Respiration Flashcards
What is respiration ?
Respiration is the process by which cells break down simple food molecules, such as sugar, and release the energy they contain.
What is glycolysis ?
Oxidative break down of glucose to pyruvate
Give a summary of glycolysis ?
- Glycolysis takes place in cytoplasm
- Glucose is broken down into pyruvate
- Oxygen is not involved
- Only a small amount of energy is released
- Glycolysis produces both ATP and NADPH
What occurs to the pyruvate 3C after glycolysis ?
-Under anaerobic conditions pyruvate undergoes fermentation
-Fermentation can produce ATP in the absence of oxygen.
- Designed to recycle the NADH so that glycolysis can continue.
Where does the TCA cycle occur ?
In the matrix of the mitochondria
Where is the electron transport chain located ?
In the inner mitochondrial membrane
What does the TCA cycle generates ?
Generates NADH and FADH2 that are passed on to electron - transport chain
What is NADH and FADH are oxidised back to in the electron transport chain ?
NAD and FAD
Explain the process of oxidative phosporylation ?
Electrons from NADH pass down a series of electron carriers and are donated to oxygen to form water
- These carriers are organised into groups of carriers complexes
- Associated with these complexes are proton (H+) pumps
- These proton pumps pump protons out of the mitochondria and thus set up a gradient across the inner membrane
- This proton gradient is used to provide the energy for ATP synthesis
- This process is termed OXIDATIVE PHOSPHORYLATION
What does the TCA cycle generates ?
High energy electrons carried by activated carrier molecules NADH and FADH that are passed on to electron transport chain
What does the movement of electrons coupled with the pumping of protons create ?
A steep proton gradient
What does Atp synthase use to produce ATP ?
ATP synthase uses the energy stored in the electrochemical proton gradient to produce ATP
During NADH oxidation what does an electron pair cause ?
Causes 10 protons to be pumped across the membrane
For each NADH in the oxidative phosphorylation process how many ATP are produced ?
2.5
What is the total amount of ATP produced in respiration ?
30
Explain why NADPH produced in the cytosol yields fewer ATP than NADH produced in mitochondria ?
As mitochondrial inner membrane is not permeable to NADH
What else does respiration do other than providing energy ?
Intermediates are withdrawn from these pathways to provide the carbon for the synthesis of a large number of macromolecules
What are the 3 enzyme steps that control the TCA cycle ?
- PYRUVATE DEHYDROGENASE
- inhibited by ATP, ACETYL CoA and NA
- ISOCIRATE DEHYDROGENASE
-inhibited by NADH and ATP - activated by ADP
- KETOGLUTARATE DEHYDROGENASE
Inhibited by NADH, ATP and Succinylcholine CoA
What are the 3 steps in glycolysis that controls it and can’t be reversed ?
- HEXOKINASE
-PHOSPHOFRUCTOKINASE
-PYRUVATE KINASE
What is HEXOKINASE controlled by ?
- GLC - 6- PHOSPHATASE
What is PHOSPHOFRUCTOKINASE controlled by ?
FRUCTOSE-1,6-BISPHOSPHATASE
What is pyruvate kinase controlled by ?
pep carboxykinase
What allows cells to switch from glucose breakdown to glucose synthesis ?
Feedback regulation
Whats the main mechanism that used to maintain glucose levels in the blood ?
GLUCONEOGENSIS
Occurs when pyruvate, lactate, glycerol and some amino acids get converted to glucose due to fasting, starvation and intense exercise.
What is the key mechanism in recycling lactate ?
Lactate generated primary in muscle cells during intense exercise
- Lactate is moved to liver where it is converted to glucose through GLUCONEOGENESIS
Glucose then returns to the muscle cells where it is used for glycolysis.
