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MC Biochem 2 > Test 2 shit > Flashcards

Test 2 shit Flashcards

1
Q

This is where photosynthesis takes place?

A

chloroplasts

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2
Q

these membranous structures in chloroplasts are stack, flattened disks.

A

Thylakoids

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3
Q

This is the principle photoreceptor in chloroplasts of green plants

A

chlorophyll A

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4
Q

chlorophyll a contains this ion in the center of the tetrapyrrole

A

magnesium

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5
Q

Plastocyanin requires this cofactor for activity

A

copper

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6
Q

what is the prosthetic group of ferredoxin-NADP+ reductase

A

FAD

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7
Q

This is one of the accessory pigments in plants

A

B-carotene

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8
Q

this electron carrier of photosystem I is an iron sulfur protein

A

ferredoxin b

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9
Q

Photosystems II responds to waves shorter than this value

A

680 nm

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10
Q

the inner membarne of a chloroplast surrounds a space called the

A

stroma

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11
Q

the process in which a positive charge forms on one molecule by the loss of a photo excited electron, and a negative charge forms on another by a gain of an electron is referred to as

A

photo induced charge seperation

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12
Q

P700 is the pigment reaction center for___

A

photosystem I

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13
Q

The manganese center of photosystem II converts __ to+___

A

H2O to O2

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14
Q

electrons flow from photosystem I to photosystem II through the

A

cytochrome bf

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15
Q

In the light reactions of photosynthesis, the cooperation between photosystem I and photosystem II creates a flow of electron from H2O to

A

NADP+

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16
Q

The light induced electron transfer in photosynthesis result in the transfer of __ into the thylakoid space

A

H+ or prtons

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17
Q

In ___, ATP is generated without the commitment of NADPH

A

cyclic phosphorylation

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18
Q

The transfer of excitation energy from one molecule to one nearby through electromagnetic interactions is called

A

resonance energy transfer

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19
Q

How is light used in photosynthesis?

A

The light is used to generate high energy electrons with great reducing potential

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20
Q

How many chloroplasts does a typical plant have?

A

1 to 100

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21
Q

Light absorbed by a chlorophyll a causes

A

an electron to move from ground state to an excited state

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22
Q

Bacterial reaction centers a analogous to

A

Photosystem I and II

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23
Q

The D1 and D2 subunits of photosystem II

A

span the thylakoid membrane

  • are similar to each other
  • are homologous to the L and Mchains of the bacterial center
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24
Q

Light absorption induces electron transfer from P680 to__

A

Pheophytin

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25
Q

What is the original source of electrons used to neutralize the special pair in photosystem II?

A

H2O

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26
Q

The pathway of electron flow from H2O to NADP+ in photosynthesis is referred to as

A

Z scheme of photosynthesis

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27
Q

How many protons are transferred into the thylakoid lumen after absorption of four photons?

A

12

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28
Q

What are the light harvesting molecules?

A

Carotenoids

Chlorophyll b

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29
Q

How is chloroplast similar to mitochondria?

A

both are site of ATP synthesis

  • both have inner and outer membrane
  • The thylakoids of chloroplast are analogous to membrane cristae structure
  • both may have rise from symbiotic event
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30
Q

these organisms can synthesize glucose from CO2 and water

A

autotrophs

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31
Q

This is one of the products of photorespiration

A

phosphoglycolate

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32
Q

This is another name for ribulose 1,5-bisphosphate carboxylase/oxygense

A

rubisco

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33
Q

this is the pathway that ensures that sufficient amount of CO2 are available to minimize wasteful photorespiration

A

C4

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34
Q

the reduced form of this molecule is critical to reducing reactive oxygen species

A

glutathione

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35
Q

this enzyme is involved in both the Clavin cycle and the pentose phosphate pathway

A

transketolase

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36
Q

this metabolic adaptation is employed by plants living in hot dry climates

A

Crassulacean acid metabolism

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37
Q

This is a readily transportable and mobilizable sugar in plants

A

sucrose

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38
Q

these organisms obtain energy from chemical fuels

A

heterotrophs

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39
Q

This prosthetic group is tightly bound to the enzyme transketolase

A

TPP

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40
Q

The pentose phosphate pathway is also called

A

phosphogluconate pahtway
hexose monophosphate pathway
pentose shunt

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41
Q

the enzymes that catalyze the dark reaction of photosynthesis are located in the ___ of the chloroplast

A

stroma

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42
Q

The first of the Calvin cycle involves the addition of CO2 to ___to produce 2 molecules of 3-phosphoglycerate

A

ribulose 1,5-bisphosphate

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43
Q

The binding site of Mg2+ to rubisco involves the formation of a ___ group between lysine and Co2

A

carbamate

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44
Q

In photorespiration, the oxidation of glycol ate to glyoxylate occurs in the __

A

peroxisomes

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45
Q

The enzyme transketolase, transfers a ___ carbon fragment from a ketose to an aldose

A

2

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46
Q

In C4 plants, carbon dioxide is added to ____ to form oxaloacetate, which is reduced to malate, which carries CO2 to the bundle sheath cells

A

PEP

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47
Q

The oxidative phase of the pentose phosphate pathway produces ___which is required for lipid biosynthesis

A

NADPH

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48
Q

A ___ intermediate is formed between the carbonyl group of the ketose substrata and the 3-amino group of a lysine residue of transaldolase

A

Schiff base

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49
Q

Hemolytic anemia is caused by a deficiency of the enzyme

A

glucose 6-phosphate dehydrogenase

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50
Q

What is the source of carbons for the calvin cycle

A

Carbon dioxide

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51
Q

In the Calvin cycle, 3-phosphoglycerate is converted into which hexose phosphate?

