed limbs, 4 pairs of eyes, fangs with
poison in mouth, blood circulation with
heart tube, respiratory system and
nervous system
•
•
•
Trichinella Spiralis and Trichocephalus
Trichiurus – characterization and medical
significance
...
Class Archnida
(spiderlike)
...
o Arachnids – class of joint legged
invertebrate animals, eight legs, no
antennae and no wings, chelicerae
serves in feeding and defense,
Subclass Acaro (ticks)
...
Acarus
Siro
...
o Genus Argas (soft tick) – oval, small,
flat, ectoparasites, spiracles, nocturnal
feeders, 4 pairs of 6 segmental legs, 4
pulps, blood sucking, transmit
borreliosis and tick paralysis
o Genus Ixodidae (hard tick) – oval, hard
scutum, recurved teeth, hard dorsal
scutum on anterior dorsal surface in the
female, covers whole dorsum in males,
reddish brown, 4 pairs of 6 segmental
legs, blood sucking, vectors for
relapsing fever, tick paralysis and lime
disease, protozoan disease
o Acarus Siro – small, oval, eyeless,
anterior part has 2 pairs of legs,
posterior part has 2 pairs of legs,
transmission occurs by personal contact
– lesions and itching
o Diagnosis by examination of lesions
•
Class Insecta
...
o Pediculus – greyish white body, 2
antennae, flagellum , oval head, 6 legs,
segmented body in 3 segmented thorax
and 9 segmented abdomen, transmits
European typhus and borreliosis
o Phthirius – 1-2mm length, crab shaped
body, 6 legs, 9 segmented thorax and 9
segmented abdomen, found in pubic
area, common eyelid infection,
transmitted by sexual contact, causes
itching and lesions, sucks blood to feed
o
•
•
•
Cimex Lectularius and Pulex Irritans –
characterization and medical significance
...
Phlebotomus Papatasii – characterization
and medical significance
...
3 pairs
of legs, 1 pair of wings, 15 segmented
antennae, female have long proboscis
for blood sucking, anopheles transmits
malaria
Family Muscidae/flies/ Glossina Palpalis –
medical significance
...
Atavistic traits
...
o Choroda dosalis (notichorda) –
developed around neural tube for
protection, neural tube in every
chordate embryos provides stiffening of
body, digestion track, circulation system
o Class Pisces
Order Selaclina (sharks) –
cartilaginous fish
Order Chondrostei (Atlantic
sturgeon) – cartilaginous fish
Order Telleostei (tuna, seahorses) bonyfish
Order Crosso
o
Class Amphibia
Order Urodela (Salamanda) – have a
tail
Order Amura (Frogs) – without tail
o
Class Reptilia
o
Order Sauria (Lizard)
Order Chamieliontes (Chamelon)
Order Opidia (Snakes)
Order Chelonia (Turtles, Tortoise)
Order Crocodilia (Crocodiles)
Class Aves
Order Ratita – running bird
Order Natantes – swimming bird
o
Class Mammalia
Order Monotremata (Platypus,
Echidna)
Order Marsupialis (Kangaroo)
Order Plaxentalia
Atavistic traits – during
embryogenesis some organs appear
and then vanish, reappearing of
trails which had disappeared
generations before because the
gene for the trail is still in DNA
•
Cell Reproduction: Haploid – diploid cycle
...
o Prokaryotic cells reproduce by binary
fission
...
o Reproductive process starts with
chromosome replication, the new
chromosome attaches itself to plasma
membrane and two chromosomes
migrate to opposite ends of cell, plasma
membrane in middle of cell grows
inward until it closes to separate the
cell into two daughter cells
...
Diploid cells
reproduce by mitosis making exact copy
of daughter cells
...
o Haploid cells have only one complete
set of chromosomes
...
Gametes
...
Nucleus and cytoplasm
divide into 2
...
Followed by cytokinesis which is
division of cytoplasm to form two
identical daughter cells
...
DNA
synthesis begins in S-phase where
semiconservative replication of DNA
occurs
...
Meiosis is whereby the number of
chromosomes in daughter cells is
reduced by half to produce haploid
gametes
...
Meiosis 2 – chromosomes each
consisting of two sister chromatids
attached at centromere align on central
pole, centromeres split, daughter
chromosomes move to opposite poles
of cell
...
Segregation alleles so only one of
original gene pair is included in each
gamete, independent assortment of
homologous chromosomes so gamete
inherits half from each parent
...
Sex and sexual traits
...
o Sex is combination of features regarding
the reproduction of organisms
...
