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Biology 2311-- Fall 2022 > Exam 2 Chapter 7 > Flashcards

Exam 2 Chapter 7 Flashcards

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1
Q

What are autotrophs?

A

Autotrophs harvest sunlight and convert radiant energy into chemical energy

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2
Q

Heterotrophs

A

Live off of energy produced by autotrophs, extracting energy via digestion and catabolism

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3
Q

What is cellular respiration?

A

A collection of metabolic reactions that breaks down food molecules to produce energy in the form of ATP

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4
Q

What is aerobic respiration?

A

A form of cellular respiration in eukaryotes and many prokaryotes where oxygen is a reactant in the ATP producing process

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5
Q

What is anaerobic respiration?

A

A form of cellular respiration in some prokaryotes where a molecule other than oxygen (such as sulfate or nitrate) is used in the ATP producing process

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6
Q

What is the goal of respiration?

A

Production of ATP

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7
Q

Describe the respiration and photosynthesis cycle

A

Glucose is broken down via cellular respiration to produce CO2 and Water and synthesize atp. This CO2 and water is synthesized via photosynthesis, using energy from sunlight and producing oxygen in the process to form glucose as an end product

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8
Q

What type of reaction does respiration involve?

A

Redox reactions (energy released from oxidation reactions in the form of electrons) and electrons shuttled by electron carriers to an electron transport chain

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9
Q

What is the final electron acceptor in aerobic respiration?

A

Oxygen (eukaryotes and many prokaryotes)

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10
Q

What is the final electron acceptor in anaerobic respiration?

A

inorganic molecule other than oxygen (occurs in some prokaryotes)

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11
Q

Why are redox reactions important?

A

Electrons release energy as they pass from a donor molecule to an acceptor molecule, and this free energy is available for cellular work

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12
Q

Methane oxygen reaction

A

Methane is oxidized since it loses some of its shared electrons, and o2 is reduced since it gains electrons

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13
Q

Is NAD the reduced or the oxidized form?

A

Oxidized

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14
Q

What is the equation for cellular respiration?

A

C6H12O6 + 6O2 + 32 ADP + 32 P= 6H2O6CO2+ 32 ATP

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15
Q

What is the delta g value for aerobic respiration?

A

Delta g= -686 kcal/mol of glucose, must be released in small steps

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16
Q

True or false: ATP is generated by the transfer of electrons from one energy level to another

A

True

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17
Q

What are some characteristics of carriers?

A

Soluble, membrane-bound, move within the membrane, easily oxidized and reduced, some carry protons too

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18
Q

What enzymes are used in transfer of electrons to an electron carrier?

A

Dehydrogenase

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19
Q

What is the most common electron carrier?

A

The coenzyme NAD, which is reduced to become NADH

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20
Q

What are the four stages of oxidation of glucose?

A
  1. Glycolysis
  2. Pyruvate oxidation
  3. Krebs
  4. Electron transport chain and chemiosmosis
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21
Q

Where does glycolysis occur?

A

Cytosol

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22
Q

Where does pyruvate oxidation and krebs cycle occur?

A

mitochondrial matrix

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23
Q

What is the delta g of aerobic respiration?

A

-686 kcal/mol of glucose, must be released in small steps

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24
Q

What is substrate-level phosphorylation?

A

A reaction that transfers a phosphate group from a substrate to ADP

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25
Q

Examples of feedback inhibition in glycolysis

A

ATP, NADH, and citrate allosterically inhibit phosphofructokinase
AMP activates phosphofructokinase

Glucose-6 phosphate inhibits hexokinase

Fructose 1,6 bisphosphate activates pyruvate kinase

Pyruvate kinase is inhibited by ATP and acetyl coA

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26
Q

Feedback inhibition in pyruvate oxidation

A

Pyruvate dehydrogenase is inhibited by NADH

27
Q

Feedback inhibition in citric acid cycle

A

Citrate synthase is inhibited by ATP and citrate

28
Q

T or F: individual electron carriers of the ETS are organized from high to low free energy

A

T

29
Q

NADH and FADH are easily ____ and oxygen is easily ________

A

oxidized, reduced

30
Q

What type of transport is used to power the movement of H+ into the intermembrane space

A

active transport

31
Q

What is proton motive force?

A

The stored energy produced by a proton and voltage gradient; this energy is used for atp synthesis and cotransport of substances to and from mitochondria

32
Q

Chemiosmosis

A

Powers ATP synthase; H+ diffuses back into matrix since higher concentration in intermembrane space. The membrane is relatively impermeable so protons reenter matrix through ATP synthase instead, using the energy to make ATP

33
Q

Describe structure of ATP synthase

A

Basal unit in inner membrane is connected by stalk to headpiece in matrix; a stator bridges basal and headpiece, and proton-motive force moves protons through basal unit into the matrik; H+ flow causes headpiece to rotate (chemiosmosis)

34
Q

What is the theoretical yield?

