Unit 1 Biology revision: Topic 1 and 2 Overview

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Preview of Unit 1 Biology revision: Topic 1 and 2 Overview

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REVISION NOTES
Structure of starch and why it is suitable as a storage molecule..
1. Starch is made up of amylose (20-30%) and amylopectin (70-80%)
2. Amylose is a straight chain with no double bonds and has 1-4 glycosidic links
3. Amylopectin has branches and is made up of 1-4 and 1-6 glycosidic links
4. The branches make it easy for energy release (hydrolysis)
5. It has a compact structure
6. A lot of glucose can fit into a smaller space
7. The molecule is large and insoluble
8. Starch has no osmotic effect and does not diffuse out of cells
Structure of glycogen as storage molecule
1. Large molecule made up of many monomers, allowing large amount of storage
2. Compact, large amounts can be stored in a cell
3. Insoluble, does not have an osmotic effect]
4. Large molecule, cannot pass out of cells
5. Can be easily hydrolysed when energy is needed.
How does the structure of an artery relate to its function?
1. The smooth inner lining reduces friction
2. Narrow lumen( helps maintain high BP)
3. Folded lining allows artery to stretch
4. Wide wall(withstands high BP)
5. Artery can recoil( maintaining high BP and pushing along the blood)
6. Large amounts of fibrous tissue, elastic fibres and collagen means it can easily change shape
Capillary Vein
No valves Valves
Pores No pores
Narrow lumen Wide lumen
One cell thick More than one cell thick
No elastic fibres or collagen Has elastic fibres and collagen
Drug Uses Risks
Calcium channel Anti-hypertensive drug Headache
blockers Block calcium channels in muscle cells in the Dizziness
lining of the arteries. Calcium must pass Swollen ankles
through channels for muscles to contract. Arrhythmia
Blockage due to drug prevents contraction
Constipation
and blood vessels don't constrict, lowering BP
ACE inhibitors Anti-hypertensive drug Arrhythmia
Cough

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Reduces production of angiotensin II. The Dizziness
angiotensin II causes vasoconstriction. The Kidney failure
enzyme prevents the hormone being
produced and reduces Blood Pressure.
Diuretics Increases volume of urine produced and rids Dizziness
body of excess fluids and salts Nausea
This decreases cardiac output. Muscle cramps
ACE inhibitors and diuretics are often
prescribed together.…read more

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Semilunar valves:
Location: base of aorta
Function: prevents backflow of blood into ventricles during diastole and atrial systole.…read more

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This converts fibrinogen into fibrin
6. The strands of fibrin form a tangles mesh as they are insoluble
7. With the presence of calcium ions and vitamin K
8. Platelets become trapped in this tangles mesh
Atherosclerosis
1. Damage to artery wall (e.g. toxins inhaled by cigarette smoke)
2. Inflammatory response
3. White blood cells accumulate
4. Build-up of cholesterol ( an atheroma deposit)
5. Calcium salts and fibrous tissue build up at the site and result in a hard swelling called plaque.
6.…read more

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Topic 2
Why risk of CF is not zero when neither are carriers
Mutations may occur during production of gametes
False negatives may occur
Screening does not test all possible mutations
Mutations may occur after fertilisation
Phospholipid bilayer explained
1. Fatty acid tails are hydrophobic
2. They orientate themselves away from water/polar
3. Phosphate heads are hydrophilic
4. They turn themselves towards water
5. Cytoplasm/ tissue fluid is polar so the heads face towards fluid and the tails face away.…read more

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ATP energy is used in this process
Facilitated diffusion
1. Channel proteins are used
2. Channels can open or close
3. Large/ polar/ charged molecules can pass through membrane in this way
4. Molecules move down the concentration gradient
How do phospholipids contribute to the structure of a cell membrane
1. Phospholipids allow for fluidity or movement
2. Movement in the membrane allows the membranes to fuse
3.…read more

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TESTING AND THERAPY
How is gene therapy carried out?
1. A normal allele is used
2. haemoglobin chain
3. The gene is introduced onto the DNA
4. Cells in the bone marrow are treated
5. Vectors are used as the mode of transport
6. E.g. liposome or virus
7. The vector is delivered through injection
8. The treatment must be repeated as cells die and new faulty cells are created.
Amniocentesis
1. Amniotic fluid removed from the ,others amniotic sac
2.…read more

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Abortion is wrong
An abnormality may be found
This could result in a problem with future employment
Not fully understanding risks of testing
Accidental miscarriage
Who has the right to make the decision for the foetus
No-one has the right to choose f they will live or die.
How is pre-implantation genetic diagnosis performed to detect CF?
1. IVF is used(created in test tube and then transferred into womb)
2. The DNA of the embryo is analysed
3.…read more

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Importance of primary structure of an enzyme in relation to its function
1. Primary structure determines an enzyme's 3D folding
2. The types of amino acids determine types of bonds and interactions
3. Position of amino acids determines position of bonds
4. Shape of an active site is determined by the primary structure
5. The shape of an active site must be correct to bind to the right substrate
6. Amino acids /R groups are involved in the chemical reaction
7.…read more

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Core practical- Vitamin C content in fruit juices
1. DCPIP is used
2. Juices are used
3. Colour changes from blue to colourless or pink
4. Procedure would need to be repeated at regular time intervals
5. Control variable mentioned- e.g. temperature of juice/ volume of DCPIP
6. Draw graphn for both sets of results
Procedure:
1. Volume of 1 drop recorded
2. 2cm3 of DCPIP put into test tube, 1 drop of Vit C added
3. Test tube shaken every drop
4.…read more

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