Respiration

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How does glucose enter cells from tissue fluid?
Facilitated diffusion using specific glucose carrier
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Where does glycolysis take place?
Cytoplasm
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What is the first step of glycolysis?
Phosphorylation of glucose to form glucose phosphate, using phosphate from ATP.
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What are the reasons for phosphorylation of glucose?
Keeps glucose in cell by removing “pure” glucose, so glucose will always diffuse down its concentration gradient from the tissue fluid into the cell. Also it activates glucose for biosynthesis reactions.
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What happens to phosphorylated glucose?
Phosphorylated again using another ATP molecule to form two molecules of Triose Phosphate.
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How is ATP released in glycolysis?
Triose sugar is changed in several steps to form Pyruvate
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Why is the hydrogen atom released in glycolysis important?
Stores energy that is later used in the respiratory chain to make more ATP.
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What is the role of coenzyme NAD?
Takes up H atom released in glycolysis to the respiratory chain so becomes NADH.
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Where does the link reaction and the Krebs cycle take place?
Mitochondrial Matrix
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What is the link reaction?
Pyruvate loses a CO2 and a hydrogen to form 2 carbon Acetyl which is compined with CoA so called Acetyl CoA
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What happens when Acetyl CoA enters the Krebs cycle?
2 C acetyl transferred from acetyl CoA to 4 C compound to form 6 C citrate. This is broken down in several steps to re-form 4 C, producing CO2 and H2 . Some ATP made.
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Where does the respiratory chain occur?
Inner mitochondrial membrane
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What is the role of NADH and FADH in the respiratory chain?
Bind to proteins and release their hydrogens as a proton and electron. NAD and FAD returned to Krebs cycle to collect more hydrogen
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What happens to electrons in the respiratory chain?
Passed along the chain, gaining energy which is used to pump protons across membrane by active transport through proteins, forming proton gradient across membrane.
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What is the role of oxygen in the respiratory chain?
Acts as the final electron acceptor and combines with the electrons and protons to form water
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What is the use of the proton gradient?
Stores energy of the electrons. Potential energy of proton gradient used to generate ATP in ATP synthase enzyme which has a proton channel. As protons fall down, energy used to make ATP.
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What is the final yield of ATP from respiration?
32 molecules of ATP.
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Why is ATP an immediate source of energy?
It is soluble so energy can be quickly released quickly.
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Give 3 uses of ATP.
Muscle contraction. Active transport. Biosynthesis (building up larger molecules from smaller ones)
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What happens during anaerobic respiration?
There is no oxygen so the final reaction cannot take place, water won't be made so no electrons can leave respiratory chain so NADH cannot unload H. No NAD so some enzymes of krebs and glygolysis can't work.
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Why are there only 2 ATP molecules made in anaerobic respiration?
Because glycolysis regenerates NAD for it to continue.
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What happens when animals and bacteria respire anaerobically?
Pyruvate is made into lactate which is a reduction so NADH is used and NAD is regenerated to be used in glycolysis. Energy remaining in the lactate molecule can be retrieved when oxygen is available.
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Why can't anaerobic respiration continue for a long time?
Lactate is poisonous and causes muscle fatigue and prevents enzymes working properly.
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What happens when plants and fungi respire anaerobically?
Pyruvate is made into ethanol which is a reduction. NAD regenerated. Ethanol is 2 carbon compound and CO2 is also formed. Reaction is reversible so energy cannot be retrieved by the cells.
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What is another name for Ethanolic anaerobic respiration?
fermentation.
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Card 2

Front

Where does glycolysis take place?

Back

Cytoplasm

Card 3

Front

What is the first step of glycolysis?

Back

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Card 4

Front

What are the reasons for phosphorylation of glucose?

Back

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Card 5

Front

What happens to phosphorylated glucose?

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