Male – the
seminal vesicles, prostate gland,
copulation gland (penis)
...
o Secondary sex features include hair,
hypodermic fat, bone and muscle
systems
...
Determination of sex is of which the
development of the organism
orientates towards the male or female
under hereditary or external factors
influence
...
XO
are male sex in some insects as no Y
chromosome
...
Differentiation of sex includes the
development of gonads, sexual ducts
and external sexual organs
...
o X chromosome inactivation – in normal
female somatic cells, most genes but
not all on one of X chromosomes is
inactive
...
In a 49 XXXXX cell, there is one active
and 4 inactive
...
Either X
chromosome inherited from father (Xp)
or mother (Xm) may be inactivated with
equal likelihood
...
o On average, half of cells in a female
have an inactive Xm and half have
inactive Xp
...
Max number of
Barr bodies is equal to the number of
inactivated X chromosomes
...
Bad recessive genes can be expressed
when good genes are inactivated
...
Gametogenesis
...
Not typical forms of sexual
reproduction
...
Descendants are identical to each other
and parents
...
Includes mixing of genomes of both
parents and descendants normally vary
...
o Human fertilization is union of egg and
sperm usually in the ampulla of the
fallopian tube to form a zygote cell or
fertilized egg
...
•
Embryonic period – stages
...
o Week 1-3 – about 7 days after
fertilization, the blastula attaches to the
uterus wall (endometrium) and
performs implantation between mother
and embryo, an umbilical cord is also
formed
...
The brain, spinal cord,
tear and gastrointestinal tract forms
...
o Week 4-5 – chemicals produced by
embryo to stop menstrual cycle
...
Organogenesis
o
o
•
Epiboly – expansion of one cell
sheet over the other cells
Ingression – cells move with
pseudopods
Invagination – forming math anus
and archenteron
Delamination – external cells divide
leaving the daughter cells in the
cavity
Polar proliferation – cells at the
polar ends of the blastula/gastrula
proliferate
begins
...
Week 6-8 – Myogenesis and
neurogenesis progressed so embryo
capable of motion and eyes form
...
At end of 8h week, embryonic
stage ends and foetal stage begins
...
o
o
Reasons and factors of the embryonic
development
...
o Cleavage – division of cells with no
significant growth in the early embryo
producing a cluster of cells the same
size as the original zygote
...
Mammals also
form blastocyst characterized by inner
cell mass
...
Mechanism – blastula,
blastopore formation, cell migration to
form layers
...
Factors of embryogenesis – internal
(genetic) is nucleus, external
(epigenetic) is cytoplasm and
environment
...
o Birth/hatching – death
...
o
o
o
o
o
o
•
Juvenile and adolescent phase – biggest
growth stages, hormones and growth
factors stimulate and regulate growth
...
Salmon
and lobster continue to grow at adult
stage
...
After surgical
removal of 70% of liver, liver grows
back to its size rapidly
...
Death – end of individual development,
irreversible cessation of biological
process
...
o Regeneration is the process of renewal,
restoration and growth that makes
genomes, cells, organs, organisms that
cause disturbances or damage
...
o Use of transplanted tissue and organs in
medicine is not classified as
regenerative medicine because tissue
and organs were not grown specifically
for use as therapeutic agents
...
Synthetic stem cells
then grown in culture and
differentiated into appropriate cells
indicated for treating the patient’s
disease or injury
...
o To take cells from animal or plant for
placement in a culture medium (in vitro
- outside organism)
...
o Lymphocyte cultures stops mitotic
division
o In transplantation immunology, observe
reactions suitable to donator or not
...
o The ability to return to life after
apparent death – suspended animation
...
o Adapting to harsh environmental
condition lower organisms spend the
unfavorable seasons through the year in
a state of ‘uta-minime’ and then return
back to normal
o Hypothermia – reduction of core body
temperature to 32 degrees or lower as
that due to exposure to cold weather as
a means of decreasing metabolism of
tissues and the need of oxygen
...
Low body temperature, slow breathing
and heart rate and low metabolic rate
...
Myocardial hibernation: chronic but
reversible cardiac dysfunction caused
by chronic myocardial ischemia,
persisting at least until blood flow
restored
...
Apply in advance narcosis to brain
centers which control
thermoregulation
...
Molecular base of heredity, DNA and RNA
– structure and functions
...
The chains are antiparallel and one runs
in 3 to 5 direction and other 5 to 3
...
A-form is
more compact
...
o The chromatin in eukaryotic cells
consists of DNA complex with histones
in nucleosomes
...
