Metabolic Pathways 2.1

Question 1

Describe the meaning of a metabolic pathway

Answer 1

integrated and controlled pathways of enzyme catalysed reactions within a cell.

Question 2

what kind of routes can metabolic pathways have

Answer 2

Reversible: molecule can be converted back

Irreversible: molecule is permanently changed

Alternative routes: more than one possible route

Question 3

describe anabolic reaction

Answer 3

involve the building up of large molecules from smaller molecules and require energy

Question 4

describe catabolic reaction

Answer 4

breakdown larger molecules into smaller molecules and release energy.

Question 5

definition of metabolism

Answer 5

all of the thousands of biochemical reactions which take place in cells

Question 6

describe metabolic reactions

Answer 6

several stages involving the conversion of one metabolite to another, each step controlled by a particular enzyme

Question 7

a common function of proteins embedded:
Enzymes

Answer 7

activate by binding/ signal molecules on outside(surface proteins) catalyse many reactions inside the cell

Question 8

a common function of proteins embedded:
Protein pores

Answer 8

holes in the membrane, small in the diameter. letting only small molecules in (opening and closing determined by signal bonding)

Question 9

a common function of proteins embedded:
Pumps

Answer 9

carry ions through the membrane ( from low to high)

Question 10

describe induced fit model

Answer 10

when the shape of the active site changed shape to better fit the substrate after the substrate binds

Question 11

describe enzyme specificity

Answer 11

enzymes have a specific shape, their active site is shaped to fit a specific substrate. This is complementary

Question 12

what are metabolic pathways controlled by

Answer 12

the presence or absence of particular enzymes. each step is controlled by a specific enzyme

Question 13

What is the role of the active site

Answer 13

it binds to the substrate with which it has high affinity
It decreases the activation energy of the reaction
It releases products with low affinity for the active site

Question 14

5 factors which can affect the rate at which an enzyme works

Answer 14

1. temperature
2. pH
3. enzyme concentration
4. substrate concentration
5. end product concentration

Question 15

what happens when the substrate concentration is low

Answer 15

many enzyme active sites not occupied so reaction rate low

Question 16

what happens when substrate concentration is high

Answer 16

more substrate enzyme complexes can form increasing reaction rate

Question 17

what is product concentration

Answer 17

when end product reaches critical concentration, the end product can inhibit an earlier enzyme in the metabolic pathway.

Question 18

what’s an inhibitor

Answer 18

substances which prevent enzyme activity, these can be feedback inhibitors, competitive or non competitive.

Question 19

whats a competitive inhibitor

Answer 19

compete with the substrate to fit into the active site
inhibitor can do this because its structure is similar to substrate
Inhibitor blocks active site so reaction rate is reduced

Question 20

what’s a non competitive inhibitor

Answer 20

binds elsewhere on the enzyme, this causes active site to change shape, prevents substrate from binding.