Metabolic Pathways

Question 1

Metabolic pathways are

Answer 1

integrated and controlled reactions within a cell

Question 2

Metabolic pathways are reactions controlled by

Answer 2

presence or absence of enzymes which act as catalysts

Question 3

In animals, specific metabolic pathways can produce

Answer 3

vitamins and haemoglobin

Question 4

Metabolic pathways are a series of reactions that

Answer 4

start with a substrate

finish with end product

Question 5

Anabolic

Answer 5

requires energy

build up large molecules from smaller ones (biosynthesis)

Question 6

Catabolic

Answer 6

releases energy

break down large molecules into smaller ones (degradation)

Question 7

example of anabolic reaction

Answer 7

synthesis of glycogen from glucose

Question 8

example of catabolic reaction

Answer 8

process of food digestion, where different enzymes break down food particles so they can be absorbed by small intestine

Question 9

Metabolic pathways can be

Answer 9

reversible and irreversible

most are reversible

Question 10

All metabolic pathways have to be regulated and controlled to…

Answer 10

Stop build up of an end products that isnt needed

Question 11

Active site has

Answer 11

high affinity to substrate as well as being specific to substrate, this orientates reactants into correct position for reaction to take place

Question 12

Binding of enzyme to substrate does what?

Answer 12

lowers activation energy of reaction

Question 13

rate of enzyme reaction can be affected by?

Answer 13

substrate concentration

Question 14

As substrate concentration increases

Answer 14

enzyme reaction increases until all active sites are occupied by substrates, then all active sites are occupied, enzyme is saturated

Question 15

When all active sites are occupied, the enzyme is said to be?

Answer 15

Saturated

Question 16

At point of saturation, adding more substrates…

Answer 16

Makes no difference to reaction rate

Question 17

Inhibitors

Answer 17

can be used to stop enzyme binding to substrate - as a result inhibitors can directly control progress of metabolic pathway

Question 18

3 types of inhibition

Answer 18

Competitive
Non-competitive
Feedback

Question 19

Competitive Inhibition

Answer 19

Occurs when an inhibitor molecule binds to active site of enzyme

Stops substrate from binding

compete with substrate because have similar molecular shape

Question 20

How to reverse competitive inhibition

Answer 20

Increase substrate concentration

Substrate eventually dilutes inhibitor so all enzyme molecules bind to substrate

Question 21

Example of competitive inhibitor

Answer 21

Sarin

Question 22

Non-competitive inhibition

Answer 22

An inhibitor does not bind to active site bit binds to a different part of enzyme, this changes the active site shape, this stops substrate binding to enzyme and decreases reaction rate

Question 23

Example of non-competitive inhibitors

Answer 23

cyanide, mercury or silver

Question 24

Graph of inhibitors

Answer 24

Steep and high - no inhibitor

slower but same end height - competitive inhibitor

slower and lower - competitive inhibition

Question 25

Feedback inhibition

Answer 25

End product in a metabolic pathway binds to an enzyme at start of pathway

Question 26

Negative feedback process

Answer 26

Stops metabolic pathway and so prevents further synthesis of end product until end product concentration decreases. Higher concentration of end product, quicker metabolic pathways stops