The DNA that joins
one nucleosome core to the next is a
bond with histones
...
Set of chromosomes in cell makes up its
genome which has about 2 billion base
pairs of DNA arranged into 46
chromosomes
...
Transmission of genetic
information in genes is achieved in
complementary base pairing
...
A-U and G-C and G-U
...
RNA major role in protein synthesis
...
3 consecutive
nucleotides known as codon in mRNA
encode amino acid or stop signal for
protein synthesis
...
tRNAs function
at specific sites in the ribosome during
translation, which is a process that
synthesizes a protein from an mRNA
molecule
...
Ribosome RNA – the RNA component of
the ribosome, essential for protein
synthesis
...
DNA repairs
...
o
o
o
o
•
o
DNA is replicated by uncoiling of the
helix, strand separation by breaking of
the hydrogen bonds between the
complementary strands and synthesis
of the new strands by complementary
base pairing
...
DNA
helicases are unwinding enzymes and
cause the parent DNA strands to
unwind and separate from one another
at the origin of replication to form two
Y shaped replication forks
...
Topoisomerases produce breaks in the
DNA and then rejoin them
...
DNA polymerases join the nucleotides
with phosphodiester bonds
...
Transcription
...
o Transcription is process through which a
DNA sequence is enzymatically copied
by an RNA polymerase to produce a
complementary RNA
...
Transcription leads to translation
of genetic code into a functional
protein
...
o Initiation of transcription requires core
promoter sequence in DNA
...
o TATA Box is a DNA sequence that
indicates where a genetic sequence can
be read and decoded
...
o Activators and corepressors are
responsible for modulating
transcription rate
...
Elongation – RNA polymerase traverses
the template strand and uses base
pairing complementarity with the DNA
template to create an RNA copy
...
Unlike DNA replication, mRNA
transcription can involve multiple RNA
polymerases on a single DNA template
...
Termination – involves cleavage of the
new transcript
...
mRNA – messenger RNA is a copy of a
gene
...
Carry information
stored in the DNA in the nucleus to
cytoplasm where ribosomes can make it
into protein
...
rRNA – ribosomal RNA is structural
component of ribosome
...
Translation
...
o Process in which cellular ribosomes
create proteins
...
Messenger RNA produced
by transcription is decoded by the
ribosome to produce a specific amino
acid chain
...
o In eukaryotes, translation occurs across
the endoplasmic reticulum membrane
in a process called vectorial synthesis
...
Then a
o
o
o
•
transfer RNA carrying the amino acid
methionine binds to the start codon of
the mRNA sequence
...
The large ribosomal
subunits binds to form the complete
initiation complex
...
Each corresponding
amino acid is added to the growing
chain and linked via a bond called a
peptide bond
...
Termination occurs when the ribosome
reaches a stop codon (UAA, UAG, UGA)
...
The new protein is released
and the translation complex comes
apart
...
Definition and
characteristics
...
o It is a triplet code where the codons are
adjacent and because many 64 codons
specify the same amino acid, the
genetic code is degenerate
...
o Usually multiple codons differ only in
the third codon position
...
Transitions in the third
position have no effect
...
o Open reading frame is the part of a
reading frame that has the potential to
o
•
code for a protein or peptide
...
Overlapping genes occur when the
coding region of one gene partially or
completely overlaps that of another
...
Gene and regulation of the gene activity
operons and its functions
...
May determine a
characteristic of an individual by
specifying a polypeptide chain that
focus a protein or part of a protein pr
encode an RNA molecule or regulate
the operation of other genes
...
Binding of the repressor
protein to the operator gene blocks the
movement of the transcribing enzyme
RNA polymerase thus prevents RNA
transcription by the structural genes
...
Because histones are rich in
lysine and arginine they have a net
positive charge and are basic proteins
...
Histones thus prevent
transcription by bringing about
supercoiling of DNA
...
o The genes are transcribed together into
an mRNA strand and so genes
contained in the operon are expressed
together or not at all
...
Negative control involves the binding of
a repressor to the operator to prevent
transcription
...
Heredity material; chromosomes –
composition, sub microscopic and
microscopic structure
...
It is a single piece of coiled DNA
containing many genes, regulatory
elements and other nucleotide
sequences
...
Chromosomal DNA encodes most of
genetic information
...