A

38 atp for bacteria, 36 for eukaryotes (NADH=3 ATP, FADH2= 2 ATP)
10 NADH + 2 ATP = 30+ 4= 34, 4 from glycolysis and krebs is 38 but 2 ATP are used to transport pyruvate into mitochondrial matrix

35
Q

Actual yield

A

Prokaryotes= 32, eukaryotes= 30 (2.5 NADH, 1.5 FADH2)

-leaky inner membrane and use of proton gradient for other purposes contributes to this loss

36
Q

What did Racker and Stoeckenius show?

A

H+ gradient powers ATP synthesis by ATP synthase
1. Experimenters made a synthetic vesicle with membrane from an archaean that only had bacteriorhodopsin,which is a light-activated proton pump.
2. Researchers made vesicles with bacteriorhodopsin and ATP synthase, which was oriented so that the headpiece was on the outside of the vesicles. That way, the H+ brought in from the bacteriorhodopsin could move into the basal unit and spin the headpiece to turn ATP. They found that in the dark, no atp was synthesized.

37
Q

What was the conclusion of Racker and Stoecknius’ experiment?

A

A H+ gradient and proton motive force powers ATP synthesis by ATP synthase, which also supports the chemiosmotic hypothesis for ATP synthesis in mitochondria

38
Q

What is the chemiosmotic theory?

A

Proposes that mitochondrial electron transfer produces a H+ gradient and that this gradient powers ATP synthesis

39
Q

When oxygen is present, pyruvate is oxidized to ______

A

Acetyl-coA

40
Q

Without oxygen, pyruvate is ______ to help _______ NADH into NAD+

A

reduced, oxidized

41
Q

What are some possible products of pyruvate:

A

With oxygen: acetyl-coa, krebs, etc in mitochondria (produces nadh which becomes nad in the etc, donating electrons to o2 to become h2o)

Without oxygen: lactate or acetaldehyde, co2, and ethanol

42
Q

How is NADH recycled to NAD in aerobic respiration?

A

Oxygen is the final electron acceptor, and a significant amount of ATP is produced

43
Q

How is NADH recycled in fermentation?

A

Oxygen is not available, so the electrons carried by NADH are transferred to an acceptor molecule; final electron acceptor becomes another organic molecule, and ATP is supplied by glycolysis, while NAD is produced by step 6

44
Q

What is fermentation?

A

An alternative pathway for releasing energy so cells can produce ATP without using oxygen

45
Q

What is anaerobic respiration?

A

Oxygen is not a reactant and electrons transferred to another atom like sulfur instead; methanogens and sulfur bacteria use this method

46
Q

What are the two types of fermentation?

A

Lactate fermentation- pyruvate becomes lactate; this occurs in bacteria, plant tissues, and skeletal muscles, and its used to make buttermilk, yogurt, and pickles

Alcoholic- pyruvate becomes ethyl alcohol and CO2, and this occurs in plant tissues, invertebrates, protists, bacteria, and single-celled fungi like yeasts. It makes bread and alcoholic beverages

47
Q

What are faculative anaerobes?

A

Can switch between fermentation and full oxidative pathways depending on oxygen supply; E.coli in the digestive tract, lactobacillus in yogurt and buttermilk, and S. cerevisia in winemaking, brewing, and baking are all examples. Vertebrate muscle cells also use fermentation to produce lactate when the demands of the cell exceed the supply of oxygen

48
Q

Strict anaerobes

A

Fermentation is the only source of ATP for bacteria and fungi that lack enzymes to carry out oxidative phosphorylation; most strict anaerobes require an oxygen-free environment (botulism and tetanus)

49
Q

Strict aerobes

A

Absolute requirement for oxygen and cannot live only by fermentation; brain cells

50
Q

Warburg effect

A

Higher than normal rates of glycolysis, contributing to large amounts of lactate

51
Q

Amino acids undergo _______ to become a molecule that enters the respiration cycle

A

deamination

52
Q

Alanine becomes

A

pyruvate

53
Q

Asparate becomes

A

oxaloacetate

54
Q

glutamate becomes

A

alphaketoglutarate

55
Q

glycine becomes

A

3-phosphoglycerate

56
Q

phenylalanine and tyrosine become

A

phosphoenolpyruvate

57
Q

Can glycolysis and the citric acid synthesize other cellular molecules?

A

Yes, and if glucose is made from these intermediates, it is called gluconeogenesis

58
Q

Fats are broken down to ____ and ____

A

fatty acids and glycerol (glycerol is contributed to g3p and enters at reaction 6)

59
Q

What are fatty acids converted to?

A

acetyl groups via beta oxidation (oxygen-dependent process)

60
Q

The respiration of fats is more/less efficient than glucose

A

more

61
Q

what molecule directs products of many oxidative pathways into citric acid cycle?

A

coA

62
Q

Timeline of metabolism

A
  1. ability to store chemical energy in atp
  2. glycolysis (all living organisms)
  3. anaerobic photosynthesis using h2s
  4. use of h2o in photosynthesis (permanent change in earths atmosphere)
  5. nitrogen fixation
  6. aerobic respiration
63
Q

Why do synthesized moecules have higher free energy than co2 and h20?

A

Weaker covalent bonds such as C-C, C-H have more potential to be broken

64
Q

How is energy from glucose released outside of an organism?

A

Heat

Biology 2311-- Fall 2022 (12 decks)

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