mitochondria and peroxisomes

Question 1

what does the number of mitochondria in the cell depend on?

Answer 1

metabolic requirements of the cell

Question 2

why is mitochondria different from most organelles?

Answer 2

it has its own circular DNA similar to prokaryotic DNA

Question 3

explain endosymbiosis with reference to mitochondria

Answer 3

small free living prokaryotes were engulfed but not consumed by larger eukaryotes and the two developed a symbiotic relationship.
smaller organism provides ATP and the larger one provides nutrients

Question 4

where are proteins in the mitochondria made?

Answer 4

in its own ribosomes

Question 5

what are the functions of mitochondria?

Answer 5

fatty acids are broken down to acetyl CoA
→decarboxylation of pyruvate to acetyl CoA
→ breaks down acetyl CoA
→ oxidative phosphorylation
→thermogenesis to generate heat
→apoptosis

Question 6

what is abnormal in patients with beri beri?

Answer 6

higher than normal serum levels of pyruvate and ketogluarate (alpha)

Question 7

what are the functions of peroxisomes?

Answer 7

production of cholesterol and phospholipids
→contain enzymes that use oxygen to oxidize substrates
→produce hydrogen peroxide
→important in breaking down long chain fatty acids
→steps in synthesis of certain lipids
→breakdown of excess purines to uric acid

Question 8

what targets peroxisomal proteins to the peroxisomes?

Answer 8

PTS (peroxisome targeting signal)

Question 9

What are some symptoms of Beriberi?

Answer 9

→ damage to the peripheral nervous system
→ pain in the limbs
→weakness of the musculature
→distorted skin sensation
→the heart may be enlarged and cardiac output inadequate

Question 10

Describe the structure of peroxisomes

Answer 10

→ approximately 0.1-1 μm in diameter.
→surrounded by a single lipid bilayer membrane.
→ no DNA or ribosomes (meaning they do not make the proteins that they contain, they instead acquire them).