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Biology > Enzymes, intro to cellular respiration > Flashcards

Enzymes, intro to cellular respiration Flashcards

0
Q

There are different forms of some enzymes that…

A

assist different reactions.

  • cytosolic version of enzyme
  • mitochondrial version of enzyme (ex slide 5 lecture 12)
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1
Q

Can enzymes work in forward and reverse directions?

A

Some enzymes can

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2
Q

activity

A

total amount of reactant converted to product (over time)

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3
Q

number of enzyme molecules

A

genes

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4
Q

activity of each enzyme molecule

A

pH, temperature etc.
concentrations of substrates
inhibitors and activators

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5
Q

inhibitors

A

molecules that interact in some way with the enzyme to prevent it from working in the normal manner

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6
Q

enzyme activator

A

molecules that bind to enzymes and increase their activity

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7
Q

factors that affect enzyme activity

A

cofactors

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8
Q

cofactors

A 
nonprotein enzyme helpers
coenzyme
inorganic  (such as a metal ionic form)
-ex magnesium needed for hexokinase 
-forms complex with ATP
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9
Q

Coenzyme

A

organic cofactor

EX. vitamins

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10
Q

The regeneration of ATP

A

an organism at work us ATP continuously, but ATP is a renewable resource that can be regenerated by the addition of phosphate to ADP

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11
Q

what happens if the inhibitor attaches to the enzyme by covalent bonds?

A

inhibition is usually irreversible

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12
Q

Many enzyme inhibitors bind to the enzyme by weak interactions…

A

in which case inhibitions is reversible.

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13
Q

some reversible inhibitors resemble the normal substrate molecule…

A

and compete for admission into the active site

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14
Q

Competitive inhibitors

A

reduce the productivity of enzymes by blocking substrates from entering active sites

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15
Q

How can competitive inhibitors be overcome?

A

by increasing the concentration of substrate so that as active sites become available, more substrate molecules than inhibitor molecules are around to gain entry to the sites

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16
Q

noncompetitive inhibitors

A

do not directly compete with the substrate to bind to the enzyme at the active site. Instead they impede enzymatic reactions by binding to another part of the enzyme.

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17
Q

What does the noncompetitive inhibitors interaction cause?

A

This interaction cause the enzyme moleules to change its shape in such a way that the active site becomes less effective at catalyzing the conversion of substrate to product.

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18
Q

What does regulation of enzyme activity help?

A

helps control metabolism

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19
Q

Allosteric regulation

A

protein’s function at one site is affected by the binding of a regulatory molecule to a separate site.

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20
Q

allosteric activator

A

binds to the allosteric regulatory site

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21
Q

how can a substrate activate the enzyme?

A

by stabilizing it

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22
Q

feedback inhibition

A

When ATP allosterically inhibits an enzyme in an ATP generating pathway, the result is feed back inhibition

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23
Q

What happens in feedback inhibition?

A

a metabolic pathway is switched off by the inhibitory binding of its end product to an enzyme that acts early in the pathway.

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24
Q

certain cells use this five step pathway to synthesize the amino acid isoleucine from threonine…

A

as isoleucine accumulates, it slows down its own synthesis by allosterically inhibiting the enzyme for the first step of the pathway. feedback inhibition thereby prevents the cell from wasting chemical resources by making more isoleucine than is necessary

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25
Q

If the cell is not using products(isoleucine)….

A

…product of the pathway builds up

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26
Q

if the cell is using product (isoleucine)…

A

product of the pathways does not build up

-initial substrate can bind to active site

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27
Q

sites of enzyme activity

A
  • cytoplasm/cytosol
  • membranes
    - plasma membrane
    - endomembranes
    - mitochondrial membrane,
    - thylakoid membrane
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28
Q

how is sunlight a part of metabolism?

A

by converting the energy of sunlight to a usable form of chemical energy, photosynthesis is the source of virtually all metabolic energy in biological lsystems

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29
Q

major catabolic pathways- exergonic breakdown of organic molecules

A
  • fermentation
  • anaerobic respiration
  • aerobic respiration-oxygen
    • glycolysis
    • Krebs cycle
    • oxidative phosphorylation
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30
Q

Aerobic respiration

A

a form of cellular respiration that requires oxygen in order to generate energy

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31
Q

oxidized

A

glucose and other substrates are

“burned”

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32
Q

oxidation

A

loss of electrons

33
Q

reduction

A

gain of electrons

34
Q

fermentation

A

catabolic process, is a partial degradation of sugars or other organic fuel that occurs without the use of oxygen

35
Q

aerobic respiration

A

most efficient catabolic pathway,
oxygen is consumed as a reactant along with the organic fuel.
cells of most eukaryotic and many prokaryotic organisms can carry out aerobic respiration.

