Biological molecules

Question 1

structure and function of starch

Answer 1

Amylose: long, unbranched alpha glucose chain. coiled to make it compact, easier for storage

Amylopectin: long, branched chain of alpha glucose. branches allow for easy hydrolysis so glucose can be released quickly

Question 2

Structure and function of glycogen

Answer 2

highly branched for fast glucose to energy release, needed in animals due to movement
compact so good for storage

Question 3

Who provided evidence for semi-conservative replication

Answer 3

Meselson and Stahl

Question 4

Inorganic ions

Answer 4

Fe2+ - haemoglobin
H+ - determine pH
Na+ - co transport and synapses
PO4 3- -ATP, DNA

Question 5

4 stages of the cell cycle

Answer 5

growth phase 1- cell grows, organelles made
synthesis - DNA replicated ready to divide
growth phase 2 - cell grows, proteins for cell division made
mitosis - nucleus divides

Question 6

Carrier proteins

Answer 6

move large molecules across the membrane by facilitated diffusion or also active transport

Question 7

Channel proteins

Answer 7

move charged particles through the membrane by facilitated diffusion

Question 8

Co-transport

Answer 8

• Na+ dissolves into the cell down the concentration gradient, through a co-transport protein
• glucose carried into the cell
  -glucose diffuses out down a conc gradient, by facilitated diffusion

Question 9

ELISA - testing for antibodies

Answer 9

-antigen bound to bottom of well plate
-blood plasma added to the well
-well washed to remove any unbound antibodies
-secondary antigen with specific enzyme added to the well and binds to the antibody if present
-well washed to remove any unbound antibodies
-solution added containing substrate that produces a coloured product when attached to enzyme

Question 10

How is mitotic index calculated

Answer 10

cells in mitosis / total no. cells in field of view

Question 11

Why does rate with competitive vs non-competitive inhibitors differ

Answer 11

Competitive inhibitor binds to active sites of enzyme but non-competitive inhibitor binds at allosteric site / away from active site;
(Binding of) competitive inhibitor does not cause change in shape of active site but (binding of) non-competitive does (cause change in size of active site);
So with competitive inhibitor, at high substrate concentrations (active) enzyme still available but with non-competitive inhibitor (active) enzymes no longer available;
At higher substrate concentrations likelihood of enzyme-substrate collisions increases with competitive inhibitor but this is not possible with non-competitive inhibitor