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Unit 15

Unit 15

Cocci bacteria shape start from the size of diameter 500-1000
nanometres
...
Spirilla
are long and measure from 1 to over 100, 000 nanometres
...
This shows that bacteria cells are larger then viruses
...
They are
small loops of genetic material/DNA
...
The transfer
of plasmids to another cell is known as bacterial sex
...
As pointed out before, the genes in plasmids
provide the bacteria cell with genetic advantages such as antibiotic resistance
...
It contains
dissolved substances
...
There aren’t any organelles in a prokaryotic cell so chromosomal
DNA which isn’t an organelle floats in the cytoplasm of a prokaryotic cell
...
All
cellular components are suspended in the cytoplasm
...
The cytoskeleton is
the internal framework of the cell
...

Many chemical reactions occur in the cytoplasm
...


• Flagellum: This is swished for the movement of the cell (propulsion)
...
Allows the bacterial cell to move
...


• Cell Wall: The cell wall comprises of sugars and is usually rigid
...
The
cell wall surrounds the cell membrane of the bacterial cell
...
The cell wall has a specific role as a filtering mechanism
...
The cell wall
in other words acts as a pressure vessel
...
Prevents the bursting from osmotic pressure, which is called lysis
...

Mesosomes play a role in cell wall formation
...
It also has the role of increasing
the surface area of the plasma membrane of the cell, which aids the cell with
increase in the efficiency of respiration
...
The cell
membrane surrounds the cytoplasm of the cell
...
The cell membrane is a highly
selective barrier of the cell as it prevents the diffusion of materials into and out of the
bacterial cell
...
It is selectively permeable to ions and organic molecules
...
Separates the interior to the
surroundings/environment
...
It is a
protective coating of the Bacteria cell
...
It is a Polysaccharide layer that lies on the outside of the bacterial cell
envelope
...

They are rigid and anchor to the surface
...
It is used to help in the
attachment of bacterium to surfaces
...
Site for protein synthesis
...
This
doesn’t make the purpose different
...
Ribosomes comprise of two subunits,
which are a large subunit and a small subunit
...
The small subunit has the role to bind onto a specific mRNA sequence
...


• Nucleoid: The nucleoid is the area of the bacterial cell, which contains most of the
genetic material of the cell
...

The nucleoid may contain RNA, proteins and enzymes used for cellular processes
...
The nucleoid is sort of a nucleus of a bacterial cell
but without the nuclear membrane
...






Unit 15

Bacterial shapes:
This is a Cocci Shaped bacteria
dividing into two
...
Some named examples are
Staphylococcus and Streptococcus
...
It is an
oval with pilus on its surface but doesn’t
always have pilus on its surface
...

Named examples for this shape are
Clostridium and Streptobacillus
...
As seen in the image, it has a
spiral/coil/helical shape
...

Consists of open coils in the
diagram
...
The genetic material in other words
is held in the nucleus
...
Ribosome synthesis occurs in the nucleolus of the nucleus
...
The nucleus comprises
of chromosomes, which again comprise of DNA
...
Function is to control gene expression
...
The nucleus holds the instructions of the making of proteins
...


• Centriole: This part of the cell is essential for cell reproduction
...
Centrioles help with cell division as they



help with the formation of the spindle fibres, which separate chromosomes
during mitosis/cell division
...


• Nuclear envelope/membrane: This is a two-layered lipid bilayer



membrane, which consists of pores where mRNA can leave from into the
cytoplasm
...
This lipid bilayer surrounds the nucleolus and genetic material/DNA(it
encloses the nucleus)
...
The nuclear membrane encloses the

• Nuclear pore: The nuclear pore consists of the transportation of molecules



between the cell nucleus and cytoplasm
...
The nuclear pore is a protein-lined channel in the
nuclear membrane
...


• Plasma membrane: This is a flexible membrane, which is a phospholipid



bilayer, which controls the movement of waters, chemicals and wastes from the
cell
...
The phospholipid
bilayer comprises of both hydrophilic and hydrophobic components
...
This means that the cells
components are separated from the environment whilst vital chemicals and
nutrients needed for survival is able to be taken up by the cell
...
Separates the interior to the
surroundings/environment
...



Unit 15

• Ribosome: Ribosomes are the sites of protein synthesis; are involved with the



manufacturing of proteins
...
Both in
eukaryotic and prokaryotic cells, the ribosomes are the sites of protein synthesis
...
These subunits compose of rRNA as well as protein
...
The large subunit is then
present to form a complete ribosome
...
It
transfers RNA for the synthesis of polypeptides/proteins
...


• Cytoplasm: The cytoplasm is a complex fluid within the cell
...
It is a jelly-like fluid, which organelles such as the nucleus
float
...

All cellular components are suspended in the cytoplasm
...
The cytoskeleton is
the internal framework of the cell
...

Many chemical reactions occur in the cytoplasm
...