In eukaryotes nuclei, chromosomes are
packed into chromatin, allowing the
long DNA molecules to fit into the cell
nucleus
...
o Chromatin is composed of many coiled
strands of DNA bound to histones and
non-histone proteins
...
o Euchromatin is the less coiled portion of
the chromosomes, visible as finely
dispersed granular material in the
electron microscope and as lightly
o
o
o
o
o
o
o
o
stained basophilic areas in the light
microscope
...
Deoxyribonucleoprotein (DNP) – Fibres
are the main structure unit of the
chromatin and is the complex of DNA
and protein in which DNA is usually
found upon cell disruption and
isolation
...
Telomeres defer the
degradation of genes near the ends of
chromosomes by allowing chromosome
ends to shorten during chromosome
replication
...
Metacentric – X-shaped chromosomes
with the centromere in the middle so
that the two arms of the chromosomes
are almost equal
...
Sub-metacentric have arms unequal in
length and the kinetochore is present in
the sub median position
...
Telomeres may extend
from both ends of the chromosome
...
Acrocentric – chromosome in which the
centromere is located quite near one
end of the chromosome
...
Humans
normally have five pairs of acrocentric
chromosomes
...
•
•
Karyotype – definition and evolution
...
o Is the number and appearance of
chromosomes in the nucleus of a
eukaryotic cell
...
o Karyotype changes during evolution
...
o Human karyotype contain 22 pairs of
autosomal chromosomes and one pair
of sex chromosomes
...
Males have both X and
Y chromosome denoted 46 XY
...
Inheritance
...
Law of segregation: the
principle stating that during the
production of gametes the two
copies of each hereditary factor
segregate so that offspring
acquires one factor from each
parent
...
o
o
o
o
Allele is an alternative form of the same
gene
...
Sex-linked traits
are located on genes on the sex
chromosomes
...
X-linked dominant inheritance – genetic
inheritance by which a dominant gene
is carried on the X chromosome
...
Alport’s syndrome
...
All female
children of an affected father will be
affected
...
colour blindness
...
Y-linked (holandric inheritance) – the
determination of a phenotypic trait by
an allele or gene on the Y chromosome
...
Y chromosome deletion are a
frequent genetic cause of male
infertility
...
A
gene for which at least two alleles exist
is said to be polymorphic, eg
...
The ABO system in humans is controlled
by 3 alleles (IA, IB, IO)
...
IO is the recessive allele and
produces no antigen
...
4 types of Mendelian inheritance
patterns, autosomal
dominant/recessive, X-linked
recessive/dominant
Autosomal – gene responsible for
the phenotype is located on one of
the 22 pairs of autosomes
X-linked – the gene that encodes for
the trait is located on the Xchromosome
Dominant – conditions that are
manifest in heterozygous
Recessive – conditions are only
manifest in individuals who have
two copies of the mutant allele
o
o
Autosomal dominant – the individual
has just one copy of the mutant allele,
each offspring has 50% chance on
inheriting the mutant allele, eg
Huntington
Autosomal recessive – when just one
copy of the mutant allele, when 2
carriers mate, each child has 25%
o
o
•
chance of being unaffected, 25% being
affected and 50% chance of unaffected
carrier eg
...
Retinitis pigmentosa
Interactions between alleles and genes
o Incomplete dominance is when one
allele for a specific trait is not
completely expressed over its paired
allele
...
You see a blend of red and white
showing pink
...
o Co-dominance both traits show through
as neither phenotype is recessive
...
o Over dominance is a condition in
genetics where the phenotype of the
heterozygote lies outside the
phenotypical range of both homozygous
parents
...
Sickle Cell Anaemia
o Lethal interactions between two alleles
– recessive lethal gene together cause
death, dominant lethal gene Huntington
o Alleles of different genes work together
to produce a complement protein eg
the genes that produce the alpha
hemoglobin polypeptide and the gene
that produces the beta hemoglobin
polypeptide work together to produce a
complete hemoglobin protein
o Epistasis is the effect of one gene being
dependent on the presence of one or
more modifier genes
...
A gene
o
o
o
o
o
o
o
o
o
•
whose phenotype is expressed is called
epistatic
...
Polimery is when more genes have the
same information and belong together
...
Pleiotropy occurs when one gene
influences two or more seemingly
unrelated phenotypic traits
...
An
example is phenylketonuria, a human
disease that affects multiple systems
but is caused by one gene defect
...
Lethal factors cause embryonic death
and sub lethal factors cause later death
(around puberty)
Gene deletion is a mutation in which a
part of a chromosome or a sequence of
DNA is missing
...
Terminal deletion occurs towards the
end of a chromosome
...
