Respiration Flashcards
examples of transporting substances across membranes
active transport using sodium-potassium pump in cell membrane
exocytosis of digested bacteria from WBC
state 4 reasons why we need respiration
transporting substances across membranes
anabolic reactions
movement
maintaining body temp
examples of anabolic reactions
synthesis of DNA from nucleotides
synthesis of proteins from amino acids
examples of movement
cellular movement of chromosomes via spindle
mechanical contraction of muscles
what are the stages of aerobic respiration
glycolysis
link reaction
krebs cycle
oxidative phosphorylation
how large are the mitochondria
0.5 – 1 micrometres in diameter
describe the structure of a mitochondria
two phospholipid bilayers - outer + inner membrane
intermembrane space
matrix
cristae
what is cristae
projections of the inner membrane that increase the surface area for oxidative phosphorylation
describe the inner mitochondrial membrane
Folded (cristae)
- large surface area – membrane hold many chains / enzymes
Less permeable
Site of electron transport chain
Location of ATP synthase enzymes
describe the outer mitochondrial membrane
Smooth
Permeable to some small molecules
compartmentalisation
describe the inter-membrane space
proteins pumped into this space by electron transport chain
Has low pH – high conc of protons
Conc gradient across inner membrane form during oxidative phosphorylation – essential for ATP synthesis
describe the matrix
Aqueous solution in inner membranes of mitochondrion
Has ribosomes / enzymes / circular mitochondrial DNA
enzymes for krebs cycle + links reaction
label this
overall description of glycolysis
phosphorylation + splitting of glucose
overall description of link reaction
decarboxylation + dehydrogenation of pyruvate
overall description of krebs cycle
cyclical pathways with enzyme-controlled reactions
overall description of oxidative phosphorylation
production of ATP through oxidation of hydrogen atoms
where does glycolysis occur
cell cytoplasm
where does link reaction occur
matrix of mitochondria
where does krebs cycle occur
matrix of mitochondria
where does oxidative phosphorylation occur
inner membrane of mitochondria
what are the 4 stages of glycolysis
phosphorylation
lysis
oxidation
dephosphorylation
what happens in phosphorylation - glycolysis
Glucose phosphorylated by 2 ATP
Forms fructose / hexose bisphosphate – 6C
Glucose + 2ATP → Fructose bisphosphate
what happens in lysis - glycolysis
Fructose bisphosphate splits into two molecules of triose phosphate 3C
Another phosphate group added to each one – 2 triose bisphosphate
Fructose bisphosphate → 2 Triose phosphate
what happens in oxidation - glycolysis
Hydrogen removed from each molecule of triose phosphate + transferred to coenzyme NAD - triose phosphate is oxidised
Forms 2 molecules of reduced NAD
4H + 2NAD → 2NADH + 2H+
what happens in dephosphorylation - glycolysis
Phosphates transferred from intermediate substrate molecules
Forms 4 ATP through substrate – linked phosphorylation
Forms 2 pyruvate molecules 3C
describe glycolysis in full
- Phosphorylation
Glucose phosphorylated by 2 ATP
Forms fructose / hexose bisphosphate – 6C
Glucose + 2ATP → Fructose bisphosphate
- Lysis
Fructose bisphosphate splits into two molecules of triose phosphate 3C
Another phosphate group added to each one – 2 triose bisphosphate
Fructose bisphosphate → 2 Triose phosphate
- Oxidation
Hydrogen removed from each molecule of triose phosphate + transferred to coenzyme NAD - triose phosphate is oxidised
Forms 2 molecules of reduced NAD
4H + 2NAD → 2NADH + 2H+
- Dephosphorylation
Phosphates transferred from intermediate substrate molecules
Forms 4 ATP through substrate – linked phosphorylation
Forms 2 pyruvate molecules 3C
what are the end products per glucose molecule of glycolysis
2 pyruvate molecules
Net gain of 2 ATP
2 reduced NAD
draw out glycolysis in a diagram
what type of reaction is glycolysis
anaerobic
what is the link reaction also known as
oxidative decarboxylation
what type of reaction is the link reaction
aerobic
describe the link reaction in full
(2) Pyruvate enters mitochondrial matrix via active transport
Carbon dioxide is removed
Hydrogen removed – oxidative decarboxylation
Hydrogens accepted by NAD – form NADH
The 2C acetyl group is bound by coenzyme a forming acetylcoenzyme A (acetyl CoA)
Acetyle CoA delivers acetyl group to krebs cycle
put the link reaction into a digram
what is CoA
Consists of nucleoside (ribose + adenine ) + a vitamin
what are the end products of the link reaction per glucose molecule
2 Acetyl CoA molecules
2 Carbon dioxide molecules
2 Reduced NAD molecules
describe the krebs cycle
Acetyl CoA delivers acetyl group to krebs cycle
2C acetyl group combines with 4C oxaloacetate to form 6C citrate
Citrate molecule undergoes decarboxylation + dehydrogenation and is reverted back to oxaloacetate via redox reactions
more specifically - describe the regeneration of oxaloacerate
- Decarboxylation of citrate
Releases 2 molecules of carbon dioxide as waste gas
- Oxidation / dehydrogenation of citrate
Releases H atoms that reduce coenzyme NAD and FAD
8H + 3NAD + FAD → 3NADH + 3H+ + FADH2
- Substrate – level phosphorylation
Phosphate transferred from intermediate to ADP
Forms 1 ATP
draw out the krebs cycle
what are the end products of the krebs cycle per gluclose molecule
