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Biochemistry (material for exam II) > glycolysis and Gluconeogenesis > Flashcards

glycolysis and Gluconeogenesis Flashcards

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1
Q

The equation for glycolysis

A

glucose—-> two molecules of pyruvate + 2ATP

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2
Q

is glycolysis anaerobic or aerobic

A

anaerobic

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3
Q

Where does glycolysis occur

A

The cytoplasm

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4
Q

In mammals what is the only fuel that the brain uses under nonstarvation conditions

A

glucose

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5
Q

In mammals what is the ONLY fuel that red blood cells can use

A

Glucose

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6
Q

Pyruvate and lactate can be salvaged by being resynthesizes to glucose in the metabolic process of

A

gluconeogenesis

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7
Q

Sources of glucose in the diet

A

Starch, Glycogen, Disaccharides (especially sucrose and lactose)

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8
Q

GLUT 1 has a _____ affinity for glucose and is mostly found where

A

high, RBCs

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9
Q

GLUT2 is the main transporter of glucose in the

A

Liver

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10
Q

GLUT2 has a _____ affinity with ____ regulation

A

low affinity, No regulation

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11
Q

GLUT3 is the main glucose transporter in

A

Neurons

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12
Q

GLUT4 is mostly found in

A

skeletal muscle, heart, adipose

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13
Q

GLUT4 are dependent on

A

Insulin

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14
Q

Glycolysis occurs in the

A

Cytosol

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15
Q

What is the purpose of Stage 1 of glycolysis

A

Trapping and preparation phase

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16
Q

How many ATP are produced in stage 1 of glycolysis

A

none. 2 ATP are actually consumed

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17
Q

What is the final product of stage 1 of glycolysis

A

Fructose 1,6 Biphosphate

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18
Q

Stage 1 of glycolysis consists of how many steps

A

3: A phosphorylation, an isomerization, and a second phosphorylation reaction

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19
Q

What is the principle strategy of stage 1 of glycolysis

A

to trap the glucose in the cell and form a compound that can be readily cleaved into 2 phosphorylated 3 carbon units

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20
Q

What are the two irreversible enzymes used in stage 1 of glycolysis

A

step one- Hexokinase/Glucokinase (in the liver)

step 3: Phosphofructose kinase (PFK) (committed step)

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21
Q

what are some differences between hexokinase and glucokinase

A

Glucokinase is in the liver and pancreas B cells while hexokinase is in all other tissues
Hexokinase is readily inhibited by Glucose 6-Phosphate; Glucokinase is not
Glucokinase is has positive feeback from glucose, fructose 1-phosphate, and insulin)
Glucokinase has negative feeback from Glucagon and fructose 6-phosphate

