Respiration (Module 5)

Question 1

Need for cellular respiration:

Answer 1

All organisms (animals, plants, microorganisms) need to respire to release energy for metabolic use, for example active transport, digestion and movement, anabolic reactions (building of polymers), cilia movement

Question 2

Site of respiration in eukaryotes and prokaryotes:

Answer 2

Eukaryotes: cytoplasm and mitochondria
Prokaryotes: cytoplasm and cell membrane

Question 3

Structure of mitochondria:

Answer 3

Inner and outer mitochondrial membrane, cristae, matrix

Question 4

Outer membrane of mitochondria:

Answer 4

Contains transport proteins that allow the active transport of pyruvate into the cystol (cytoplasm of mitochondria)

Question 5

Inner membrane of mitochondria:

Answer 5

Contains electron transport chain and ATP synthase

Question 6

Cristae:

Answer 6

Inner folding of membrane to increase SA:V

Question 7

Intermembrane space of mitochondria:

Answer 7

Increases hydrogen ion gradient for chemiosmosis

Question 8

Matrix:

Answer 8

Contains suitable enzymes and pH for Krebs cycle

Question 9

Site of glycolysis:

Answer 9

Cytoplasm of the cell

Question 10

Glycolysis summary:

Answer 10

Phosphorylation, lysis, oxidation, ATP formation (anerobic respiration)

Question 11

Glycolysis in more detail:

Answer 11

PHOSPHORYLATION: Hexose sugar is phosphorylated by 2 molecules of ATP, which is less stable (so cannot move outside of the cell) to form hexose biphosphate
LYSIS: Hexose biphosphate (6C) is broken down to two 3C molecules, triose phosphate
OXIDATION: Two hydrogen atoms are removed from the triose phosphate to reduce NAD (one triose phosphate reduces one triose phosphate)
ATP FORMATION: Substrate level phosphorylation occurs to form 2 ATP per 3C molecule.
*At the end of glycolysis, 2 pyruvate molecules are formed

Question 12

Steps of aerobic respiration:

Answer 12

Link reaction (oxidative decarboxylation), Krebs cycle, electron transport chain

Question 13

Site of the link reaction:

Answer 13

Within the mitochondrial matrix

Question 14

Link reaction in more detail:

Answer 14

• Pyruvate enters mitochondrial matrix via active transport (carrier proteins)
• Pyruvate then undergoes oxidative decarboxylation (both hydrogen and CO2 are removed)
• The removed hydrogen reduces NAD to NADH
• The decarboxylation causes the molecule to go from 3C to 2C
• The 2C molecule is bound to coenzyme A to form acetylCoA

Question 15

Site of Krebs cycle:

Answer 15

Mitochondrial matrix:

Question 16

Processes of the Krebs cycle:

Answer 16

Substrate level phosphorylation, decarboxylation, dehydrogenation

Question 17

Krebs cycle in detail:

Answer 17

• AcetylCoA (2C) joins oxaloacetate (4C) to form citrate (6C)
• Citrate undergoes decarboxylation and dehydrogenation to reduce NAD and forms a 5C molecule
• The 5C molecule undergoes dehydrogenation to reduce NAD and decarboxylation
• Substrate level phosphorylation occurs to form ATP
• Dehydrogenation occurs twice to reduce NAD and FAD to reform oxaloacetate (4C)