Lecture 5

Question 1

What are mitochondria derived from

Answer 1

Common ancestral organelle from endosymbiotic alphaproteobacterium (oxygen-using non photosynthetic prokaryote) into a host related to archaea

Question 2

Mitochondria structure

Answer 2

-intermembrane space
-inner and outer membrane
-inner membrane formed into cristae
-matrix
-F0 and F1 complexes

Question 3

How are mitochondria moved around the cell?

Answer 3

Moved by microtubules of the cytoskeleton

Question 4

Where are mitochondria found in cells

Answer 4

Regions with high ATP consumption/energy requirement

Question 5

Outer membrane of mitochondria

Answer 5

-Similar to most other eukaryotic membranes
-Major protein component is porin which forms large aqueous channels

Question 6

Inner membrane of mitochondria

Answer 6

Contains three types of membrane complexes:
-electron transport chain
-ATP synthase
-specific transporters of metabolites (depending on cell type)

Question 7

What is more controlled inner or outer membrane

Answer 7

Inner membrane

Question 8

Cristae

Answer 8

-Increase surface area
-Energy inducing membrane
-Impermeable to most small ions as part of inner membrane

Question 9

Matrix

Answer 9

Inside of the mitochondria (inside membranes)
-enzymes in krebs cycle
-ribosomes
-mitochondrial DNA

Question 10

ATP structure

Answer 10

triphosphate, ribose and adenine

Question 11

Generation of energy to synthesise ATP

Answer 11

-via oxidation of organic molecules (diet)
-the electrons lose potential energy when they end up being shared unequally ie spending more time near electronegative atoms such as oxygen

Question 12

NAD full name

Answer 12

nicotinamide adenine dinucleotide

Question 13

How many electrons and protons reduce NAD+

Answer 13

2 electrons and 1 proton from an organic molecule makes NADH

Question 14

Why must the reaction of hydrogen and oxygen be done in multiple steps in the ETC

Answer 14

Hydrogen+oxygen-> water causes a large amount of energy in the form of heat and light ie an explosion

Question 15

Glycolysis steps

Answer 15

1. Glucose (from diet)
2. Immediately ATP is hydrolysed and the inorganic phosphate phosphroylates the glucose
3. Glucose-6-phosphate is converted to fructose 6-phosphate
4. Phosphofructokinase transfers a phosphate group from ATP to the opposite end of the sugar
5. Aldolase ‘cleaves’ the sugar molecule into two different 3 carbon sugars
6. The sugar is oxidised by the transfer of electrons to NAD+
7. Using energy from step 6 a phosphate is attached making a high energy product (subtrate level phosphorylation)
8. The phosphate is removed to ADP forming pyruvate

Question 16

Krebs Cycle (citric acid cycle or tricarboxylic acid)

Answer 16

1. Acetyl coA reacts with oxaloacetate to form citrate releasing coenzyme A
2. Citrate is converted to isocitrate releasing water
3. Isocitrate is oxidised in multiple steps to reform oxaloacetate forming 3 NADH and 1 FADH2

Question 17

Electron transport chain:

Answer 17

2. High energy electrons from NADH and FADH2 are passed onto protein complex
3. The protein complex passes to the next protein in the chain which releases energy and reduces the energy of the electrons
4. step 2 continues down the chain and reduces the electron energy
5. Eventually the electrons are passed on oxygen to generate water
6. Energy used to produce a H+ gradient across the inner mitochondrial membrane
   NO ATP IS MADE IN THE ELECTRON TRANSPORT CHAIN

Question 18

Chemiosmosis to produce ATP

Answer 18

1. High H+ in intermembrane space causes a gradient
2. H+ moves down ATP synthase causing a complimentary change
3. This change produces ATP

Question 19

ATP synthase structure

Answer 19

F0 portion is a H+ channel
F1 head is the site of ATP synthesis

Question 20

Movement of H+ through F0

Answer 20

-causes rotation of the rotor and central stalk while the stator keeps the enzymatic F1 stationary
-provides energy for ATP synthesis
-10H+ moving back into the matrix generates ~3 ATP molecules

Question 21

Mitochondrial poisons: Cyanide

Answer 21

Prevents the passage of electron from one of the cytochromes thereby blocking the ETC. Very fast

Question 22

Mitochondrial Poisons: 2,4-Dinitrophenol

Answer 22

Makes the inner membrane leaky to H+ so that a gradient cannot be established. The ETC still works but just creates a lot of heat - ‘burnt from the inside out’

Question 23

What is brown fat

Answer 23

Specalised type of adipose tissue to keep warm

Question 24

Mycoclonic epilepsy and ragged-red fiber disease

Answer 24

-mitochondrial genetic disease
-mutation in the mitochondrial encoded tRNA Lys gene
-affects the translation of mitochondrial proteins
-abnormal mictochondria morphology
-multisystem disease which mainly effects muscles and nerves (epilepsy and weakness)
-no cure