Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Bioc 221 > BIOC 221 - Midterm #1 > Flashcards

BIOC 221 - Midterm #1 Flashcards

1
Q

What constitutes life?

A

self-sustaining chemical system capable of darwinian evolution

  • metabolism
  • self-replication
  • adaptation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

autotrophs

A

use CO2 from environment as carbon source

often photosynthetic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

heterotrophs

A

obtain carbon from complex molecules (ex.glucose) not from environment
(obtain c by degrading nutrients from autotrophs)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

metabolism

A

entire set of enzyme catalyzed transformations of organic molecules in living cells;
the sum of anabolism and catabolism

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Anabolism

A

phase of intermediary metabolism concerned with the energy-requiring biosynthesis of cell components from smaller precursors.


How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Catabolism

A

the phase of intermediary metabolism concerned with the energy-yielding degradation of nutrient molecules.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

(a) Energy containing nutrients –(catabolism)–> (b) Energy-depleted end products

A

a) carbohydrates, fats, proteins
b) CO2, H2O, NH3

energy releases yields high energy compounds (ATP, NADH, NADPH, FADH2)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

(a) Precursor molecules –(anabolism)–> (b) Cell macromolecules

A

a) proteins, polysachs, lipids, nucleic acids
b) amino acids, sugars, fatty acids, nitrogenous bases

uses high energy compounds

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

(2) types of metabolic pathways

A

1) branched

2) linear

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

(3) non-linear types of metabolic pathways

A

1) convergent (catabolic)
2) cyclic
3) divergent (anabolic)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

In each Metabolic Pathway, a principal ____ is modified by a series of chemical ___ catalyzed by___.

A

metabolite
reactions
enzymes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

The series of reactions that modify a principal metabolite often involve…

A

cofactors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

The end product of a metabolic pathway can have (3) fates

A

a) used immediately
b) used to initiate another pathway
c) stored by the cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Primary (Basic) Metabolism:

A

Metabolic processes that are necessary for the maintenance of life

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Primary metabolites:

A

Intermediates or products of primary metabolism such as amino acids, sugars, lipids, nucleotides, organic acids, polyols, and vitamins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Secondary (specialized) Metabolism:

A

pathways that are not absolutely required for the survival of the organism. Highly evolvable and pliable.

- derived from primary metabolites

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

•Unlike primary metabolites, absence of secondary metabolites does not result in ___ ___ , but rather in long-term impairment of the organism’s survivability, reproduction, or aesthetics, or perhaps in no significant change at all.

A

immediate death

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Types of Chemical Transformation in Cells

A

(4-1) Cleavage/formation of C-C bond

(4-2) Internal rearrangements, isomerizations, and eliminations (including condensation reactions)
(4-3) Group transfers (phosphoryl, methyl, formyl …)
(4-4) Free radical reactions
(4-5) Oxidation-reductions (co-factors – NADH, NADPH, FADH2 - store reducing power)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

(4-1) Cleavage/formation of C-C bond


A

1) homolytic cleavage

2) heterolyic cleavage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

(4-1) Nucleophilic Carbon-Carbon bond formation reactions

A

1) aldol reaction

2) claisen condensation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

1) aldol reaction

A

A nucleophilic carbonyl addition reaction, in which the electrophile is the carbonyl carbon of an aldehyde or ketone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

2) claisen condensation

A

A nucleophilic enolate can also attack the carbonyl carbon of a carboxylic acid derivative in a nucleophilic acyl substitution reaction.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Free energy

A

portion of total energy of a system that is released

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

2nd law of thermodynamics:

A

In all natural processes, the entropy of universe always increases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

KNOW AMINO ACID STRUCTURES AND PKA’s

A

!!!

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

Why is S more suitable than O for Acetyl-Coenzyme A?

A

S is larger than O, so S-CoA is better LG (more stable with (-) charge)

Better LG in forward rxn
Better Nu in reverse rxn

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

heterolytic cleavage

A

one atom gets both electrons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

homolytic cleavage

A

both atoms get one electron each

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

(2) criteria for spontaneity

A

1) ΔG (ΔSuniv > 0)

2 Q/Keq

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

ΔG = ?

