Carbs part two Flashcards
(181 cards)
1
Q
The synthesis of glycogen from glucose
A
Glycogenesis
2
Q
the breakdown of glycogen to glucose
A
Glycogenolysis
3
Q
The breakdown of glucose
A
glycolysis
4
Q
Cycle that breaks down acetyl coA and represents completion of glucose oxidation
A
Tricarboxylic acid (TCA) cycle
5
Q
process wherein electrons are passed from a series of donors and acceptors, ultimately resulting in ATP production
A
Electron Transport Chain
6
Q
the production of glucose from non-carbohydrate intermediates
A
gluconeogenesis
7
Q
What are, arguably, the two most important tissues when discussing glucose metabolism?
A
Liver
muscle
8
Q
what takes up approx 20% circulating glucose and regulates blood glucose by breaking down liver glycogen and also undergoing gluconeogenesis?
A
Liver
9
Q
what takes up approx 80% of circulating glucose?
A
muscle
10
Q
Where does glycogenesis occur?
A
predominately in muscle and liver
11
Q
when does glycogenesis occur?
A
During periods of energy excess
12
Q
Is glycogenesis an anabolic or catabolic reaction?
A
Anabolic
13
Q
Is glycogenesis energy producing or energy consuming?
A
consuming
14
Q
What happens to glucose as soon as it enters the cell in glycogenesis?
A
glucose is phosphorylated, producing glucose-6-phosphate.
15
Q
What enzyme catalyzes glucose in the liver for step one of glycogenesis?
A
glucokinase (hexokinase IV)
16
Q
What enzyme catalyzes glucose in the muscle for step one of glycogenesis?
A
hexokinase
17
Q
in glycogenesis, Where does the phosphate transfer too after G-6-P is produced? what does it produce?
A
C6 to C1, producing glucose-1-phosphate
18
Q
what state is glucose in when UDP-glucose is formed?
A
“activated”
19
Q
In glycogenesis, what is the product of Uridine Monophosphate (UMP) coupling to G-1-P?
A
Uridine diphosphate-glucose (UDP-glucose)
20
Q
In glycogenesis, what powers the coupling of UMP to G-1-P, forming UDP-glucose?
A
Uridine triphosphate (UTP) hydrolysis
21
Q
In glycogenesis What protein forms a short chain of up to 8 units of glucose molecules?
A
glycogenin
22
Q
What bond forms when UDP-Glucose molecules attach to glycogenin in step 4 of glycogenesis?
A
alpha 1-4 bonds.
23
Q
In glycogenesis, what enzyme further extends glycogen chains over 8 units of glucose molecules?
A
glycogen synthase
24
Q
In glycogenesis, what enzyme creates the a1,6 bonds at branching points?
A
branching enzyme
25
what is a highly branched arrangement of glucose molecules consisting of a(1-4) and a(1-6) glycosidic bonds?
glycogen
26
Does glycogen have more or less branch points than amylopectin?
more
27
What are the 3 possible fates of glucose 6 phosphate?
1. Glycolysis (burn)
2. Glycogenesis
3. (liver exclusive) hydrolyzed by G-6-Pase and exported via GLUT transporter membrane as a free glucose molecule
28
When UDP-Glucose molecule attach to glycogen, it attaches the first _ units of glucose molecules.
What type of bond?
8
alpha 1-4 bonds.
29
after 8 units of glucose molecules have been attached to glycogen, what enzyme extends glycogen chains further?
glycogen synthase (alpha 1-4 bonds).
30
What type of response is G-6-P allosterically inhibiting hexokinase?
Negative Feedback Loop
31
What type of reaction does insulin have?
anabolic/catabolic
anabolic
32
Is glucose uptake in the liver insulin dependent?
Insulin promotes glucose uptake in liver, but not directly. Insulin indirectly promotes uptake by increasing phosphorylation (trapping) and utilization of glucose.
The liver has other glucose transporters not insulin dependent (GLUT 1,2,3)
33
What inhibits glycogen synthesis?
glucagon and epinephrine
34
What is the difference between glucagon and epinephrine
Glucagon works in the liver
epinephrine works in the muscle
35
What type of relationship does glycogen synthase and glycogen phosphorylase have?
Reciprocal/Inverse. The stimulation of one inhibits the other just as much.
36
What Glucose transporter provides glucose entry into the cell in the Liver?
