AQA Bio A Level Unit 1 Flashcards
1
Q
Describe the primary structure of all proteins. (2)
A
(a) 1. Sequence/order of amino acids;
- (Joined by) peptide bonds;
2
Q
What is hydrolysis?
A
- Breaks a chemical bonds between two molecules;
- Using water;
3
Q
What is a condensation reaction?
A
- Creates a chemical bond
- Removing a molecule of water
4
Q
Glycogen - Describe the structure of Glycogen (3)
A
- Polysaccharide of α-glucose;
- (Joined by) glycosidic bonds;
- Branched structure
5
Q
Glycogen - Glycogen structure
related to function (5)
A
- Insoluble (in water), so doesn’t affect water potential;
- Branched / coiled / (α-)helix, so makes molecule compact;
- Polymer of (α-)glucose so provides glucose for respiration;
- Branched / more ends for fast breakdown / enzyme action;
- Large (molecule), so can’t cross the cell membrane
6
Q
Glycogen - Glycogen compared
with cellulose (4)
A
- Cellulose is made up of β-glucose (monomers) and glycogen is made up of α-glucose (monomers);
- Cellulose molecule has straight chain and glycogen is branched;
- Cellulose molecule has straight chain and glycogen is coiled;
- Glycogen has 1,4- and 1,6- glycosidic bonds and cellulose has only 1,4- glycosidic bonds
7
Q
Starch – Relate 3 properties to its
function (3)
A
- Insoluble;
- Doesn’t affect water potential;
- Helical;
- Compact;
- Large molecule;
- Cannot leave cell
8
Q
Test for reducing sugar (2)
A
- Heat with Benedict’s reagent (1);
- colour change from blue to brick-red (1)
9
Q
Test for a non reducing sugar (3)
A
- Heat with Benedict’s reagent and no colour change (1);
- boil with acid (HCl) and then neutralise with (NaHCO3) (1);
- re- heat with Benedict’s reagent and colour change from blue to brick-red (1)
10
Q
Test for starch (2)
A
- Add iodine in potassium iodide solution (1);
- colour change from brown to blue-black (1)
11
Q
How are triglycerides formed (3)
A
- One glycerol and three fatty acids;
- Condensation(reactions) and removal of three molecules of water;
- Ester bond(s) (formed);
12
Q
Sucrose is a disaccharide formed by a condensation reaction between which monosaccharides? (2)
A
- Glucose;
- Fructose;
13
Q
How is cellulose formed? (3)
A
- Condensation (reactions) and removal of water;
- Many β-glucose monomers;
- Glycosidic bonds
14
Q
Test for a lipid (2)
A
- (Mix / shake sample) with ethanol, then water;
Sequence is important - White / milky (emulsion);
15
Q
Protein - Protein Structure (7)
A
- Polymer of amino acids;
- Joined by peptide bonds;
- Formed by condensation;
- Primary structure is order of amino acids;
- Secondary structure is folding of polypeptide chain due to hydrogen bonding; (into alpha helix or beta pleated sheet)
- Tertiary structure is 3-D folding due to hydrogen bonding and ionic/disulphide bonds between R groups;
- Quaternary structure is more than one polypeptide chains;