Notesale: Turn your study into money

Document Preview

Extracts from the notes are below, to see the PDF you'll receive please use the links above

---

Topic 1: Lifestyle, Health and Risk
Open circulation system - a simple heart pumps blood into interstitial spaces/cavities where
diffusion occurs, the blood returns to the heart through small valves
Closed circulation system - blood vessels allow higher pressures and is more efficient (becomes
capillaries), valves ensure single direction of flow, supports larger active animals
Single circulatory system - heat pumps deoxygenated blood to gills, gaseous exchange occurs in
gills, blood flows around body then returns to heart (only flows through heart once)
Double circulatory system - right ventricle pumps blood to lungs, left ventricle pumps blood around
body then back to heart (flows through heart twice)
Animals and larger organisms have a double circulatory system to overcome the shortcomings of a
simple/single circulatory system
...
A double circulation system means blood (containing oxygen and food) travels
around the whole body constantly at a high pressure to maintain a metabolic rate
...

Properties of water that make it ideal as a solvent in transport:
Dipolar nature - unevenly distributed charge (H end slightly positive, O end slightly negative),
hydrogen bonding between charges hold water molecules together (allowing cohesion and
attraction and increasing boiling point)
Solubility - ionic substances (e
...
NaCl) and polar molecules (with polar groups e
...
-OH) dissolve
easily as the ions are attracted to the charged ends of the water molecule
High specific heat capacity - due to strong hydrogen bonds means a lot of energy is required to
heat water, beneficial for preventing rapid temperature change in body (homeostasis maintained)
and aquatic environments
High boiling point - due to number of hydrogen bonds and the energy required to break them
Artery

Vein

Capillary

no valves

valves

no valves

narrow lumen, thick wall

large lumen, thin wall

narrow lumen, thin wall

more collagen, smooth muscle
and elastic fibres

less collage, smooth muscle and
elastic fibres

no collagen, smooth muscle or
elastic fibres

maintain high pressure

allow flow back to heart

maintain high pressure to reach
further parts of body

Cardiac cycle:
Atrial systole - atria have been filled so contract, atrioventricular valves open, ventricles are relaxed
so blood flows in
Ventricular systole - atrioventricular valves close, semilunar valves open, atria relax, ventricles
contract, blood flows out of heart
Diastole - all valves close, atria and ventricles relax, blood flows into atria

Atherosclerosis:
Endothelial dysfunction - damage cause by high blood pressure or smoking
Inflammatory response - atheroma of white blood cells and cholesterol forms
Plaque formation - calcium salts and fibrous tissue create calcified plaque, loss of elasticity
Raised blood pressure - lumen narrows so blood pressure increases
Dangerous positive feedback - response causes elevated blood pressure which can lead to
another artery wall being damaged
Blood clotting:
Platelet plug - platelets stick to damaged wall and each other
Thromboplastin release - from damaged tissue

Prothrombin converted to thrombin - by thromboplastin catalyst, Ca2+ and vitamin k
Fibrinogen converted to fibrin - by thrombin catalyst
Fibrin mesh traps platelets and red blood cells to form a clot
Correlation - one event has a relationship to another event but does not cause it
Causation - one event is the result of the occurrence of the other event
Design of studies:
Sample selection - sample should include all relevant persons (e
...
male and female, all ages)
Sample size - sample should be large enough to be valid
1
...
16
Ethics of invertebrate use - less developed nervous system, short life anyway, no consent, no way
to know if they are in pain
CVD Treatments:
Antihypertensives - reduce blood pressure, cause dizziness and dehydration
Statins - inhibit LDL cholesterol production, cause tiredness and vomiting
Anticoagulants - reduce clotting by inhibiting vitamin k production, risk of bleeding
Platelet Inhibitors - reduce clotting by inhibiting platelet production, bleeding in gastrointestinal tract

Topic 2: Genes and Health
Gas exchange surfaces:
Good blood supply - enables oxygen to be carried away quickly and food to be replaced quickly,
maintains the concentration gradient
Large SA/V ratio - there is a larger surface for diffusion to occur
Thickness of surface - thin surfaces allow quicker diffusion
Concentration gradient - higher concentration gradient means faster diffusion
Fick’s Law:

Lung structure:
Blood supply - pulmonary circulation system
Large SA/V ratio - alveoli
Thickness of surface - thin cell walls (of capillaries/alveoli)
Concentration gradient - between alveolar air and blood
Cell membranes:
Phospholipid - hydrophilic phosphate head, hydrophobic fatty acid tails
Intrinsic protein - proteins that span the whole bilayer (carrier or channel)
Extrinsic protein - proteins that occupy only one side of the bilayer
Extrinsic molecules - glycoprotein, glycolipids, cholesterol
Fluid-Mosaic model - bilayer controls entering/exiting substances, dense phospholipid heads and
lighter tails, extrinsic proteins dissociated easily, intrinsic proteins made of hydrophilic and
hydrophobic amino acids
Osmosis - net movement of water particles through a partially permeable membrane from an area
of high concentration to low concentration
Passive transport:
Diffusion - movement of particles from an area of high concentration to low concentration, requiring
no energy (occurs through bilayer for hydrophobic, small and non polar molecules)
Facilitated diffusion - movement of particles from an area of high concentration to low
concentration gradient through channel or carrier protein, requiring no energy (transports
hydrophilic, large and polar molecules through membrane)
Channel protein - molecule is transported through, passive transport

