key area 2.1 - metabolic pathways Flashcards
1
Q
metabolism
A
- sun of all the biochemical reactions occurring within a living organism
2
Q
metabolic pathway
A
- integrated and controlled pathways of enzyme catalysed reactions within a cell
- these can be reversible, irreversible or there may be alternative routes
3
Q
anabolic pathways
A
- type of pathway that brings about the build up of large molecules from smaller molecules
- usually requires energy
- eg protein synthesis
4
Q
catabolic pathways
A
- type of pathway that bring about the break down of complex molecules to simpler ones
- usually releases energy
- eg protein => amino acids
5
Q
alternative routes
A
- steps in a metabolic pathway that allow regular steps to be bypassed
6
Q
structure of plasma membrane
A
- made of bilayer of phospholipids and proteins which are on the surface and embedded within the membrane
- phospholipids are in constant motion making membranes flexible
- known as fluid mosaic model
7
Q
roles of proteins in plasma membrane
A
- pores
- protein pumps
- enzymes
8
Q
protein pore
A
- proteins in a membrane which allow certain molecules to move across the membrane by passive diffusion
- makes membranes selectively permeable
9
Q
active transport
A
- movement of molecules or ions through a cell membrane from a region of lower concentration to a region of higher concentration
- requires energy as it goes against concentration gradient
10
Q
protein pump
A
- proteins in a membrane which actively pump molecules against the concentration gradient by active transport
- requires energy
11
Q
diffusion
A
- movement of molecules or ions from the region of high concentration to a region of lower concentration down the concentration gradient
- requires no energy
12
Q
enzyme
A
- protein made by living cells that act as a biological catalyst
- some proteins in the membrane catalyse steps within cellular metabolic processes
13
Q
activation energy
A
- energy required to initiate a reaction called its activation energy
- substrate must overcome an energy barrier before reaction can begin
- enzymes reduce the activation energy needed for a reaction to occur
14
Q
induced fit
A
- the active site of an enzyme changes shape to form the substrate more closely, increasing the rate of reaction
15
Q
affinity
A
- degree of chemical attraction between reactant molecules
- active site has high affinity for the substrate molecules
- product moves away from active site as it has low affinity for the active site
16
Q
substrate concentration
A
- maximum rate at which any enzyme catalysed reaction can proceed depends on concentration of substrate molecules
- an increase in substrate concentration drives the reaction in the direction of the end product and increase the rate of the reaction
17
Q
competitive inhibitors
A
- competitive inhibitors are a similar shape to the substrate and bind to active site of enzyme, preventing substrate from binding
- reduces rate of reaction
- can be revered by increasing substrate concentration (increases the chance of the substrate binding to enzyme rather than inhibitor)
18
Q
non-competitive inhibitors
A
- non competitive inhibitors have different structure from substrate so don’t fit into active site
- they bind to the enzyme at an allosteric site (don’t need to know name)
- shape of active site is changed so substrate can no longer bind to enzyme and reaction is not catalysed
- cannot be reversed and increasing substrate concentration doesn’t work since inhibitors are not competing with substrate
19
Q
feedback inhibition
A
- the end product of a metabolic pathway acts as an inhibitor (non competitive) to an enzyme earlier in the pathway
- this blocks the pathway and prevents any further synthesis of the end product
- occurs when end product in the metabolic plateau reaches a critical concentration
20
Q
transition state
A
- state of reactant molecules that have absorbed enough energy to break the binds and allow the reaction to occur