A

Glucose 1-phosphate
Glucose 6-phosphate
Fructose 6-phoshate

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52
Q

Which sugars are converted into ribulose 5-phosphate by a single enzyme step

A

ribose 5-phosphate

xylose 5-phosphate

53
Q

Which form of thioredoxin activates certain Calvin cycle enzymes

A

reduced

54
Q

Which coenzyme is required by glyceraldehyde 3-phosphate dehydrogenase in chloroplasts to convert 3-phosphoglycerate into glyceraldehyde 3-phosphte

A

NADPH

55
Q

The C4 pathway is necessary in tropical plants because

A

at high temperatures, the oxygenate activity of rubisco is high

56
Q

What is the energy cost of the C4 pathway

A

30 molecules of ATP are used per hexose molecule made

57
Q

the purpose of the pentose phosphate pathway is to

A

generate NADPH

synthesize 5-carbon sugars

58
Q

Which of the following tissues does not contain the enzymes for an active pentose phosphate pathway

A

Skeletal muscle

59
Q

Which cofactor is required in glutathione reductase to aid in the reduction of oxidized glutathione by NADPH

A

FAD

60
Q

Why are components of the Calvin cycle called the “dark reactions”

A

unlike photosynthetic reactions the reactions of Calvin cycle do not depend on light to proceed

61
Q

Describe the stages of the Calvin cycle

A

1) fixation of CO2 by reaction with ribulose 1,5-bisphosphate to form 2 molecules of 3-PG
2) the formation of hexose sugars from 3-PG
3) the regeneration of ribulose 1,5-Bisphosphate

62
Q

most of the glucose residues in glycogen are linked by this type of bond

A

a-1,4 glycosidic bond

63
Q

This is the activated form of glucose that is required for glycogen synthesis

A

UDP-glucose

64
Q

This is the process by which a bond is cleaved by the addition of orthophosphate

A

phosphorylysis

65
Q

This type of bond is located at the branch points in glycogen

A

a-1,6 glycosidic bonds

66
Q

This is the liver enzyme that cleaves the phosphate from glucose 6-phosphate

A

glucose 6-phosphatase

67
Q

this enzyme catalyzes the phosphorylation of glycogen phosphorylase

A

phosphorylase kinase

68
Q

this enzyme is the 8 subunit of phosphorylase kinase

A

Calmodulin

69
Q

This hormone signifies the starved state

A

glucagon

70
Q

This protein serves as the primer used by glycogen synthase

A

glycogenin

71
Q

this enzyme serves as the glucose “sensor” enzyme in liver cells

A

phosphorylase a

72
Q

Phosphorylase requires the coenzyme ___ for activity

A

pyridoxal phosphate

73
Q

phosphoglucomutase requires the intermediate ___ for the interconversion of glucose 1-phosphate and glucose 6-phosphate

A

glucose 1,6-bisphosphate

74
Q

In skeletal muscle, the binding of ___converts phosphorylating b into the active form

A

AMP

75
Q

Phosphorylase kinase becomes fully active by being phosphorylated and binding

A

calcium ions

76
Q

____ stimulates glycogen breakdown in muscle by initiating a cAMP signal-transduction pathway

A

epinephrine

77
Q

Glycogen synthase catalyzes the transfer of a glucose residue from UDP-glucose to one of the ____ ends of glycogen

A

non reducing

78
Q

the glycogen branching enzyme moves a block of ___ or so glucose residues to form a branch point at least four residues from a preexisting branch

A

7

79
Q

glycogen synthase is converted into the active form by the action of ___

A

protein phosphatase 1, PP1

80
Q

The complete oxidation of glucose residues from glycogen produces ___ ATP

A

31

81
Q

Insulin stimulates glycogen synthase by inactivating ___

A

glycogen synthase kinase

82
Q

the major sites of glycogen storage is

A

Liver

skeletal muscle

83
Q

The key enzyme I glycogen degradation is

A

glycogen phosphorylasae

84
Q

Conversion of glucose 1-phosphate to glucose 6-phosphate is carried out by the enzyme

A

phosphoglucomutase

85
Q

what molecule must be excluded from the active site of glycogen phosphorylase

A

water

86
Q

how is phosphorylase b converted into phosphorylase A

A

addition of a phosphate to a serine residue

87
Q

Why is the T state of glycogen phosphorylase less active

A

the active site is partially blocked

88
Q

what physiological conditions render phosphorylase b less active?

