Explain Protein Synthesis
Transcription - takes place in the nucleus - DNA Helix unzips: DNA helicase (enzyme) - hydrogen bonds break - this exposes template strands, the 3 bases called 'a triplet' - RNA nucleotides pair with bases of DNA - mRNA produced, 3 bases called a codon ( thymine replaced by uracil) - leaves nuclear pore into cytoplasm.
Translation - takes places in the ribosomes in the cytoplasm - tRNA pairs it's 3 bases (anti-codon) with the exposed codon of the mRNA - hydrogen bonds form between bases - attached to each tRNA in a specific amino acid - amino acid sequence is a polypeptide - joined by peptide bonds - new protein made.
How is water regulated in the mucus
Too much water - Na+ is actively pumped across the basal membrane - Na+ diffuses through sodium channels in the apical membrane - Cl- diffuses down the electrical graident - water is drawn out of the cells by osmosis due to high salt concentration in the tissue - water is drawn out of the mucus by osmosis.
Too little water - Cl- is pumped into cell across basal membrane - Cl- diffuses through the open CFTR channels - Na+ diffuses down the electrical gradient - elevated salt concentration in the mucus draws out the cell via osmosis - water is drawn into mucus via osmosis.
With CF - CFTR channel is absent or not functional - Na+ channel is permanently open - water is continuously removed from the mucus via osmosis.
Describe the process of a blood clot
Name for a blood clot is a 'thrombosis' - blood clots form from slow flowing blood or whe endothelium is damaged - platelets come into contact with damages area and change from flat to sperical with long projections, causing a platelet plug - soluble plasma protein prothrombin is converted into thrombin - thrombin is an enzyme that catalyses the fibrinogen reaction - fibrinogen is another soluble plasme protein that changes into fibrin - fibrin is an insoluble protein, that act as a 'mesh' trapping everything inside.
Descrive the process of Atherosclerosis
The endothelium becomes damaged, maybe by high blood pressure or toxins - inflammatory response occurs, which means white blood cells move into the damaged area. - These accumilate cholesterol, which leads to a deposit known as an 'atheroma'. - Calcium salts and fibrous tissue also build up, this hardens and is now a plaque. this reduces the elasticity of the artery. - Due to the narrowing of the artery, blood pressure will increase, this process is known as positive feedback as it will cause more damage to the artery.
Explain all the different saccharides
Saccharies and Carbohydrate general formula is - Cx(H2O)n
Monosaccharides (CH20) are single sugar molecules e.g. glucose, fructose and galactose. (+ lactose)
Disaccharides are 2 single sugar molecules combined - formed by condensation reaction producing glycodisic bonds, e.g. maltose (2 glucose molecules) , sucrose (glucose+fructose) galactose (glucose+lactose)
Polysaccharides are many monosaccharides joined via a condensation reaction making glycosidic bonds. - e.g. starch (storage molecule), compact low solubility with the little osmotic effect. Made of amylose, 200-5000 glucose molecules - straight chain - 1'4 glycosidic bond link.
As well as, Amylopectin (also a polymer of glucose molecules) - 1'6 glycosidic bond causing it to branch.
Examples and Descriptions of Lipids
- 3 fatty acids and 1 glycerol - condensation reaction occurs, removing water. - Ester bond formed.
Saturated - maximum no. of Hydrogen molecules - no double carbon bond - animal fats and dairy products - closely packed with strong intermolecule forces = solid ( -butter)
Monosaturates - only 1 double bond between carbon atoms in each fatty acid
Polyunsaturates - more then 1 carbon-carbon double bond. - Double bonds cause 'kinks' in chains that are not closely packed, they have weak intermolecular bonds = Liquids (-oil)
Compare Arteries and Veins
Arteries - narrow lumen - more smooth muscle, elstic fibres and collogen (tough + durable) - Thicker walls - no valves - oxygenated blood AWAY from heart, except Pulmonary Artery - Deoxygenated blood from right atria to lungs.
Veins - wider lumen - less smooth muscles, elastic fibres and collogen - Thinner walls - valves - Deoxygenated blood FROM heart, except Pulmonary Vein - Oxygenated blood from lungs to left atria.
Explain Cardiac Cycle
ATRIAL SYSTOLE- pressure in the atria increase due to blood returning from veins - increased pressure opens the atrioventricular valves - allowing blood to enter ventricles - atria contracts forcing and remaining blood down.
VENTRICULAR SYSTOLE - ventricles contract from apex of heart upwards - increasing pressure and therefore closing the atrioventricular vavles - the semilunar valves open and blood does into the arteries,
DIASTOLE - as the atria and ventricles relax, pressure falls - a decrease in pressure of ventricles causes the semilunar valves to close - decrease in pressure in atria means blood is drawn into the heart from the veins.
What are the methods of Transport?
Active Transport - the NET movement of molecules from an are of high concentration to low concentration until equilibrium is reached.
Passive - no energy required, - hydrophobic molecules.
Falicated diffusion - area of high-low concentration until equilibrium is reached - through channel proteins or via carrier proteins that change shape. - passive, no energy required.
Osmosis - a type of diffusion involving water molecules - from area of high to low concentreation - passive - no energy required.
Active Transport - against the concentration gradient through carrier preoteins, requires ATP.
EXOCYTOSIS - used for bulk transport out of the cell - vesicles fuse with the cell surface membrane.
ENDOCYTOSIS - used for bulk transport of substances into the cell - vesicles are created from cell surface membrane.
Explain the 4 stages of Protein Structure
Primary - 2 amino acids joined by condensation reaction, making a dipeptide or polyperptide (3+) - peptide bonds form between the amino acids - proteins are made from 2 or more of these polypeptide chains - the sequence of the amino acids in the chain is known as the primary structure.
Secondary - interactions of the amino acids may cause the chain to twist - coiling to form an 'alpha helix', hyrdogen bonds form between C=O and -NH, stabilises shape. - Several chains may link together with hydrogen bonds holding the 'parallel chains' together - known as 'beta pleated sheets'
Tertiary - polypeptide chains often bend and folds to produce a precise 3 dimentional shape - disulphide bridges formed stabilising molecule. - R groups become polar, attracting water (hyrdophilic) non polar groups are hydrophobic - e.g. enzymes.
Quaternary - only when there are multiple polypeptide chains e.g. haemoglobin.