ch8: severely lacking in ATP Flashcards
outline control of metabolic pathways (6)
metabolic pathways: a cycle of reactions
diff enzymes control each reaction in the cycle
end product production stops if end product accumulates
accumulation can inhibit 1st enzyme → avoid build-up of intermediates
↑ end product conc → ↑ inhibition
non-competitive:
end product attaches to allosteric site → change shape of the active site → prevent binding of substrate
until the level of the end-product is reduced
negative feedback
reversible
e.g. ATP inhibiting phosphofructokinase
outline how enzymes catalyse reactions (7)
lower activation energy: energy needed to overcome energy barrier that prevents reaction
↑ rate of reaction
substrate joins with enzyme at active site → form enzyme-substrate complex
active site specific for a particular substrate
enzyme binding with substrate brings reactants closer together to facilitate chemical reactions
induced fit model: change in enzyme conformation when enzyme-substrate complex forms → substrate more reactive
remains unchanged at the end of reaction
outline the importance of enzymes to metabolic processes (4)
lower activation energy: energy needed to overcome energy barrier that prevents reaction
↑ rate of reaction
a specific enzyme for each reaction
metabolic process blocked if an enzyme is inhibited/absent
end-product inhibition can control metabolic pathways
differences in metabolism as cells produce different enzymes during differentiation
describe a model that accounts for the ability of enzymes to catalyse reactions (6)
induced fit model
accounts for ability of some enzymes to bind to several substrate
enzyme with active site to which substrates bind
enzyme active site and substrate do not match up exactly
enzyme-substrate complex forms
enzyme changes shape once bound
change in shape facilitates bonds breaking
reduces activation energy
once reaction is complete, products leave and enzyme can work again
explain the effect of inhibitors on the activity of enzymes (8)
google docs
inhibitors ↓ rate of reaction
draw a labelled diagram of a mitochondrion as seen in an electron micrograph (4)
google docs
distinguish between aerobic and anaerobic respiration (5)
google docs
outline the process of glycolysis (6)
occurs in cytoplasm substrate is glucose phosphorylation of glucose → glucose 6-phosphate requires 2 ATP glucose → converted into 2 pyruvates 2 NADH net gain of 2 ATP per glucose
explain the reactions that occur in the matrix of the mitochondrion that are part of aerobic respiration (8)
link reaction: pyruvate combines with coenzyme A → coenzyme A accepts acetyl group to form acetyl CoA
oxidative decarboxylation: pyruvate oxidised to NADH
NADH & carbon dioxide are formed with each decarboxylation
involves oxidation & release of energy
Krebs cycle
acetyl CoA releases acetyl group
acetyl group is joined to a 4-C molecule → 6-C molecule → 5-C molecule → 4-C molecule → original 4-C molecule
ATP formed by substrate level phosphorylation
oxygen accepts electrons
each pyruvate produces 2 carbon dioxide, 3 NADH, 1 FADH2 & 1 ATP
explain how chemical energy for use in the cell is generated by electron transport and chemiosmosis (9)
occurs during aerobic respiration
oxidative phosphorylation = ATP production using energy from oxidising foods during electron transport chain
chemiosmosis = formation of proton gradient by the movement of H+
NAD & FAD is reduced by gaining 2 electrons
NADH delivers electrons to electron transport chain in the inner mitochondrial membrane
electrons release energy as they are passed between carriers along the chain
oxygen is the final electron acceptor
electron carriers act as proton pumps
protons pumped into cristae against conc gradient → generate proton gradient
ATP synthase in inner mitochondrial membrane
energy released as protons go thru ATP synthase back to the matrix
phosphorylates ADP: ADP + Pi → ATP
describe the role of oxygen in aerobic cell respiration (4)
highly electronegative
allows max yield of energy from glucose → complete oxidation
produce water
final electron acceptor at the end of electron transport chain
allows more electrons to be delivered to the electron transport chain
allow NAD/FAD to be generated
help maintain proton gradient across inner mitochondrial membrane by accepting protons
describe two adaptations of the mitochondria, each related to its function (2)
small gap between inner and outer membrane for a proton gradient to develop
cristae in inner membrane → large surface area of inner membrane for chemiosmosis
ATP synthase generates ATP from ADP + Pi
electron transport chains generate a proton gradient for releasing energy from reduced NAD
matrix contains enzymes for Krebs cycle and link reaction
ribosomes for protein synthesis
draw the absorption spectrum of chlorophyll (4)
google docs
draw a labelled diagram of the structure of a chloroplast seen with an electron microscope (4)
google docs
inner and outer membrane: two concentric continuous lines close together
granum: a stack of several disc-shaped subunits
thylakoid: one of the flattened sacs
stroma
70S ribosomes
starch granules
explain the light-dependent reactions/role of water/H+ in photosynthesis/explain chemiosmosis as it occurs in photophosphorylation (8)
water only plays a role in non-cyclic photophosphorylation
cyclic photophosphorylation: electron returns to photosystem I
chemiosmosis = formation of proton gradient by the movement of H+
photophosphorylation = production of ATP
chlorophyll in photosystem II absorb light → photoactivation produce excited electrons
electrons pass along a series of carriers in thylakoid membrane in electron transport chain
require electrons from photolysis
photolysis = splitting of water
produce oxygen and H+
oxygen is released as a waste product
protons pumped across thylakoid membrane → H+ gradient
small thylakoid space enhances gradient
ATP synthase generates ATP due to kinetic energy from movement of H+ as it diffuses through by chemiosmosis
ATP synthase = protein complex in thylakoid membrane
ADP + Pi → ATP
electrons from photosystem II passed to I → photoactivation produce excited electrons
electrons from photosystem I passed to NADP+
NADP+ accepts H+ → NADPH produced → passed to light-independent reactions
ATP and NADPH are used by light independent reactions in the stroma
carbon fixation to RuBP produces glycerate 3-phosphate in Calvin cycle
ATP and NADPH are used to transform glycerate 3-phosphate to triose phosphate