A

high ATP and low calcium ion levels

89
Q

what is the function of liver glycogen degradation

A

for glucose export to other tissues when glucose levels are low

90
Q

Phosphorylase kinase is regulated by

A

calcium ions

cAMP activated PKA

91
Q

two critical hormones that signal for glycogen breakdown are?

A

glucagon and epinephrine

92
Q

the key regulatory enzyme in glycogen synthesis is

A

glycogen synthase

93
Q

Why is glycogen branching important

A

branching increases the solubility of glycogen

branching increases glycogen synthesis and degradation by increasing potential sites of action

94
Q

Which of the following occur after a carbohydrate rich meal

A

blood glucose levels increase leading to glycogen storage in the liver

95
Q

what is the normal glucose concentration in the blood?

A

80-120mg/100mL(4.4-6.7mM)

96
Q

what are the 3 steps in glycogen degradation

A

1) release of glucose 1-phosphate from glycogen
2) remodeling of glycogen substrate
3) formation of glucose 6-phospahte from glucose1-Phosphate

97
Q

Why can’t glucose 1-phosphate diffuse out of the cell?

A

there is no membrane transporter

-negative charge traps it

98
Q

Triacylglycerols are stored in these cells in animals

A

adipose

99
Q

the approximate energy yield from complete oxidation of fatty acids

A

9kcal/g

100
Q

these amphipathic molecules facilitate the digestion of fats by incorporating dietary triacylglycerols into micelles in the intestine

A

bile salts

101
Q

This molecule is the form in which triacylglycerols are transported rom the intestine to the rest of the body

A

chylomicrons

102
Q

This molecule is required to translocate long chain fatty acyl groups in the mitochondria

A

carnitine

103
Q

This is the pathway by which an acyl CoA is degraded into acetyl CoA

A

B oxidation (Fatty acid degradatino)

104
Q

This is another name for vitamin B12

A

Cobalamin

105
Q

The availability of this metabolite determines whether acetyl CoA, made from fatty acids can enter the citric acid cycle

A

Oxaloacetate

106
Q

This compound is considered as one of the ketone bodies

A

D3-hydroxybutyrate
Acetoacetate
Acetone

107
Q

this molecule is the form in which acetyl groups are carried across the mitochondrial membrane from the matrix to the cytoplasm

A

citrate

108
Q

In eukaryotes the degradation of fatty acids occur in the

A

matrix of the mitochondria

109
Q

The first step of B-oxidation is a ___ -linked oxidation of the fatty acyl chain

A

flavin

110
Q

What stimulates the breakdown of triacylglycerols by activation of a hormone-sensitive lipase

A

Epinephrine

glucagon

111
Q

B-oxidation of odd numbered fatty acids produce

A

Acetyl CoA

Propionyl CoA

112
Q

The synthesis of fatty acids take place in ___ of the cell

A

cytoplasm

113
Q

The coenzyme required for fatty acid synthesis is

A

NADPH

114
Q

the commited step of fatty acid synthesis is the formation of

A

malonyl-CoA

115
Q

What are the ketone bodies that are a major fuel source of the heart muscle

A

Acetoacetate and B-hydroxybutyrate

116
Q

Prostaglandins and Thromboxanes are synthesized from __, a 20 carbon fatty acid

A

arachidonate

117
Q

Fatty acids are the building blocks of

A

phospholipids

glycolipids

118
Q

Why are triacylglycerols an excellent design for energy storage

A

anhydrous and reduced

119
Q

enzymes that digest the triacylglycerol into free fatty acids and monoacylglycerol are called

A

lipases

120
Q

The hormone ___ induces lipolysis, where as the hormone ___ inhibits the process

A

Glucagon

Insulin

121
Q

The function of the enzyme acyl CoA synthetase is

A

ATP-dependent activation of fatty acids using CoA

122
Q

What are the coenzyme(s) involved in the degradation of saturated fatty acyl CoA

A

FAD

NAD+

123
Q

How many round of B-oxidation would be required for a 16-C fatty acyl chain to be degraded to Acetyl CoA

A

7

124
Q

What types of reactions do cobalamin enzymes catalyze

A

Intramolecular rearrangements
methylations
reduction of ribonucleotides to deoxyribonucleotides

125
Q

How does the B-oxidation differ In peroxisomes

A

the initial dehydrogenation reaction is different in that electrons are transferred to O2 to yeild H2O2

126
Q

What organs or tissues prefer to use ketone bodies such as acetoacetate as a fuel energy source instead of glucose

A

Heart muscle

renal cortex

127
Q

what is the commited step in fatty acid synthesis

A

synthesis of malonyl CoA

128
Q

How is acetyl carboxylase globally regulated

A

Phosphorylation-off

Dephosphorylation-on

129
Q

How are fatty acid larger than 16 carbons formed

A

by elongation reactions catalyzed by the enzymes on the endoplasmic reticulum

MC Biochem 2 (31 decks)

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