Active transport - movement of particles from an area of high concentration to low concentration,
requires ATP energy
Carrier protein - molecule binds to protein, protein undergoes transformational change, molecule is
released, active transport
Endocytosis - bulk transport, vesicles are treated from membrane
Exocytosis - bulk transport, vesicles fuse with membrane
Mononucleotides - pentose deoxyribose/ribose linked to phosphate and nitrogenous base
(thymine, uracil, cytosine, adenine, guanine)
Polynucleotides - mono nucleotides linked through condensation reactions
RNA - ribose, uracil, no oxygen
DNA - deoxyribose, thymine, oxygen
Pyrimidine - two ring structure, cytosine and
thymine
Purine - one ring structure, adenine and
guanine
Complementary base pairing with hydrogen
bonds

Protein synthesis:
Transcription:
DNA helices unwinds and unzips the DNA strand
RNA polymerase binds to start of gene
mRNA created from template (antisense) strand (thymine becomes uracil)
mRNA leaves nucleus though nuclear pore and goes to ribosome in cytoplasm
DNA strands wound back up by DNA helices
Translation:
mRNA goes between ribosome and subunit
If codon matches anticodon on tRNA, amino acid on tRNA joins amino acid chain on ribosome
Start and stop codons identify the start and end of the amino acids
Protein leaves cell by exocytosis
Genetic code:
Triplet - each amino acid is made of three bases
Non-overlapping - each codon is read only once, start and stop codons identify the beginning and
end of chains
Degenerate - there is more than one codon for an amino acid
Gene - sequence of bases on a DNA molecule that codes for a sequence of amino acids in a
polypeptide chain

Amino Acids:
Dipeptides and polypeptides are formed by condensation
reactions of peptides, forming peptide bonds
Primary structure - sequence of amino acids
Secondary structure - spatial arrangement of atoms due to
R group interactions, beta pleated sheet (H bonds and
antiparallel chains), alpha helix (H bonds and double
stranded helix)
Tertiary structure - bent/folded chain becomes a 3D
globular shape stabilised by bonds (ionic, covalent and
disulphide bridges)
Quaternary structure - proteins with multiple polypeptide chains form globular or fibrous structures
stabilised by H bonds and London forces
Globular protein - folded chains, 3D shape linked to function, soluble, such as haemoglobin (four
chains each with a haem group that can bind to iron)
Fibrous protein - coiled chains that can be cross linked, insoluble, such as collagen (uses
crosslinks to be a stable structure)
Enzymes:
Primary structure determines bonds and linkages that create an active site specific to a certain
substrate
Enzymes bing to substrates to form an enzyme-substrate complex
Lock and key - enzyme is specific to only on substrate
Induced fit - enzyme is flexible and can change shape of active site slightly
Enzymes are biological catalysts that reduce activation energy
Intracellular - catalyse reactions inside cells
Extracellular - produced by cells, catalyse reactions outside of cells
DNA replication:
DNA polymerase links adjacent nucleotides after they pair with complementary bases
Conservative - DNA completely copied, one molecule with two parent strands, one molecule with
two new strands
Fragmentary - all strands made up of mixture of parent and new nucleotides
Semi-conservative - each molecule contains one parent and one new strand
Meselson and Stahl:
Grow bacteria with N15 and transfer to N14, kills cells and extract DNA then place in centrifuge
Under UV light, first generation are all in the middle, second generation middle and top, third
generation middle and more top
This proves semi-conservative as there is no ‘heavy’ (so not conservative), mixture of medium and
light (fragmentary would make only medium)
Mutations:
Errors in DNA replication can lead to an inferior/incorrect protein being synthesised
Mutations can be caused by x-rays, ionising radiation and chemicals
Point - changes in individual gene due to miscopying a nucleotide(s) (deletion, insertion,
substitution)
Chromosomal - entire chromosome is lost or repeated during cell division (deletion, duplication,
inversion, translocation)
CF can be caused by deletion of three nucleotides
Allele - variation of a gene caused by mutation
Genotype - the genetic make up of an organism determined by their DNA
Phenotype - the physical appearance of an organism determined by their DNA
Recessive - requires two of the same allele in order to be expressed
Dominant - requires one of the alleles to be expressed

Incomplete Dominance - a heterozygous organism with one dominant and one receive allele where
the dominant allele is only partially expressed
Homozygote - the two alleles are identical
Heterozygote - the two alleles are non-identical
Cystic fibrosis:
Gas exchange - mucus build up increases diffusion barrier/distance, lowers concentration gradient
Digestive system - mucus build up in stomach decreased pH of stomach acid, makes conditions
less favourable for digestive enzymes
Reproductive system - development of vas deferens in men affected so sperm is not delivered for
ejaculation, cervical mucus causes decreased chance of fertilisation
Genetic Screening:
Identification of carriers - by screening patients, carriers of genetic diseases can be identified and
probabilities of children getting that disease can be calculated
Prenatal testing:
Amniocentesis - amniotic fluid removed using needle, foetal and red blood cells tested, 1% chance
of spontaneous abortion, gender can be determined, later results, test carried out late in pregnancy
CVS - sample from placenta taken via uterus, Y (male) chromosomes inactivated so diseases from
father not identified, high risk of spontaneous abortion, earlier results, test carried out earlier in
pregnancy



---