c1.1- enzymes and metabolism Flashcards
metabolic reactions
chemical reactions that keep living organisms alive
anabolic reactions
reactions that build things up
anabolic reaction eg [2]
- condensation
- combining monomers into polymers
catabolic reactions
reactions that break things down
catabolic reactions eg [2]
- hydrolysis
- digesting polymers into monomers
fibrous protein interaction w water
insoluble in water
function of fibrous proteins
structural: support and strength
- extra cellular matrix inside: collagen (strengthening tissues)
fibrous proteins eg [2]
- keratin
- elastin
globular proteins interaction w water
soluble in water (mostly)
globular proteins function
functional (enzymes, antibodies, transport)
globular proteins eg [5]
- amylase
- insulin
- haemoglobin
- immunoglobulins
- Na+/K+ pump
proteome
complete set of proteins expressed by an organism
genome
entire set of dna instructions found in a cell
substrate
reactant in a biochemical reaction that binds to the enzyme’s active site
enzyme
globular protein which acts as a biological catalyst that speeds up metabolic reaction by lowering the activation energy
catalyst
speeds up chemical reactions and will not be used up
active site
region on the surface of an enzyme which substrates bind and catalyses the reaction
active site function + why
- attract substrate because polar/non polar region
- depends on composition of r group
shape of active site and substrate
complementary + specific
when substrate is locked into the active site
reaction is catalysed then products are released and enzyme is used again
induced fit model
- substrate inducing a conformational change in the active site
- after: enzyme reverts to original shape
induced fit model pros
stressed the substrate (weaken the bonds) so reduces the activation energy of the reaction
how to increase the amount of enzyme-substrate complex [4]
- increase temp
- increase kinetic energy
- increase conc of substrate
- increase conc of enzyme
result of factors being increased [2]
- increased chance of successful collision
- increased rate of reaction
activation energy
amount of energy that must be put into a reaction to make it occur
lactose intolerance occurs because
ppl unable to produce the enzyme- lactase in insufficient quantities
composition of lactose + effect
dimer
- 2 sugars (galatose and glucose)
- slow when u try to absorb it
how does increased lactose in the intestines lead to diarrhea
- increased lactose in the intestines
- can not be digested due to the lack of lactase
- bacteria can use the lactose to reproduce
- the increase in bacteria population causes water potential in the intestine to drop
- blood has a higher water potential
- water diffuses from blood into small intestine using osmosis
- diarrhea occurs
solutions for lactose intolerance
- take a lactase supplement
- drink lactose-free milk
how to produce lactose-free milk
immobilise lactase with alginate beads
y body temperature at 37 when optimum is 40?
- bacteria assume optimum is 37
- when they evolve: bacteria enzyme optimum is also 37
- need u to survive and do things for them
- when we are invaded: can increase temp then the bacteria enzymes denature but our enzymes work better
optimum pH
enzymes only operate within a narrow range of pH
deviation from the optimum pH
- hydrogen bonds between amino acids in the structure of the enzyme are broken
- loss of shape
temp graph
notes
- asymmetrical
pH graph
notes
- symmetrical
conc graph
notes
- reaches a plateau
metabolic pathways
chains or cycles of enzyme-catalysed reactions
competitive enzyme inhibition
competitive inhibitor binds with active site so the substrate is blocked and cannot bind on the active site
competitive enzyme inhibition eg
statins
name of enzyme blocked: HMG-CoA reductase
why
- less cholesterol produced in the body
non-competitive enzyme inhibition
binding to allosteric site causing a conformational change in the active site so the substrate wont fit
competitive enzyme inhibition graph
3 lines
notes
competitive enzyme inhibition graph explanation
- the higher the concentration of inhibitor, the slower the rate of reaction
- if increase concentration of substrate then can counter concentration of inhibitor
- even with competitive inhibition, the same maximum rate of reaction will be achieved if more substrate is added
- did not change the number of enzymes available
non competitive inhibition graph
3 lines
notes
non competitive inhibition graph explanation
- as the concentration of inhibitor increases, the rate of reaction decreases
- fewer functional active sites available for reaction - maximum rate of reaction is also reduced- with fewer functional active sites
- enzyme has reduced ability to process the substrates, even if the substrate concentration is increased
irreversible binding of inhibitor causing
changes to the active site via covalent bonds
irreversible binding of inhibitor + competitive inhibition eg: detailed
penicillin (antibiotic)
- inhibits transpeptidases → forms permanent covalent bond with a particular amino acid in the active site → enzyme breaks cross links in the bacterial cell
enzyme catalysed reactions intracellular or extracellular
can be both
glycolysis
linear metabolic reaction
kreb + calvin cycle
enzyme catalysed, cyclical metabolic pathways
feedback inhibition eg
first enzyme- threonine deaminase
first substrate- threonine
end product- isoleucine
product
substances after the catalysed reaction
collision
substrates and the active sites of enzymes will randomly hit each other
why the presence of water is critical for most enzyme reactions
diffusion to allow movement (brownian motion)
y enzymes tend to move slower than substrates
usually larger than substrates → more kinetic energy required to move
enzymes involved in anabolism
synthase
enzymes involved in catabolism
hydrolase
advantages of immobilising enzymes
can be reused easily- easily separated from the product
3 ways enzymes are immobilised
- alginate gel
- glass
- bonding with other enzymes to make bigger aggregates
y lactose free milk is produced [3]
- galactose and glucose sweeter than lactose
- lactose tend to crystallise when milk is used to make into ice cream
- lactose is slower for bacteria to use for fermentation to make yogurt and cheese
process that lactose-free milk produced by immobilised enzymes
- lactase immobilise in alginate beads
- milk cycled through the alginate beads, lactase breaks down lactose into glucose and galactose in the milk
activation energy
minimum energy that substrates need to overcome in order for a reaction to occur
how do enzymes lower the activation energy of a reaction
- when substrate binds to the active site, substrate is altered to reach transition state
- can be converted into products and be separate from enzyme’s active site
- this binding lowers the activation energy
inhibitor
substance that binds to an enzyme and reduce the enzyme’s activity
what is necessary for substrate molecule and active site to come tgt
molecular motion
how does size of substrate affect its movement
large- limits movement during interactions with enzymes
what can gene mutations causing active site conformational change in transpeptidase lead to
bacterial resistance in penicillin
characteristic of active site + substrate’s effect
- not rigid
- substrate can induce slight changes in the shape of active site
how can end product inhibition be regulated
metabolic pathway regulated according to the requirement for its end product
end product + non-competitive inhibition eg
1st enzyme- threonine deaminase
1st substrate- threonine
end product- isoleucine
penicillin types of inhibition
irreversible
competitive
end product
what does penicillin bind to
DD transpeptidase
how does penicillin work [4]
- forms permanent covalent with certain amino acids in the active site
- enzymes break cross links in the bacterial cell
- cell wall is weakened
- bacteria killed by lysis