Glut 2
37
What Glucose transporter provides glucose entry into the cell in the muscle?
GLUT 4
38
What enzyme causes glucose phosphorylation in the liver?
Glucokinase
39
What enzyme causes glucose phosphorylation in the Muscle?
Hexokinase
40
Is there negative feedback inhibition of G6P on glucokinase?
No
41
Is there negative feedback inhibition of G6P on hexokinase?
Yes
42
Is insulin needed for activation of glucokinase?
yes
43
Is insulin needed for activation of hexokinase?
yes
44
does insulin activate glycogen synthase in the liver?
yes
45
does insulin activate glycogen synthase in the muscle?
yes
46
Is Glucose 6 phosphatase present in the liver?
yes
47
Is Glucose 6 phosphatase present in the muscle?
no
48
are there glucagon receptors present in the liver?
yes
49
are there glucagon receptors present in the muscle?
no
50
Is glycogen phosphorylase present in the liver?
yes
51
Is glycogen phosphorylase present in the muscle?
yes
52
What regulates glycogen synthase and glycogen phosphorylase?
Insulin
glucagon in the liver
epinephrine
local factors
53
What does Glucose-6-phosphatase do?
Located in the liver, maintains euglycemia by converting G-6-P to free glucose
54
How does glycogenolysis maintain euglycemia?
1. turns G6P into glucose molecules via G-6-Pase
2. Glycolysis
55
What is the breaking down of glycogen to individual glucose units?
Glycogenolysis
56
Where does glycogenolysis primarily take place?
primarily in liver and muscle
57
what stimulates glycogenolysis?
during periods of energy deficit
58
is glycogenolysis an anabolic or catabolic reaction?
catabolic
59
What does glycogen produce when it is cleaved by glycogen phosphorylase at the start of the glycogenolysis process?
glucose-1-phosphate and the residual glycogen chain
60
What does glucose-1-phosphate convert into after it is cleaved by glycogen phosphorylase in glycogenolysis?
glucose-6-phosphate
(G-6-P)
61
what can glucose-6-phosphate do after being converted from G-1-P in glycogenolysis?
1. glycolysis for oxidation
2. converted to free glucose via glucose-6-phosphatase
62
Why does muscle glycogen not enter circulation?
muscle lacks glucose-6-phosphatase
63
What process is the breaking down of glucose to pyruvate?
Glycolysis
64
Where does glycolysis occur at in the cell?
in the cytoplasm of all cells
65
When does glycolysis occur?
during periods of demand
example: exercise
66
is glycolysis an anabolic or catabolic reaction?
catabolic
67
Is glycolysis energy yielding or energy consuming?
energy yielding
68
What step in the metabolic breakdown of glucose is glycolysis?
First step
69
What does glycolysis yield?
1. 2 ATP
2. 2 three-carbon pyruvate molecules
70
Does glycolysis function under aerobic or anaerobic activity?
both aerobic and anaerobic
71
What steps are the "Investment phase" of glycolysis?
steps 1-5
72
What steps are the "payoff" phase of glycolysis?
steps 6-10
73
How does the muscle differ from the liver during glycogenesis?
1. G-6-P will inhibit hexokinase in the muscle, but not in glucokinase. It gets to choose how much glucose to take in.
2. The muscle does not shuffle glucose out to the stream.
74
Once G-6-P enters the cell and it's fate is glycolysis, What does it convert into?
Fructose-6-P
75
In glycolysis, What is the enzyme that phosphorylates F-6-P to form fructose-1,6-bisphosphate?
PFK - Phosphofructokinase
76
Can F-1,6-BP turn back into F-6-P?
No
77
How is glycolysis regulated?
Increase in AMP (cell needs energy)
Decrease in ATP and citrate (energy needs met)
78
Does F-6-P catalyzed by PFK-1 use ATP when forming F-1,6-BP?
yes
79
What has been invested in glycolysis?
2 ATP
two 3C molecules of G-3-P.
80
In glycolysis, what is formed when an inorganic P is added to G-3-P?
1,3 Bis P glycerate (1,3-BPG)
81
In glycolysis, what is formed when PEP donates the P to ADP in the final step?
ATP and Pyruvate
82
What is the starting product and what is the ending product of glycolysis?
Started with glucose
ended with ATP and pyruvate (net 2 ATP)
83
Investment or Payoff phase of glycolysis?
2 ATP are used to form 2-G3P molecules from one molecule of glucose
Investment Phase
84
Investment or Payoff phase of glycolysis?
4ATP are formed via substrate level phosphorylation; 2NADH; 2 pyruvate
Payoff phase
85
The disaccharide maltose, upon hydrolysis will yield:
2 glucose units
86
Which of the following indicates high energy demand in a cell?
a. Increased AMP concentration
b. Increased ATP concentration
Increased AMP concentration
87
Glycogenolysis in skeletal muscle occurs because of the action of the enzyme _____, which is stimulated by the hormone ______.
Glycogen phosphorylase, epinephrine
88
After glycolysis, what is the metabolic pathway that completes the oxidation of glucose?
TCA cycle
89
Where does the TCA cycle occur?
mitochondria
90
What are the three fates of pyruvate created from glycolysis
1. Oxidative decarboxylation
2. Lactate- Intercellular Shuttle
3. Lactate- Intracellular shuttle
91
What shuttle operates by converting oxaloacetate into malate using NADH and the enzyme malate dehydrogenase (MDH) in the cytosol. Malate then enters the mitochondria, where MDH reverses the reaction, converting malate back to oxaloacetate and regenerating NADH. To complete the shuttle cycle, oxaloacetate is transformed into aspartate via aspartate transaminase (AST) and exits the mitochondria where it can be converted back into oxaloacetate.
Malate-Aspartate Shuttle
92
What shuttle uses a different mechanism to transport electrons from NADH to the ETC. In the cytosol, glycerol-3-phosphate dehydrogenase uses NADH to convert DHAP into glycerol-3-phosphate. Once at the inner mitochondrial membrane, membrane-bound glycerol-3-phosphate dehydrogenase turns glycerol-3-phosphate back to DHAP, generating FADH2 in the process. FADH2 moves its electrons to the ETC via CoQ. This shuttle is less efficient
Glycerol-Phosphate shuttle
93
What 2 shuttles can the lactate formed from pyruvate take?
One of two ways.
1. Intercellular
2. intracellular
94
Is "cell-to-cell - the Cori cycle" Intercellular or Intracellular?
Intercellular
95
Is Lactate being shuttled into mitochondria where it undergoes oxidation to pyruvate by way of mitochondrial LDH Intercellular or intracellular
Intracellular
96
Lactate is
a. a waste product produced of metabolism
b. formed only under anaerobic conditions
c. the cause of muscle soreness
d. none of the above
d. none of the above
97
Why can't lactate be converted into glucose via gluconeogenesis in the muscle?
because the muscle doesn't have glucose-6-phosphate
98
How is lactate transported to the liver?
intercellular shuttle (the Cori Cycle)
99
What happens to lactate when it gets to the liver?
converted to glucose via gluconeogenesis.
100
When lactate is turned into glucose in the liver, what tissue uses it for energy when it returns to the blood stream?
used by the muscle as an energy source
101
What cycle refers to:
movement of lactate out of the cell>to liver>convert to glucose>goes to muscle as energy source
the Cori Cycle
102
In Intracellular transport, what transporter does pyruvate and lactate enter the mitochondria through?
monocarboxylate transporter (MCT)
103
What is formed in the ETC that is needed for the TCA cycle and glycolysis?
NAD
104
what is the formation of glucose from non-carbohydrate precursors
gluconeogenesis
105
Where does gluconeogenesis occur at?
Liver, Kidney, Intestine
106
When does gluconeogenesis occur?
Periods of low blood glucose
107
Is gluconeogenesis energy producing or energy consuming?
energy consuming
108
how does the body maintain blood glucose levels approximately 4 hours after a meal?
Glucose from that meal can no longer sustain blood glucose concentrations, so the body first starts to break down liver glycogen.
109
how does the body maintain blood glucose levels approximately 12-18 hours after a meal?
liver glycogen stores will run low, and in order to maintain glucose levels, the body will make glucose from non carbohydrate precursors via gluconeogenesis.
110
How does gluconeogenesis differ from glycolysis?
gluconeogenesis synthesizes glucose, consumes ATP and uses NADH. glycolysis burns glucose, produces ATP and uses NAD+.
111
Substances that enter the pathway.
precursors
112
What are three gluconeogenesis precursors?
1. Pyruvate/lactate
2. glycerol
3. glucogenic amino acids
113
How is glycerol a precursor for gluconeogenesis?
from mono, di, and triglycerides
-but not fatty acids
114
what state does gluconeogenesis occur?
fasting state
115
what is PEPck?
PEP carboxykinase
116
What relationship does glycolysis and gluconeogenesis have?
reciprocal/inverse
117
What is an alternative pathway for glucose oxidation that does not generate ATP?
Pentose Phosphate pathway
118
What are products of the pentose phosphate pathway?
NADPH and ribose-5-phosphate
119
what product of the pentose phosphate pathway can lead to an increase in uric acid production and used for synthesis of nucleotides and nucleic acids?
ribose-5-phosphate
120
What product of the pentose phosphate pathway is used for various pathways including lipid synthesis?
NADPH
121
When is the pentose phosphate pathway increased?
following a high carb meal
122
Does the pentose phosphate pathway happen with a lot of glucogenesis or glycolysis?
glycolysis
123
What pathway is a "detour from glycolysis"?
pentose phosphate pathway
124
what glycogen storage disease describes:
Exercise intolerance with muscle pain and cramps
lactate levels fail to increase (and may decrease) after intense exercise
Rhabdomyolysis: breakdown of damaged muscle cells and release into blood stream; can cause renal stress and eventual failure
patients tend to feel "second wind" after approx. 10 min of exercise.
McArdle's Disease (GSD-V)
125
Why do patients tend to feel a "second wind" after 10 minutes of exercise?
they lack glycogen-phosphorylase. after 10 minutes, the fat starts to breakdown to provide energy.
126
What nutritional intervientions help exercise tolerance for McArdle's Disease?
Ketogenic diet
127
What glycogen storage disease describes:
Most common of all glycogen storage diseases (~1 in 50,000 births)
severe hypoglycemia, increased glycogen in liver and kidney
hepatomegaly (enlarged liver) develops in childhood
Van Gierke's Disease (GSD I)
128
What is a:
mixture of fructose and glucose
55-65% fructose (35-45% glucose)
a major sweetener in most food products
High fructose corn syrup
(HFCS)
129
Fructose is cheaper and sweeter (g for g) than _____ or ______.
sucrose or glucose
130
what are two major dietary sources of fructose?
1. sucrose
2. High fructose corn syrup
131
how much of fructose taken up by the liver in the first pass?
~75%
132
Why is Fructose dangerous?
contributes to Fatty Liver and Very Low Density Lipoproteins (VLDLs)
133
How does overconsumption of fructose contribute to ATP depletion? what is a product?
ATP is used to phosphorylate fructose. when you can't remake ATP fast enough, there starts to be ATP depletion; resulting in uric acid.
134
what major regulatory step in glycolysis does fructose skip resulting in an increase in acetyl CoA?
Phosphofructokinase
135
What is a result of fructose bypassing PFK and increasing acetyl CoA?
some acetyl CoA is converted to fat. an increase of acetyl CoA increase risk of obesity and fatty liver, and increased VLDL secretion from liver
136
What describes a group of diseases marked by a high level of glucose?
Diabetes
137
What group of diseases is a result from defects in insulin production, insulin action, or both?
diabetes
138
Auto-immune disorder in which the body's immune system destroys the pancreatic beta cell, where insulin is produced
Type I Diabetes
139
Is Type I diabetes typified by insulin deficiency or insulin resistance?
Insulin deficiency
140
what rapidly breaks down when there is lack of insulin?
fat and muscle
141
lack of what hormone causes fat and protein breakdown in the muscle cell?
insulin
142
What is a disorder in which the body does not adequately utilize the insulin produced by the pancreas?
Type II diabetes
143
What term describes the inability to adequately use insulin?
Insulin resistance
144
What diabetes accounts for 95% of diabetes cases in adults?
Type II diabetes
145
What is a systemic consequence of insulin resistance in fat cells?
Increase in lipolysis (breakdown of fat)
146
What is a systemic consequence of insulin resistance in the liver?
Increase in hepatic glucose output (gluconeogenesis)
Increase in VLDL production
147
What is a systemic consequence of insulin resistance in muscle?
Decrease in glucose uptake due to inability to bind to GLUT4
decrease in glycogen synthesis due to lack of glycogen synthase
148
What is a systemic consequence of insulin resistance in blood vessel?
decrease in vasodilation ability (vessel constriction)
149
For the A1C test what is the diagnostic criteria percentage for diagnosing diabetes?
at or above 6.5% with a positive test
150
For the Fasting plasma glucose test what is the diagnostic criteria for diagnosing diabetes?
at or above 126 mg/dL with a positive test (no caloric intake for atleast 8 hours)
151
For the 2-hour plasma glucose test what is the diagnostic criteria for diagnosing diabetes?
at or above 200 mg/dL after 75 g of glucose in water
And positive test
152
For the random plasma glucose test what is the diagnostic criteria for diagnosing diabetes?
at or above 200 mg/dL in a patient with symptoms of hyperglycemia
153
What are the three tests used to diagnose diabetes?
1. A1C test
2.a fasting plasma glucose test
3. an oral glucose tolerance test
154
What happens to glycogen in the liver during exercise?
glycogenolysis. want glucose to travel to muscle.
155
What happens to blood glucose in the muscle during exercise?
glycogenolysis. want glucose to make ATP to use in the muscle
156
How is blood glucose regulated during exercise?
As it goes from liver to blood blood glucose concentration is increased
goes from blood to muscle - decrease
157
When doing high intensity exercise, does blood glucose increase or decrease?
decrease because demand is so high
158
Type 2 diabetes progresses from _____ to ______.
insulin resistance
diabetes
159
Type 2 diabetes progresses from insulin resistance to diabetes over
a. weeks
b. years
c. decades
d. both b and c
d. both b and c
160
With type 2 diabetes progression, what does the pancreatic beta cell do to normalize glucose levels?
compensates by increasing insulin secretion
161
In type 2 diabetes progression, What results in the beta cells beginning to fail thus insulin secretion failing?
hyperglycemia
162
In type 2 diabetes progression, what is required to maintain blood glucose after the pancreatic beta cells begin to fail?
exogenous insulin
163
What is a limitation of the hbA1C diagnostic test?
Can't use it for pregnant women because 3 months (the turnover rate of blood) will be drastically changing.
164
What is a limitation of the fasting plasma glucose test?
You can have insulin resistance, but because of increased insulin production blood glucose may look normal.
165
What is a limitation of an oral glucose tolerance test?
the load of glucose will be metabolized differently in varying body weight/sizes.
166
Regarding Progression of Diabetes, what does this line represent?
a. Insulin Resistance
b. Insulin Production
c. Fasting Blood Sugar
a. Insulin resistance
167
Regarding Progression of Diabetes, what does this line represent?
a. Insulin Resistance
b. Insulin Production
c. Fasting Blood Sugar
b. Insulin Production
168
Regarding Progression of Diabetes, what does this line represent?
a. Insulin Resistance
b. Insulin Production
c. Fasting Blood Sugar
c. Fasting blood sugar
169
Does this graph represent someone with or without diabetes after a normal meal?
without diabetes
starts below 126 mg/dl
low after 2 hours
170
Does this graph represent someone with or without diabetes after a normal meal?
with diabetes
starts above 126 mg/dL
high after 2 hours
171
What does glucagon stimulate?
glycogenolysis and gluconeogenesis
the breakdown pathways
172
How can glucagon make diabetes worse?
both glycogenolysis and gluconeogenesis puts sugar in the blood.
173
Is T1D and T2D associated with hyper or hypoglucagonemia?
hyperglucagonemia
174
Condition in which women without previously diagnosed diabetes exhibit high blood glucose levels during pregnancy, especially in 3rd timester?
gestational diabetes
175
How many pregnancies are affected by gestational diabetes?
3-10%
176
is gestational diabetes symptomatic or asymptomatic?
asymptomatic
177
How is gestational diabetes diagnosed?
Either OGTT or FGT.
Never A1C
178
Do gestational diabetes symptoms resolve?
Symptoms resolve following pregnancy
179
What are gestational diabetes risks the baby may have?
excessive birth weight
initial low blood sugar
childhood obesity
type 2 diabetes later in life
180
What are gestational diabetes risks the mother may have?
Pre-eclampsia during pregnancy
difficult delivery
Increased risk of type 2 diabetes especially if GD required exogenous insulin
181
How is gestational diabetes thought to be a natural phenomenon?
Placental hormones thought to mediate the insulin resistance
Most women become insulin resistant during pregnancy, which is thought to secure glucose supply to the growing fetus
