M5 Ch18 Respiration

Question 1

What are the four stages of respiration?

Answer 1

4 stages of respiration:
-Glycolysis
-Link Reaction
-Krebs Cycle
-Electron transport chain

Question 2

What are the stages involved in glycolysis?

Answer 2

Glycolysis stages:
1 = Phosphorylation
2 = Lysis
3 = Phosphorylation
4 = Dehydrogenation and formation of ATP

Question 3

Glycolysis - Stage 1 - Phosphorylation

Answer 3

Glycolysis - Stage 1 - Phosphorylation:
-Glucose phosphorylated by the addition of two phosphates from 2 ATP molecules
-Glucose split by hydrolysis
-Hexose Biosphate created and 2 molecules of ATP are used up

Question 4

Glycolysis - Stage 2 - Lysis

Answer 4

Glycolysis - Stage 2 - Lysis
-Molecule destabilised and split into 2 triose phosphate (2xTP)

Question 5

Glycolysis - Stage 3 - Phosphorylation

Answer 5

Glycolysis - Stage 3 - Phosphorylation:
-Another phosphate added to each TP to form triose biphosphate

Question 6

Glycolysis - Stage 4 - Dehydrogenation and formation of ATP

Answer 6

Glycolysis - Stage 4 - Dehydrogenation and formation of ATP:
-Two triose biphosphates are oxidised (H removed) to form 2 pyruvate molecules
-Coenzyme NAD collects H molecules to form 2 reduced NAD
-4 ATP produced from phosphates released
-2 ATP are used at the start of glycolysis so there is a total net gain of 2 ATP molecules

Question 7

Summary of products from glycolysis

Answer 7

Summary of products from glycolysis:
-2 pyruvates and reduced NAD
-Net gain of 2 ATP’s (4 overall produced but 2 used at the start)

Question 8

Where does the processes of respiration occur in mitochondria?

Answer 8

-Glycolysis occurs in the cytoplasm
-Link reaction occurs in the matrix
-Krebs cycle occurs in the matrix
-Electron transfer chain (in oxidative phosphorylation) utilises proteins found in the crista membranes

Question 9

What occurs in the link reaction (between glycolysis and the krebs cycle)

Answer 9

Link Reaction:
-Pyruvate (3C) => Acetate (2C) => Acetyl CoEnzyme A (2C
-NAD is reduced and CO2 released when pyruvate become acetate
-Products per link reactions = CO2, NADH, Acetyl CoA

Question 10

How many times does the Krebs Cycle occur per glucose molecule?

Answer 10

The krebs cycle repeats twice per glucose molecule

Question 11

What are the stages of the Krebs Cycle?

Answer 11

-DENA DENA A FA NA
-DENA = Decarboxylation + NADH production
-DENA = Decarboxylation + NADH production
-A = ATP production
-FA = FADH production
-NA = NADH production
-Citrate and Oxatoacetate are also involved

Question 12

What are the products of the krebs cycle per glucose molecule?

Answer 12

Products of the krebs cycle per glucose molecule:
-4x CO2
-2x ATP
-8x H in pairs
-6x NADH
-2x FADH

Question 13

Contrast NADH and FADH

Answer 13

-NADH accepts 1 H ion whereras FADH accepts 2 H ions
-NADH releases electrons to carriers at the start of the ETC
-FADH releases electrons after start of the ETC -> so fewer protons are actively transported

Question 14

What are the stages of oxidative phosphorylation?

Answer 14

Oxidative phosphorylation:
1 = NADH and FADH release H atoms
2 = Hydrogens break up into protons and electrons
3 = Electrons enter ETC + are taken up by electron carriers
4 = Energy generated by electrons used to pump protons, forming an electrochemical gradient
5 = Protons diffuse down the gradient through ATP synthase - this causes phosphorylation of ADP
6 = Water is formed as electrons leave the last electron carrier and is accepted by O2 - H2 also joins -> H20

Question 15

Why is the maximum theoretrical yield of ATP not often obtained

Answer 15

Maximum ATP yield not always obtained because:
-Some NADH and FADH used elsewhere
-Some ATP used to transport pyruvates inyo mitochondria after glycolysis

Question 16

Overall ATP yield of repiration

Answer 16

-1 glucose molecule -> 33 ATP molecules produced

Question 17

What is substrate level phosphorylation?

Answer 17

Substrate level phosphorylation = ATP production involving the transfer of a phosphate group from a short lived reactive susbtance (eg Creatine Phosphate)
->Different from OX-PH as does not involve chemisomosis stage

Question 18

What are obligate anaerobes?

Answer 18

Obligate anaerobes = can’t survive in prescence of oxygen
-Prokaryotes and some fungi

Question 19

What are facultive anaerobes?

Answer 19

Facultive Anaerobes = synthesises ATP by both anaerobic and aerobic respiration

Question 20

What are obligate aerobes?

Answer 20

Obligate arobes = can only synthesis ATP with oxygen
-Can anaerobically respire for only short periods of time to supplement ATP supplies

Question 21

What is fermentation?

Answer 21

Fermentation: complex organic compounds broken down to inorganic anaerobically/use of ETC
-Compounds not fully broken down so there are less ATP produced from aerobic respiration

Question 22

Alcoholic fermentation process

Answer 22

Alcoholic fermentation:
-Yeast + some plant root cells -> produces ethanol and carbon dioxide
-Pyruvate -» Ethanal -» Ethanol
-CO2 given off when ethanal regenerated, ethanol regenerated by accepting Hydrogen from NADH

Question 23

Lactate Fermentation process

Answer 23

Lactate fermentation: produces lactase in animal cells
-Puyruvate + NADH -> Lactate _ NAD
-Catalysed by lactate dehydrogenase
-Lactate dissolves into solution to form lactic acid in anaerobic respiration
-Pyruvate accepts a hydrogen from NADH to regenerate lactate
-Lactate fermentation cannot occur indefinetly because ATP quantity too low and lactic acid lowers pH which denatures proteins

Question 24

What are respiratory substances?

Answer 24

Respiratory substance = molecule that can be broken down to release ATP
-Eg glucose, lipid, protein
-More hydrogens = greater the energy value

Question 25

What is respiratory quotient? (RQ)

Answer 25

RQ = ratio of the volume of oxygen absorbed + the amount of CO2 given off in respiration
RQ = volume of CO2 given off / volume of O2 taken in
-High RQ = anaerobic respiration is taking place
-Can’t do for lactase as no CO2 given off
-Measured using a respirometer