A

RTlnQ/Keq

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

ΔG° = ?

A

Q=1, lnQ=0
so
ΔG° = -RTlnKeq

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

If Q > Keq

A

reverse spontaneously

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

If Q < Keq

A

forward spontaneously

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What does ΔG tell us about rate of reaction?

A

NOTHING

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

Reaction rate is governed by?

A

Activation Energy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

(2) ways we can drive forward an unfavorable reaction

A

1) mass action (product depletion by metabolite channeling)

2) reaction coupling

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

If a spontaneous process is one that is accompanied by a decrease in free energy, then when is system at equilibrium?

A

when free energy reaches a minimum, and no further decrease is possible

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

Why is Q/Keq criteria for free energy?

A

because when Q/Keq = 1 or Q = Keq, system is in dynamic equilibrium (position of minimum free energy) and ΔG = 0

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

If S is less stable than P, @ equilibrium…

A

P > S
Keq > 1
spontaneous forward

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

If S is more stable than P, @ equilibrium…

A

S > P
Keq < 1
spontaneous reverse

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

ΔG’°

A

free energy change for rxn going from standard conditions

1 M, pH 7, 25°C, 1 atm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

ΔG’

A

free energy change going from set of specific initial conditions to equilibrium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

ΔG’ depends on?

A

Q value

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

ΔG’° reveals?

A

how far the initial conditions is from equilibrium of the reaction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

Hydrolysis Reactions

A
  • uses H2O to split 2 molecules

tend to be strongly favorable (spontaneous)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

How much does Keq vary with small change in ΔG’°?

A

exponentially

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

Isomerization Reactions

A

have smaller free energy changes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

ΔG° of Isomerization between Enantiomers?

A

0

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

If ΔG° > 0, under what conditions will forward reaction occur spontaneously?

A

conditions where RT lnQ is overly negative so ΔG becomes negative despite positive ΔG°.

  • Q &laquo_space;1
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

Mass Action

A

driving reaction forward by altering concentration of S or P

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

Driving a reaction forward by Mass Action

A

Q&laquo_space;1 so [S]»[P]

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

(2) ways for Q «1

A

1) large [S] - accumulate substrate

2) small [P] - deplete product

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

Which way is most practical to achieve Q &laquo_space;1 ?

A

accumulating high [S] is not desirable in cells (E costs)

- PRODUCT DEPLETION

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

Product Depletion

A

using product as soon as it is made through metabolite channeling (back to back runs enzymes work together - enzyme complex)
- enzyme of next step ready

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

Reaction Coupling via Common Intermediate

A

unfavorable rxn can be driven forward when coupled to a favourable rxn if sum of ∆G values is negative

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

exergonic

A

system release free energy (catabolic)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

endergonic

A

system gains free energy (anabolic)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

enthalpy

A

heat of system

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

∆H

A

enthalpy change - amount of heat released/absorbed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
60
Q

Entropy

A

S - measure of randomness, disorder, freedom of motion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
61
Q

What is meant when a reaction is Entropy driven?

A

a spontaneous, endothermic reaction (∆H >0)

- ∆S is largely (+) so ∆H -T∆S is negative

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
62
Q

Factors that contribute to larger free energy?

A

anything that destabilizes reactant (raise E level of S) and stabilizes product (lower E level of P)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
63
Q

Products are stabilized by?

A

1) ionization
2) isomerization (tautomerization)
3) resonance
4) solvation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
64
Q

Solvation

A

an interaction of solute with solvent leading to stabilization of solute species in solution.
in MOST cases, formation of solution is favoured by +∆S by mixing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
65
Q

Isomerization

stabilizes product how?

A

e delocalization

more than one compound/product can exist so ∆S >0

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
66
Q

Resonance

A

allows for delocalization, in which overall E of molecule is lowered since its electrons occupy a greater volume, more stable

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
67
Q

Ionization

A

ions are surrounded by H2O or solvent
more micro states, higher degree of freedom
increased S by mixing

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
68
Q

Chemical basis for large free-E change associated with ATP hydrolysis

A

1) hydrolysis with relief of charge repulsion
2) resonance stabilization
3) ionization
4) greater hydration of ADP & Pi relative to ATP

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
69
Q

ATP Hydrolysis is accompanied by? resulting in?

