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BMSC 220 > Chapter 8 > Flashcards

Chapter 8 Flashcards

1
Q

What is the mitochondria?

It’s structure?

A

Energy generating factories of cell
Critical for cell viability
Uses oxidative phosphorylation to break down carbs and lipids to make ATP
Capable of division

double membrane bound
Originated as bacteria infecting cell
Contains RNA and DNA polymerases, has ribosomes and tRNAs, and genetic code
Slide 17 picture

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2
Q

What are the inner and outer membrane of the mitochondria?

A

Outer membrane- contains porins which are proteins that form transmembrane channels
Similar to plasma membrane
Inner membrane- site of ATP production by oxidative metabolism
Only barrier between matrix and cytoplasm
Contains cristae folds
Slide 11 pictures

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3
Q

What is the intermembrane space and matrix in the mitochondria?

A

Intermembrane space- like cytoplasm sue to porin channels
Proteins reside here that are used in protein import and export and other stuff
Matrix- half protein
Has majority of enzymes in oxidative metabolism
Contains higher pH and negative charge relative to cytoplasm
Site of mitochondrial DNA, RNA, and protein synthesis
Picture on slide 12

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4
Q

What is the mitochondrial genome? (3 Characteristics)

A
  1. Located in matrix
  2. Is circular DNA with one origin of replication (all genes transcribed at the same time)
  3. Is maternally inherited
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5
Q

What are the characteristics of the human mitochondrial genome?

A

Genes encode rRNAs for mitochondrial ribosomes, mitochondrial tRNAs, 13 proteins in electron transport/oxidative phosphorylation
Different tRNAs because they are the only ones used to translate mitochondrial mRNAs is to protein (22 tRNAs recognize 20 amino acids)
Use a different genetic code as well

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6
Q

How do mitochondria cells adjust to meet changing energy demands of cells? (4 ways)

A
  1. Changing their size or shape (fission or fusion)
  2. Changing location within cells
  3. Increasing number of mitochondria within cell (fission)
  4. Increasing DNA copy number in the mitochondria
    Slides 17-21
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7
Q

What are the two ways mitochondria are created?

A
  1. Fusion- shares genetic material and proteins
  2. Fission (division)- distributes mitochondria evenly yo daughter cells during cell division and increases the number of mitochondria in a cell when more energy is needed

Continual fusion and fission allow mitochondria to modify their morphology within the cell
Slide 23 and 24 pictures

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8
Q

What does mitochondrial fission require? (4 things)

A
  1. DNA replication
  2. RNA synthesis
  3. Membrane generation via
    phospholipid transfer from ER
  4. Protein synthesis within mitochondria & protein importation from cytoplasm
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9
Q

What is catabolism in mitochondria?

A

Breakdown of large molecules into smaller molecules that releases chemical energy
Most of this energy is captured by ATP to form phosphoanhydride bonds (high energy bonds)
Hydrolysis of these bonds provides energy for most cellular reactions

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10
Q

How does metabolism work in the mitochondria? (Citric acid cycle, whats produced etc)
Where is the only place ATP is made in mitochondria?

A

Acetyl CoA is created 1 of 2 ways
It then enters the citric acid cycle which produces 3 NADH and 1 FADH2 which are used to make ATP in electron transport chain
Slide 28

ATP is only made from electron transport chain in mitochondria

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11
Q

What are the 2 sources of acetyl CoA?

A
  1. Pyruvate- product of glucose breakdown in glycolysis
  2. Fatty acids- product of fat (triacylglyceride) breakdown
    Slide 28
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12
Q

What happens when NAD+ is reduced to NADH? (Protons and electrons)
What about when it’s oxidized?

A

NAD->NADH Accepts a proton and two electrons
NADH->NAD releases a proton and 2 electrons
Slide 30

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13
Q

What is oxidative phosphorylation and the electron transport chain in mitochondria?

A

Takes electrons from NADH and FADH2 from citric acid cycle and combines them with O2 to produce H2O

Energy released from oxidation reduction reactions is used to drive ATP synthesis through chemiosmotic coupling, storage of energy is in a proton gradient which is used to drive ATP synthesis

Electron transport is coupled to ATP synthesis
Slide 32-33

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14
Q

What are the two electron carriers (negatively charged molecules that can transfer a proton)?

A
  1. Coenzyme Q(ubiquinone)- lipid soluble electron carrier (electrons carried to complex III)
  2. Cytochrome c (Cyt C)- peripheral membrane protein on outer face of inner membrane (electrons carried to complex IV)
    Slide 32
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15
Q

How are protons moved from matrix to intermembrane space?

A

Release of small packets of energy as electrons transferred down chain or carriers and complex’s are used to move protons
Phospholipid bilayer of inner membrane is impermeable to ions so protons cross through protein channel
This allows energy in electrochemical gradient to be harnessed and converted to ATP in complex V
Slide 36

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16
Q

What is ATP synthase? (Structure, What it produces)

How many protons are required to synthesize 1 ATP?

