Week 4: Energy Transfer in Cell Flashcards

1
Q

What is potential energy vs. kinetic energy vs. heat energy?

A

Potential Energy- stored, ie. chemical bond, ion gradient

Kinetic Energy - motion, ie. cells.

Heat energy - conversion b/w potential and kinetic energy

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2
Q

How does energy generation occur in cell? Give ATP -> ADP equation

A

Energy generation - mitochondria - convert energy into ATP - energy ‘currency’ cell

ATP + H2O → ADP + Pi

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3
Q

What are the 3 stages of food molecule breakdown (catabolism)?

A
  1. Digestion 2. Glycolysis. 3. Oxidation
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4
Q

Describe stage 1 of catabolism

A

Enzymes (mouth + gut) convert polymeric molecules in food into monomeric subunits - digestion - occurs outside many cells or in organelles. After, the small organic molecules enter cytosol where gradual oxidative breakdown begins.

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5
Q

Describe stage 2 of catabolism

A

Breakdown of subunits to Acetyl CoA (mostly in cytoplasm). Glycolysis splits each glucose into two pyruvates. Occurs in cytosol and also generates ATP and NADH. The pyruvate is transported into mitochondrion’s matrix where an enzyme converts pyruvate into CO2 and acetyl CoA. NADH is also produced.

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6
Q

Describe stage 3 of catabolism

A

in mitochondria. Complete oxidation of Acetyl coA to H2O and CO2. (mitochondrial matrix and inner membrane). Acetyl group is transferred to oxaloacetate molecule to form citrate which enters citric acid cycle. Acetyl group is oxidized to CO2 with production of large amounts of NADH. The high-energy electrons from NADH are passed along enzyme series within mitochondrial inner membrane - electron-transport chain, where energy is released to drive oxidative phosphorylation - produces ATP and consumes O2.

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7
Q

What is the overall equation for catabolism?

A

Food + O2 → ATP + NADH + CO2 + H2O

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8
Q

Describe Glycolysis.

A

Glycolysis occurs in cytosol, does not require oxygen. Turns glucose into 2 pyruvate - lower in energy - releases 2 molecules of ATP per molecule overall and 2 NADH (nicotinamide adenine dinucleotide).

Glucose -> 2 pyruvate + 2 ATP + 2 NADH

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9
Q

Describe fermentation in muscles

A

Glucose -> glycolysis to form pyruvate -> uses NADH to create lactate

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10
Q

Describe fermentation in yeast

A

Glucose -> glycolysis to form pyruvate -> loses CO2, uses NADH to form ethanol.

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11
Q

How do animals cope with transient deprivation?

A

One way - synthesize food reserves in times of plenty. A cell must decide whether to route key metabolites into anabolic or catabolic pathways.

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12
Q

Describe ATP generation

A
  1. electron transfer, proton pump (energy from electrons used to pump protons across membrane) 2. Flow of protons through ATP synthase (via proton gradient)
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13
Q

Define chemiosmotic coupling

A

Chemiosmotic coupling - proton gradient used to drive ATP synthesis - mitochondria + chloroplasts - also drives movement of flagella.

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14
Q

What are some characteristics of mitochondria?

A

Mitochondria divide by fission. Can change shape based on cell needs. Are closely associated with microtubules. High concentrations are found in cells with greatest energy needs.

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15
Q

What are the 4 compartments of mitochondria?

A

Matrix (metabolic enzymes), inner membrane (cristae - proteins of oxidative phosphorylation + transport of molecules into matrix), outer membrane (porins), intermembrane space (enzyme that phosphorylate other nucleotides).

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16
Q

Describe Oxidative phosphorylation

A

Electrons are passed along ETC, energy released fuels proton pumps across inner membrane. Protons then flow back into matrix down concentration gradient through ATP synthase - allows synthesis of ATP from ADP and Pi

17
Q

Describe ATP synthase

A

Protons pumped out via ETC flow back into matrix. The change in protein conformation allows formation of ATP from ADP + Pi. Can work in either direction dependent on proton gradient and can either generate or consume ATP.

18
Q

What else can proton gradient in mitochondria do?

A

The proton gradient also drives various small charged molecules and metabolites across mitochondrial inner membrane.

19
Q

What gradient drives pyruvate import by mitochondria?

A

pH (proton)

20
Q

What gradient drives ADP-ATP exchange?

A

Voltage

21
Q

Describe chloroplast

A

Internal membrane bound - thylakoid compartment w/thylakoid membrane.

22
Q

Describe 2 stages of photosynthesis

A

Stage 1: chlorophyll captures energy from light and transfers it to produce ATP and NADPH (light reactions)

Stage 2: ATP and NADPH used to manufacture sugars from CO2 (carbon fixation reactions)

23
Q

What do plants do with generated sugar?

A

stored as starch in chloroplast or consumed for ATP by supplying mitochondria to supply citric acid cycle → oxidative phosphorylation.