Respiration Flashcards
Role of the outer membrane of mitochondria
- separate contents of mitochondria from rest of cell
- create a cellular compartment with idea conditions for aerobic respiration
Role of innermembrane of mitochondria
- contains electron transport chains and ATP synthase
Cristae
- projections/infolding of inner membrane
- increases the surface area available for oxidative phosphorylation
Matrix
- contains enzymes for the Krebs cycle and link reaction
- contains mitochondrial DNA and ribosomes
- fluid of the mitochondria
Summary of aerobic respiration
glycolysis - link reaction - Krebs cycle - oxidative phosphorylation
Summary of anaerobic respiration
glycolysis - fermentation
Glycolysis
- first stage
- occurs in cell cytoplasm
- splits glucose into 2 pyruvate molecules
- produces 2x NADH
- net yield 2 ATP
Link reaction
- links anaerobic glycolysis to aerobic respiration stages
- occurs in mitochondrial matrix
- pyruvate is decarboxylated and reduced to form acetate
- acetate is then bound to coenzyme A
- produces acetyl coA, 1x CO2, 1x NADH (per each molecule of pyruvate)
Kerbs cycle
- occurs in mitochondrial matrix
- involves decarboxylation, dehydrogenation and substrate level phosphorylation
- Produces CoA, 3x NADH, 1x ATP, 1x reduced FAD, 2x C02 (per cycle)
Role of NAD in respiration
- accepts protons and electrons released during glucose breakdown
- role in all stages of cellular respiration
- accepts 1 H
Role of FAD in respiration
- Only accepts hydrogens in the Krebs cycle
- accepts 2 hydrogens
How many ATP molecules are synthesised from reduced NAD and reduced FAD
- reduced NAD results in synthesis of 3 ATP molecules (or 2.5)
- reduced FAD results in synthesis of 2 ATP molecules (or 1.5)
Net yield of ATP from aerobic and anaerobic respiration
- Aerobic= 38
- anaerobic= 2
Different types of organisms (respiration wise)
- Obligate anaerobes = can’t survive in the presence of oxygen e.g. some prokaryotes
- Facultative anaerobes = synthesis ATP by aerobic respiration in O2 present, but can switch to anaerobic in absence e.g. yeast
- Obligate aerobes= can only synthesis ATP in presence of oxygen e.g. mammals
Fermentation
- a form of anaerobic respiration
- process by which complex organic molecules are broken into smaller inorganic molecules without the use of oxygen or an electron transport chain
- organic compounds not fully broken down, so less ATP produced
- small quality of ATP produced by substrate level phosphorylation
What is alcoholic fermentation
- occurs in yeast and some plant root cells
- end products= CO2 and ethanol
What is lactate fermentation
- occurs in animal cells
- produces lactate
How does a lack of oxygen lead to stopping of aerobic respiration
- no oxygen to act as the final electron acceptor
- flow of electrons and ATP synthesis stops
- reduced NAD and FAD are no longer able to be oxidised as nowhere for electrons to go
- NAD and FAD not regenerated so decarboxylation and oxidation of pyruvate and Krebs cycle stops
Features of lactate fermentation
- pyruvate acts as a hydrogen acceptor- takes hydrogen from NADH
- reaction catalysed by lactate dehydrogenate
- pyruvate is converted to lactate
- NAD is regenerated- keeps glycolysis going, so small net yield of ATP
- reversible process
Why can’t lactate fermentation occur indefinitely
- the reduced ATP quantity not enough to maintain vital processes for long
- lactic acid accumulation causes a fall in pH so enzymes don’t function efficiently
Summary of Lactate fermentation
pyruvate + hydrogen = lactate
Features if alcoholic fermentation
- irreversible process
- pyruvate is converted to ethanal
- catalysed by pyruvate decarboxylase
- ethanal can accept a H ion from NADH, forming ethanol
- regenerated NAD can now act as a coenzyme in glycolysis
- can occur indefinitely
- however, ethanol becomes toxic to yeast cells if accumulates over 15%
Respiratory quotient equation
= CO2 produced / O2 consumed
What is the average respiratory quotient for carbs, lipids, proteins, normal respiration and anareobic
- carbs= 1.0
- protein= 0.9
- lipids= 0.7
- normal activity (aerobic)= 0.8/0.9
- anaerobic respiration= >1
