Respiration

Question 1

4 stages of respiration?

Answer 1

Glycolysis, links reaction, Krebs cycle, oxidation phosphorylation

Question 2

Equation for respiration

Answer 2

Glucose + oxygen —-> carbon dioxide + water (exothermic)

Question 3

Structure of ATP?

Answer 3

Adenine base, 3 phosphate molecules bonded in a row to the pentose sugar

Question 4

What is ATP used for?? 3 categories

Answer 4

Muscle contraction
Active transport
Biosynthesis (building molecules like proteins synthesis, DNA replication )

Question 5

What are ATPase enzymes used for??

Answer 5

Used to catalyse the hydrolysis of ATP into ADP+Pi and energy

Question 6

What is metabolism?

Answer 6

All the chemical reactions on going in a cell

Question 7

What is a metabolite?

Answer 7

An intermediate in metabolic pathways eg pyruvate

Question 8

Structure of mitochondria:

Answer 8

Double membrane
Stalked particles (ATP synthase) on cristae
folded projections of inner membrane/ Cristae
Matrix
Porins (protein channels in the outer membrane)

Question 9

Where does the Krebs cycle take place?

Answer 9

Matrix

Question 10

What are porins and stalked particles?

Answer 10

Porins are protein channels in outer membrane of mitochondria that let most small molecules in
Stalked particles are enzyme complexes of ATP synthase on the cristae

Question 11

Benefit of compartmentation in respiration?

Answer 11

It keeps metabolites (products and reactants of each stage) separate as each stage occurs at a different location

Question 12

Do Glycolysis, Krebs cycle and Electron transport chain occur in anaerobic conditions?

Answer 12

Glycolysis is anaerobic

Krebs cycle and electron transport chain are aerobic

Question 13

How does glucose enter the cell and where from?

Answer 13

Facilitated diffusion through a specific carrier protein from the tissue fluid

Question 14

How does insulin effect regulate the amount of glucose that enters a cell

Answer 14

The hormone controls the specific glucose carrier proteins in the membrane of the cell

Question 15

Summary of glycolysis

Answer 15

Glucose -> phosphorylated glucose-> GALP (3C)->GP (3C, acid)->Pyruvate (3C)

Question 16

Phosphorylation of glucose, how and why?

Answer 16

Adding a phosphate group to glucose

1) removes pure glucose, increasing the conc gradient, so pure glucose wants to diffuse into the cell from tissue fluid
2) activates the glucose for biosynthesis

Question 17

How is GALP formed?

Answer 17

Glucose +ATP -> phosphorylated glucose
PG + ATP-> 2GALP
Therefore Glucose + 2ATP -> 2GALP (3C)

Question 18

What happens when GALP is oxidised?

Answer 18

Forms GP (glycerate 3 phosphate) an acid
This releases energy to form ATP and a H+ ion
The hydrogen is taken and carried to the electron transport chain by coenzyme NAD which gets reduced in the process (NADH)

Question 19

What happens to GP?

Answer 19

GP is simply converted into Pyruvate (3C)

ATP is made

Question 20

What is the reverse of glycolysis?

Answer 20

Gluconeogenesis (turning pyruvate into glucose)

Question 21

What happens to pyruvate in the absence of oxygen?

Answer 21

Converted into lactate or ethanol

Question 22

The link reaction links glycolysis to the Krebs cycle, but what happens in this stage?

Answer 22

Pyruvate enters mitochondrial matrix and is converted into Acetyl CoA

Question 23

Describe the change of pyruvate in the links reaction, and what happens to the products

Answer 23

Pyruvate loses CO2 and H+
Forming an acetyl compound (2C) which binds to a coenzymeA forming acetyl coA
- CO2 diffuses by lipid diffusion into the tissue fluid and then blood -> out the lungs
- H+ is taken up by NAD becoming reduced

Question 24

Summary of Krebs cycle

Answer 24

Acetyl coA binds with a 4C compound which is then broken down to reform the 4C compound releasing ATP, H+ and CO2

Question 25

What is the name of the 4 carbon compound that binds with acetyl coA and what does it form?

