Mitochondria

Question 1

Mitochondrion

Answer 1

It is the energy-generating organelle of the cell

Question 2

ATP production

Answer 2

NADH and flavin adenine dinucleotide ( FADH2), reduced coenzymes, generated by glycolysis, fatty acid metabolism and the tricarboxylic acid (TCA) cycle are oxidised via the electron transport chain to create the proton motor force required by ATP synthetase to make ATP (oxidative phosphorylation)

Question 3

New Mitochondria

Answer 3

New mitochondria are generated by a division called mitochondrial fission

Question 4

Mitochondrial fusion

Answer 4

M also have the ability to fuse together, joining membranes and compartments to yield a single larger mitochondrion

Question 5

Different Mitochondria shapes

Answer 5

The dynamic flux between fusion and fission gives rise to diverse mitochondrial sizes and structures visible when observing mitochondrial morphology.
The difference in shape is due to different M having different functions.

Question 6

Mitophagy

Answer 6

Old or depolarised/damaged M are removed

Question 7

Mitochnodrial genome

Answer 7

mtDNA is histone-free, circular, double-stranded DNA molecule with around 16569 base pairs
-They are intronless genes
-It encodes rRNAs, tRNA’s and 13 proteins, these are subunits of the oxidative phosphorylation pathway
-Nuclear genes encode for many proteins required for Mt function such as DNA repair enzymes

Question 8

Other critical roles of M

Answer 8

-Carbon skeletons
-Calcium buffering
-Nitrogen metabolism
-Programmed cell death

Question 9

Carbon skeletons

Answer 9

They provide carbon skeletons for biomolecules such as amino acids, glucose and fatty acids

Question 10

Calcium buffering

Answer 10

-Mitochondria serve as a critical store of intracellular calcium
-Ca enters into the M matrix via the mitochondrial calcium uniporter MCU due to the high electronegative potential of the membrane (-180mV) while its extrusion depends on the NA+/Ca2+ exchanger and H+/Ca2+

Question 11

Nitrogen metabolism

Answer 11

it occurs via the metabolism of glutamate used in transamination reactions and the glutamine used to shuttle nitrogen around the body as well as the urea cycle
-Iron containing molecules such as heme are also synthesies in the M

Question 12

Programmed Cell Death

Answer 12

M activate caspases through the release of Cytochrome C and other factors from the intermembrane space when pro-apoptotic stimuli trigger Bcl-2 family members and the permeability transition pore