Turner-syndrome
Haploidy is 23 chromosomes, single set
of chromosomes
Cytoplasmic heredity is the transmission
of characters from parent to offspring
through the cytoplasm of the germ cell
...
o Environment is the sum of all living and
non-living things that surround an
organism, or group of organisms
...
o Heredity – the genetic transmission of
characteristics from parent to offspring
...
Phenocopy - an individual showing
features characteristic of a genotype
other than its own, but produced
environmentally rather than genetically,
eg
...
Penetrance is the proportion of people
with a particular genetic change who
exhibit signs and symptoms of a genetic
disorder
...
Many
people with a mutation in the BRCA 1 or
BRCA 2 will develop cancer during their
lifetime, but some will not
Variable expressivity – phenotype is
expressed to a different degree among
individuals with the same genotype eg
...
Phenotype variations:
modifications
...
Phenotype is a combination formed of
features and properties formed as a
result of the interaction of the genotype
and environment
...
Change in colour
of Chinese primrose growing in
different temperature conditions,
plants have the same genotype but
different phenotypes
...
Phenotype is an organism observable
characteristics or traits such as its
morphology, development, biochemical
or physiological properties, behavior
...
o The genotype is the genetic makeup of
a cell, an organism or an individual
...
o Combinative mutability is determined
by the possibility of combining the
parents’ chromosomes and genes in the
offspring in various combinations
through sexual reproduction
o Mutational through the process of DNA
replication and mitosis, the hereditary
information is passed from the mother
to the daughter cell unchanged
...
o Classification of the mutations by:
o
According to the causing factor –
spontaneous, induced
According to their phenotypic
expression – biochemical,
physiological, morphological
Depending on type of accepted cell
– somatic, generative
According to inheritance type –
recessive, dominant
According to their direction –
straight, reversed
According to type of alterations in
the genotype – gene (point),
chromosomal (translation),
genomic (polyploidy, aneuploidy)
Most mutations occur as recessive and
are caused by mutagenic factors –
physical (ionizing, radiation X-rays, UV),
chemical (nitrogen acid, anti
metabolites), biological (viruses,
metabolites)
•
Gene (point) mutations: definition, kinds,
mechanism: molecular diseases
...
o According to the number of the
affected nucleotides
Block – deletion, inversion,
duplication, translation
Point – substitution, translation or
trans version, deletion or insertion
of a single nucleotide
o
o
o
o
o
o
o
According to consequences for the
protein synthesis – missense, nonsense,
frameshift mutations
Mutations of structural genes are
expressed by proteins altered in quality
(Hemoglobinosis)
Mutations of the regulating sequences
are expressed by protein normal in
quality but altered in quantity
(Thalassemia)
Transition mutations – one purine base
is replaced by another purine base or
one pyrimidine base is replaced by
another pyrimidine base
Trans version mutations – a purine base
is exchanged for a pyrimidine base or a
pyrimidine base is exchanged for a
purine base
Insertion or deletion leads to changes in
the reading frame of the mRNA
...
Exchange of one
amino acid with another in the
polypeptide chain of the protein (sicklecell anemia)
...
o
o
o
o
o
o
o
o
o
•
Nonsense mutation is a point mutation
in a sequence of DNA that results in a
premature stop codon or a nonsense
codon in the transcribed mRNA and in a
truncated, incomplete an usually nonfunctional protein
...
Eg (Thalassemia)
Frame shift mutation caused by
insertions or deletions of a number of
nucleotides in a DNA sequence that is
not evenly divisible by three
...
The earlier in the sequence the
deletion or insertion occurs, the more
altered the protein is
...
Regulator gene is involved in a
controlling the expression of one or
more other genes
...
Alpha thalassemia – chromosome 16,
genes HbA1 and HbA2
Beta thalassemia – chromosome 11,
mutations in HbB gene, decreased beta
chains
Tay-Sachs disease – genetic mutation
on chromosome 15
Cystic fibrosis/mucouscidosis –
autosomal recessive genetic disorder
Chromosomal (structural) mutations;
definition, different rearrangements;
chromosomal diseases
...
Duplication – a portion of the
chromosome is duplicated, resulting in
extra genetic material, caused by
unequal crossing over that occurs
during meiosis between misaligned
homologous chromosomes
...
Inversion is a chromosome
rearrangement in which a segment of a
chromosome is reversed end to end
...
Two types
paracentric and pericentric, increased
risk of infertility
...
Isochromosome
18p syndrome, restricted growth,
epilepsy
...
Can arise spontaneous or
by mutagens like radiation
...