36
Q

anaerobic respiration

A

some prokaryotes use substances other than oxygen as reactants in a similar process that harvests chemical energy without oxygen

37
Q

Cellular respiration

A

includes both aerobic and anaerobic processes, but is often used to refer to the aerobic process.
is the set of metabolic reactions and processes that take place in the cells that take place in the cells of organisms to convert biochemical energy from nutrients into ATP.
considered an exothermic redox reaction, releases heat.

38
Q

what reactions are involved in respiration?

A

catabolic reactions

39
Q

redox reaction

A

transfer of one or more electrons from one reactant to another

40
Q

what makes them good fuels?

A

organic molecules that have an abundance of hydrogen are excellent fuels because their bonds are a source of hilltop electrons, whose energy may be released as these electrons fall down an energy gradient when they are transferred to oxygen.

41
Q

How is the redox reaction involved in cellular respiration?

A

occurs when glucose C5H12O6 (Fuel) is oxidized to carbon dioxide,
Hydrogen (H) and electrons removed from glucose
oxygen (O2) is reduced to water-hydrogen added to oxygen

42
Q

biological oxidation

A

series of steps

43
Q

Abiotic oxidation of free hydrogen gas

A

heat light
explosion
uncontrolled

44
Q

Biological electron carrier NAD+ (nicotinaminde adenine dinucleotide)

A

The H atoms are not transferred directly to O, but instead are usually passed first to an electron carrier, a coenzyme called NAD+

45
Q

Why is NAD+ well suited as an electron carrier?

A

because it can cycle easily between oxidized (NAD+) and reduced (NADH) states

46
Q

How does NAD+ trap electrons from glucose and the other organic molecules in food?

A

enzymes called dehydrogenases remove a pair of hydrogen atoms from the substrate, thereby oxidizing it, the enzyme delivers the 2 electrons along with 1 proton to its coenzyme, NAD+, The other proton is released as a H ion (H+) into the surrounding solution

47
Q

Why is oxygen the terminal electron acceptor need in CR?

A

The low energy electrons that emerge from the electron transport system are taken up by O2. The negatively changed O molecules take up protons from the medium and form water.

48
Q

cellular respiration

A

glucose is oxidized to carbon dioxide and oxygen is reduced to water

49
Q

electrons lose energy as….

A

they are transferred to oxygen

50
Q

Electrons are passed from glucose to NAD+…

A

(forming NADH) in a stepwise fashion through ETC to oxygen

51
Q

Energy released is used to make….

A

ATP

52
Q

how is oxidative phosphorylation powered?

A

powered by redox reaction
ETC
most ATP
O is last electron acceptor

53
Q

substrate level

A

phosphorylation:
enzyme transfers Pi
directly from substrate to ADP

54
Q

What happens if energy is released from a fuel all at once?

A

it cannot be harnessed efficiently for constructive work.

55
Q

Glycolysis

A

a series of reactions that ultimately splits glucose into pyruvate.
occurs in almost all living cells, serving as the starting point for fermentation or cellular respiration.

56
Q

Citric acid cycle

A

a chemical cycle involving 8 steps that completes the metabolic breakdown of glucose molecules begun in glycolysis by oxidizing acetyl to carbon dioxide; occurs within the mitochondrion in eukaryotic cells and in the cytosol or prokaryotes; together with pyruvate oxidation, the second major stage in cellular respiration.

57
Q

glycolysis

A
  • Splitting of sugar
  • breaks down glucose into two molecules of pyruvate (a 3 carbon sugar)
  • harvests chemical energy by oxidizing glucose to pyrucate
58
Q

What phases does glycolysis go through?

A

2 phases, 10 steps
energy investment phase
energy payoff phase

59
Q

glycolysis, which occurs in the cytosol, begins the degradation process by…

A

breaking glucose into two molecules of a compound called pyruvate

60
Q

What happens in glycolysis?

