metabolic pathways 1.6

Question 1

metabolic pathways

Answer 1

integrated and controlled pathways of enzymes catalysed reactions within a cell

Question 2

the 2 types of metabolic pathways

Answer 2

catabolic and anabolic

Question 3

catabolic reactions

Answer 3

breakdown large molecules into smaller molecules and release energy

Question 4

anabolic reactions

Answer 4

build up large molecules from smaller molecules and require energy

Question 5

what do reversible and irreversible steps allow in metabolic pathways

Answer 5

allow the process to be controlled precisely

Question 6

what do alternative routes in metabolic pathways allow

Answer 6

allow steps in the pathway to be bypassed

Question 7

what controls metabolic pathways

Answer 7

by the presence or absence of particular enzymes and the regulation of the rate of reaction of key enzymes (controlling the activity of key enzymes)

Question 8

activation energy

Answer 8

the energy needed to break chemical bonds in the reactants

Question 9

what is the rate of chemical reactions indicated by

Answer 9

the amount of chemical change that occurs per unit of time

Question 10

what’s the transition stage

Answer 10

when the reactant molecules have absorbed enough energy (normally heat energy) to make them unstable, their bonds break and the reaction can now occur

Question 11

enzymes

Answer 11

biological catalysts which speed up the rate of reactions by lowering the activation energy

Question 12

induced fit

Answer 12

-when the substrate binds at the active site it changes shape slightly to better fit the substrate
-this lowers the activation energy by weakening the chemical bonds of the substrate molecules
-the subsequent products of the reaction have a low affinity for the active site

Question 13

affinity

Answer 13

chemical attraction

Question 14

what type of affinity does the substrate have for the active site

Answer 14

a high affinity

Question 15

what determines the orientation of reactants

Answer 15

the shape of the active site when a reaction involves two or more substrates

Question 16

what happens when the substrate concentration increases

Answer 16

the rate of reaction also increases until all of the enzymes active sites are occupied by substrate molecules and then the rate of reaction remains at a steady rate

Question 17

what effects the direction of enzyme reactions

Answer 17

substrate and product concentration

Question 18

what happens if product concentration is too high

Answer 18

the enzymes can work in reverse to convert some of it back to the substrate

Question 19

competitive inhibitors

Answer 19

-bind at the active site preventing the substrate from binding
-similar shape to substrate
-can be reversed by increasing substrate concentration so that it outnumbers the competitive inhibitors

Question 20

non competitive inhibitors

Answer 20

-bind away from the active site but change the shape of the active site preventing the substrate from binding
-cannot be reversed by increasing substrate concentration

Question 21

feedback inhibition

Answer 21

-occurs when the end product in the metabolic pathway reaches critical condition
-the end product the inhibits an earlier enzyme blocking the pathway, preventing further synthesis of the end product