enzymes Flashcards
define protein
- type of biomacromolecule made of amino acid chains folded into a 3d shape
why are proteins important?
why are they functionally diverse?
- crucial to the functioning and development of all living organisms
- carries out essential cellular functions of life
- many roles in structure, function and regulation of the body’s cells, tissues and organs
explain the diversity of proteins
arises through the ability to create many combinations of:
- amino acids
- polypeptide chain lengths, shapes, sizes
= folds into different functional structures post translation
what would happen to a protein’s functionality if it was incorrectly folded?
- changes to original sequence of amino acids= protein cannot fold correctly
- end up with the wrong shape= cannot carry out its function/specialised role
–> must be folded inot the correct shape to function
define proteome
whole set of proteins produced by an organism or cell
WITHIN EACH CELL
genome = same
proteome= different
what are enzymes?
type of protein that speed up (catalyses) chemical reactions inside cells
- lowers the activation energy of reaction
change in substrate conc= ↑or↓ enzyme produced to conserve ATP
what are some properties of enzymes?
- specific: active site is complementary shaped to substrate= only binds to specific reactant
- reusable: remain unchanged during reaction= can catalyse future reactions
what is the role of enzymes on biochemical pathways?
regulates biochem pathways by interacting with substrate molecules in series of intermediate steps
- form enzyme-substrate complexes
- chemical bonds can be broken down= smaller molecules
- chemical bonds set to create larger complex molecules
influence entire biochem pathways by catalysing each step
what is enzyme optimum conditions
enzymes operate most efficiently with their narrow range of set conditions
- activity is greatest= max products produced per unit of time
compare the lock and key and the induced fit model
- active site is proper shape to substrate
- active site has somewhat complementary shape to substrate: active site changs to fit when binding to substrate forming substrate complex
what is denaturing
- certain conditions disrupt the bonds within enzyme and changes its 3d shape
- active site changes shape= substrate can no longer bind
- enzyme= non-functional
what is a coenzyme
non-protein organic molecules that assist enzyme function
- bind to active site to donate energy or molecules= changes structure
(cannot be immediately reused)
define cycling of enzyme
coenzyme leaves enzyme and recycled after reaction
- accepts more energy so it can assist in more reactions
- repeatedly loaded and unloaded, transferring from high and low energy levels
what is the difference in the role of NADPH and ATP
NADPH: transfer hydrogen ions from LDP to LIP
ATP: carrier molecule that transfers energy from LDP to LIP
used in LIP to synthesise carbohydrate
what is the role of NAD+
picks up H to become NADH
- needed for e- transport
describe atp and adp cycling
⬆️atp during LDS as adp has phosphate group re-added
⬇️atp during LIS as it releases energy, losing phosphate group
describe NADPH and NADH cycling
⬆️ NADPH during LDS-> loaded with H+ ions split from water
⬇️ NADPH during LIS-> used up and unloading H+ for glucose production
what are enzyme inhibitors?
molecules that decrease enzyme function
- decreases interaction with intended substrate
= decrease or halt chemical pathway
how do competitive inhibitors effect enzymes
- similar shape= binds to active site
- blocks substrate from binding= halt reaction
how do non-competitive inhibitors effect enzymes
- bind to allosteric site (other location, non-active site)= change enzyme shape
- active site changed= substrate doesn’t fit/can’t bind to active site
what is reversible inhibition
bonds formed between enzyme and inhibitor are weak= effect of inhibitor are not permanent
- slows r.o.r (does not stop it forever)
how do you overcome reversible inhibition?
inhibitor and substrate compete for active site=> increase substrate conc
(effects cannot be overcome by increasing substrate conc in irreversible)
what is irreversible inhibition
bonds formed between enzyme and inhibitor are strong= permanent
- stops enzyme catalysed reaction
what is the effect of water availability on photosynthesis
(typically in excess=> doesn’t normally decrease)
-⬇️water in external environment= stomata closes to conserve water
- CO2 cannot enter= conc ⬇️ (used up)
- o2 cannot exit= conc ⬆️ (waste buildup
=> photorespiration ⬆️ photosynthesis⬇️
effect of water availability on c3 plants
c3: imbalanced gases
- rubisco functioning= ⬇️photosynthesis, wasteful photorespiration
effect of water availability on c4 plants
c4: less effected
- adaptions to combat photorespiration= maintain stable photosynthetic rates
- impacted under extreme water stress
effect of water availability on cam plants
mechanisms to photosynthesis with stomata closed
= photosynthetic rate least affected
effect of temperature on c3, c4 and cam plants
⬆️temp= evaporation (water loss effect)
- all plants impacted by temp (each step reliant on enzyme)
(optimal temp is higher in c4 and can plants= better adapted for hotter temps)
