Mitochondria

Question 1

Exaggerated increase in ATP level that would

Answer 1

inhibit respiration

Question 2

What can prevent an exaggerated increase in ATP level?

Answer 2

partial uncoupling of respiration

Question 3

Uncoupling proteins (UCPs) are ?
Found in which cell?
Present in ?

Answer 3

• Mitochondrial transporters present in the inner membrane of mitochondria.
• Found in all mammals and in plants.
• Present in mitochondria of brown adipocytes (fat cells), the thermogenic cells that maintain body temperature.

Question 4

Uncoupling dissipates energy of ———- ———– as —-

Answer 4

substrate oxidation as heat

Question 5

Uncoupling allows __________ _______ of _______ that are essential to metabolic pathways.

Answer 5

continuous reoxidation of coenzymes

Question 6

Electron leakage can occur to form _____ which link to ______ & _________

Answer 6

form oxygen free radicals (linked to ageing & cancer)

Question 7

( Respiration - ATP / Mitochondria membrane)
For Heat generation?
For Energy conservation?

Answer 7

For Heat generation- uncoupled / Proto leaky

For Energy conservation- well coupled / Proto non- leaky

Question 8

Bacteria make ATP during respiration by

Answer 8

pumping protons outwards and allowing the protons to re-enter the cell via an ATP synthase – just like mitochondria

Question 9

mitochondria (size)

Answer 9

Large organelles, easily visible using light microscopes

Usually depicted as cylinders around 0.5 – 1 mm in diameter and up to 7 mm long, but actually are remarkably plastic and can change shape and move around the cell.

They can even fuse with one another and then move apart again.

Question 10

mitochondria (no of cell)

Answer 10

The number of mitochondria per cell varies according to the energy requirements of the cell.

Average cell: 200

Liver cell: 1000-2000 mitochondria (20% of the total cell volume)

Skeletal muscle: 4000 (in athletes)

Some cells (e.g. fat cells, skin cells) only have a few mitochondria

Question 11

mitochondria (structure)

Answer 11

Two highly specialised membranes (inner and outer) that creates an intermembrane space and the internal matrix.

Question 12

mitochondria (inner membrane structure/ function)

Answer 12

The inner membrane is a highly specialised lipid bilayer that is particularly impermeable to ions and is the site of the electron transport chain and ATP synthesis.

The inner membrane is also highly convoluted, forming folds called cristae

Question 13

cristae

Answer 13

highly convoluted folds formed by the inner membrane projecting into the matrix and serve to greatly increase the surface area of the inner membrane.

Question 14

mitochondria (matrix function)

Answer 14

The matrix contains enzymes that metabolise pyruvate and fatty acids to produce acetyl CoA and also enzymes that oxidise acetyl CoA in the citric acid cycle

Question 15

Reduction /Oxidation ?

Exammple

Answer 15

Reduction is the addition of an electron e-
Oxidation is the removal of an electron e-

H = e- + H+

FAD + 2H -> FADH2

NAD+ + 2H NADH + H+
NAD+ + 2 e- + 2H+ NADH + H+
NAD+ + 2 e- + 2H+ NAD+(2 e-+H+) + H+

[Electrons reduce / Protons (H+) neither reduce nor oxidise]

Question 16

1 molecule of glucose yields a net production of______

Under aerobic conditions, it can yield _______

Answer 16

1 molecule of glucose yields a net production of 2 ATP molecules.

Under aerobic conditions this can increase to 4 ATP molecules.

Question 17

Glucose can be metabolised through _____to produce energy

The reactions occur at ________

Answer 17

Glucose can be metabolised through oxidation to produce energy (glycolysis).
These reactions occur in the cytosol.

Question 18

The citric acid cycle occurs in ?

and produced _________ for _________

Answer 18

in the mitochondrial matrix and produces reduced electron carriers (e.g. NADH or FADH2) for the electron transport chain.

Question 19

At the electron transport chain, Electrons are passed through _________ to ________

Answer 19

Electrons are transferred from NADH or FADH2 to pass through a number of proteins including cytochromes (each with an iron atom) to O2

Question 20

the electron transport chain’s function

Answer 20

to break the large free-energy drop from food to O2 into smaller steps that release energy in manageable amounts.

Question 21

Transfer of electrons from NADH to O2 occurs at

Answer 21

occurs through three large respiratory enzyme complexes (multiprotein complex) located in the inner mitochondrial membrane, in the cristae.

Question 22

At the electron transport chain, electrons drop in _______ to _____, forming _____

Answer 22

drop in free energy as they go down the chain and are finally passed to O2, forming H2O

Question 23

The three respiratory enzyme complexes

Answer 23

• NADH dehyfrogenase complex - Largest complex, > 40 polypeptide chains
• Cytochrome b-c(1) complex - 11 polypeptide chains, Functions as a dimer
• Cytochrome oxidase complex - 13 polypeptide chains

Question 24

The cytochrome oxidase complex accounts for

Answer 24

around 90% of the total oxygen uptake in most cells.

Question 25

Cyanide

Answer 25

is extremely toxic because it binds tightly to the cytochrome oxidase complex, stopping electron transport and greatly reducing ATP production.

Question 26

The cytochrome C protein also plays a crucial role in

Answer 26

in the regulation of cell death

Question 27

Carriers of electrons

Answer 27

• Iron sulphur proteins (FeS)

- Cytochromes

Question 28

Carriers of electrons + H+ (H carriers):

Answer 28

• Flavin mononucleotide (FMN)
• Flavin adenine dinucleotide (FAD)
• Ubiquinone (Q)
• Oxygen

Question 29

Some components of the respiratory chain carry electrons only. T/F

Answer 29

F

All components of the respiratory chain carry electrons. Some carry H+ as well.

Question 30

ATP synthase

Answer 30

A multi-subunit protein with a mass of more than 500,000 Da that is responsible for producing ATP

Question 31

ATP synthesis is coupled to electron transport T/F

Answer 31

True

Question 32

chemiosmosis

Answer 32

the use of energy in a H+ gradient to drive cellular work

• Electron transfer in the electron transport chain causes proteins to pump H+ from the mitochondrial matrix to the intermembrane space
• H+ then moves back across the membrane, passing through channels in ATP synthase
• ATP synthase uses the flow of H+ to drive phosphorylation of ADP to ATP

Question 33

Glucose + O2 -> CO2 + H20 produce how much energy

ADP + Pi -> ATP produce how much energy

Answer 33

Glucose + O2 -> CO2 + H20 produce
+ 686 Kcal/mol

ADP + Pi -> ATP produce - 7.3 Kcal/mol

Question 34

In respiration 1 glucose gives how many ATP

Answer 34

38

Question 35

Efficiency of (ATP) produced from glucose?

Answer 35

ATP from glucose = 38 x 7.3 kcal/mol (277 kcal/mol)

Efficiency = 277/686 = 40% ( remainder lost as heat)

Question 36

What cause membranes be leaky?

Draw the molecular structure

Answer 36

DNP makes membranes leaky to protons and uncouples

Question 37

Key concept of energy prduction

Answer 37

• Redox reaction
• Glycolysis
• Citric acid cycle
• Electron transport chain coupled with ATP synthase