A

2 subunits (F0 and F1)
F0 forms channel which protons can move while F1 catalyzes the synthesis of ATP
Flow of protons drives rotation of F1 which drives ATP synthesis
4 protons are required to synthesize 1 ATP
1 NADH- 3 ATP
1 FADH2- 2 ATP
Slide 37

17
Q

What is the electrochemical gradient?

A

Protons have a charge therefor the proton gradient is both chemical and electrical in nature which is the electrochemical gradient
This gradient causes of flow of protons which generates ATP

18
Q

What is brown adipose tissue (brown fat)?

A

Part of adipose tissue distributed among white adipose tissue
Predominant in newborn human
I’m adults but decreases with age

Broke far have higher levels of innervation, vascularization, pious droplets, and mitochondria

19
Q

How is cellular communication key in correct synthesis in electron transport chain?

A

Transcription of genes in both the nucleus and mitochondria have to be coordinated very closely to ensure this correct synthesis

20
Q

How are proteins made for mitochondria?

A

Most nuclear encoded mitochondrial proteins are synthesized on free ribosomes in the cytoplasm then imported in by several different mechanisms

21
Q

What are the two mechanisms for targeting proteins from cytoplasm to mitochondria and specific location without mitochondria?

A
  1. Targets proteins to interior compartments of mitochondria- amino terminal mitochondrial targeting presequence for matrix proteins plus additional internal compartment targeting sequences for some inner membrane proteins
  2. Targets proteins to outer compartments- internal mitochondrial targeting sequence plus internal compartment targeting sequences for intermembrane space, outer membrane, and some inner membrane proteins
22
Q

What are internal compartment targeting sequences?

A

Group of amino acid targeting sequences that include:
Outer membrane targeting sequence
Inner membrane targeting sequence
Intermembrane space targeting sequence

Targets cytosine proteins to mitochondria

23
Q

What is the first mechanism of import of mitochondrial matrix and inner membrane proteins with amino terminal presequence? (Tim, Tom)

A

Slide 47
Tom complex- translocations of outer membrane
Tim complex- translocations of inner membrane
Hsp70- chaperones that keep proteins unfolded until reaching final destination
MPP- matrix processing peptidase that cleaves targeting sequence following transport
1- contains internal inner membrane sequence
2- no inner membrane targeting sequence

24
Q

How are proteins sorted containing internal targeting sequences to the inner membrane? (Tim Tim)

A

2 intermembrane space chaperones Tim9 and Tim10 carry protein to Tim22 complex
Oxa-translocase in inner membrane for proteins synthesized within matrix of mitochondria
1- inner membrane protein encoded by nuclear DNA (ETC, translocases m)
2- inner membrane protein encoded by mitochondrial DNA (ETC)
Slide 48

25
Q

How are proteins sorted that contain internal targeting sequences to intermembrane space and outer membrane? (Mim, SAM)

A

Mim1- inserts proteins with a single alpha helical transmembrane domain inserted into outer membrane
SAM- sorting and assembly machinery, moved proteins from intermembrane space to outer membrane
1- outer membrane protein with alpha helix transmembrane domain
2- outer membrane protein with beta sheet transmembrane domains
3- intermembrane space protein
Slide 49

26
Q

How are phospholipids produced in mitochondria?

What is cardiolipin?

A

They are synthesized in the ER
Then transferred to mitochondria by cytoplasmic phospholipid transfer proteins
Cardiolipin- unique 4 fatty acyl tail phospholipid found in mitochondrial inner membrane (synthesized within mitochondria)

27
Q

What is retrograde signalling and anterograde signalling?

A

Retrograde- singles from organelles are involved in regulating nuclear gene expression
Function in a cell is controlled by feedback from another part of cell
Anterograde- signals from nucleus regulate function of an organelle

28
Q

What are chloroplasts?

A 
Known as plastids
Semi autonomous, endosymbiotic origin, own genetic system, can divide
3 membranes: inner outer and thylakoid
Photosynthetic organelles of plants
# can vary between cells
29
Q

How do chloroplasts generate ATP?

A

An electron transport chain similar to mitochondria but more complex uses photons from the sun to generate ATP
Also generates oxygen

Photosystem I and photosystem II are in charge of oxidation reduction reactions that move electrons through transport chain

30
Q

What are peroxisomes?

A

Single membrane organelles of eukaryotes, can replicate but do not contain their own genetic material
They detoxify cells and carry out various metabolic functions (oxidizing, oxidize purines, amino acids, methanol, and fatty acids)
Are another site of lipid synthesis

31
Q

How are fatty acids oxidized in peroxisomes?

A

The oxidation of fatty acids in peroxisomes produce H2O2 which is then broken down into water and oxygen by the enzyme catalase

32
Q

What is glycolate and how is it taken care of in plants?

A

When oxygen enters the Calvin cycle instead of CO2 it produces glycolate which is toxic to cells
Glycolate is transferred to peroxisomes, concerted to glycine then converted to serine in the mitochondria
Serine returns to chloroplast and Calvin cycle via peroxisome

BMSC 220 (12 decks)

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