5.1 Respiration in cells

Question 1

what is cellular respiration

Answer 1

A series of chemical reactions that yields ATP which is used as a source of energy for metabolic reactions, and the process also generated heat.

Question 2

what are the different stages in respiration and where do each of them take place

Answer 2

1. glycolysis - cytoplasm
2. link reaction - mitochondrial matrix
3. Krebs cycle - mitochondrial matrix
4. Oxidative phosphorylation - cristae (inner mitochondrial membrane)

Question 3

describe the process of glycolysis

Answer 3

1. Hexose molecules are phosphorylated by ATP
   - 2 X ATP reduced to ADP
2. molecule is broken down to 2 X glycerate 3-phosphate (GP)
3. 2 X glycerate 3-phosphate oxidised to 2 X pyruvate
   - 2 NAD reduced to NADH
   - 4 ADP converted to ATP

Question 4

where do the following take place
1. link reaction
2. Kreb cycle

Answer 4

1. mitochondrial matrix
2. mitochondrial matrix

Question 5

Describe the process of the Link reaction (starting from the end of glycolysis)

Answer 5

1. pyruvate is transported from the cytoplasm to the mitochondrial matrix
2. Pyruvate is decarboxylated and acetate is produced
   - carbon dioxide removed
   - NAD reduced to NADH
3. Acetate combines with coenzyme A and this forms acetyl coenzyme A

Question 6

Describe the process of the Kreb Cycle

Answer 6

1. Acetyl coA combines with a 4C compound to make a 6C compound (citric acid) and releasing coenzyme A
2. the 6C molecule is decarboxylated and dehydrogenated to form 5C acid
   - CO2 is released
   - NADH is released
3. 5C compound goes through a series of reactions to form a 4C compound, releasing another CO2 molecule, NADH, 1 ATP, and FADH2
4. The 4C compound re combines with acetyl coA in the link reaction to restart the process

Question 7

where does the electron transport chain take place

Answer 7

in the inner mitochondrial membrane (cristae)

Question 8

what are the two stages of oxidative phosphorylation

Answer 8

1. the electron transport chain
2. chemiosmosis

Question 9

describe the process of what occurs in the electron transport chain during oxidative phosphorylation

Answer 9

1. NADH, FADH2 and other hydrogen carriers from previous stages release hydrogens
2. Hydrogens split into proton and electron
3. electrons are passed from protein to protein in mitochondrial membrane which releases energy
4. protons use this energy to be actively transported -