Topic 1 and Topic 2 exam questions Flashcards
- ADD TO IT BY ADDING ABT ACE INHIBITORS ECT
function and structure of LDL (low density lipoprotein)
- saturated fat, protein and cholesterol attached to it
- moves cholesterol from liver to bloodstream
- binds to receptor sites on cell membranes so they can be taken up by cells needed and removes the cholesterol from blood
- high levels of LDL leads to blockage of membrane receptors -> blood cholesterol levels rise
function and structure of HDL (high density lipoproteins)
- unsaturated fat, protein and cholesterol
- transport cholesterol from body tissues to liver, where its broken down
- reduces blood cholesterol + removes fatty plaques that form during atherosclerosis.
what are the two storage polysaccharides and why are they this?
glycogen and starch
- insoluble so have no osmotic effect and they are compact
structure of starch
- amylose: unbranched. 1,4 glycosidic bonds between alpha glucose. helix shape so more compact for storage
- amylopectin: branched. 1,4 and 1,6 glycosidic bonds between alpha glucose. the branches = more terminal gluose = easier to be hydrolysed for use during cellular respiration OR added for storage.
structure of glycogen
- 1,4 and 1,6 glycosidic bonds between alpha glucose
- branched. more branched than amylopectin
- branches = more terminal glucose molecules can be added/removed by hydrolysis
- allows for quick release/storage of glucose = meets needs of cells as animal cells are very metabolically active.
what are the different types of mutations
- deletion
- insertion
- substitution
- duplication
- inversion
what is the result of an insertion
- nucleotide randomly inserted into DNA sequence
- changes amino acid tht would have been coded for by original base triplet as it creates a new diff triplet of bases
- would cause frameshift mutation -> every triplet downstream of the insertion is also changed
- could dramatically change amino acid sequence produced from gene and therefore ability of polypeptide to function
what is result of a deletion mutation
- nucleotide randomly deleted from DNA sequence
- changes triplet in which deletion has occurred and also every grp of 3 bases downstream on deletion (frameshift mutation)
- could dramatically change the amino acid sequence produced and therefore the ability of the polypeptide to function
what is the result of a substitution mutation
when base in dna sequence randomly swapped for different base
- might not alter amino acid at all due to degenerate nature of genetic code (when a single amino acid might be coded for by more than one tripley)
- missense mutation causing it to alter a single amino acid
- nonsense mutation creating a premature stop codon, so polypeptide chain is incomplete, affecting final protein structure and function,
how does change in primary structure cause difficulties in a way an enzyme works
- different primary structure results in a different
sequence of amino acids - this results in change in R groups which changes the {folding / bonding /
secondary structure / tertiary structure } - changing { shape / charge } of the active site prevents
substrate from being able to bind - which means that enzyme no longer can catalyse reaction
what does secondary structure refer to
- relates to hydrogen bonds forming between the amino group and the carboxyl group (the ‘protein backbone’)
what does tertiary structure refer to
- The way that the whole protein folds to make a three dimensional structure.
bonds that form in the tertiary structure
- hydrogen bonds
- ionic bonds
- disulphide bonds (between cysteine amino acids)
- weak hydrophobic interactions between non-polar R groups
quaternary structure
- proteins that have more than one polypeptide chain
- same bonds as in tertiary structure are involved
structure of globular proteins
- compact
- sort of spherical
- non-polar R groups are faced towards centre of protein and polar face outside the protein
- they have specific shapes due to the interactions between the r groups
- some are conjugated proteins with a prosthetic grp
what are prosthetic groups
- permanent non protein part of a protein molecule
function of globular proteins
orientation of R groups means that they are generally soluble in water which means they can be easily transported around organisms and be involved in metabolic reactions
eg:
- enzymes, antibodies, haemoglobin and myoglobin
structure and function of haemoglobin
- globular protein
- oxygen transport molecule
- made of 4 polypeptide chains that each have an iron containing haem group
- oxygen attaches to the iron with the haem group
- its a conjugated protein as its attached to another chemical group
structure of fibrous protein
long chains, do not fold up into a ball shape.
