Question

Describe the process of glycolysis. What part of the cell does this reaction take place in?

Describe the Krebs cycle. What part of the cell does this reaction take place in?

Describe the electron transport chain. What part of the cells does hit reaction take place in?

What molecule stores the energy that is generated during cellular respiration?

Answer 1

1.)
Step 1 - Glucose is phosphorylated. Two phosphate groups are added to glucose to form hexose biphosphate. These two phosphate groups are provided by two molecules of ATP.

Step 2 - Lysis of hexose biphosphate. Hexose biphosphate splits into two molecules of triose phosphate.

Step 3 - Each triose phosphate molecules is oxidised. Two atoms of hydrogen are removed from each molecule. The energy released by the oxidation is used to add another phosphate group to each molecule. This will result in two 3-carbon compounds, each carrying two phosphate groups. NAD+ is the hydrogen carrier that accepts the hydrogen atoms lost from each triose phosphate molecule.

Step 4 - Two pyruvate molecules are formed by removing two phosphate groups from each molecule. These phosphate groups are given to ADP molecules and form ATP.

Glycolysis occurs in the cytoplasm of cells. Two ATP molecules are used and 4 ATP molecules are produced. Therefore there is a net yield of two ATP molecules. Also, two NAD+ are converted into NADH + H+ during glycolysis.

Answer 2

2.)
The Krebs Cycle

Step 1 - In the first stage of the Krebs cycle, the acetyl group from acetyl CoA is transferred to a four carbon compound. This forms a six carbon compound.

Step 2 - This six carbon compound then undergoes decarboxylation (CO2 is removed) and oxidation (hydrogen is removed) to form a five carbon compound. The hydrogen is accepted by NAD+ and forms NADH + H+.

Step 3 - The five carbon compound undergoes decarboxylation and oxidation (hydrogen is removed) again to form a four carbon compound. The hydrogen is accepted by NAD+ and forms NADH + H+.

Step 4 - The four carbon compound then undergoes substrate-level phosphorylation and during this reaction it produces ATP. Oxidation also occurs twice (2 hydrogens are removed). The one hydrogen is accepted by NAD+ and forms NADH + H+. The other is accepted by FAD and forms FADH2. The four carbon compound is then ready to accept a new acetyl group and the cycle is repeated.

The carbon dioxide that is removed in these reactions is a waste product and is excreted from the body. The oxidations release energy which is then stored by the carriers when they accept the hydrogen. This energy is then later on used by the electron transport chain to produce ATP.

Answer 3

3.)
The Electron Transport Chain

Inside the inner membrane of the mitochondria there is a chain of electron carriers. This chain is called the electron transport chain. Electrons from the oxidative reactions in the earlier stages of cell respiration pass along the chain. NADH donates two electrons to the first carrier in the chain. These two electrons pass along the chain and release energy from one carrier to the next. At three locations along the chain, enough energy is released to produce ATP via ATP synthase. ATP synthase is an enzyme that is also found in the inner mitochondrial membrane. FADH2 also donates electrons but at a later stage than NADH. Also, enough energy is released at only two locations along the chain by electrons from FADH2. The ATP production relies on energy release by oxidation and it is therefore called oxidative phosphorylation.

Answer 4

4.)
ATP

Answer 5

♥.♥

Answer 6

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Answer 7

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Answer 8

awee ♥♥♥ :)