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22
Q

What is PFK inhibited by

A

ATP and Citrate

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23
Q

What is AMP induced by

A

AMP, Fructose 2,6 Biphosphate

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24
Q

Hexokinase like all other kinases requires what for activity

A

Magnesium or another divalent metal ion

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25
The isomerization of glucose 6-phosphate to fructose 6-phosphate is a conversion of an ____ into a _____
aldose into a ketose
26
What is the allosteric enzyme that sets the pace of glycolysis
PFK
27
aldolase converts F-1,6 BP into
DHAP and GAP
28
what is the only glycolytic enzymopathy that is lethal
Triose phosphate isomerase deficiency
29
When there is high ATP, high NAD+, and low NADH | DHAP is favored over GAP and converted to
Glycerol 3-phosphate-----> triacylglycerols---> fat
30
Stage 3 of glycolysis is started by oxidative phosphorylation fo GAP to form _____ (and the reduction of ___ to ____)
1,3 BPG ( and the reduction fo NAD+ to NADH)
31
In stage 3 of glycolysis ADP is phosphorylated to ATP by enzyme ______ and 3-PG is formed via _____
Phosphoglycerate kinase, via substrate transfer
32
What does phosphoglycerate mutase do in glycolysis
it moves the phosphate on 3-phosphoglycerate to the 2 carbon thus forming (2-phosphoglycerate)
33
What does Enolase do in glycolysis
Dehydration of 2-PG forms PEP (phosphoenolpyruvate), an enol with high phosphoryl-transfer potential (unstable)
34
What does pyruvate kinase do in glycolysis
transfers phosphoryl group form PEP to ADP to form ATP | PEP is converted from unstable enol to pyruvate, a stable ketone
35
What are the three enzymes in glycolysis that are irreversible
Hexokinase/glucokinase PFK (phosphofructokinase) pyruvate kinase
36
In aerobic environment pyruvate goes to the
TCA cycle
37
In an anaerobic environment pyruvate is converted to ____ by _____ and ____
lactate, lactate dehyrogenase and NADH
38
Pyruvate kinase is induced by
insulin | fructose 1,6 BP
39
Pyruvate kinase is inhibited by
Alanine ATP Glucagon
40
Pyruvate can be converted into what three things
Ethanol, lactate, and Acetyl CoA
41
Alcoholic fermentation and lactate production have no net oxidation-reduction why
The NADH formed in the oxidation of glyceraldehyde 3-phosphate is consumed in the reduction of pyruvate
42
Fructose from the liver can enter the glycolysis pathway as
DHAP and GAP
43
Fructose can enter as _____ from most most tissue other than the liver
Fructose-6P (F-6P)
44
Galactose enters the glycolysis pathway as
Glucose-6P (G-6P)
45
In the liver F-2,6-BP has what regulatory effect
Activates PFK
46
What effect does citrate have on PFK
it inhibits it in the liver
47
Pyruvate kinase is regulated by
allosteric effectors and covalent modification
48
High levels of glucagon and low levels of insulin leads to what
increase in cAMP pathway and thus increase in protein kinase A this leads to an increase in Fructose 6-Phosphate. Also leads to an inhibition of pyruvate kinase. This means an increase in gluconeogenisis and an inhibition of glycolysis
49
The brain depends on what as its primary fuel source
glucose
50
what is RBCs only fuel source
Glucose
51
The daily glucose requirement of the brain is about
120g
52
What is the whole bodies daily glucose need
160g
53
How much glucose is present in body fluids
about 20grams
54
how much glucose is readily available from glycogen
190grams
55
How long are direct glucose reserves sufficient to meet glucose needs
for about a day
56
Neurotransmitters in the brain (Glutamate, Glutamine, GABA) are formed form intermediates of
The TCA cycle in the brain (more specifically alpha-ketoglutarate)
57
What are the major precursors of gluconeogenesis
Lactate, amino acids, and glycerol (but not fatty acids)
58
What is the purpose of gluconeogenesis
converts pyruvate into glucose
59
What are the four enzymes that are present in the gluconeogensis pathway but not in glycolysis
pyruvate carboxylase---- converts pyruvate (with ATP, and HCO3) to oxaloacetate ( ADP and Phosphate released) phosphoenolpyruvate carboxykinase- converted with GTP converts oxaloacetate to phosphoenolpyruvate (GDP and CO2 released) Fructose 1,6-bisphosphatase- converts fructose 1,6 diphosphate with H2O (Phosphate released) Glucose 6-phosphatase- with H2O converts glucose 6-phosphate to glucose (phosphate released)