- little to no tertiary structure
- highly repetitive number of amino acid sequences which creates very organised structures
- lots of hydrophobic R groups so insoluble in water
- strong as well, so good for structure
eg: keratin, elastin, collagen
function of fibrous proteins
- they are strong, and insoluble so good for structural molecules.
structure and function of collagen
- fibrous protein
- three polypeptide chains wind around each other and form rope-like strands held together by hydrogen bonds between chains
- each strand cross-links each other to provide tremendous strength.
what are the three ways in which genetic testing can be used
- confirm diagnosis of a certain genetic disease
- to identify carriers so that they can detect abnormal alleles, helping to make informed decision about having children
- for testing embryos
amniocentesis
- insert needle into amniotic fluid
- collect fetal cells that have fallen off foetus and placenta
- carried out around 15-17 weeks of pregnancy and 1% risk of miscarriage
what is chorionic villus sampling?
- remove small sample of placental tissue (which includes cells of embryo or foetus) through abdomen or through vagina
- can be carried out between 8-12 weeks as no need to wait for amniotic fluid to develop
- riskier than amniocentesis.
what is non-invasive prenatal diagnosis
- analyses DNA fragments in mother’s blood plasma during pregnancy
- 10-20% of cell free dna would be from embryo
- cell free fetal dna can be detectable at about 4-5 weeks but the levels are too low to be analysed at this stage. its more likely to collect after 7-9 weeks
blood clotting process (CLOTTING CASCADE)
- platelets come into contact with damaged blood vessel
- platelets change shape from flattened disks to spheres with long projections
- they stick to each other, form PLATELET PLUG
- release thromboplastin and then calcium ions with vitamin K, causes prothrombin to change to thrombin.
- this causes soluble fibrinogen to form into insoluble fibrin
- a mesh of fibrin forms, trapping more platelets and rbc to form a clot.
how atheroma forms + atherosclerosis develops
- damage to endothelium -> either due to high bp/toxins from cigarette smoke
- inflammatory response. wbc leave blood vessel, move to artery wall and accumilate in damaged area.
- these cause chemicals from blood to accumilate (cholesterol)
- build up of cholesterol and lipids clumping together causes an atheroma
- calcium salts + fibrous tissues also build up leading to plaque formation
- causes artery to lose elasticity and harden
- hardening of arteries and narrowing of them both further increase the BP
integral membrane proteins
- proteins embedded into the membrane
- channel or carrier proteins
peripheral protein
found either on outer or inner surface of the membrane
- not embedded within membrane
function of cholesterol
regulates membrane fluidity:
- increases fluidity at low temp -> stops becoming too rigid (the cholesterol stops the phospholipid tails from packing too close together)
- decreases fluidity at higher temp by cholesterol molecules binding to hydrophobic tails, stabilising + causing to pack more closely
also increases mechanical strength and stability of membranes, as w/o it membranes would break down + cells would burst.
define gene
sequence of bases on DNA molecule that codes for sequence of amino acids in polypeptide chain
define allele
version or form of a gene
define incomplete dominance
when neither allele is dominant and resulting phenotype is a mix - white and red snap dragon crossing = pink
define phenotype
observable characteristics of an organism
define mass transport
bulk transport of substances to all parts of an organism using mass flow
why do single celled organisms not need a specialised gas exchange surface?
- dont need because they rely on diffusion to take in oxygen/remove waste products
- they can rely on this method because they usually have a large surface area to volume ratio. and they have short diffusion distances
explain how structure of human lungs enables rapid gas exchange
- many alveoli provide a large surface area (1)
- {alveoli/capillaries} have walls that are one cell thick providing a short distance for diffusion (1)
- high concentration gradient maintained by {circulation / ventilation} (1)
- extensive capillary network around alveoli provides large surface area for gas exchange
explain why water is a good solvent
- it is a polar molecule
- surrounds other polar molecules, forming hydrogen bonds and allowing them to dissolve
how does glucose enter muscle cells through the cell membrane
- it is a large molecule, so by carrier proteins via facilitated diffusion, from high concentration to low concentration
compare and contrast molecular structures of globular and fibrous proteins
- both are chains of amino acids joined by peptide bonds (1)
- both contain named bonds (holding molecule in its three dimensional shape) (1)
- globular proteins have hydrophilic groups on the outside whereas fibrous proteins have hydrophobic groups on the outside (1)
- globular have tertiary or quaternary structures whereas fibrous have little or no tertiary structure (1)
- globular are folded into compact shapes whereas fibrous have long chains (1)
describe formation of glycogen from glucose
- condensation reaction (releases water)
- forms 1,4 and 1,6 glycosidic bonds
describe how structure of glycogen is related to it’s function as a storage molecule
- compact so more can be stored
- its a branched molecule so allows for more rapid hydrolysis
people with cystic fibrosis require higher energy than people without cystic fibrosis. theyre also more likely to develop problems in pancreas.
men with cystic fibrosis are less likely to be able to release sperm
discuss why a person with cystic fibrosis could have these symptoms
- they have a gene mutation causing a non-functioning CFTR protein channel
- the chloride ions cannot move out of the epithelial cells
- so the accumulation of sodium and chloride ions in cell causes water to move out of mucus by osmosis
- this means that the mucus is thicker and sticker than normal
- for the pancreas, this would mean that enzymes cannot enter the intestine as the pancreatic duct is blocked with the sticky mucus.