A chromosome translocation is a
chromosome abnormality caused by
rearrangement of parts between
nonhomologous chromosomes
...
Robertsonian translocation (ROB) is a
rare form of chromosomal
rearrangement that, in humans, occurs
in the five acrocentric chromosome
pairs, namely 13, 14, 15, 21 and 22
...
Chromosome
translocations are significant in human
fertility, birth defects and cancer
...
Problems with larynx and
nervous system
...
1 to 50 000
live birth
...
Retinoblastoma (del 13q) is a rare
malignant tumour of the retina,
affecting young children
...
Translocation
of a q-arm part of chromosome 8 on
chromosome 14
...
Translocation of a fragment
chromosome 9 on 22
...
Definition, types, human syndromes
...
Aneuploidy is the presence of an
abnormal number of chromosomes in a
cell, for example when having 45 or 47
chromosomes when 46 is expected in a
human cell
...
Pateu’s Syndrome, Trisomy 13, ( 47,13t)
is a chromosomal condition associated
with severe intellectual disability and
physical abnormalities in many parts of
the body
...
Edward’s syndrome, (47, 18t),
Trisonomy 18, is caused by the
presence of all or part of an extra 18
chromosome
...
The condition
leads to impairments in both cognitive
ability and physical growth that range
from mild to moderate developmental
disabilities
...
Klinefelter’s syndrome (47, XXY) is a
genetic disorder that affects males
...
Most males have one Y
and one X chromosome
...
Superwoman syndrome (47, XXX), is
when there is an extra X chromosome
in the female
...
Caused by nondisjunction during
meiosis 2 in spermatogenesis
...
o Innate immunity refers to nonspecific
defense mechanisms that come into
play immediately or within hours of an
antigen's appearance in the body
...
o Acquired (adaptive or
specific) immunity is not present at
birth
...
As a person's
immune system encounters foreign
substances (antigens), the components
of acquired immunity learn the best
way to attack each antigen and begin to
develop a memory for that antigen
...
Primary is thymus and
bone marrow
...
o T-cells (thymus), B-cells (bone marrow),
macrophages
...
They can be
distinguished from other lymphocytes,
such as B cells and natural killer cells, by
the presence of a T-cell receptor on
the cell surface
...
They function in
the humoral immunity component of
the adaptive immune system by
secreting antibodies
...
Immune response – diversity and memory
...
o Humoral immunity, also called the
antibody-mediated beta
cellularisimmune system, is the aspect
of immunity that is mediated by
macromolecules (as opposed to cells)
found in extracellular fluids such as
secreted antibodies, complement
proteins, and certain antimicrobial
peptides
...
They act as a critical part of the
immune response by specifically
recognizing and binding to particular
antigens, such as bacteria or viruses and
aiding in their destruction
...
An epitope,
also known as antigenic determinant, is
the part of an antigen that is recognized
by the immune system, specifically by
antibodies, B cells, or T cells
...
o Cell mediated immunity is an immune
response that does not involve
antibodies, but rather involves the
activation of phagocytes, antigenspecific cytotoxic T-lymphocytes, and
the release of various cytokines in
response to an antigen
...
They not
only help activate B cells to
secrete antibodies and macrophages to
destroy ingested microbes, but they
also help activate cytotoxic T cells to
kill infected target cells
...
Lymphokines are a subset of
cytokines that are produced by a type
of immune cell known as a lymphocyte
...
T-cells become cytotoxic killer cells and
can kill the target cell
...
o Are exogenous and endogenous
substances which are able to cause
immune response of the organism
...
o Antigenicity expresses the strength of
the antigen and its ability to induce a
stronger or weaker immune response
...
o Immunogenicity is the ability of the
antigen to induce immunity, refers to
the infectious agents
...
o Specificity – reveals the structural
particularities of each antigen molecule
...
o Autoantigen is an antigen that is a
normal bodily constituent and against
which the immune system produces
autoantibodies
...
o Xenoantigen is an antigen that occurs in
organisms of more than one species
...
The
ABO/H system
...
The four blood types (A, B, AB,
and O, in which O designates blood that
lacks both antigens) are important in
determining the compatibility of blood
for transfusion
...
If an alloantigen is presented to a
member of the same species that does
not have the alloantigen, it will be
recognized as foreign
...
o The major alloantigen system in
humans, which is based on 3
carbohydrate antigens expressed on red
cells, encoded on chromosome 9q34
...
Type A or AB blood causes an
immune reaction in type Bs
...