4 molecules of carbon dioxide
6 NADH molecules
2 FADH molecules
2 ATP molecules
conenzymes in respiration
CoA
NAD
FAD
importance of CoA
CoA binds to acetyl group (2C) + forms acetyl CoA
Supplied acetyl group to krebs cycle
importance of NAD / FAD
Transfer the hydrogen atoms they got when they were reduced to the electron transport chain on inner mitochondrial membrane
how much reduced NAD is formed throughout respiration and where from
2 x 1 = 2 from Glycolysis
2 x 1 = 2 from the Link Reaction
2 x 3 = 6 from the Krebs cycle
how much reduced FAD is formed throughout respiration and where from
2 x 1 = 2 from the Krebs cycle
what is the model of oxidative phosphorylation
chemiosmotic theory
describe the full process of oxidative phosphorylation
Hydrogen atoms donated by NADH + reduced FAD
Hydrogen atoms split into H+ and electrons
High energy electrons enter electron transport chain
Release energy as they move through
Released energy used to actively transport protons across inner mitochondrial membrane = from matrix into intermembrane space
Conc gradient established
Protons return to matrix via facilitated diffusion – through channel protein ATP synthase
movement of protons down conc gradient provides energy for ATP synthesis
oxygen – final electron acceptor
combines with protons + electrons at end of transport chain to form water
describe the electron transport chain
Made up of series of membrane proteins / electron carriers
Positioned close together
why are the H+ needed to be actively transported across the membrane
Inner membrane impermeable to H ions so electrons carriers are needed to pump proton
what membrane are these protons being pumped across
from matrix into intermembrane space
across inner membrane
talk through this diagram
what are the consequences of lack of oxygen
no final acceptor of electrons
electron transport chain stops functioning
No more ATP is produced via oxidative phosphorylation
Reduced NAD and FAD aren’t oxidised by an electron carrier
No oxidised NAD and FAD are available for dehydrogenation in the Krebs cycle
Krebs cycle stops
what are Obligate anaerobe
can’t survive in oxygen – prokaryotes
what are Facultative anaerobes
synthesis ATP by aerobic respiration if oxygen is present but can switch to anaerobic in absence – yeast
what are obligate aerobe
only make ATP in presence of oxygen
organism as a whole
what is fermentation
process by which complex organic compounds are broken down into simpler inorganic compounds without oxygen or electron transport chain
how is ATP produced in fermentation
by substrate-level phosphorylation
Production of ATP with transfer of phosphate group from short-lived, highly reactive intermediate – creatinine phosphate
what is alcoholic fermentation
Pyruvate converted to ethanal
(Catalysed by pyruvate decarboxylase)
Ethanal then accept hydrogen atom from reduced NAD – ethanol
Regenerated NAD – enzyme + glycolysis occurs
why is less ATP produced in fermentation than aerobic respiration
glucose not fully broken down
what type of reaction is alcoholic fermentation
Irreversible + can continue indefinitely
disadvantages of alcoholic fermentation
- less ATP produced
- ethanol - toxic to yeast
how does lactate fermentation work
Pyruvate – act as hydrogen acceptor - takes hydrogen from reduced NAD
(Catalysed by lactate dehydrogenase)
Pyruvate then converted into lactate
NAD regenerated
Glycolysis can continue
where does lactate fermentation occur
in mammals
disadvantages of lactate fermentation
Cannot occur indefinitely
Reduced quality of ATP produced not enough to maintain metabolic process
Accumulation of lactic acid – reduced pH – proteins denaturing
Respiratory enzymes + muscle filaments will cease to function at low pH
what catalyses lactate fermentation
lactate dehydrogenase
what catalyses alcoholic fermentation
pyruvate decarboxylase
compare aerobic + anaerobic respiration
stages
oxidation of glucose
total ATP produced
location
products
examples of respiratory substrates
Glucose
Other carbohydrates
Lipids
Proteins
(Only respired aerobically when all other substrates used up // Structural + functional roles )
which respiratory substrate has the greatest + lowest energy values
why is there a difference in energy values
Substrate molecule broken down + hydrogen atoms available
Hydrogen carrier molecules – NAD / FAD – gain these hydrogens
transfer them to the inner mitochondrial membrane
reduced NAD + FAD release hydrogen atoms - split into protons + electrons
protons pumped across inner mitochondrial membrane into intermembrane space
proton gradient – chemiosmosis – ATP production
protons oxidised to form water
molecules with higher hydrogen content – greater proton gradient + form MORE ATP
why does lipids have the greatest energy value
fatty acids in lipids – long hydrocarbon chain – lots of hydrogen atoms
what can pyruvate be used for
what is the formula for the respiratory quotient
what will cause different RQ values
different number of carbon-hydrogen bonds
more carbon-hydrogen bonds means more hydrogen atoms in proton gradient
more ATP produced
more oxygen therefore needed to breakdown molecule
RQ value of glucose + why
glucose – equal amount of carbon dioxide + oxygen
RQ value of 1
what substrate has the lowest RQ value
lipids
why is respiration not entirely efficient
some H+ leak back into matrix