- means that substances cannot be broken down in small intestine + absorbed into blood
- the pancreatic enzymes trapped behind mucus also damage pancreatic cells, such as those producing insulin
- also forms cysts in pancreas
- means that less insulin produced, so less glucose taken into the cells
- sperm cannot leave the testes as sperm ducts are blocked with mucus so cannot pass through and less able to release sperm
explain how structure of artery wall is adapted to both withstand and maintain high blood pressure
- lots of collagen in walls which provides strength to withstand pressure
- the muscles contract which allows the constriction of arteries for pressure
- elastic fibres allow for stretch and recoil (so lumen can return to original size)
describe structure of DNA nucleotide
- pentose sugar - deoxyribose
- phosphate joined at carbon 5
- nitrogenous base joined at carbon 1
- carbon 3 joins to next phosphate group via condensation reactions, forming a phosphodiester bond
why are enzymes biological catalysts
they are proteins which reduce the activation energy of biological reactions (can also say speed up rate of reaction)
compare and contrast the molecular structure of collagen and an enzyme
- both are chains of amino acids joined by peptide bonds
- both have bonds involved in holding molecule in 3d shape
- enzyme is folded into compact structure (lots of tertiary structure) whereas collagen has long, parallel chains with cross links
- enzyme has an active site, but collagen does not
- enzyme has some hydrophillic groups/amino acids on the surface (as its globular protein) whereas collagen does not
what happens when theres excess water in mucus
- detected by the epithelial cells
- carrier proteins in basal membrane pump sodium ions out the cell
- decreases sodium ion conc in cells, so theres a concentration gradient across the apical membrane
- sodium ions in mucus diffuse into the cell from the apical membrane into the epithelial cell (facilitated diffusion through the ENaC)
- raises conc of Na ions in the basal membrane = potential difference between tissue fluid and apical membrane mucus
- electrical gradient is created which causes negatively charged chloride ions to diffuse out mucus into tissue fluid
- this increases ion conc in tissue fluid = water drawn into tissue fluid from the epithelial cell by osmosis, then water conc in cell drops + solute conc increases
- this means water drawn out of mucus into the epithelial cells by osmosis
what happens when theres not enough water in mucus - healthy person
- chloride ions are pumped from the basal membrane into the cell
- creates concentration gradient in apical membrane with the concentration of chloride ions being higher in cell than apical membrane
- chloride ion imbalance causes the CFTR protein channel to open so the chloride ions can now diffuse into the apical membrane, into the mucus
- opening of CFTR channel blocks the ENaC channel. creates a potential difference and electrical gradient between mucus and tissue fluid
- sodium ions diffuse out tissue fluid and move down electrical gradient, into mucus
- elevated salt conc in mucus draws water out of epithelial cells by osmosis till solutions are isotonic
explain why cystic fibrosis affects rate of oxygen uptake in lungs
- thick, sticky mucus accumilates
- this accumilation = canot be moved by cilia
- restricts air flow through bronchioles
- also increases diffusion distance + reduces surface area for gas exchange in alveoli
Explain why thicker mucus is produced if the functioning of the CFTR channel protein is impaired.
- chloride ions canot leave the cell and enter mucus though cftr channel proteins
- sodium ions do not move out of cells + into mucus
- therefore water moves into the cells + out of mucus by osmosis
explain why different mutations in CFTR gene can lead to differences in severity of the symptoms of cystic fibrosis
- diff mutations will have diff effects on protein produced
- chloride ion transport is affected by extent of changes to CFTR protein
- this varies the stickines/thickness of the mucus
As levels of activity increase, the heart can respond to the changing demand for oxygen.
During the cardiac cycle there are pressure changes in the chambers of the heart.
Explain how pressure differences in the heart ensure efficient pumping of the blood into the arteries.
- pressure increases in ventricles
- greature pressure in ventricles than in the atria
- causes av valves to close
- causes semilunar valves to open which forces blood into the arteries
