Mitochondria and chloroplasts

Question 1

Mitochondria structure

Answer 1

2 membranes, outer permeable (molecules eg ATP can pass), inner not permeable and folded so its convoluted, large SA
Matrix is where enzymes of krebs reside

Question 2

Choroplast

Answer 2

Made of 3 membrane systems- outer, inner, thylakoid

Thylakoid highly folded, have integral mem proteins important for PS eg PS I and PS II

Question 3

Primary function of mitochondria and chloroplasts

Answer 3

ATP synthesis

Question 4

ATP uses

Answer 4

fuel cellular processes
Anabolic reactions of cells responsible for growth and repair processes
Catabolic reactions release energy needed to drive anabolic reactions
ATP is the energy intermediate used to link energy yielding to energy requiring processes

Question 5

Where is ATP synthase found

Answer 5

Mitochondrial inner membrane - ATP synthesised in the matrix.
Choroplast thylakoid membrane. ATP synthesised in the stroma
Inner membrane of eubacteria

Question 6

Type of ATPase

Answer 6

Large multisubunit F-type ATPase made up of an F0 which is integral (carrier part) in the membrane and an F1 peripheral (lollipop part)

Question 7

Structure of ATP synthase

Answer 7

Large lollipop head attached through a stalk to transmembrane carrier for protons
As protons pass through carrier (F0) stalk spins, causes conformational changes in F1 that facilitate production of ATP from ADP and PI

Question 8

Direction of proton flow

Answer 8

mitochondria intermembrane space to matrix

in chloroplasts from lumen of thylakoid to stroma of chloroplast

Question 9

What is a form of stored energy

Answer 9

proton gradient

Question 10

2 parts of proton gradient

Answer 10

delta V- difference in voltage ie membrane potential

delta pH ie H+ conc gradient

Question 11

How many protons needed to synthesise 1 ATP

Answer 11

3

Question 12

How can formation of ATP be reversed

Answer 12

Use hydrolysis of ATP to pump protons

Question 13

How is the proton gradient across the mitochondrial membrane generated?

Answer 13

Coupling of electron transfer to proton pumping across the membrane
HIgh energy electrons passed along ETC, transfers release/lose energy used to pump H+ across membrane creating an electrochemical proton gradient

Question 14

How can protons be pumped across membranes by coupling to electron transfers?

Answer 14

transfer of electron from integral membrane protein A to B gives B a negative charge, which attracts a proton. Electron transferred to C, proton loses its affinity for B because no longer negative charge, so is released the other side of the membrane

Question 15

3 protein pumping complexes in mitochondria

Answer 15

NADH hydrogenase, Cytochrome bc1 comple, cytochrome oxidase complex (in order)

Question 16

What happens to protein pumping complexes

Answer 16

Receive electrons from oxidation of food molecules (fats and carbohydrates) in the citric acid/krebs cycle, passed onto NADH, which becomes reduced and passes electrons onto protein complexes, becoming oxidised and forming NAD+.

Question 17

Formation of H20

Answer 17

Electrons passed onto oxygen held in the cytochrome oxidase complex, which forms water

Question 18

NADH

Answer 18

Nicotinamide adenine dinucleotide

Question 19

Mobile electron carriers- Ubiquinone

Answer 19

small lipid like molecule

Carries electrons from NADH hydrogenase to cytochrome bc1 complex

Question 20

Mobile electron carriers- Cytochrome C

Answer 20

Carries electrons from cytochrome bc1 complex to cytochrome oxidase complex

Question 21

Chemiosmotic coupling-

and what is it known as in mitochondria?

Answer 21

Linkage of electron transport, proton pumping and ATP synthesis
Known as oxidative phosphorylation in mitochondria

Question 22

Electron transfer potential

Answer 22

Reducing agents ranked according to this
NADH high (-ve value)
H20 low (+ve value)

Question 23

Trend in redox potential (electron affinity) across the mitochondria ETC

Answer 23

increases

electrons losing energy

Question 24

NADH hydrogenase nature

Answer 24

Flavin nucleotides, FeS

Question 25

Cytochrome bc1

Answer 25

Heme (iron-containing compound of the porphyrin class which forms the non-protein part of haemoglobin ), FeS

Question 26

Cytochrome C

Answer 26

Heme

Question 27

Cytochrome oxidase

Answer 27

Heme, CuA and CuB

Question 28

Fe-S centres

Answer 28

not part of the protein backbone, accessory groups bound to the protein.
Deduce paths of electrons within proteins based on FeS centres/structures

Question 29

Citric acid cycle overview

Answer 29

2 carbons in (acetyl CoA), 2 carbons released as CO2.

Each turn of the cycles produces 3 NADH, 1 GTP and 1 FADH2

Question 30

Mitochondria matrix

Answer 30

enzymes of citric cycle, mito DNA

Question 31

Inner membrane mito

Answer 31

Electron transfer proteins, ATP synthase, transport proteins

Question 32

Outer membrane mito

Answer 32

Large pores, lipid synthesis, and conversion of lipid substrates into forms that can be metabolised in the matrix

Question 33

Majority of ATP generated by oxidation of glucose

Answer 33

Produced by ATP sythase

Question 34

Agents that interfere with oxidative phosphorylation

Answer 34

Cyanide and CO inhibit cytochrome oxidase
Block passage of electrons to O2
No ATP synthesis

Question 35

What else can movement of proteins across intermembrane cause

Answer 35

production of heat, achieved by a protein called thermogenin which provides a path for protons to return to the matrix without passing through the F0F1 complex
The energy is dissipated as heat

Question 36

Mitochondrial uncouplers

Answer 36

Uncoupling proton gradient from ATP synthase. Protons flow through holes made in membrane instead, generate heat