5-12 Respiration Flashcards by Marli Matthews

What are the 4 stages of aerobic respiration?

Glycolysis
Link reaction
Krebs cycle
Oxidative phosphorylation

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What is the first stage of Glycolysis?

Phosphorylation of glucose to glucose phosphate

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What is the second stage of Glycolysis?

splitting the phosphorylated glucose

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What is the third stage of Glycolysis?

oxidation of triose phosphate

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What is the fourth stage of Glycolysis?

production of ATP

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What are the products of Glycolysis?

2 molecules of ATP
2 molecules of NADH
2 molecules of pyruvate

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What occurs during the link reaction?

Pyruvate is oxidised to acetate, it then loses a carbon atom and two hydrogens and combined with CoenzymeA to make acetyl CoA

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What are the products of the link reaction?

acetyl CoA
NADH
1 molecule of CO2

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What is the first stage of the Krebs cycle?

Acetyl CoA combines with a 4-carbon molecule to make a 6-carbon molecule

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What is the second stage of the Krebs cycle?

the 6-carbon molecule loses carbon dioxide and hydrogen to give a 4-carbon molecule and a molecule of ATP due to substrate-level phosphorylation

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What is the third stage of the Krebs cycle?

the 4-carbon molecule can then combine with another acetyl CoA

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What are the products of the Krebs cycle?

reduced coenzymes
1 molecule of ATP
3 molecules of carbon dioxide

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What is the significance of the Krebs cycle?

breaking down macromolecules
it produces ATP
it regenerates the 4-carbon molecule to continue the cycle

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What is the equation for aerobic respiration?

C6H12O6 + 6O2 = 6CO2 + 6H2O

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Where does respiration take place?

In the mitochondria

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What is substrate level phosphorylation?

Where phosphate comes from the other molecules in the reaction
When the phosphate used to phosphorylate ADP comes from an intermediate molecule

What is oxidative phosphorylation?

Energy comes from the movement of electrons down the concentration gradient
Phosphate ions can come from anywhere

What are the alternative respiratory substances?

Lipids and proteins

How are lipids used as respiratory substances?

Lipids are hydrolysed to glycerol and fatty acids
Glycerol is phosphorylated and enters glycolysis

The fatty acid component is broken down into 2C fragments: link reaction

Lipids release over double the energy of the same mass of carbohydrate

How are proteins used as respiratory substances?

Protein is hydrolysed to amino acids
It is deaminated before entering the respiratory pathway at different points depending on the number of carbon atoms

3C carbons are converted to pyruvate
4C and 5C become intermediates

Which parts of aerobic respiration can not continue when there is an absence of oxygen? Why is this?

The Krebs cycle and the electron transfer chain

Because soon all the FAD and NAD will be reduced

What are the two types of anaerobic respiration?

In plants and some microorganisms: the pyruvate is converted to ethanol and carbon dioxide
In animals: the pyruvate is converted to lactate

What happens to the lactate produced during anaerobic respiration?

It is oxidised back to pyruvate
This can then either be oxidised further to release energy or converted into glycogen

This happens when oxygen becomes available again

What are the negative effects of the buildup of lactate?

It will cause cramp and muscle fatigue

It is an acid so causes pH changes which affects enzymes

What are the two ways in which energy from cellular respiration is derived?

Substrate level phosphorylation in glycolysis and the Krebs cycle Oxidative phosphorylation in the electron transfer chain

What is the process of glycolysis?

Glucose has 6 carbons ATP adds phosphate which splits it into two 3C molecules (triose phosphate) Hydrogen (H+) is removed from each of the triose phosphates which reduces NAD to form NADH (reduction) Phosphate is combined with ATP to produce 2 ATP per 3C molecule (phosphorylation) Pyruvate is the final product

What is the process of the link reaction?

Starts off with pyruvate (3C) It loses a carbon dioxide molecule Two hydrogens are lost which are then accepted by NAD to form NADH The 2C acetate combines with coenzyme A to form acetyl coenzyme A

What is the overall word equation of the link reaction?

Pyruvate + NAD + Coenzyme A = Acetylcoenzyme A + NADH + CO2

What is the chemiosmotic theory of the electron transport chain?

The hydrogen atoms produced during glycolysis and the Krebs cycle combine with the coenzymes NAD and FAD NADH and RedFAD donate the electrons of the hydrogen atoms to the first molecule in the electron transport chain Electrons pass along a chain of electron transfer chain carrier molecules in a series of oxidation-reduction reactions The electron movement releases energy which causes the active transport of protons across the inner mitochondrial membrane and into the inter-membrane space The protons accumulate in the inter-membrane space before they diffuse back into the mitochondrial matrix through ATP synthase channels embedded in the inner mitochondrial membrane At the end of the chain, the electrons combine with these protons and oxygen to form water Oxygen is therefore the final acceptor of electrons

What are the alternative respiratory substances?

Lipids and proteins

What happens to the lactate produced during anaerobic respiration?

It is oxidised back to pyruvate This can then either be oxidised further to release energy or converted into glycogen This happens when oxygen becomes available again

What are the negative effects of the buildup of lactate?

It will cause cramp and muscle fatigue | It is an acid that causes pH changes which affect enzymes

What are the two ways in which energy from cellular respiration is derived?

Substrate level phosphorylation in glycolysis and the Krebs cycle Oxidative phosphorylation in the electron transfer chain