8.2

Question 1

Where does glycolysis occur?

Answer 1

cytoplasm

Question 2

What are the processes in respiration?

Answer 2

• glycolysis
• link reaction
• krebs cycle
• electron transport chain
• chemiosmosis

Question 3

oxidative phosphorylation =?

Answer 3

electron chain transport + chemiosmosis

Question 4

What are the components in a mitochondria?

Answer 4

• matrix
• outer & inner membrane
• cristae
• small inner membrane space
• 70s ribosomes
• naked loops of DNA passed unchanged from mother -> child

Question 5

matrix

Answer 5

• where glycolysis occurs

Question 6

electron tomography

Answer 6

is a technique for obtaining 3D structures of sub-cellular structures using micrographs

Question 7

reduction

Answer 7

• electrons are gained
• oxygen is removed
• hydrogen is gained

Question 8

oxidation

Answer 8

• electrons are lost
• oxygen is added
• hydrogen is lost

Question 9

what is the most common hydrogen carrier?

Answer 9

NAD (nicotinamide adenine dinucleotide)

Question 10

what is the most common hydrogen carrier?

Answer 10

• NAD (nicotinamide adenine dinucleotide)

Question 11

what is glycolysis?

Answer 11

is the splitting of glucose into pyruvate

Question 12

pyruvate

Answer 12

3C compounds

- this is then used in the link reaction

Question 13

what happens in glycolysis?

Answer 13

• phosphorylation
• lysis
• oxidation
• ATP formation

Question 14

Describe the processes that occur in the mitochondria when oxygen is present

Answer 14

• pyruvate get decarboxylated/ Co2 is removed and reduced NAD is formed when entering the mitochondrion
• acetyl group reacts w reduced coenzyme A to form acetylCoA
• acetyl CoA enters the Krebs cycle
• 2 Coo2 are removed as waste
• electron rich NADH + H+ molecule is formed
• for each turn of the Krebs cycle, 3NADH + H & 1 FADH2 are formed
• 1 ATP formed per pyruvate each turn (by substrate level phosphorylation)
• reduced NAD & FADH2 enter ETC
• oxidative phosphorylation uses energy released by ETC to produce ATP
• as electrons move along the ETC, protons move into the intermembrane space
• creates proton gradient across the membrane
• ATP synthesised by flow of protons back across the membrane through ATP synthase
• ATP is synthesised by chemiosmosis
• ETC reduces oxygen -> oxygen is the final hydrogen (& electron) acceptor forming water

Question 15

Explain how ATP is generated by the ETC & chemiosmosis

Answer 15

• NAD carriers is reduced by gaining 2 electrons
• reduced NAD is produced in glycolysis
• reduced NAD delivers electrons to the ETC
• ETC is in mitochondrial innermembrane
• electrons release energy as they flow along the chain/from carrier to carrier
• electrons from ETC accepted by oxygen(final electron acceptor)
• proteins in the inner mitochondrial membrane act as proton pumps
• protons are pumped into the intermembrane space
• generate a proton gradient
• ATP synthase is an enzyme located in the inner membrane
• energy released as protons pass down the gradient
• ATP synthase converts ADP to ATP
• oxidative phosphorylation

Question 16

what is oxidative decarboxylation?

Answer 16

process in which carbon dioxide is produced through the removal of a carbon group as a result of oxidation reactions

Question 17

Inner membrane

Answer 17

contains the integral proteins that make up the electron transport chain & ATP synthase → electron transport & chemiosmosis

Question 18

Outer membrane

Answer 18

contains the contents of the mitochondrion -> enables optimal conditions for aerobic respiration. Allows pyruvate to get into the mitochondria for the link reaction

Question 19

What is the role of NADH + H+?

Answer 19

to transfer hydrogen to the ETC

Question 20

What is the main compound used in cell respiration & why?

Answer 20

carbohydrates

• bc lipids are harder to transport & digest
• proteins potentially release toxic nitrogenous compounds when broken down

Question 21

Where does the Krebs cycle take place?

Answer 21

In the fluid matrix of the mitochondria

Question 22

When is energy released in a cell?

Answer 22

ATP releases inorganic phosphate.

Question 23

What is phosphorylation?

Answer 23

The reaction where a phosphate group is added to an organic molecule. The phosphate group is usually transferred to ATP
- prevents diffusion out of cell

Question 24

Phosphorylated molecules

Answer 24

less stable & therefore reacts more easily in the metabolic pathway

Question 25

Phosphorylation(glycolysis)

Answer 25

a hexose sugar(e.g glucose) is phosphorylated by 2 ATP molecules & becomes hexose biphosphate

Question 26

Lysis (glycolysis)

Answer 26

the hexose biphosphate then splits into 2 triose phosphates (3C sugars)

Question 27

Oxidation (glycolysis)

Answer 27

hydrogen removed from the triose phosphosphates via oxidation( NADH becomes NADH+) - 2 molecules of NADH are produced in total (1 from each 3C sugar)

Question 28

ATP formation(glycolysis)

Answer 28

4 ATP molecules are released as the triose phosphates are converted into pyruvate

Question 29

where does the link reaction occur?

Answer 29

in the mitochondrial matrix

Question 30

What is chemiosmosis?

Answer 30

the diffusion of ions across a semi-permeable membrane, through a carrier protein

Question 31

What happens in chemiosmosis

Answer 31

- The proton motive force will cause H+ ions to move down their electrochemical gradient and diffuse back into matrix - This diffusion of protons is called chemiosmosis and is facilitated by the transmembrane enzyme ATP synthase - As the H+ ions move through ATP synthase they trigger the molecular rotation of the enzyme, synthesising ATP

Question 32

What are the distinct steps in the ETC

Answer 32

- proton pump creates an electrochemical gradient (proton motive force) - ATP synthase uses the subsequent diffusion of protons(chemiosmosis) to synthesise ATP - oxygen accepts electrons & protons to form water

Question 33

How does ADP convert into ATP?

Answer 33

- it is phosphorylated