A

H+ release

acidification

70
Q

Mechanical example of coupling reaction

A

work done raising object ∆G > 0

loss of potential energy of position ∆G < 0

71
Q

What leads to metabolic acidosis?

A

glycolysis and ATP hydrolysis

72
Q

The donation of energy by ATP generally involves?

A

a covalent participation of ATP in group transfer reactions

raising free E content of product

73
Q

Why is ATP a suitable energy carrier?

A

1) despite large ∆G’°, ATP is kinetically stable @ pH 7 (high Ea for hydrolysis so requires an enzyme & therefore rxn can be regulated)
2) [ADP] & [Pi] are much lower than than 1 M so Q/Keq «< 1 so ∆Gp is larger than ∆G°

74
Q

Why is ATP hydrolysis slow?

A

has high Ea
(rate constant) k = Ae^(-Ea/kT)
since Ea is large, k will be small

75
Q

ATP thus serves as the universal energy currency in all living cells. Why?

A

Because of its intermediate position on
scale of group transfer potential, ATP can carry energy from high E phosphate
compounds produced by catabolism ) to compounds such as glucose,
converting them into more reactive species.

76
Q

Majority of ATP is synthesized how?

A

regenerated from ADP

77
Q

ATP Hydrolysis Equation

A

ATP(4-) + H2O –> ADP(3-) + Pi(2-) + H+

78
Q

to ensure large negative ∆Gp, it is important to?

A

maintain high intracellular [ATP]

79
Q

How often does a typical ATP molecule shuttle out of mitochondria (site of synthesis) and back into it (as ADP) for recharging?

A

once per minute

80
Q

energy used by human cells require hydrolysis of how many mols of ATP daily?

A

100 - 150 mols

81
Q

Each ATP molecule is recycled how many times per day?

A

~ 1000 times per day

(150 mols per day/0.2 mols in body) = 750 times recycled

82
Q

ATP cannot be stored for long so?

A

its consumption closely follows its synthesis

83
Q

Phosphoenolpyruvate (PEP)

structure
what is responsible for its high ∆G’°?

A

phosphate ester

tautomerization of pyruvate from enol to keto form
keto more stable

84
Q

1,3-Biphosphoglycerate (1,3-BPG)

structure
what is responsible for its high ∆G’°?

A

acyl phosphate

ionization (- H+) and resonance of product (3-PG)

3-Phosphoglyceric acid 3-Phosphoglycerate
(loss of H+)

85
Q

Phosphocreatine (PCr)
structure
what is responsible for its high ∆G’°?

A

(P)-Arg res - Gly res - CH3

resonance stabilization (between the 2 primary amino groups)

86
Q

For ALL reactions with phosphate transfer, what contributes to large negative ∆G’°?

A

resonance stabilization of Pi

87
Q

Equation of PCr and ATP

A

PCr(2-) + ADP(3-) + H+ –> Cr + ATP(4-)

88
Q

PCr function when [ATP] is high and in excess?

A

PCr is made as E reservoir for rapid buffering and regeneration of ATP in situ

89
Q

in situ means to ?

A

examine the phenomenon exactly in place where it occurs

90
Q

Advantages of PCr as E reservoir?

A

1) REGULATION
high [ATP] leads to fat synthesis

2) good buffering for H+ produced from ATP hydrolysis

91
Q

Hydrolysis of Acetyl CoA (rxn)

A

Ac-CoA + H2O -> acetate + CoA(S-) + H+

92
Q

Hydrolysis of Acetyl CoA is favored by?

A

ionization of CoASH to CoAS- + H+

93
Q

How does ATP react?

A

displacement by oxygen, nitrogen - transfer of phosphoryl

94
Q

Adenylyl =?

A

AMP

(P)-Ribose-Adenine

95
Q

Phosphoryl Transfer Reactions to Regenerate ATP

A

2ADP ATP + AMP
GTP +ADP ATP + GDP

ADP + PCr Cr + ATP

96
Q

Electrons flow from metabolic intermediates to?