Conversely, type O blood has
no A or B antigens – type Os are
universal donors
...
o ABO locus encodes specific
glycosyltransferases that synthesize A
and B antigens on RBCs
...
In RBCs, the
enzyme that synthesizes the H antigen
is encoded by the H locus
...
The ABO locus
is located on chromosome 9, contains 7
o
o
o
•
o
exons
...
Exon 6
contains the deletion that is found in
most O alleles and result in a loss of
enzymatic activity
...
The
deletion causes a frameshift and results
in translation of an almost entirely
different protein that lacks enzymatic
activity
...
Produces the H
antigen on RBCs
...
Enzyme that it catalyzes the production
of H antigen in bodily secretions
...
A&B genes code
for transferase enzymes
...
o It is the second most important blood
group system, after ABO
...
The
commonly used
terms Rh factor, Rh positive and
Rh negative refer to the D antigen only
...
Number of dominant
alleles determines quantity of the
expressed Rhesus antigens
...
o The Rh antigens are expressed since
birth and there are no natural
antibodies against them
...
The mother-fetus
immunological conflict during
pregnancy
...
o
o
•
Often during delivering her child,
erythrocytes of fetus enter the blood
circulation of the mother and immunize
her this way
...
No bad consequnces at first
pregnancy but at second, quantities of
anti-Rh antibodies are very high, they
move though placenta and can harm
fetus
...
Prophylactics of the mother-fetus
immunological conflict is performed
through injecting the mother before
giving birth with a serum containing
anti-Rh antibodies which destroy the
fetal erythrocytes
...
If compatible by the
ABO(H) system, then mother-fetus
conflict is stronger
...
o Also called immunoglobulins, are large
Y-shaped proteins which function to
identify and help remove foreign
antigens or targets such as viruses and
bacteria
...
o Each antibody consists of 4
polypeptides, 2 light L and 2 heavy H,
connected by disulfide bonds between
cysteine remainders
...
o Antibodies are divided into IgM, IgG,
IgA, IgD and IgE
...
o IgG, the most abundant type of
antibody, is found in all body fluids and
protects against bacterial and viral
infections
...
IgM, is a basic antibody that is produced
by B cells
...
It is the first
antibody to appear in response to initial
exposure to an antigen
...
IgE are antibodies produced by the
immune system
...
These
antibodies travel to cells that release
chemicals, causing an allergic reaction
...
Cells of the immune system
...
o T lymphocytes develop in the thymus
...
Th1 form an antigenic
bridge between T and B cells and
secrete Gama interferon and
interleukin
...
o T-effector cells have cytotoxic action (Tkillers) and express the CD8 marker,
which release the perforin protein
which perforates the target cell
...
o T-cells of delayed hypersensitivity (Tdh)
express the CD4 marker, and identify
antigens related with MHC Class II
molecules
...
o T amplificatory cells amplify activity of
the T-cells
...
o B-lymphocytes are a type of white
blood cell of the lymphocyte subtype
...
o B cells express IgD, IgG or IgA receptors
...
o B-memory cells have long life and
ensure fast production of cells/
...
o B2 cells are located in secondary
lymphoid organs and are thymus
dependent B cells
...
o B suppressor cells suppress function of
Te effector cells
...
o MHC (also called human leukocyte
antigens, HLAs) is the mechanism by
which the immune system is able to
differentiate between self and nonself
cells
...
The system is called H2 in mice and HLA
(human lymphocyte antigen) in humans
o The importance of MHC proteins is that
they allow T cells to distinguish self
from non-self
...
Without this presentation, other
o
o
o
A cytoplasmic region, containing
sites for phosphorylation and
binding to cytoskeletal elements
...
A highly conserved alpha 3 to which
CD8 binds to
...
The
beta 2 microglobulin associates
with the alpha chain and helps
maintain the proper conformation
of the molecule
...
H2 system of the mouse
...
Class 1 MHC molecules are composed
of two chains, a long alpha and a short
beta chain called beta 2 microglobulin
...
Both chains
have 4 regions:
A cytoplasmic region, containing
sites for phosphorylation and
binding to cytoskeletal elements
...
A highly conserved alpha 2 domain
and Beta 2 domain to which CD4
binds to
...
o
o
o
o
•
Each MHC molecule has only one
binding site, different peptides bind
only one at a time
...
MHC molecules are membrane bound;
recognition by T cells requires cell to
cell contact
...
A peptide must associate with a given
MHC of that individual – first level of
control
...
Cytokines especially interferon gamma,
increase the level of expression of MHC
...
Transplantation immunology
...
