Biological molecules

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Explain what is meant by a polymer.
(Molecule) made up of many identical/similar molecules/monomers/
subunits;
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Describe the structure of an amino acid molecule and explain how amino acids link together.
1 Amino acid based on carbon with four groups attached; 2 Amino/ NH2 and carboxyl / COOH; 3 R-group/ side chain + hydrogen; 4 R-group differs from one amino acid to another; 5 Amino acids joined by condensation; 6 Bond formed between NH2 and COOH; 7
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Explain how proteins are suited for their roles as receptor molecules.
Many different sorts of proteins;
Different primary structures/sequences of amino acids;
Tertiary structure;
Shape; allowing formation of receptor/binding site/site into which
substance/substrate fits;
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Explain how the structure of fibrous proteins is related to their functions.
Long chains of aa;
Folding of chain into a coil / folds / helix / pleated sheet; Association of several polypeptide chains together;
Formation of fibres / sheets explained; 2 H bonds / Disulphide bonding (In context);
Fibres provide strength (and fle
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Describe how you would use a biochemical test to show that a solution contained protein.
Biuret / alkali + copper sulphate;
Lilac/purple/mauve/violet;
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With reference to named parts of the diagram, explain the difference between the terms:
Triglyceride and phospholipid; Phospholipid has (one) phosphate / Phosphoric acid; 
replacing fatty acid;
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Saturated and unsaturated.
Saturated – all valencies of C filled / saturated with hydrogen / all (C–C)
single bonds / no double bonds;
fatty acid 1 is saturated/fatty acids
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Describe a chemical test you could carry out to show that a piece of coconut contains lipids.(3)
(Crush in) ethanol / alcohol;
Add (to) water (Order of adding is critical for this point);
Emulsion / white colour
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Describe how you could use Benedict’s reagent to test a urine sample for the presence of glucose.
Add (Benedict’s) reagent (to urine sample) and heat / heat the mixture;
red/ brown/ orange/ green/ yellow;
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Describe a further biochemical test to find out if a substance is a non-reducing sugar.
Heat with acid, then neutralise / hydrolyse using enzyme;
(heat) with Benedict’s (solution);
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The structure of a cholera bacterium is different from the structure of an epithelial cell from the small intestine. Describe how the structure of a cholera bacterium is different.
1 Cholera bacterium is prokaryote; 2 Does not have a nucleus/nuclear envelope/ has DNA free in cytoplasm/has loop of DNA; 3 and 4 Any two from No membrane-bound organelles/no mitochondria / no golgi/ no endoplasmic reticulum/etc; 5 Small ribosomes on
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Give 2 ways in which pathogens can cause disease when they enter the body of their host.
Damage/destruction of cells/tissues Production of toxins;
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Describe the difference between an endotoxin and an exotoxin.
Endotoxins produced from the breakdown of bacteria (cell walls);
(allow burst / lyse – do not allow decompose)
exotoxins secreted / released (from living cells) (not produced);
endotoxins are lipopolysaccharides;
exotoxins are protein;
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How V.cholerae causes Diarrhoea
1. The cholera bacterium adheres to the epithelium and secretes the cholera toxin CT. CT enters the epithelial cells and activates a chloride ion channel in the cell membrane. 2. This causes chloride ions to diffuse out of the cells into the lumen. 3
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Oral rehydration solutions (ORS) are used to treat diarrhoeal disease. What does an ORS consist of and how does it work?(5)
1. Contains glucose/starch/ carbohydrate / sugar; 2. Sodium/salt; 3. Co-transport / symport; 4. Sodium and glucose taken up (from lumen); 5. Lowers water potential in cells/ increases water potential gradient; 6. Water taken up by osmosis
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Parts of the prokaryotic cell
Cell (surface) membrane: regulates entry/exit/selectively permeable; Mesosome: respiration/cell division; Cell wall: (mechanical) protection/prevents (osmotic) lysis; Slime layer/capsule: protection (against e.g. antibiotics); Flagellum, movement o
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Other cards in this set

Card 2

Front

Describe the structure of an amino acid molecule and explain how amino acids link together.

Back

1 Amino acid based on carbon with four groups attached; 2 Amino/ NH2 and carboxyl / COOH; 3 R-group/ side chain + hydrogen; 4 R-group differs from one amino acid to another; 5 Amino acids joined by condensation; 6 Bond formed between NH2 and COOH; 7

Card 3

Front

Explain how proteins are suited for their roles as receptor molecules.

Back

Preview of the front of card 3

Card 4

Front

Explain how the structure of fibrous proteins is related to their functions.

Back

Preview of the front of card 4

Card 5

Front

Describe how you would use a biochemical test to show that a solution contained protein.

Back

Preview of the front of card 5
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