Metabolism and Survival - Metabolic Pathways

Question 1

active transport

Answer 1

movement of molecules or ions through a cell membrane from a region of lower concentration to a region of higher concentration; as this goes against the concentration gradient it requires energy

Question 2

alternative route

Answer 2

step(s) in a metabolic pathway that allow the regular steps to be bypassed

Question 3

anabolism

Answer 3

type of metabolic pathway that brings about the build up of large molecule from small molecules

usually requires energy

Question 4

protein pore

Answer 4

proteins in a membrane which allow certain molecules to move across the membrane by facilitated diffusion

Question 5

protein pump

Answer 5

proteins in a membrane which actively pumps molecules against the concentration gradient by active transport

requires energy

Question 6

catabolism

Answer 6

type of metabolic pathway that brings about the break down of complex molecules to simpler ones

usually releases energy

Question 7

diffusion

Answer 7

movement of molecules or ions from a region of high concentration to a region of lower concentration down the concentration gradient

Question 8

metabolism

Answer 8

sum of all the biochemical reactions occurring within a living organism

Question 9

metabolic pathway

Answer 9

integrated and controlled pathways of enzyme catalysed reactions within a cell

Question 10

plasma membrane

structure

Answer 10

• selectively permeable
• made of a bilayer of phospholipids and proteins which are on the surface and embedded within the membrane

Question 11

activation energy

Answer 11

energy required to break the chemical bonds in the reactants in a chemical reaction

Question 12

active site

Answer 12

region of an enzyme molecule where the complementary surface of its substrate molecule becomes attatched

Question 13

affinity

Answer 13

degree of chemical attraction between reactant molecules

Question 14

catalyst

Answer 14

substance that increases the rate of a chemical reaction and remains unaltered by the reaction

Question 15

enzyme

Answer 15

protein made by living cells that act as a biological catalyst

Question 16

induced fit

Answer 16

a change in the shape of an enzymes active site to accommodate its substrate ensuring a close contact between the enzyme and substrate (increasing the chance of the reaction taking place)

Question 17

reaction rate

Answer 17

the amount of chemical change that occurs per unit time

Question 18

transition state

Answer 18

state of reactant molecules that have absorbed enough energy to break the bonds and allow the reaction to occur

Question 19

allosteric site

Answer 19

non-active location on an enzyme molecule which a non-competative inhibitor may become attatched

Question 20

competative

inhibition

Answer 20

• competative inhibitors are of similar shape to the substrate and bind to the active site of the enzyme preventing the substrate from binding
• this can be reversed by increasing the concentration of the substrate (increasing the chance of the substrate binding rather than the inhibitor)

Question 21

non-competative

inhibition

Answer 21

• non-competative inhibitors bind to the enzyme at an allosteric site which causes a change to the shape of the active site
• this means the substrate can no longer bind to the active site and the reaction is no longer catalysed
• increasing the concentration of the substrate does NOT reverse the effect since they are not competing with the substrate

Question 22

feedback

inhibition

Answer 22

• the end product of a metabolic pathway acts as an inhibitor (non-competitively) to an enzyme earlier in the pathway
• this blocks the pathway and prevents further synthesis of the end product
• this can make some metabolic pathways self regulating

Question 23

inhibitor

Answer 23

regulatory molecule that halts or decreases that rate of an enzyme controlled reaction