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BIO 111 > Chapter 7 > Flashcards

Chapter 7 Flashcards

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Biology 101 flashcards
1
Q

autotrophs

A

able to produce their own organic molecules through photosynthesis

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2
Q

heterotrophs

A

live on organic compounds produced by other organisms

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3
Q

respiration

A

all organisms use cellular respiration to extract energy from organic molecules

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4
Q

oxidations

A

loss of electrons

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5
Q

dehydrogenations

A

lost electrons are accompanied by protons
* a hydrogen atom is lost (1 electron, 1 proton)

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6
Q

T or F: cellular respiration is a series of reactions

A

true

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7
Q

nicotinamide adenosine dinucleotide (NAD+)

A
  • An electron carrier
  • NAD+ accepts 2 electrons and 1 proton to become NADH
  • Reaction is reversible
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8
Q

aerobic respiration

A

final electron receptor is oxygen (O2)

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9
Q

anaerobic respiration

A

final electron acceptor is an inorganic molecule (not O2)

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10
Q

fermentation

A

final electron acceptor is an organic molecule

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11
Q

aerobic respiration formula

A

C6H12O6 + 6O2 —–> 6CO2 + 6H2O
* ΔG: -686kcal/mol of glucose
* This large amount of energy must be released in small steps rather than all at once.

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12
Q

electron carriers

A
  • Many types of carriers used: soluble, membrane-bound, move within membrane
  • All carriers can be easily oxidized and reduced
  • Some carry just electrons, some electrons and protons
  • NAD+ acquires 2 electrons and a proton to become NADH
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13
Q

ATP

A

Cells use ATP to drive endergonic reactions
-ΔG = -7.3 kcal/mol
2 mechanisms for synthesis of ATP
1. Substrate-level phosphorylation
* Transfer phosphate group directly to ADP
During glycolys
2. Oxidative phosphorylation
* ATP synthase uses energy from a proton gradient

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14
Q

oxidation of glucose

A

The complete oxidation of glucose proceeds in stages:
1. Glycolysis
2. Pyruvate oxidation
3. Krebs cycle
4. Electron transport chain & chemiosmosis

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15
Q

glycolysis

A
  • converts 1 glucose (6 carbons) to 2 pyruvate (3 carbons)
  • 10 step biochemical pathway
  • occurs in the cytoplasm
  • Net production of 2 ATP molecules by substrate level phosphorylation
  • 2 NADH produced by the reduction of NAD+
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16
Q

for glycolysis to continue, NADH must be recycled to NAD by either:

A

Aerobic respiration:
* oxygen is available as the final electron acceptor
* produces significant amount of ATP
Fermentation:
* occurs when oxygen is not available
* organic molecule is the final electron acceptor

17
Q

fate of pyruvate

A

depends on oxygen availability
* when oxygen is present, pyruvate is oxidized to acetly-CoA, which enters the Krebs cycle
* without oxygen, pyruvate is reduced in order to oxidize NADH back to NAD+

18
Q

oxidation of pyruvate

A

if oxygen is present, pyruvate is oxidized
** occurs in the mitochondria in eukaryotes
** multienzyme complex called pyruvate dehydrogenase catalyzes the reaction
* occurs at the plasma membrane in prokaryotes

19
Q

products of pyruvate oxidation

A

For each 3-carbon pyruvate molecule:
* 1 CO2
* 1 NADH
* 1 Acetyl-CoA which consists of 2 carbons from pyruvate attached to coenzyme A
* Acetyl-CoA proceeds to the Krebs cycle

20
Q

Krebs Cycle

A
  • oxidizes the acetyl group from pyruvate
  • occurs in the matrix of the mitochondria
  • Biochemical pathway of 9 steps in 3 segments
    1. Acetyl-CoA + oxaloacetate –> citrate
    2. Citrate rearrangement and decarboxylation
    3. Regeneration of oxaloacetate
21
Q

Acetyl-CoA and the Krebs Cycle

A
  • releases 2 molecules of CO2
  • reduce 3 NAD+ to 3 NADH
  • reduce 1 FAD (electron carrier) to FADH2
  • produce 1 ATP
  • regenerate oxaloacetate
22
Q

Electron Transport Chain

A

= a series of membrane-bound electron carriers
* embedded in the inner mitochondrial membrane
* electrons from NADH and FADH2 are transferred to complexes of the ETC
* each complex:
- a proton pump creating proton gradient
- transfers electrons to next carrier

23
Q

chemiosmosis

A
  • accumulation of protons in the intermembrane space drives protons into the matrix via diffusion
  • membrane relatively impermeable to ions
  • most protons can only reenter matrix through ATP synthase
24
Q

energy yield of respiration

A

Theoretical energy yield:
- 32 ATP per glucose for bacteria
- 30 ATP per glucose for eukaryotes

Actual energy yield:
- reduced yield is due to:
* “leaky” inner membrane
* use of the proton gradient for purposes other than ATP synthesis

25
Q

regulation of respiration

A

feedback inhibition
1. In glycolysis
* phoshofructokinase is allosterically inhibited by ATP and/or citrate
2. In pyruvate oxidation
* pyruvate dehydrogenase inhibited by high levels of NADH
* citrate synthetase inhibited by high levels of ATP

26
Q

uncoupling of electron transport system

A
  • multiple molecules can inhibit the electron transport system
  • make the membrane “leaky” to H+
  • prevent the ATP synthase from producing ATP as the H+ moves through the channel
27
Q

NADH

A

reduced form of nad plus
takes to electrons to get from nad plus to nadh

28
Q

oxidative phosphorylation

A
  • atp synthase uses energy from proton gradient
  • when h ions travel through facilitated diffusion pump atp is released from atp rotary engine
29
Q

where does each step of cellular respiration occur?

A
  1. glycolysis- cytoplasm
  2. pyruvate oxidation- mitochondrial matrix
  3. Krebs cycle: occurs in mitocondrial matrix
  4. electron transport system: mitocondrial inner membrane
30
Q

how many ATPs are yielded through cellular respiration in bacteria and eukaryotes.

A

32- bacteria
30- eukaryotes

31
Q

what is the order of biomolecules that are the best in providing energy? from most to least

A
  1. carbs
  2. fats
  3. protein
  4. nucleic acid
32
Q

What are the products of each step of cellular respiration and how many ATPs are made via chemiosmosis

A

Glycosis- 2 ATP - 2 NADH - 2 pyruvate
pyruvate oxidation- 2 NADH
Krebs- 1 atp, 3NADH, 1 FADH, 2 co2 PER PYRVAYE times 2
ETC- 30 ATP, about 10 NADH

BIO 111 (12 decks)

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