60
what is the mitochondrial enzyme in gluconeogensis
Pyruvate carboxylase
61
What happens to oxaloacetate before further gluconeogensis
it is transported to the cytoplasm via the malate shuttle
62
Where is glucose 6-phosphatase located
in the lumen of the ER
63
Glycolysis _____ ATP, Gluconeogenesis _____ ATP
generates, consumes
64
F-2,6 BP and AMP activates
glycolysis, more specifically PFK and the converion of fructose 6-phosphate to fructose 1,6 diphosphate
65
fructose 2,6-BP and AMP inhibit
Gluconeogenesis, more specifically inhibit fructose 1,6 biphosphatase and the conversion of Fructose 1,6-BP to fructose 6-phosphate
66
ATP inhibits
PFK and Pyruvate kinase
67
Alanine inhibits
Pyruvate kinase
68
Fructose 1,6 BP activates
glycolysis and more specifically pyruvate kinase
69
AMP regulatory effects
inhibits gluconeogensis and more specifically fructose 1,6 bisphosphatase
70
What regulatory effect does H+ have
inhibits PFK and thus inhibits glycolysis
71
What regulatory effect does ADP have
inhibits phosphoenol pyruvate carboxykinase and thus gluconeogensis
72
What regulatory effect does alanine have
inhibits pyruvate kinase and thus glycolysis
73
what regulatory effect does acetyl CoA have
activates pyruvate carboxylase thus activates gluconeogenesis
74
what is the regulatory effect of ADP
inhibits pyruvate carboxylase thus inhibits gluconeogensis
75
tissue location of gluconeogenesis
liver (mostly), kidneys, small intestines
76
Favoring conditions for gluconeogensis
when blood (glucose) levels are low and glycogen stores are depleted
77
Favoring conditions for glycolysis
Favored when blood (insulin) is high
78
Tissue location for glycolysis
RBCs, exercising tissues, brain, etc.
79
Subcellular location of glycolysis
in the cytosol
80
Subcellualr location of gluconeogensis
cytosol and mitochondria
81
Postive regulators of glycolysis
Glucose, insulin, AMP, Fructose 2,6-BP, fructose 1,6-BP
82
Postive regulators of gluconeogenesis
glucagon, citrate, cortisol, thyroxine, acetyl CoA
83
negative regulators of glycolysis
Glucagon, ATP, Citrate, Glucose-6 phosphate, fructose 6-phosphate, alanine
84
negative regulators of gluconeogenesis
ADP, AMP, Fructose 2,6-BP
85
energy use and yield of glycolysis
uses: 2 ATP Yield: 4 ATP Net yield: 2 ATP/glucose oxidized (also produces 2 NADH)
86
energy use and yield of gluconeogensis
Uses: 4 ATP, 2 GTP Yield: 0 Net use: 6 ATP equivalents/ glucose synthesized
87
Sucrose is a disaccharide of
glucose and fructose
88
Lactose is a disaccharide of
glucose and galactose
89
Fructose and galactose are converted into glycolytic
intermediates
90
Fructose is quickly turned to fat in times of
high energy
91
Fructose from the liver enters the glycolytic pathway where
DHAP/GAP
92
Fructose form adipose tissue enters the glycolytic pathway where
Fructose -6P
93
Galactose enters the glycolytic pathway where
Glucose-6P
94
Glycogen enters the glycolytic pathway where
Glucose-6P
95
In the liver what is the main activator (s) for glucokinase
Glucose, Fructose 1-P, insulin
96
In the liver what is the main inhibitor (s) for glucokinase
glucagon, fructose 6-P
97
In the liver what is the main inhibitor of PFK
Citrate
98
What is the main activator for PFK in the liver
Fructose 2,6-BP
99
In the liver pyruvate kinase is largely regulated by
allosteric effectors and covalent modification | Meaning ATP and alanine inhibit and Fructose 1,6-BP induce
100
Pyruvate can be oxidized aerobically via the citric acid cycle after first undergoing
an oxidative decarboxylation to form acetyl CoA
101
Glucose 6-phosphatase is only found in
liver, kidneys, pancreatic Beta cells
102
Cortisol increases the activity of what two enzymes
Fructose 1,6 bisphosphatase, glucose 6-Phosphatase thus leading to increase in gluconeogenesis
103
Pyruvate carboxylase is a _____ enzyme
mitochondrial
104
What is the purpose of the conversion of pyruvate to oxaloacetate
so it can be transported from the mitochondria to the cytoplasm via the malate shuttle
105
Where is glucose 6-phospatase located
in the lumen of the ER of liver, kidneys, and pancreatic Beta Cells

Biochemistry (material for exam II) (10 decks)

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