A

Electron Carriers

- NADH, NADPH, FADH2, FMNH2

97
Q

Pyruvate is ___ to Lactate, subsequently ____ NADH to ____

A

reduced
oxidizing
NAD+

98
Q

Oxidation reactions generally ___ energy

A

release

99
Q

Oxidation reactions are a big part of?

A

Catabolism and ATP formation

100
Q

During Oxidation/Reduction Reactions, electrons are transferred from atom that have ___ ____ for e’s to atoms with a __ ___ for e’s

A 
lower affinity (e donors, high PE)
higher affinity (e acceptors, low PE)

PE of e used to do work

101
Q

Metabolic energy capture occurs largely through?

A

synthesis of ATP - molecule designed to provide E for biological work

102
Q

Most biological oxidations don’t involve direct transfer of e’s from S to O. Instead…?

A

A series of coupled ox-reduc rxns occurs, with e’s passed to intermediate e carriers (ex. NAD+) before they are finally transferred to O

103
Q

Why are fats more efficient fuel sources than carbohydrates?

A

carbon in fats is more REDUCED

104
Q

Dehydrogenase

A

enzyme that oxidizes substrate by reduction reaction

105
Q

(4) ways of e transfer from e donor to e acceptor

A

1) directly as electrons
2) as H atoms (H+ +e-)
3) hydride ion (H-)
4) through direct combo with O

106
Q

Reducing Equivalent refers to?

A

any of a number of chemical species which transfers the equivalent of 1 e in redox reactions

107
Q

Why do we need E carriers?

A

most bio rxns dont involve direct transfer of e from Substrate to O.
- series of ox-reduc rxns need intermediate e carriers to carry e’s

108
Q

Why is better to have a series of ox-reduc rxns rather than direct transfer of e’s?

A

PE stored in organic S is released in small incremements
- easier to control ox. + capture some E as it’s released
SMALL E TRANSFERS WASTE LESS THAN SINGLE LARGE TRANSFER

109
Q

Why is FADH2 more versatile than NADH or NADPH?

A

1) accepts 1 or 2 e’s with one or two H+

2) reduction potential changes based on binding strength

110
Q

When are group transfer rxns favorable?

A

when free E of reactants is much higher than that of products (exergonic rxn)

111
Q

Unfavorable rxns can be made possible by?

A

chemically coupling a highly favorable rxn to unfavorable rxn

112
Q

Ox-Reduc-Rxns generally involve?

A

transfer of e’s from reduced organic compounds to specialized redox cofactors (serve as source of E for ATP synthesis or used in biosynthesis (NADPH))

113
Q

Diabetes is the..

A

altered ability to regulate glucose metabolism

114
Q

Type 1 Diabetes

A

no insulin production in pancreas

115
Q

Type 2 Diabetes

A

can develop at any age

insulin resistance in fat,muscle, liver cells

116
Q

Active Transport

A

from intestinal lumen into gut epithelial cells

117
Q

Kinases

A

enzymes that catalyze phosphoryl group transfers with ATP as donor

118
Q

How does glucose get into cell?

A

glucose is actively transported into cell by Na+ driven cotransporters
- Na+ gradient provides E : [high] -> [low]
since glucose is moving from [low] ->[high]

119
Q

How does glucose get released into bloodstream?

A

passive transport

- down concentration gradient

120
Q

Glucose Oxidation

A

chemical process that provides E for organism to carry out all required activities

121
Q

During GLUCOSE OXIDATION, what happens to glucose?

A

glucose is broken down (fully oxidized) into CO2 + H2O

122
Q

Glucose Oxidation releases energy which is..

A

stored in chemical form for the cell to use (ATP, NADH)

123
Q

(3) Stages of GLUCOSE OXIDATION

A

1) glycolysis
2) citric acid cycle
3) electron transport chain

124
Q

Why is Glucose central to metabolism? (5)

1) past
2) relative stability
3) energy?
4) storage
5) conversion

A

1) one of several monosach that can be formed from formaldehyde (HCHO) under prebiotic conditions

2) most stable among common sugars
3) relatively rich in E (good fuel)
4) easily polymerized (low osmolarity) for storage (glycogen)
5) virtually all sugars can be converted to glucose so process of glycolysis is central to carb metabolism

125
Q

How many steps of glycolysis

A

10

126
Q

For cells that lack mitochondria, how do they generate ATP?

