metabolic pathways 2.1 Flashcards
cell metabolism
the sum of all biochemical reactions which take place in living cells
break down of larger molecules into smaller molecules which results in energy being released
catabolic pathways
small simple molecules joining together to form a larger complex molecule which requires energy
anabolic pathways
ATPs role is to transfer energy between ……. reactions and ……….. reactions in cells
catabolic
anabolic
why do alternative routes for metabolic pathways exist
if a specific enzyme or substrate isnt available in the pathway
what are membranes composed of
phospholipids and proteins
forms channels or….. across the membrane
allows diffusion of larger molecules
protein pores
-molecules move from higher to lower concentration down a concentration gradient
-passive process
diffusion
transports molecules by active transport
from lower to higher concentration against against the concentration gradient
requires energy provided by ATP
protein pumps
catalyse steps in metabolic pathways
e.g. ATP synthase
proteins as enzymes in cell membranes
how do enzymes speed up biochemical reactions
lowering the activation energy
why are enzymes necessary
because biochemical reactions must take place at a fast enough rate for survival
what happens to the active site when the substrate binds to the enzyme
the enzyme changes shape slightly to better fit the substrate this is induced fit.
the substrate has a ………… affinity for the active site
high
the subsequent products have a ……. infinity allowing them to leave the active site
low
why would a reversible reaction be useful
to restore the balance of a metabolites pathway, can be used to store products
-similar shape and and charge to enzymes substrate
-binds at the active site
-increasing substrate concentration results in an increase reaction rate
-leaves the enzyme still usable
competitive inhibitors
-binds to the allosteric site
-causes a conformation change so the substrate can no longer bind
-the maximum rate of reaction will be lower as there are less usable enzymes
non-competitive inhibitors
-the end product of the enzyme binds to the first enzyme in the pathway
- slows the rate or the first reaction
- rate of reaction is controlled to prevent the build up of excess end product
saves energy and resources
feedback inhibition by an end product
end product inhibition