A

6 carbon sugars is split into two 3 carbon sugars. these smaller sugars are then oxidized and their remaining atoms rearranged to form two molecules of pyruvate

61
Q

Energy investment phase

A

the cell actually spends ATP

62
Q

Steps in investment phase

A
  1. glucose is phosphorylated-chemically reactive,becomes charged, trapped in cell
  2. glucose is converted to its isomer
  3. another phosphate added to fructose-6-phosphate
  4. fructose bisphosphate split into 2 trioses (isomers of each other)
63
Q

payoff phase

A
  1. each G3P is oxidized to 1,3 bisphosphoglycerate, NAD+ reduced to NADH
    6.enzyme(kinase) transfers phosphate groups from substrate to
    ADP->ATP: substrate level phosphorylation-exergonic reaction
    -product has high potential energy
  2. relocation of phosphate group
    8.dehydration reaction to form PEP
    9.Phosphate groups added to ADPs->2ATP (substrate level phosphorylation), conversion of PEP to pyruvate
  3. pyruvate
64
Q

Used by glycolysis

A

Glucose (what your breaking down)
O2 (it accepts protons and electrons at the end to produce water)
ADP+Pi (is used to make ATP)

65
Q

Produced by glycolysis

A

CO2 ( its how all the carbons from glucose escape)

ATP (the entire point of these processes)

66
Q

what is both used and produced in glycolysis?

A

NADH (first made then used in the ETC)

NAD+

67
Q

Glycolysis is…

A
  • in cytosol

- oxidation of glucose to 2 pyruvate, 2 ATP net, pyruvate to TCA, HADH to ETC

68
Q

O2 is present:

A

pyruvate to the citric acid cycle in mitochondrion

69
Q

O2 absent

A

pyruvate oxidized via fermentation

70
Q

Where does the citric acid cycle / Krebs cycle occur?

A

In mitochondrial matrix in eukaryotes

in cytosol of prokaryotes

71
Q

pyruvate first converted to…

A

acetyl CoA upon entry into mitochondrion.

72
Q

Acetyl CoA is…

A

oxidized by Krebs cycle

73
Q

Conversion of pyruvate to Acetyl CoA

A
  1. pyruvate enters mitochondria by active transport
  2. carboxyl group removed carbon dioxide produced (will diffuse out)
  3. Two carbon fragment oxidized, NAD reduced to NADH
  4. Coenzyme Q added to acetyl group, AcetylCoA has very high potential NRG
74
Q

The citric acid cycle

A

has 8 steps, each catalyzed by a specific enzyme

for each turn of the citric acid cycle, two carbons enter in the the relatively reduced form of an acetyl group

75
Q

The citric acid cycle steps

A
  1. Acetyl group of acetyl CoA combines with oxaloacetate, forming citrate-the rest of cycle converts the citrate 6Cs back to oxaloacetate 4Cs-carbon leaves as CO2
  2. Citrate converted to its isomer
  3. Oxidation of isocitrate, reduction of NAD+ to NADH and CO2 is produced
  4. CO2 is removed from alpha ketoglutarate-attachement of CoA-reduction of NAD+ to NADH intermediate oxidized
  5. CoA displaced, GDP phosphorylated(ATP can be generated from by GTP)
  6. Succinate oxidized; hydrogens transferred to FAD
  7. Malate oxidized, NAD+reduced to NADH
  8. Oxaloacetate regenerated
76
Q

NADH produced at…

A

3 steps

77
Q

The citric acid cycle is..

A
  • in mitochondrion

- acetyl CoA combined with oxaloacetate to form citrate,citrate cycle back to oxaloacetate

78
Q

Where is oxidative phosphorylation found?

A

in the cristae of the mitochondrion of eukaryotes, plasma membrane of prokaryotes

79
Q

what is oxidative phosphorylation?

A

folding of the membrane increase the surface area for the enzymes

80
Q

electron transport chain

A
  • collection of molecules embedded in the inner membrane of the mitochondrion in eukaryotic cells, in prokaryotes they reside in the plasma membrane.
  • the folding of the inner membrane to form cristae increases its surface area, providing space for thousands of copies of the chain in each mitochondrion

Biology (16 decks)

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