• Golgi body: The process and packaging of proteins occurs in this part of the
eukaryotic cell
...
Most are used to build the
cell but some are exported through the plasma membrane for use elsewhere
...
It is found in the
cytoplasm of the cell
...
The
main functions of the Golgi body are sorting, modifying and the packaging of
proteins to ready them for secretion
...
It also creates lysosomes
...
They are sacs
that contain a fluid containing this enzyme called hydrolase enzymes
...
This can be seem as the cells
stomach


Unit 15
• Mitochondria: The mitochondria are where biochemical processes
of energy production occur/respiration occur
...
The mitochondria comprises of two
membranes; the inner membrane and outer membrane
...
The inner membrane
is a folded membrane, which is folded many times
...
Mitochondria
contain a fluid inside of it called matrix
...
An example is glucose
...
Cellular respiration is a
process, which occurs in the mitochondria
...
In other words, this is like the digestive
system of the cell, which provides the cell with its needed energy
...
Ribosomes can be found studded on the
rough endoplasmic reticulum, which makes the endoplasmic
reticulum rough
...
Rough endoplasmic reticulum, also known as RER, are
folded membranes extending throughout the cell
...
RER is also
known for the site where much protein manufacturing occurs
...
RER is attached to the
nuclear envelope of the nucleus, which allows and gives ease to the
movement of molecules though both of their membranes
...

The RER is a site of protein and lipid synthesis
...
SER is known as
the main location for the metabolism of fats
...
It is named smooth endoplasmic reticulum
because it hasn’t got ribosomes studded on it
...
It has the role of making cellular products such as lipids
and hormones
...


Unit 15

Viruses consist of around only 100-300 genes
...
This means they cannot reproduce by themselves and
cannot process nutrients
...
This results in the death of
the host cell
...


The virus penetrates the host cell; viral RNA moves into the host cells
nucleus; the viral RNA inserts itself into the nucleic acid, which
results in the replication of the viral RNA, and this moves to the cells
surface
...
The host uses the raw material as well as enzymes to do
this
...
Nucleic acid strands and protein coat subunits join to
form new virus particles
...
Part of the membrane is used as the outer protective
envelope
...


Viruses are very important and are the smallest of all microbes
...
They can survive
in freezing, boiling and chemical attacks
...
They are classified as
obligate parasites, which means that they need a host cell to replicate
themselves
...
This is a reason why
viruses cant be killed because they are non-living
...
Doctors need to find a way to inactivate viruses
...
Doctors are able to know how a
virus develops in a person
...
Viruses are used to investigate cells functions
...
and immunology
...
Viruses may be used for a number of therapies
...
Viruses may have an important use in

Unit 15
warfare, weapons and nanotechnology
...
Viruses are said to be non-living, as they don’t
have the properties that living organisms comprise of
...
Viruses also
don’t use the typical cell-division approach to replication
...


Cocci bacteria shape start from the size of diameter 500-1000
nanometres
...
Spirilla
are long and measure from 1 to over 100, 000 nanometres
...
This shows that bacteria cells are larger then viruses
...
Where DNA is
stored/ contains double stranded viral
DNA
...
The
protein coat is like the cell membrane of
the head
...


•

Helical tail: this is what connects to the
viruses baseplate; it contains retracting
cell-puncturing device for the aid when
invading and puncturing host cells and it
also has a role to hold and protect the
viruses RNA and DNA/Viral DNA
...

•

Collar/neck: connects the head to the tail
...




• Leg/tail fibre: sensors on the legs/tail

fibres recognises binding sites, which are
situated on the host cell surface
...
They are
required for the attachment of the phage
to the cell surface
...


•

Attach to host for the RNA and DNA of
virus (viral DNA) to get injected into the
host
...


•

Base plate: holds the helical tail as well as
the legs together
...
There are thousands of different virus shapes and
sizes
...

Viruses are classified on how their appearance such as their
size, shape, symmetry and groups of diseases they cause
...
Below are the main known shapes
...
Examples of viruses with this shape of virus are
myxoviruses and paramyxoviruses
...
Examples of viruses with these
shapes of virus are herpes virus and adenoviruses
...
These types of viruses only attack bacteria,
which in health terms are very important when they attack
pathogenic bacteria inside the human body
...



Below are images of different virus sizes with
different viruses
...
The organelles may have certain structures and
features, which provide ease for theses organelles to perform their
functions
...
Examples of hormones that are produced by eukaryotic
cell are insulin, which are produced in Beta cells and Glucagon,
which is produced by Alpha cells
...
Insulin raises glucose
concentration and glucagon lowers glucose concentration
...

In eukaryotic cells the labour or the work of the cell is divided
between the organelles
...
It starts
of with the nucleus
...
The nucleus is where the DNA for
the instructions for making the glucagon is found in the form of a
gene
...
The
instruction for making the specific Glucagon is taken from a DNA
molecule situated in the nucleus
...

The mRNA now attaches to a ribosome where the protein is
assembled by amino acids using the instructions from the mRNA
...
The ribosomes are
attached/found on the RER/rough endoplasmic reticulum organelle
of the cell
...
The glucagon molecule is now pinched off in
vesicles
...
The secretion of Glucagon as stated
earlier will lower the glucose concentration in the bloodstream
...
Escherichia coli uses aerobic respiration through
their membrane, which is a similar, process that mitochondrion do
...
Aerobic respiration is
what bacterial cells and mitochondrion have in common
...
Mitochondrion
produces its energy by generating a gradient of hydrogen ions
across a membrane
...

A bacterial cell has an inner and outer membrane just like a
mitochondrion
...
This is known as a periplasmic
space
...
Light energy is captured
and protons are pumped out of the cytoplasm to the periplasmic
space
...
Not only a proton
gradient but also ATP
...
The
bacteria may absorb nutrients from where they live such as some
bacteria, which absorb nutrients from the gut from food you have
consumed
...
The carrier molecules then transfer these hydrogen
atoms to the inner cell membrane of the bacterial cell where the
electron transport chain strips the electrons from the hydrogen
atoms
...
The electrons provide
energy
...
They are rigid and anchor to the surface
...
It is used to help in the attachment of bacterium to
surfaces
...




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