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AP Biology - Mrs. Unger 24-25 > Unit 4: Redox & Cellular Respiration > Flashcards

Unit 4: Redox & Cellular Respiration Flashcards

1
Q

Define

Redox Reaction

A

Paired chemical reactions in which one reactant gains an electron pair from another reactant

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2
Q

Describe

Parts of a redox reaction

A

Molecule that GAINS electron(s) is REDUCED
Molecule that LOSES electron(s) is OXIDIZED

Ae- + B -> A + Be-
A starts the reaction with an electron, which gets given to B. During the reaction:
A gets oxidized
B gets reduced

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3
Q

Describe a molecule that has been oxidized

A

Has lost electrons
Has lower potential energy
Fewer C-C or C-H bonds and/or more C-O bonds

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4
Q

Describe a molecule that has been reduced

A

Gained electrons
Has higher potential energy
Has more C-C or C-H bonds and/or fewer C-O bonds

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5
Q

What makes organic molecules “high energy”

A

Lots of C-H bonds, which can be oxidized to release energy

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6
Q

If an electron goes from a very electronegative atom to a less electronegative atom, it has been…

A

reduced
(gained potential energy; decreased stability)

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7
Q

Describe the two electron carriers used during cellular respiration

A

Oxidized (low energy) forms: NAD+ and FAD
Each gains a pair of electrons and one or two H+ ions
Reduced (high energy) forms: NADH and FADH2

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8
Q

What are electron carriers?

A

Molecules that can transfer electrons from one place to another, by easily cycling between reduced (with electrons) and oxidized (without electrons) states

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9
Q

What two ways (mechanisms) can ATP be made?

A
  1. Oxidative phosphorylation
  2. Substrate level phosphorylation
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10
Q

Describe

oxidative phosphorylation

general, for both cellular respiration and photosynthesis

A

Making ATP using an electron transport chain and ATP synthase

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11
Q

Describe

Substrate level phosphorylation

A

Making ATP by transferring phosphate from one molecule to an ADP

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12
Q

What causes the electrons to move during the ETC?

A

Each protein in the electron transport chain is more electronegative.
Electrons “hop” to sequentially more electronegative molecules

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13
Q

What is needed in all electron transport chains?

A
  • A source of electrons
  • A source of energy (which may be the electrons themselves)
  • A final electron acceptor
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14
Q

What are the two major parts of aerobic cellular respiration?

A

Oxidation of glucose
&
Oxidative phosphorylation

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15
Q

What happens during the oxidation of glucose?

General overview

A

High-energy C-H bonds in glucose are oxidized, which fuels the production of reduced electron carriers and a small amount of ATP

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16
Q

State

Steps of Glucose Oxidation

A

Glycolysis (includes investment & payoff phases)
Link reaction
Citric acid cycle / Krebs Cycle

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17
Q

Where does each step of cellular respiration occur?

A

Glycolysis (all) - Cytosol
Link & Krebs Cycle - Mitochondrial matrix
ETC - across inner mitochondrial membrane

18
Q

Identify the inputs and outputs of

Investment phase of glycolysis

A

In: Glucose and 2 ATP
Out: G3P (AKA PGAL) and 2 ADP

2 phosphates from ATP are bound to G3P

19
Q

State

Steps of oxidative phosphorylation

A

Electron transport chain
&
Chemiosmosis

20
Q

Reactants, products, and energy molecules for

Payoff phase of glycolysis

A

In: G3P, 2 NAD+, and 4 ADP
Out: Pyruvate, 2 NADH, and 4 ATP

21
Q

Reactants, products, and energy molecules for

Link Reaction

A

In: Pyruvate, coenzyme A, and NAD+
Out: Acetyl CoA, CO2, and NADH

Occurs TWICE per molecule of glucose

22
Q

Reactants, products, and energy molecules for

Krebs Cycle

A

First step:
In: Acetyl CoA, 4-carbon molecule (oxaloacetate)
Out: Coenzyme A, 6-carbon molecule (citrate)