A

rely on glycolysis to generate ATP

127
Q

(4) fates of glucose

A

1) Synthesis of structural polymers (ECM & cell wall polysach)
2) Storage (glycogen, starch)
3) ox. via glycolysis
4) ox. via PPP

128
Q

GLYCOLYSIS: step 1

A

glucose –> glucose-6-phosphate

phosphorylation
HEXOKINASE
ATP - phosphoryl donor

129
Q

First Energy Consuming Reaction of GLYCOLYSIS? why? (3)

A

Step 1

1) retention of 9 intermediates (no transporters for sugar-(p)
2) E released by ATP is partially conserved in G6P
3) P group provides binding E for formation of ES complex & increases specificity of E+S binding

130
Q

1) specific acid-base catalysis

2) general acid-base catalysis

A

1) specifically H+ and OH- (rxn rate dependant on pH)

2) involves a molecule besides water that acts as H+ donor or acceptor

131
Q

conformational change in Hexokinase after glucose binding …

A

creates binding site for ATP and excludes H2O frm active site

132
Q

GLYCOLYSIS: step 2

A

G6P –> Frucose-6-Phosphate
Conversion/Isomerization
(general acid base catalysis - Glu res)
PHOSPHO(Hexose/Glucose) ISOMERASE

glucose opens into chain form
aldose to ketose (on C2)

133
Q

Purpose of Step 2 of GLYCOLYSIS

A

1) provides C1-OH for additional phosphorylation in step 3

2) C2 carbonyl allows step 4 (splitting of 6C into 2 3C’s)

134
Q

GLYCOLYSIS: Step 3

A

F6P –> Fructose 1,6-Biphosphate
PHOSPHOFRUCTOKINASE-1 (PFK-1)

C1 phosphorylated by ATP
rate limiting step
- important control point

135
Q

GLYCOLYSIS: Step 4

A

Cleavage of F-1,6-BP –> DHAP + G3P
reversible aldol rxn
ALDOLASE
driven by low Q (mass action)

136
Q

GLYCOLYSIS: step 5

A

DHAP G3P
Isomerization
TRIOSE PHOSPHATE ISOMERASE

-driven by mass action (product G3P depletion)

137
Q

During Prep Phase..

A

2 ATP molecules invested mainly for metabolic retention

C6 -> C3 + C3

138
Q

Prep Phase (which steps?)

A

1-5

139
Q

The C3 fragments will be oxidized to…

A

capture E in the form of ATP and NADH

140
Q

GLYCOLYSIS: Step 6

A

(2) G3P -> (2) 1,3-Biphosphoglycerate
GLYCERALDEHYDE 3-PHOSPHATE DEHYDROGENASE (GAPDH)

Oxidation
reduction of NAD+ to NADH
Inorganic Phosphate

141
Q

G3P –> 1,3-BPG

A

carbonyl C oxidized to mixed anhydride C
reduction of NAD+ to NADH (e released stored in NADH & high-E anhydride linkage to phosphate)

PHOSPHOROLYSIS
Inorganic Pi attacks carbonyl C releasing S from E

(nonspontaneous)

142
Q

GLYCOLYSIS: Step 7

A

1,3-BPG -> 3-Phosphoglycerate
3-PHOSPHOGLYCERATE KINASE
High E phosphoryl transfer (generates 2 ATP)

(spontaneous)

143
Q

GLYCOLYSIS: Step 6 + 7

A

step 6 & 7 are coupled
intermediate (1,3-BPG) is channeled (product depletion)

Glyceraldehyde-3-phosphate dehydrogenase AND 3-Phosphoglycerate kinase form Enzyme complex

SUBSTRATE CHANNELING

144
Q

GLYCOLYSIS: Step 8

A

3-PG -> 2-PG
PHOSPHOGLYCERATE MUTASE

conversion

145
Q

Mutase

A

an enzyme of isomerase class that catalyzes shifting of functional groups from one position within same molecule

146
Q

Step 8 Mechanism

A

Phosphoglycerate Mutase has P group attached to HIS res.

