unit 1.6: metabolic pathways

Question 1

what is a catabolic reaction

Answer 1

breaking down larger molecules to produce smaller molecules (degradation)

Question 2

what is cell metabolism

Answer 2

the term for the thousand of biochemical reactions that occur within a living cell

Question 3

what may reactions be controlled by

Answer 3

enzymes

Question 4

what is a term for large molecules

Answer 4

macromolecules

Question 5

what is an anabolic reaction

Answer 5

biosynthesis of complex molecules from simple (small built up to large)

Question 6

what do anabolic reactions require

Answer 6

energy input

Question 7

what do catabolic reactions release

Answer 7

energy

Question 8

what is an example of a catabolic reaction

Answer 8

glucose + oxygen > CO2 + water

Question 9

what is an example of anabolic reactions

Answer 9

amino acids > proteins

Question 10

give an example of a reversible pathway

Answer 10

anaerobic respiration in mammals
glucose <> lactic acid

Question 11

give an example of an irreversible pathway

Answer 11

anaerobic respiration in yeast
glucose > CO2 + ethanol

Question 12

what is a metabolic pathway

Answer 12

a sequence of reactions that is controlled by the absence of presence of a particular enzyme

Question 13

what may a pathway contain to keep precise control

Answer 13

reversible steps
irreversible steps

Question 14

give an example of an irreversible step in respiration

Answer 14

conversion of glucose to intermediate 1

Question 15

why is glucose to intermediate 1 irreversible

Answer 15

to keep glucose concentration low
promote continued glucose diffusion

Question 16

what do enzymes contain

Answer 16

active site

Question 17

where does the substrate bind

Answer 17

active site

Question 18

what is the energy required to start a chemical reaction known as

Answer 18

activation energy

Question 19

what is the result of a reaction rate in the absence of enzyme or catalyst

Answer 19

slow
large activation energy needed

Question 20

what is the result of a reaction rate in the presence of enzyme or catalyst

Answer 20

quick
small activation energy needed

Question 21

what is induced fit

Answer 21

where the active site changes shape to better fit the substrate

Question 22

what is the result of induced fit

Answer 22

reaction more likely to occur

Question 23

what is the active site

Answer 23

flexible structure

Question 24

what does a substrate have for the active site

Answer 24

high affinity

Question 25

what does a product have for the active site

Answer 25

low affinity

Question 26

what happens to products after the reaction has occurred

Answer 26

diffuse away

Question 27

how can a cell control enzyme activity

Answer 27

keeping reactions (and enzymes) in compartments e.g. lysosomes or mitochondria changing enzyme shape (most effective)

Question 28

what is the term for the presence of enzymes

Answer 28

constant expression

Question 29

what is the method of controlling enzyme activity

Answer 29

inhibition

Question 30

what are the 3 types of inhibition

Answer 30

competitive non-competitive feedback

Question 31

what is the shape of a competitive inhibitor

Answer 31

similar to the substrate

Question 32

what happens in competitive inhibition

Answer 32

the substrate and inhibitor compete for the active site, less substrates bind to the active site

Question 33

what is the result of competitive inhibition

Answer 33

decreased reaction rate

Question 34

how can competitive inhibition be reversed

Answer 34

increasing substrate concentration

Question 35

why does increasing substrate concentration reverse the inhibitory effect

Answer 35

more substrate than inhibitors to compete for an active site

Question 36

what is non-competitive inhibition

Answer 36

where an inhibitor binds somewhere on the enzyme (not the active site) and changes the shape of the active site

Question 37

what is the result on reaction rate during non-competitive inhibition

Answer 37

decreased as substrates can no longer bind to the changed active site

Question 38

what happens if you increase substrate concentration during non-competitive inhibition

Answer 38

nothing as inhibitor does not compete with substrate

Question 39

what is feedback inhibition

Answer 39

an end product inhibits an earlier enzyme blocking the pathway

Question 40

why may feedback inhibition occur

Answer 40

if a product reaches a critical concentration

Question 41

what is an example of feedback inhibition

Answer 41

amino acid isoleucine is produced through conversion of threonine in 5 enzyme controlled steps in bacteria as isoleucine builds up, it binds to enzyme 1 inhibiting further production of isoleucine ensuring only what is needed is produced