All other steps:
In: Citrate, 3 NAD+, 1 FAD, and 1 ADP+Pi
Out: Oxaloacetate, 3 NADH, 1 FADH2, and 1 ATP

Occurs TWICE per molecule of glucose

23
Q

Reactants, products, and energy molecules for

Electron Transport Chain

of cellular respiration

A

In: O2, NADH, and FADH2
Out: H2O, NAD+, and FAD

24
Q

Reactants, products, and energy molecules for

Chemiosmosis

A

In: ADP and Pi
Out: ATP

Occurs TWICE per molecule of glucose

25
Q

Describe what happens during the ETC of cellular respiration

A
  • NADH and FADH2 are brought to the inner mitochondrial membrane
  • Electrons from electron carrier are passed to the electron transport chain
  • Electrons move to more and more electronegative proteins in the chain
  • As electrons move through chain, protons (H+ ions) are pumped from matrix to intermembrane space
  • Electrons bind to final electron acceptor, O2, resulting in the formation of H2O
26
Q

Describe what happens during chemiosmosis of cellular respiration

A
  • ADP and phosphate bind to ATP synthase complex
  • Protons (H+ ions) from the intermembrane space flow through channel in ATP synthase to the mitochondrial matrix
  • Passive movement of protons through ATP synthase spins part of the complex
  • Mechanical rotation of ATP synthase complex catalyzes the reaction of ADP and phosphate to ATP
27
Q

How many ATP are made in each stage of aerobic cellular respiration?

A

Glycolysis: 2 (net)
Link: 0
Krebs: 2 (1 per acetyl CoA)
Oxidative phosphorylation: Variable (22ish to 28ish)

28
Q

Define

Fermentation

A

Partially oxidizing glucose without the use of oxidative phosphorylation

29
Q

Describe

The purpose of fermentation

A

A way of using glycolysis to generate ATP, then using pyruvate as an oxidizing agent for NADH to regenerate NAD+ (to be used in doing more glycolysis)

30
Q

Identify

Two types of fermentation

A

Alcohol (or ethanol)
&
Lactic Acid

31
Q

Describe

Alcohol fermentation

A
  • Glucose is converted to pyruvate using glycolysis, producing 2 ATP
    * This also reduces NAD+ to NADH
  • Pyruvate is reduced to ethanol and CO2
    * This also oxidizes NADH to NAD+
  • Glycolysis can continue so long as pyruvate continues to oxidize NADH back to NAD+
32
Q

Describe

Lactic Acid fermentation

A
  • Glucose is converted to pyruvate using glycolysis, producing 2 ATP
    * This also reduces NAD+ to NADH
  • Pyruvate is reduced to lactice acid2
    * This also oxidizes NADH to NAD+
  • Glycolysis can continue so long as pyruvate continues to oxidize NADH back to NAD+
33
Q

What molecules, besides glucose, can be catabolized for energy?

A

Starch and other polysaccharides
Triglycerides (fatty acids = HIGH ENERGY!)
Proteins, but as a last resort

34
Q

Chemical Formula for Cellular Respiration

A

C6H12O6 + 6 O2 -> 6 CO2 + 6 H2O

35
Q

What is

Glucose

A

C6H12O6
6 carbon molecule

36
Q

What is

G3P

A

3 carbon molecule with phosphate attached
Made at the end of investment phase of glycolysis
Glyceraldehyde 3-phosphate
AKA PGAL
phosphoglyceraldehyde

37
Q

What is

Pyruvate

A

3 carbon molecule
Made at the end of glycolysis

38
Q

What is

Acetyl CoA

A

Coenzyme A + a 2-carbon acetyl group
Made during the link reaction and used in the Krebs Cycle

39
Q

4 carbon molecule in Krebs Cycle

A

Oxaloacetate
This is a low-energy, highly oxidized molecule

40
Q

6 carbon molecule in Krebs Cycle

A

Citric acid
This has more potential energy in it than oxaloacetate, but is still way more oxidized than glucose

AP Biology - Mrs. Unger 24-25 (27 decks)

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