Answer 25

Oxaloacetate | Forming citrate

Question 26

What happens to the H+ made in the Krebs cycle

Answer 26

Taken up by FAD or NAD to the electron transport chain

Question 27

How many integral proteins consist of the electron transport chain?

Answer 27

5 | 4- protein carriers and ATP synthase

Question 28

Why is oxygen needed in the electron transport chain?

Answer 28

Oxygen is the final electron acceptor which also binds to Hydrogen to form water

Question 29

Describe how the proton gradient is made in the electron transport chain:

Answer 29

- FADH and NADH bind to integral proteins releasing their H+ and electrons (becoming oxidised) - Electrons pass along the chain of integral proteins in the inner membrane, exciting the proteins to move the Protons across the inner mitochondrial membrane by active transport forming a proton gradient

Question 30

What is the purpose of FADH or NADH?

Answer 30

To shuttle H+ and electrons back and forth from the Krebs cycle to the electron transport chain

Question 31

How is ATP made from the proton gradient in electron transport chain?

Answer 31

As 4 protons travel down the conc. gradient through the ATP synthase enzyme channel across the inner mitochondrial membrane they spin the globular head which generates 1 ATP

Question 32

Why is the synthesis of ATP called oxidative phosphorylation?

Answer 32

Because in the ETC oxygen (the final electron acceptor) is used to phosphorylated (add a phosphate group) to ADP

Question 33

What is chemiosmosis?

Answer 33

Storing energy by creating a proton gradient across a membrane

Question 34

Summary of oxidative phosphorylation:

Answer 34

1) NADH oxidised releasing H+ and e- returning to Krebs cycle 2) electron passes along the chain of proteins exciting them 3) Oxygen combines with hydrogen and the electron to form water 4) the energy of the electron is stored as a proton gradient and then used to make ATP

Question 35

Why is Oxygen needed for respiration to work?

Answer 35

Oxygen accepts electrons and H+ to form water - without oxygen electrons don’t leave the ETC so no NADH can unload any H+ - so there’s no NAD at Krebs cycle as bottle neck of NADH at ETC - Without coenzymes NAD the enzymes in Krebs cycle and glycolysis don’t work

Question 36

How many ATPs does anaerobic respiration make?

Answer 36

2

Question 37

What co enzyme is needed for glycolysis?

Answer 37

NAD

Question 38

How is reducing pyruvate into lactate an advantage?

Answer 38

This oxidises NADH and therefore regenerates NAD so more glycolysis can occur generating 2 ATP

Question 39

What happens in anaerobic respiration in animals and bacteria?

Answer 39

Pyruvate is reduced into lactic acids | NAD is regenerated to be reused in glycolysis

Question 40

How does anaerobic respiration lead to cramp?

Answer 40

Produces lactic acid which lower pH in muscle slowing down enzymes causing cramp and fatigue

Question 41

What are the differences between anaerobic respiration in plants and humans?

Answer 41

Plant: produces ethanol and CO2, irreversible reaction Human: produces lactate, reversible (can be oxidised back in pyruvate)

Question 42

Similarities between anaerobic respiration in plants and animals

Answer 42

Reduction of pyruvate oxidises NADH into NAD to repeat glycolysis

Question 43

Explanation of anaerobic respiration in plants from pyruvate:

Answer 43

Pyruvate is reduced into ethanol and CO2 | This oxidises NADH regenerating NAD for glycolysis

Question 44

Another name for anaerobic respiration in plants?

Answer 44

Fermentation

Question 45

How many ATP are made in complete respiration

Answer 45

32

Question 46

What is substrate level phosphorylation?

Answer 46

When ATP molecules are made directly by enzymes in glycolysis or Krebs cycle