  • E transfers P to 2C
    intermediate: 2,3-BPG
  • P from C4 transferred to His res of E
147
Q

Logic of Step 8

A

necessary prep for next step (dehydrogenation) which generates high E PEP

  • makes C2 more acidic allowing dehydration
148
Q

GLYCOLYSIS: Step 9

A

2-PG -> Phosphoenolpyruvate
ENOLASE
dehydration - loss of H2O

149
Q

Glycolysis: Step 10

A

PEP -> Pyruvate
PYRUVATE KINASE

tautomerization enol to keto form of pyruvate

150
Q

(ATP) Energy-Expending Steps of Glycolysis

A

1 (glucose -> G6P)

3 (F6P -> F-1,6-P)

151
Q

(ATP) Energy-Forming Steps of Glycolysis

A

7 (1,3-BPG -> 3-PG)

10 (PEP -> pyruvate)

152
Q

Net gain of GLYCOLYSIS

A

2 ATP + 2 NADH

153
Q

Most steps are close to ___ where ∆G is almost zero.

Which steps have largest negative ∆G?

A

Steps 1, 3, 10
1- glucose to G6P
3- F6P to F-1,6-P
10 - PEP to pyruvate

154
Q

Step 8: Isomerization of 3PG to 2PG

What if this step was skipped?

A

3PG would be converted to a compound, which is then transformed to more stable keto form, forming a β-keto acid - (less stable than α-keto acid) which is unstable due to decarboxylation producing acetaldehyde (hangover molecule)

155
Q

Why is Arsenate (AsO4 3-) a bad substitute for step 6?

A

the product of the reaction is unstable and decomposes in water to product 3-phosphoglycerate without generating ATP

(G3P is oxidized but phosphorylation isnt coupled with it)

156
Q

(1) Fate of G6P other than glycolysis

A

PPP

- ribose & NADPH

157
Q

(2) Fates of pyruvate other than CAC

A

1) Fermentation (ethanol & CO2)

2) Lactate

158
Q

Pyruvate’s Fate: AEROBIC CONDITIONS

A

imported into mitochondria
oxidized to acetate (Ac-CoA)
then completely oxidized by CAC & ox. phos. to CO2 + H2O

159
Q

How is NAD+ ultimately reoxidized?

A

by passing its e- to O2 in mitochondrial respiration

160
Q

What is the limiting factor of GLYCOLYSIS?

A

reduced NAD+ level

161
Q

Aerobic Conditions equation

A

pyruvate + CoA + NAD+ -> Ac-CoA + CO2 + NADH

162
Q

Pyruvate’s Fate: ANAEROBIC CONDITIONS or HYPOXIA

A

NADH can’t be reoxidized by O2 to NAD+

LACTATE FERMENTATION

163
Q

Lactate Fermentation

A

Under Anaerobic Conditions/Hypoxia (low O2)
Pyruvate –> Lactate (reduction)
oxidizes NADH to NAD+ (for glycolysis)

best buffering for H+ produced during ATP hydrolysis + catabolism

164
Q

Glucose -> Pyruvate

A

Glucose + 2NAD+ + 2ADP + 2Pi -> 2Pyruvate + 2ATP + 2NADH + 2H+ + 2H2O

165
Q

Pyruvate -> Lactate

A

2 Pyruvate + 2NADH + 2H+ -> 2Lactate + 2NAD+

166
Q

Glucose –> Lactate

A

Glucose + 2ADP + 2Pi –> 2Lactate + 2ATP + 2H2O

167
Q

After Lactate Fermentation?

A

can accumulate during strenuous exercise

- eventually diffuses into bloodstream and is reconverted to glucose in liver (gluconeogenesis)

168
Q

Does Lactate Fermentation cause Metabolic Acidosis?

A

NO! in fact, it alleviates it.

169
Q

What causes Metabolic Acidosis?

A

Glycolysis and ATP hydrolysis

170
Q

Alcohol Fermentation

A

Pyruvate converted to acetaldehyde, then reduced to ethanol by NADH regenerating NAD+ for glycolysis

Bioc 221 (4 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions