Valencik Carb Metabolism I Flashcards
1
Q
In general, the currency to generate energy is (blank)
A
glucose
2
Q
Determining whether a nutrient will be broken own for energy (catabolism) or used to make something (anabolism) is dependent upon what three things?
A
the delta G
Concentration of Products and Reactants
Enzymes
3
Q
Blank are different genes with the same enzymatic activity.
A
isoform/ isozymes
4
Q
What are the 6 things that regulate metabolism?
A
DNA Hormones Vitamins Allosteric Effectors Epigenetics Toxins
5
Q
(blank) Modulates enzymes that are already made, different isozymes can have different effectors.
A
allosteric effectors
6
Q
Which have long term effects and which have short term effects?
allosteric effectors
hormones
A
allosteric-short term
hormones-long term
7
Q
(blank) secretes insulin and glucagon in response to changes in blood glucose concentration
A
pancreas
8
Q
(blank) processes fats, carbs and proteins from diet, synthesizes and distributes lipids, ketone bodies, and glucose for other tissues and converts excess nitrogen to urea
A
liver
9
Q
Where do we generate ATP?
A
mitochondria
10
Q
Where do we synthesize/ process proteins and process membrane lipids?
A
ER/Golgi
11
Q
Where do Biosynthetic pathways, Nonoxidative catabolism and Storage of energy reserves (fat and glycogen) occur?
A
cytoplasm
12
Q
Where do we hydrolyze macromolecules?
A
lysosomes
13
Q
where do oxidative reactions take place?
A
peroxisomes
14
Q
How do you regulate enzymatic activity?
A
altering amount
altering availability
modulating activity
15
Q
(blank) is the main carb transported in humans
A
glucose
16
Q
During fasting, the (blank) maintains blood glucose levels
A
liver
17
Q
blood glucose is taken up by (blank) diffusion in most tissues
A
facilitated diffusion
18
Q
When do you have severe hypoglycemia?
A
blood glucose levels below 40mg/100 mL
19
Q
What does the brain like more, glucose or ketones?
A
glucose!!! Will use ketones if necessary
20
Q
What are the four major roles of carb metabolism?
A
- generate energy from glucose
- maintain blood glucose levels
- channel alternative monosaccharides into energy producting pathways
- synthesize biosynthetic monosaccharide precursors
21
Q
WHat are the sources of blood glucose?
A
food
glycogen
gluconeogenesis
LIVER!
22
Q
What is the main source of glucose for the blood?
A
liver
23
Q
How does glucose travel in the blood?
A
attached to albumin
24
Q
Fasting begins (blank) hours after eating. Then decreasing levels of insulin/glucagon stimulates (Blank) then (blank)
A
3
glycogenolysis
gluconeogenesis
24
Fasting begins (blank) hours after eating. Then decreasing levels of insulin/glucagon stimulates (Blank) then (blank)
3
glycogenolysis
gluconeogenesis
25
What is glycogen? what is glycogenolysis?
storage form of glucose
| breakdown of glycogen
25
What is glycogen? what is glycogenolysis?
storage form of glucose
| breakdown of glycogen
26
What is glucagon? When is most liver glycogen depleted?
a hormone formed in the pancreas that promotes the breakdown of glycogen to glucose in the liver.
After an overnight fast (10-12 hours)
26
What is glucagon? When is most liver glycogen depleted?
a hormone formed in the pancreas that promotes the breakdown of glycogen to glucose in the liver.
After an overnight fast (10-12 hours)
27
What process turns glucose into lactate?
glycolysis
27
What process turns glucose into lactate?
glycolysis
28
What process turns lactate into glucose?
gluconeogenesis
28
What process turns lactate into glucose?
gluconeogenesis
29
What process turns glucose into glycogen
glycogenesis
29
What process turns glucose into glycogen
glycogenesis
30
Glycolysis turns a C6 into a (blank)
2 molecules of C3
30
Glycolysis turns a C6 into a (blank)
2 molecules of C3
31
Glycolysis is the biochemical pathway through which a molecule of the six-carbon sugar glucose is converted to two molecules of the three-carbon compound pyruvate. In this process, free energy is sequestered in the form of (blank) molecules.
two ATP
31
Glycolysis is the biochemical pathway through which a molecule of the six-carbon sugar glucose is converted to two molecules of the three-carbon compound pyruvate. In this process, free energy is sequestered in the form of (blank) molecules.
two ATP
32
What are the 6 enzyme classes?
```
transferase
isomerase
lyase
oxioreductase
hydrolase
ligases
```
32
What are the 6 enzyme classes?
```
transferase
isomerase
lyase
oxioreductase
hydrolase
ligases
```
33
Which classes of enzymes are used in glycolysis?
transferase
isomerase
lyase
oxioreductase
33
Which classes of enzymes are used in glycolysis?
transferase
isomerase
lyase
oxioreductase
34
what cells undergo glycolysis?
all cells
34
What do oxioreductases do?
transfer electrons
35
What do lyases do?
break apart (or join) nonhydrolytically
35
What do lyases do?
break apart (or join) nonhydrolytically
36
What do isomerases do?
rearrange
36
What do isomerases do?
rearrange
37
The first reaction of glycolysis is catalyzed by the enzyme (blank), which mediates the transfer of ATP's γ phosphoryl group to the number-6 carbon of glucose. IS this reaction reversible?
hexokinase (if low conc. of glucose) or Glucokinase (if high conc. of glucose)
no
37
Which enzyme is used in the presence of low amounts of glucose, hexokinase or glucokinase? WHich has a large Vmax?
WHich is inhibited by G6P?
hexokinase (it has a smaller Km)
glucokinase
hexokinase
38
What do ligases do?
couple hydrolysis of phosphanydride to bond formation
38
What do ligases do?
couple hydrolysis of phosphanydride to bond formation
39
Where do you find the glut 1 transporter and what is its function?
most tissues
| basal glucose uptake
39
Where do you find the glut 1 transporter and what is its function?
most tissues
| basal glucose uptake
40
Where do you find the glut 2 transport and what is its function?
liver, intestine, pancreatic B cells
| high-capacity glucose uptake
40
Where do you find the glut 2 transport and what is its function?
liver, intestine, pancreatic B cells
| high-capacity glucose uptake
41
Where do you find glut 3 tranporter and what is its function?
brain
| neuronal glucose uptake
41
Where do you find glut 3 tranporter and what is its function?
brain
| neuronal glucose uptake
42
Where do you find glut 4 transport and what is its function?
muscle, adipose tissue, heart
| insulin-dependent glucose uptake
42
Where do you find glut 4 transport and what is its function?
muscle, adipose tissue, heart
| insulin-dependent glucose uptake
43
Where do you find glut 5 transporter and what is its function?
intestine
| fructose transport
43
Where do you find glut 5 transporter and what is its function?
intestine
| fructose transport
44
what cells undergo glycolysis?
all cells
44
what cells undergo glycolysis?
all cells
45
What are the three major stages of glycolysis?
priming
splitting
oxioreduction-phosphorylation stage
45
What are the three major stages of glycolysis?
priming
splitting
oxioreduction-phosphorylation stage
46
What stage is this:
| D-Glucose + 2 ATP4-→D-fructose 1,6-bisphosphate4- + 2 ADP 3- + 2 H+
Priming stage
46
What stage is this:
| D-Glucose + 2 ATP4-→D-fructose 1,6-bisphosphate4- + 2 ADP 3- + 2 H+
Priming stage
47
What stage is this:
| 2 D-Glyceraldehyde 3-phosphate2- + 4 ADP3- + 2 Pi- + 2 H+→2 L-lactate- + 4ATP4- + 2 H2O
Oxioreduction-phosphorylation stage
47
What stage is this:
| D-Fructose 1,6-bisphosphate4-→2 D-glyceraldehyde 3-phosphate2-
splitting stage
47
What stage is this:
| 2 D-Glyceraldehyde 3-phosphate2- + 4 ADP3- + 2 Pi- + 2 H+→2 L-lactate- + 4ATP4- + 2 H2O
Oxioreduction-phosphorylation stage
48
Glycolysis only proceeds when delta G of all individual reactions are (Blank)
negative
49
The first reaction of glycolysis is catalyzed by the enzyme (blank), which mediates the transfer of ATP's γ phosphoryl group to the number-6 carbon of glucose. IS this reaction reversible?
hexokinase
| no
50
Which enzyme is used in the presence of low amounts of glucose, hexokinase or glucokinase?
hexokinase (it has a smaller Km)
51
What is the second reaction of glycolysis?
the isomerization of glucose 6-phosphate to fructose-6 phosphate.
52
What enzyme converts G6P to F6P?
phosphohexose isomerase
53
What catalyzes the commited step (rate-limiting step) of glycolysis?
What does a defect in this cause?
```
phosphofructokinase 1 (PFK1)
Tarui's Disease
```
54
What does PFK1 do?
it transfers ATP to F6P creating F1,6 BP
55
(blank) cleaves the 6-carbon monosaccharide fructose-1,6-bisphosphate into two 3-carbon molecules, glyceraldehyde-3-phosphate and dihydroxyacetone phosphate.
aldolase
56
When aldolase is used to turn F1,6 BP into a huge amount of DHAP and a small amount of G3P, how does the reaction move forward to continue glycolysis?
G3P is continuously consumed causing the reaction to shift towards creating more G3P and making the reaction favorable (i.e delta G is negative)
57
How do you convert the DHAP to G3P?
With a triose and fast consumption of G3P
58
The next step in glycolysis is the conversion of G3P to 1,3 bisphosphateglycerate, however this would seem energetically unfavorable, how does this reaction continue forward?
1,3BPG is rapidly consumed and the substrate NAD+ (when in high concentration) can drive the reaction forward
59
What does G3P dehydrogenase do?
catalyzes the addition of a phosphate group to G3P to make 1,3BPG
60
What is the first reaction of glycolysis in which free energy is recovered?
the reaction of 1,3 BPG and phosphoglycerate kinase turning into 3PG : ))))
61
Why can we get ATP from 1,3 BPG?
because of the high negative free energy of the hydrolysis of the phosphate group
62
What does phosphoglycerate mutase do?
turns 3PG to 2PG
63
What does ENolase do?
converts 2PG to PEP
64
What is the second reaction in which free energy is recovered in the form of ATP?
Is this reaction reversible?
How many net ATP do we have?
PEP to pyruvate via Pyruvate Kinase
NO!!!
two : )))
65
How do we get ATP from PEP?
from the hydrolysis of PEP and the tautormerism of pyruvate
66
Which form of pyruvate is more stable, the enol form or the keto form?
the keto form
67
What is the investment and what is the pay off of glycolysis?
2 ATPS
| 2 ATPS and 2 NADHs
68
What is the first reaction of glycolysis?
the conversion of glucose to g6p by glucokinase. This only happens under very high amounts of glucose due to the high Km of glucokinase.
69
where do you find glucokinase?
liver and pancreatic B cells
70
In anaerobic conditions, or in the absence of mitochondria (RBC's) coverts glucose to (blank) with a net of (blank) ATPs and regenerates (blank)
lactic acid
2 ATPs
NAD for G3P
71
What happens to the lactate at the end of anerobic respiration? HOwever, lactate can reenter glycolysis at pyruvate but not in (blank).
it is a dead end and makes cells acidic
| RBCs
72
(blank) generally moves in the blood stream back to the liver to be shuttled back into glycolysis.
lactate
73
If aerobic respiration where do we shuttle pyruvate?
into the mitochondria
74
What leads to lactic acidosis?
anything that impairs oxygen or inhibits TCA cycle
75
What will this lead to and why:
| physical excercise
lactic acidosis
| anaerobic glycolysis in muscle
76
What will these lead to and why?
| server lung disease, high altitude, drowning
lactic acidosis
| impaired respiration
77
What will these lead to and why?
| Severe anemia, Carbon monoxide poisoning, Sickling crisis
lactic acidoss
| impaired oxygen delivery
78
What will these lead to and why?
| cyanide poisoning
lactic acidosis
| inhibition of oxidative phosphorylation
79
What will these lead to and why?
| Alcohol intoxication, Von Gierke’s disease
lactic acidosis
elevated NADH/NAD+ ratio
impaired gluconeogenesis
80
What will these lead to and why?
| pyruvate dehydrogenase deficiency
lactic acidosis
| impaired pyruvate oxidation
81
What will these lead to and why?
| Leukemia, Metastatic carcinoma
lactic acidosis
| Anaerobic glycolysis by neoplastic cells
82
What traps glucose inside of the cell
glucokinase
83
What is the commited step, and catalyzes the first unique irreversible reaction in glycolysis?
PFK1
84
What is the regulation of glucokinase?
What inhibits glucokinase?
What activates it?
regulated by glucokinase regulatory protein that shuttles GK in/out of nucleus depending on glucose levels. Shuttled out if glucose is high and visa versa.
2) low levels of glucose and high levels of F6P
3) high levels of glucose and high levels of fructose
85
What is an allosteric activator of PFK1?
What is an allosteric inhibitor of it?
Why?
AMP
ATP
If you have a lot of ATP you want to shut off glycolysis.
86
What is F2, 6 bis-P?
made in the liver from F6P in the presence of insulin and is an allosteric effector (activates) of PFK1
87
WHen does F6P turn into F2, 6BP and when does F2,6BP turn into F6P?
in presence of insulin
| in presence of glucagon
88
Increase in (Blank) signals fasting, and you need blood glucose , therefore you will slow glycolysis in the liver.
glucagon
89
Increase in (blank) means you are well fed, with plenty of glucose, therefore glycolysis is allowed in the liver.
insulin
93
(blank) signals an abundance of energy being generated by the TCA cycle.
citrate
94
What are the 5 components that inhibit PFK1?
ATP, Citrate, low pH, low F2,6 BP, glucagon
95
What are the three components that inhibit pyruvate kinase?
ATP, Alanine, phosphate
96
What are the three activators of PFK1?
F2,6BP, AMP, insulin
97
Deficiency of (blank) causes problems in RBC's which results in hemolytic anemia
pyruvate kinase
98
(blank) forms an unstable mixed anhydride with G3P. After spontaneous hydrolysis, 3-phosphoglycerate (3PG) feeds back into glycolysis, but there is no net ATP from glycolysis.
arsenate
99
(blank) poisons PDH by binding to the sulfhydryl groups in dihydrolipoic acid. Much more toxic.
arsenite
100
(blank) protects teeth by inhibiting enolase preventing the formation of both pyruvic and lactic acid helping to prevent tooth decay. It also incorporates into the dentin to strengthen the surface of the teeth.
.
fluoride
101
The addition of (blank) to blood samples stops glycolysis allowing blood glucose levels to be measured.
fluoride
102
Glycolysis is different in RBCs. What is the major phosphorylated intermediate in the RBC?
What does glycolysis in the RBC bypass and what does this result in?
2,3 BPG
| Bypasses phosphoglycerate kinase reaction, therefore net ATP per mole glucose is decreased to 0.
103
RBC's are not biosynthetic cells (enucleate). They only need energy to (blank) and maintain a (blank).
survive
| membrane potential
104
What enzyme turns 1,3 BPG into 2,3 BPG in the RBC?
2,3 bisphospholycerate mutase
105
What converts 2,3 BPG into 3 PG or 2PG in the RBC?
2,3 bisphosphoglycerate phosophotase
106
RBC's use (Blank) glucose/day
15-20g
115
What allosterically stimulates pyruvate kinase?
F1,6 bisphosphate in the liver
117
WHat is the allosteric effector (activator) of pyruvate kinase?
HOw does it work?
fructose 1,6 bis-phosphate
| It feedforward stimulates
130
What are the effectors of glycolysis in the RBC:
for Hexokinase?
For PFK1?
For Pyruvate Kinase?
-G6P, -ATP
+AMP, -ATP +F2,6 BP
+F1,6BP, -ATP
131
What are the effectors of glycolysis in the RBC:
for Hexokinase?
For PFK1?
For Pyruvate Kinase?
-G6P, +ATP
-ATP, +AMP, +F2,6 BP
+F1,6BP, -ATP
132
Once the committed step of glycolysis has passed, it makes sense to stimulate the irreversible enzyme downstream which is pyruvate kinase. What does this?
F1,6 BP