Host versus
Graft (HvGR) and Graft versus Host
Reaction (GvHR)
...
o Transplantation is called the act of
engrafting of tissues or organs
...
Organs and/or tissues that
are transplanted within the same
person's body are called autografts
...
T lymphocytes of recipient
activated
...
Local inflammatory
reaction occurs, thrombi are formed
which block the blood vessels and
necrosis occurs, the graft is rejected,
o
Specific – these suppress immune
reactivity selectively such as antilymphocyte serums, complement
inhibitors
Non-specific – physical factors
(ionizing radiation), chemical
factors (corticosteroids, antibiotics),
biological factors (extract from
Japanese mushrooms, etc)
GvHR occurs at transplantation of
lymphoid cells capable of immune
response against antigens of the
recipients
...
Growth retardation
...
Occurs at allo transplantation of
marrow to an individual with
suppressed immune reactivity
(radiation diease)
•
The tolerance to foreign antigens
...
o Immune tolerance is the failure to
mount an immune response to an
antigen
...
This is the failure (a
good thing) to attack the body's own
proteins and other antigens
...
o Natural immune tolerance occurs
during the embryonic development
when the individual’s immune system
gets to know its own antigens and thus
identifies foreign antigens as its own;
hence during post embryo life it does
not react against them
...
In the development of
induced immune tolerance, the antigen
remains in the blood serum in high
concentration
...
Some portions of the immune
system itself have
immunosuppressive effects on other
parts of the immune system, and
immunosuppression may occur as an
adverse reaction to treatment of other
conditions
...
As a result, the organism
becomes susceptive to infections and
tumor formations
...
o The study of the genesis or
development of the human race
...
o Homo sapiens belong to the order or
primates
...
Parapithecus
appeared 28 million years ago
...
o Pliopithecus and Dryopithecus,
ancestors of today’s anthropoid apes,
appeared in Africa
...
The head has a balanced
position above the spine, leads to a
decrease of the size of the cervical
vertebrae and of powerful muscles at
the neck
...
The
forehead bone straightened
...
Biological and social nature of man
...
o The hard living conditions and struggle
for survival has led to the primitive man
to hunting and other types of work,
thus to the rise of human society
...
o Development of oral communication to
articulate speech
...
Human behavior is
determined by consciousness, will,
feelings and knowledge
...
Man acquired
power over natural forces due to its
social evolution
...
o Racial differentiation
Skin colour us determined by the
quantity of melanin in epithelial
cells
Form of the hair, hair of individuals
of the Caucasian and the Mongoloid
races has a round section; this
determines the straight form of the
hair
...
Form of the skull-head index, form
of facial skull, form and size of the
nose, form and size of lips
...
•
Biology and genetics of populations
...
Hardy Weinberg law
...
:Glossary
...
o Allele frequency or gene frequency, is
the relative frequency of
an allele (variant of a gene) at a
particular locus in a population,
expressed as a fraction or percentage
...
Show the genetic
diversity of a species population or
equivalently the richness of its gene
pool
...
o Population genetics is the study
of genetic variation within populations,
and involves the examination and
modelling of changes in the frequencies
of genes and alleles in populations over
space and time
...
o Alternative forms of a given gene are
called alleles, and they can be dominant
or recessive
...
Heterozygous means
having one each of two different alleles
...
o The genotype is the part (DNA
sequence) of the genetic makeup of a
o
o
•
cell, and therefore of an organism or
individual, which determines a specific
characteristic (phenotype) of that
cell/organism/individual
...
The Hardy–Weinberg principle, also
known as the Hardy–Weinberg
equilibrium, model, theorem, or law,
states that allele and genotype
frequencies in a population will remain
constant from generation to generation
in the absence of other evolutionary
influences
...
Factors affecting
...
o If an infinitely large, random mating
population is free from outside
evolutionary forces (ie mutation,
migration and natural selection) then
the gene frequency will not change over
time and the frequencies in the next
generation will be p2 for the AA
genotype, 2pq for the Aa genotype and
q2 for the aa genotype
...
o Random mating is a factor assumed in
the Hardy-Weinberg principle and is
distinct from lack of natural selection: in
viability selection for instance, selection
occurs before mating
...
Migration into or out of a
population may be responsible for a
marked change in allele frequencies
...
Hardy-Weinberg Principle
of Equilibrium
...
Ultimately,
the Hardy-Weinberg principle models a
population without evolution under the
following conditions: no mutations
...
Since each individual carries
two alleles per gene (Y or y), we can
predict the frequencies of these
genotypes with a chi square
...