Mitochondria Flashcards

1
Q

What are the compartments of the mitochondria?

A
  1. Outer membrane.
  2. Inner membrane (Iamellar or tubular cristae).
  3. Inner membrane space.
  4. Matrix.
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2
Q

What is the protein/lipid ratio of the outer membrane of the mitochondria?

A

1:1

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3
Q

What are porins?

A

Porins are proteins that cross the mitochondrial membrane and act as pores. They are non-selective permeable.

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4
Q

How are polypeptides transported across the outer membrane of the mitochondria?

A

Via translocons (TOMs)

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5
Q

What’s the protein/lipid ratio in the inner membrane of the mitochondria?

A

4:1

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6
Q

Which lipid contributes to about 20% of all lipid composition of the inner membrane of the mitochondria?

A

Cardiolipin

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7
Q

How are polypeptides transported across the inner membrane of the mitochondria?

A

Via translocons (TIMs)

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8
Q

How are molecules transported out and in of the mitochondria?

A

Multiple transport proteins (fully controlled transport).

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9
Q

What does the matrix of the mitochondria contain?

A
  1. mtDNA, mtRNAs, mt-ribosomes.
  2. Krebs cycle enzymes.
  3. Fatty acid beta-oxidation enzymes.
  4. Calcium Phosphate deposits (dense bodies)
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10
Q

Whats the main function of the mitochondria?

A

ATP production

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11
Q

What are some functions of the mitochondria besides ATP production?

A
  1. Beta-oxidation of short and medium-chain fatty acids.
  2. Participation in steroid hormone synthesis.
  3. Storage of calcium ions.
  4. Involvement in apoptosis (in brown adipose tissue cells)
  5. Generation of heat.
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12
Q

What is so special with mitochondria compared to other cell organelles?

A

It possesses a complete genetic apparatus (ribosomes, DNA, mRNA, tRNA and enzymes nessesary.)

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13
Q

How many rRNA molecules, tRNA molecules and Mitochondrial inner membrane proteins does the mitochondrial DNA encode for?

A

2 rRNA molecules

22 tRNA molecules

13 mitochondrial inner membrane proteins.

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14
Q

What does it mean that the mitochondria are semiautonomous?

A

Some proteins are encoded and synthesized inside and by the mitochondria itself and some are synthesised in the nucleus of the cell and transported to the mitochondria. Hence semiautonomous.

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15
Q

What have mitochondria evolved from according to the endosymbiotic theory?

A

Primitive bacteria capable of oxidative phosphorylation.

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16
Q

What is the average size of mitochondria?

A

1-3 micrometers.

17
Q

What is the shape of mitochondria?

A

Mostly rod-shaped. Can also be spherical or highly elongated.

18
Q

What is present in the intermembrane of the mitochondria and what happens there?

A
  1. Nucleotide kinases are present in the intermembrane of the mitochondria participating in ADP synthesis.
  2. Acts as a contact site for translocon coupling. (Connecting the translocons of the outer and inner membrane)
19
Q

Does the inner membrane of the mitochondria contain the electron transport chain?

A

Yes.

20
Q

What does the production of ATP in the mitochondria require?

A
  1. Citric acid enzymes
  2. Electron transport chains
  3. ATP synthase complexes.
21
Q

What is an electromotive force in the mitochondria?

A

The electron transport chain pumps protons from the matrix to the intermembrane space, creating a proton concentration gradient. The energy from this gradient is used by the ATP synthase complex to produce ATP. This proton gradient is called the electromotive force.

22
Q

What processes are the proton gradient across the mitochondrial membrane a source of energy for?

A
  1. ATP synthesis
  2. Active transport of molecules
  3. Incorporation of proteins
23
Q

Does the DNA of mitochondria contain histones?

A

No. The DNA of mitochondria is arranged in a closed loop)