Lecture 8 Flashcards

Mitochondria

1
Q

The mitochondria is the site of _____ respiration

A
  • Aerobic

Citric Acid Cycle,Fatty acid oxidation (b-oxidation), Electron transport chain

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2
Q

General mitochondria size is…

A

Mitochondria: 0.5 to 5 mm diameter

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3
Q

Mitochondria will contain their own (2)

A

-Contain own DNA
mtDNA: circular, no histones (bacterial-like)
-Contain own ribosomes
Bacteria: 70S ribosome
Mitochondria: 70S ribosome (bacterial-like)
Eukaryote: 80S ribosome

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4
Q

Mitochondria has a _____ membrane and replicates through ______ fission

A
  • double/binary
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5
Q

Endosymbiont Theory (4)

A
  1. Early atmosphere had no O2
    - Cells relied upon anaerobic metabolism
  2. Photosynthetic microbial organisms began to evolve (chemical energy from light energy)
    • CO2 + H2O ↔ Sugar and O2
  3. Increased O2 in the atmosphere/environment
  4. Aerobic bacteria evolved
    • Krebs cycle enzymes in cytosol
    • Electron transport chain molecules on plasma membrane
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6
Q

Endosymbiont Theory cont….

Slides 6-9

A

At about the same time:

  • Protoeukaryotes (early ancestors of eukaryotes) evolved the ability to ingest materials via phagocytosis
  • Protoeukaryotes phagocytized the aerobic bacteria (which survived the phagocytic process within a vesicular structure)
    • Developed a mutualistic relationship
      - Aerobic bacteria: survive within a protected environment
      - Protoeukaryote: new source for ATP (aerobic respiration)
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7
Q

The outer mitochondrial membrane contains _______ and will allow for ______ of fairly _______ substances

A

pores, diffusion, large

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8
Q

The mitochondria is made up of 4 structures

A
  1. Outer mitochondrial membrane
  2. Inner Mitochondrial membrane (Cristae)
    -ATP Synthase (a mitochondrial enzyme localized in the inner membrane, where it catalyzes the synthesis of ATP from ADP and phosphate, driven by a flux of protons across a gradient generated by electron transfer from the proton chemically positive to the negative side.)
  3. Intermembrane space: ↑[H+]
  4. Matrix
    mtDNA, ribosomes
    Krebs cycle enzymes
    Other enzymes
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9
Q

The outer membrane is ________ permeable, but the inner membrane is rather _________

A

-highly/ impermeable

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10
Q

How do substrates get moved in and out of the matrix?

A

Specific transport systems use either the electrical or acid/base (ΔpH) gradients (components of the proton gradient) to help move substrates in and out of the matrix.

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11
Q

NAD/NADH are also “shuttled” across the inner membrane via specific shuttles:

A
  1. Glycerol phosphate shuttle

2. Malate aspartate shuttle

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12
Q

Movement across the _______ membrane occurs freely through large _______ like ______

A
  • outer/ pores like VDAC
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13
Q

Functions of the mitochondrial outer membrane (3)

A
  • Phospholipid synthesis, fatty acid desaturation, and fatty acid elongation
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14
Q

Functions of the Inner membrane (3)

A

-Electron transport, oxidative phosphorylation, and metabolite transport

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15
Q

Functions of the Matrix (5)

A
  • RNA synthesis (transcription), Protein synthesis (translation), DNA replication, Pyruvate oxidation, TCA Cycle
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16
Q

Mitochondria DNA is ______ (circular, round, helix?) and has only ___ genes

A

-Circular/ 37 (only 13 of the 37 are involved in mitochondrial respiratory function)

17
Q

Mitochondrial Genome Encodes:

A

2 ribosomal RNA (rRNA) molecules
22 transfer RNA (tRNA) molecules
13 polypeptides (respiratory complexes)

18
Q

The 13 polypeptides participate in…

A

-building several protein complexes embedded in the inner mitochondrial membrane

19
Q

NRF-1 (Nuclear respiratory factor -1):

A
  • a nuclear encoded transcription factor that activates the expression of nuclear genes required for mitochondrial respiration
20
Q

Some respiratory complexes/proteins have some subunits that are encoded by the _____ genome and others encoded by the _______ genome

A

-nuclear, mitochondrial

21
Q

Tfam (Transcription factor A of mitochondria):

A
  • Is a nuclear encoded transcription factor that activates the expression of mitochondrial genes required for mitochondrial respiration.
22
Q

Calcineurin:

A

-Is a nuclear encoded calcium activated phosphatase

23
Q

NFAT (Nuclear factor of activated T-cells) :

A
  • Is a nuclear encoded transcription factor that translocates to the nucleus upon dephosphorylation by calcineurin. Activates the expression of various nuclear encoded mitochondrial proteins and other proteins
24
Q

PGC-1 (Peroxisome proliferator activated receptor gamma coactivator-1):

A

** Helps to turn on nuclear encoded mitochondrial genes

  • Is a nuclear encoded transcriptional coactivator that assists PPARg (peroxisome proliferator activated receptor gamma, a transcription factor) & other transcription factors (including NRF-2) in activating gene transcription of nuclear encoded genes related to mitochondrial function.
25
Q

During conditions when requirement for either more mitochondria or elevated mitochondrial function (size):
-> Physiological signals induce expression of (2)

A
  • PGC-1 and the NRFs (typically involves calcineurin and NFAT) → increased expression of nuclear and mtDNA encoded mitochondrial proteins.
26
Q

How do the proteins get into the mitochondria

A
  • TOM = translocase of outer membrane
  • TIM = translocase of inner membrane
  • Nuclear encoded mitochondrial proteins generally have an amino-terminal mitochondrial transit sequence (frequently an a-helix structure)