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Cell Biology > Mitochondria > Flashcards

Mitochondria Flashcards

1
Q

Where do mitochondria come from?

A

Harbour their own DNA

protein folding machinery

Engulfed by another cell-forming a relationship

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2
Q

What is the role of the mitochondria?

A

Powerhouse of the cell

ATP generation via oxidative phosphorylation

Site of kerbs cycle ribosome rich

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3
Q

Unique characteristics of mitochondria due to;

A

Material inheritance

Mitochondria are critical to cell function

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4
Q

What is the abundance of mitochondria in most somatic cells, lymphocyte, oocyte and sperm?

A

Most somatic cells = 100-10,000

Lymphocyte = 1000

Oocyte = 100,000

Sperm = few hundred

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5
Q

Describe mitochondrial density;

A

Related to function of the cell it resides within

Energy utilisation dictates quantity of mitochondria

More energy cell/tissue = more mitochondria

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6
Q

Describe the two membranes in mitochdria;

A

Smoother outer membrane

Highly folded inner membrane (Cristae)

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7
Q

Describe the internal fluid-filled space;

A

Mitochondrial matrix

DNA, ribosomes & enzymes

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8
Q

Describe the mitochdrial reticula;

A

Mitochondria form a ribbon-like network or reticula

Join together and break apart in relation to a variety of stimuli

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9
Q

Describe how mitochondria are dynamic;

A

Not static organelles

Responsive to inter/intracellular stimuli

Constant state of flux

Received significant communication from ER

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10
Q

Describe fusion and fission?

A

Fusion- increase in mitochondrial mass

Fission- increase in mitochondrial number

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11
Q

What is apoptosis?

A

Programmed cell death

Mitochondria play a key role in cell death

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12
Q

How is apoptosis activated?

A

Complex process which can be activated by internal / external processes

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13
Q

Describe capsases;

A

Family of enzymes - proteases

Apoptosis is activated by cleavage in a cascade

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14
Q

What is the endpoint of apoptosis?

A

the cleavage of caspase-3

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15
Q

Describe the energy source of mitochondria;

A

Cells need energy to perform biology processes

Energy generated in the form of ATP

ATP synthesised via complex metabolism of nutrients and utilisation of oxygen

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16
Q

What does the citric acid cycle complete?

A

The energy-yielding oxidation of organic molecules

17
Q

In the citric acid cycle what happens in the presence of oxygen?

A

Pyruvate enters the mitochondrion

18
Q

What must pyruvate do before the citric acid cycle begins?

A

Pyruvate must be converted to acetyl CoA, linking the cycle to glycolysis

19
Q

Where does the TCA/krebs cycle take place?

A

Mitochondrial matrix

20
Q

What does the TCA cycle oxidise?

A

Organic fuel derived from pyruvate, generating 1 ATP, 3 NADH, and 1 FADH2 per turn

21
Q

Describe the TCA cycle;

A

Has 8 steps - each catalysed by a specific enzyme

22
Q

What is the first stage of the TCA cycle?

A

The acetyl group of acetyl CoA joins the cycle by combining with oxaloacetate, forming citrate

23
Q

What is the job of the next 7 steps of the TCA cycle?

A

Decompose the citrate back to oxaloacetate, making the process a cycle

24
Q

What is produced from the TCA cycle and what does it do?

A

NADH & FASH2 produced

Relay the electrons extracted from food to the electron transport chain

25
Q

During oxidative phosphorylation what does chemiosmosis do?

A

Couples electron transport to ATP synthesis

26
Q

The electron transport chain is the…

A

Cisternae of the mitochondrian

27
Q

Why do electron transport carriers alternate reduced and oxidised states?

A

To donate and accept electrons

28
Q

Once electrons drop in free energy as they go down the chain what happens?

A

Electrons finally pass to O2 and form H20

29
Q

What are electrons passed through?

A

Proteins including cytochromes (each with an iron atom)

30
Q

What does the electron transport chain NOT generate?

A

ATP

31
Q

What is the chains function?

A

Break the large free-energy drop from food to O2 into smaller steps that release energy in manageable amounts

32
Q

What is pumped in the electron transfer chain?

A

H+ from mitochondrial matrix to the intermembrane space

33
Q

What happens H+ once pumped into intermembrane space?

A

Moves back across the membrane, passing through channels in ATP synthase

34
Q

How is phosphorylation of ATP driven?

A

ATP synthase uses the exergonic flow of H+

35
Q

What is the H+ gradient referred to as?

A

A proton-motive force

Emphasising it’s capacity to do work

36
Q

During cellular respiration most energy flows in this sequence;

A

glucose—> NADH —> electron transport chain —> proton - motive force —> ATP

37
Q

What % of energy in a glucose molecule is transferred to ATP during cellular respiration and how much ATP is made?

A

40% of energy

Making about 38 ATP

Cell Biology (30 decks)

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