Bioenergetics Flashcards
What are the 4 main stages of respiration?
Glycolysis, Link factors, Kreb’s cycle and oxidation phosphorylation
What are the 4 stages of glycolysis?
Phosphorylation, Lysis, Phosphorylation again without ATP, and dehydrogenation and formation of ATP
What happens during stage 1 of glycolysis?
Phosphorylation: 2 ATP molecules release phosphate which binds to the single glucose molecule, this then becomes hexose bisphosphate
Where does glycolysis take place?
In the cytoplasm
Explain stage 2 of glycolysis?
Lysis: The hexose bisphosphate destabilizes and produces two triose phosphates
What happens during stage 3 of glycolysis?
Phosphorylation again: Free inorganic phosphate ions bind to the triose phosphates which makes them become triose bisphosphates
Explain stage 4 of glycolysis?
Dehydrogenation and formation of ATP: 4 phosphate ions are released and become ATP molecules. 2 reduced NADH molecules are released. The triose bisphosphates become dehydrogenated and produce two pyruvates
Where do the pyruvates from glycolysis travel to after completed stage?
The matrix in the mitochondria
What do the pyruvates undergo in the matrix (first step of the link reaction)
Oxidative decarboxylation (CO2 is removed along with hydrogen)
Where is the mitochondria is ATP produced?
Inner mitochondrial membrane
What is released whilst the pyruvates are forming an acetyl group?
CO2 and NADH
What is formed as the final product in the link reaction?
Acetyl Coenzyme A
The third stage of respiration?
The Kreb’s cycle
How many times does the link reaction occur?
Twice as there are two pyruvate molecules from glycolysis
Products of the link reaction?
2 Acetyl CoA, 2 Carbon Dioxide, 2 NADH
What happens to the CO2 released in the link reaction?
It is a waste product
Where do the NADH released in the link reaction go?
To the electron transport chain
Cristae in mitochondria role?
Increase surface area for oxidative phosphorylation
The rhyme to remember the Kreb’s cycle?
DENA DENA A FA NA
The first step of the Kreb’s cycle?
Acetyl group from link reaction combines oxaloacetate to make citrate
What happens to citrate in the Kreb’s cycle?
Its is dehydrogenated and decarboxylated to release CO2, NADH and a 5C compound (DENA)
Which compound releases ATP in the cycle?
The 4C compound that was made from the 5C compound
What happens after the 4C compound releases ATP?
It releases FADH and NADH to become oxaloacetate to start the cycle all over again
The fourth stage of respiration?
Oxidative Phosporylation
First step of OP?
The NADH and FADH from Kreb’s cycle release their hydrogen atoms
What happens to the hydrogen atoms released from NADH and FADH?
They split into protons and electrons, the electrons go into the membrane
The electron transport chain?
3rd stage, electrons move into membrane complexes from hydrogen atoms, they move along the membrane transferring energy at each carrier protein
Where do the hydrogen protons go during OP?
Pumped into the inner membrane space building a pH gradient (acidic inside)
Role of ATP synthase during OP?
Moves the protons back to the matrix, rest of membrane is still IMPERMEABLE to them
What does the movement of hydrogen protons drive?
The synthesis of ATP from ADP and inorganic phosphate
Where do the protons and electrons go after ATP synthase?
They combine with oxygen and form water as the final product
The two ways to produce ATP?
Substrate level phosphorylation and Chemiosmosis
Process of chemiosmosis?
Protons flow through ATP synthase and drive rotation of head piece causing ADP + Pi to form ATP
The force used to drive formation of ATP?
Protonmotive force
Why is water an essential product of respiration?
Maintains proton and electron gradient, allows flow of protons
Why is oxygen essential in aerobic respiration?
Without it NADH and FADH cannot be re-oxidized for reuse, means no coenzymes in Link reaction or Krebs, also maintains gradient
The two types of anaerobic respiration?
Lactate fermentation and ethanol fermentation
Where does lactate fermentation occur?
In muscle cells of mammals
Where does ethanol fermentation occur?
Yeast, plants and fungi
Characteristics of anaerobic respiration?
NO oxygen included, lower ATP yield and occurs in the cytoplasm
Outline the process of lactate fermentation?
Pyruvates get oxidized by reduced NAD providing it with hydrogen, then pyruvate becomes lactate
What is a hepatocyte?
Liver cell
What catalyzes the oxidization of pyruvate?
Lactate dehydrogenase
What occurs if there is a build up of lactate?
Oxygen debt
What does hydrogen become in lactate fermentation?
Hydrogen acceptor for NAD
Hepatocytes, what do they do?
Converts lactate into pyruvates or glycogen, high O2 then pyruvates used for Link and Kreb’s, removal of lactate = heavy breathing, O2 replaces lactate that was converted into pyruvates which results in oxygen debt and fatigue.
Outline the process of ethanol fermentation?
Pyruvate from glycolysis get decarboxylated by decarboxylase to become ethanal, the ethanal then oxides with NAD and is converted into ethanol dehydrogenase to become ethanol
Yeast is described as what?
A facultative anaerobe
What is a facultative anaerobe?
Will aerobically respire to make ATP but when low O2 will switch to anaerobic respiration
What are mammals described as?
Obligate aerobe
What is an obligate aerobe?
Only synthesizes ATP in presence of O2, products need O2 to be broken down
Why is anaerobic respiration useful?
Oxidizes NAD so glycolysis can continue and dehydrogenation reactions
What are some other respiratory substrates?
Triglycerides and proteins
How are triglycerides a respiratory substrate?
They can be hydrolyzed back into fatty acids and glycerol, can be converted into pyruvate to be used in Kreb’s cycle as Acetyl CoA
How are proteins a respiratory substrate?
Hydrolyzed into amino acids and deamination before entering respiratory pathway via pyruvate
Equation to work out the respiratory quotient (RQ)?
CO2 produced/O2 consumed
