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BIO 1090 > Mitochondria and Chloroplasts > Flashcards

Mitochondria and Chloroplasts Flashcards

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Biology 101 flashcards
1
Q

Endosymbiont theory

A

double membraned organelles present in eukaryotic cells (mitochondria and chloroplasts) are derived from formerly free-living prokaryotes that were engulfed by an ancestral cell for endosymbiosis

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2
Q

Stages of the endosymbiont theory

A

Anaerobic prokaryote -> infolding of plasma membrane -> endosymbiosis -> ancestral Eukaryote

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3
Q

Chloroplast and mitochondria DNA

A
  • most DNA of mitochondria and chloroplasts has been transferred to nuclear genome
  • DNA left in those organelles is highly reminiscent of bacterial DNA
  • Because they have their own DNA, both chloroplasts and mitochondria have ribosomes
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4
Q

Products of cellular respiration

A

Carbohydrates + oxygen gas —> CO2 + H2O + ATP

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5
Q

Mitochondria membrane structure

A

have a double membrane consisting of an inner and outer membrane with aqueous compartments in between

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6
Q

Outer mitochondrial membrane (OMM)

A
  • contains many enzymes with diverse functions

- porins: large channels which when open membrane is freely permeable (ex. to ATP)

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7
Q

Inner Mitochondrial membrane (IMM)

A
  • Inner membrane has a high protein to lipid ratio (3:1)
  • double layered folds known as cristae
  • cristae increases surface area & has machinery for aerobic respiration and ATP formation
  • rich in a phospholipid called cardiolipin (characteristic of bacterial membranes)
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8
Q

Aqueous compartments of the mitochondria

A
  1. intermembrane space
  2. matrix
    - high protein gel-like consistency
    - mitochondrial ribosomes and DNA (mtDNA)
    - encodes polypeptides that are integrated into the IMM, ribosomes, tRNA
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9
Q

What is oxidative phosphorylation?

A

ATP synthesis from ADP

- takes place in the mitochondria

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10
Q

Main function of the citric acid cycle

A

Citric acid cycle uses Acetyl-CoA from glycolysis and passes sugars through the cycle to generate NADH and FADH2 which are needed in oxidative phosphorylation

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11
Q

Electron transport chain

A
  • electrons are transported down through a series of complexes which pumps protons into the intermembrane space form the matrix
  • generates an electrochemical gradient
  • high energy electrons pass from coenzymes (NADH and FADH2 - from citric acid cycle) in the matrix to electron carriers in IMM
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12
Q

Complexes in the electron transport chain

A

Complex 1: turns NADH into NAD+
Complex 2: turns FADH2 into FAD
Complex 3: gets electrons passed from CoQ
Complex 4: passes O2 which combines with H+ to create H2O
- Energy transfer at each complex is used to pump protons from the matrix into the IM space
- Ultimately low energy electron is transferred to thermal electron acceptor and H2O is produced

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13
Q

Steps of oxidative phosphorylation

A

Step 1: electron transport chain

Step 2: controlled movement of protons back across IMM

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14
Q

Controlled movement of protons back across IMM

A
  • happens via ATP synthase
  • Potential energy in electrochemical gradient across IMM converted to ATP in matrix
  • Now we are generating all of the energy our cells can utilize
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15
Q

Aerobic respiration

A

converts energy stored in food molecules to chemical energy stored in ATP. consumes oxygen and produces carbon dioxide as a waste product

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16
Q

Photosynthesis

A

Builds carbohydrates and releases oxygen from carbon dioxide and water - only happens in plants

17
Q

components of the chloroplast

A

outer membrane, inner membrane, thylakoid membrane, thylakoid lumen, grana, stroma,

18
Q

Photophosphorylation

A

The conversion of ADP to ATP using energy from the sun

  • occurs on the chloroplast
  • doesn’t replace cellular respiration
19
Q

Membrane structure of Chloroplast

A

3 membranes

  • inner membrane
  • outer membrane
  • thylakoid membrane
20
Q

Goal of Light dependent reactions

A
  • collect energy from the sun and break down water molecules to produce ATP and NADPH
  • each water molecule breaks down into two hydrogen (H) atoms and one oxygen (O) atom.
21
Q

Steps in light dependent reaction

A
  • chlorophyll in light harvesting complex
  • used light and water to generate e- O2 and H+
  • electrons enter the electron transport chain
  • ## H+ are pumped from stroma to thylakoid lumen to generate ATP
22
Q

Thylakoids

A

Third membrane system in chloroplasts

  • where the light dependent reactions happen
  • thylakoids stacked on top of each other like pancakes = granum
23
Q

Chloroplast genome

A
  • Chloroplast have circular genome and ribosomes

- A good portion of the genome from the chloroplast has been moved to the nuclear genome

24
Q

Light Independent reactions

A
  • ATP (and NADPH) made in LDR are used to make CH2O
  • also known as the calvin cycle
  • ## occurs in the stroma
25
Q

Apoptosis

A

programmed cell death facilitated by the mitochondria, happens in a safe fashion
- allows for no toxic stuff inside the cells to affect neighbouring cells when they self destruct

26
Q

What is apoptosis characterized by?

A
  1. Shrinking of cell
  2. Blebbing of the plasma membrane
  3. Fragmentation of DNA and nucleus
  4. Loss of attachment to other cells
  5. Engulphment by phagocytosis
27
Q

How is controlled cell death critical for development

A

If apoptosis is disrupted the embryological development of most if not all cellular organisms will not occur properly or at all
- ex: to get rid of webbing in the formation of hands

28
Q

2 pathways of apoptosis

A

Extrinsic and Intrinsic pathways

29
Q

Extrinsic Pathway

A

Kill signal arrives, nuclear envelope breaks down, cell fragmentation, phagocytosis and bets broken down in a controlled manner. kill signal can be removal of a stimulus

30
Q

Intrinsic Pathway

A
  • initiated by an intracellular stimuli (ex. Genetic damage, hypoxia, virus)
  • Internal cellular damage activates Bax protein and forms a pore that allows cytochrome c to come out
  • “Killer proteins” cause changes in mitochondria membrane and they leak protein (cytochrome c)
31
Q

Protein mode of action in intrinsic pathway

A
  • bax assembles into pores on the OMM,
  • cytochrome c combines with apaf 1 and procaspase 9
  • apoptosome is assembled
  • activate executioner caspases that disrupt cell adhesion, destroys lamins, activate DNases and breakdown cytoskeleton ultimatly killing the cell
32
Q

What happens if there is too little or too much apoptosis?

A

Some diseases are associated with inadvertently apoptosis

  • Too little apoptosis can lead to cancer where malignant cells will not die
  • Too much apoptosis can leave to neurodegenerative diseases like Alzheimer’s and Parkinson’s disease
33
Q

Caspases

A

Caspases are protases

enzymes that activate proteins that are involved in dismantling the cell

34
Q

3 lines of evidence for the endosymbiont theory

A
  1. mitochondria and chloroplasts have double membranes
  2. have prokaryotic-type ribosomes
  3. have their own genomes (which are circular)
    - also divide by fission like bacteria
35
Q

Where is the Bax protein found?

A

outer mitochondria membrane (not active)

36
Q

Intrinsic pathway of Apoptosis: extra facts

A
  • can be triggered by hypoxia
  • cytochrome c leaks out in the cytosol
  • executioner capsases are activated
  • nuclear lamins break down

BIO 1090 (7 decks)

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