Exam 2 Flashcards
1
Q
What is the fuel of the human body and every cell can metabolize it?
A
glucose
2
Q
What 3 forms is glucose found in?
A
- monosaccharide
- disaccharide
- polysaccharide
3
Q
What is the formula for a carbohydrate?
A
Cx(H2O)y
4
Q
What are the 2 glucose disaccharides?
A
- sucrose
- lactose
5
Q
What is sucrose made from?
A
glucose + fructose
6
Q
What is lactose made from?
A
galactose + glucose
7
Q
Starch is a ______saccharide
A
polysaccharide
8
Q
What 2 polymers make up starch?
A
amylose + amylopectin
9
Q
What is starch used for?
A
energy storage
10
Q
Is starch made of more amylose or amylopectin?
A
amylopectin (75%)
11
Q
Is amylose branch or unbranched?
A
unbranched
12
Q
Is amylopectin branched or unbranched?
A
branched
13
Q
What does starch breakdown into?
A
maltose
maltotriose
isomaltose
14
Q
Maltose is a _____saccharide and Maltotriose is a ______saccharide
A
maltose: disaccharide
maltotriose: polysaccharide
15
Q
Maltose and maltotriose have 1-4 linkages, why does isomaltose have a 1-6 linkage?
A
Amylopectin is branched and has a 1-6 linkage and that is where it comes from
16
Q
What 2 types of enzymes break down carbohydrates?
A
- soluble enzymes
- anchored enzymes
17
Q
What is an example of a soluble enzyme that breaks down carbs?
A
amylases
18
Q
Where are amylases located?
A
saliva and intestines
19
Q
What is an example of a anchored enzyme that breaks down carbs?
A
glycosidases
20
Q
Where are glycosidases located?
A
intestines
21
Q
How is monosaccharide glucose dealt with?
A
absorbed through intestine via SGLT-1
22
Q
What are glycosidases anchored to?
A
microvilli in the intestines
23
Q
What are the 3 types of microvilli-anchored enzymes?
A
- sucrase-isomaltase (alpha-glucosidase)
- maltase (alpha-glucosidase)
- lactase (beta-galactosidase)
24
Q
Sucrase-isomaltase (alpha-glucosidase) splits __________ and ___________
A
sucrose and isomaltose
25
What is isomaltose made of?
2 glucose
26
Maltase (alpha-glucosidase) splits ________
maltose
27
What is maltose made of?
2 glucose
28
Lactase (beta-galactosidase) splits ________
lactose
29
Dietary glycogen is mainly ___________
amylopectin
30
Amylases mainly break down amylopectin or amylose?
amylopectin
31
Degrading amylose via amylase leaves you with what?
maltose and maltotriose
32
Degrading amylopectin via amylase leaves you with what?
glucose and limit dextrin
33
Degrading amylose and amylopectin with amylase then microvilli-anchored enzymes leaves you with...?
glucose
34
What causes lactase restriction?
loss of beta-galactose to break down beta (1-4) & (1-6) linkage in lactose
35
What are lactase tablets?
provides the body with the enzyme beta-galactosidase to break down lactose
36
Veggies are rich in _________ and________ which require alpha-galactosidases to break them down
Raffinose
Stachyose
37
What enzyme does Beano provide to help break Raffinose and Stachyose down in veggies?
alpha-galactosidases
38
What is sorbitol and why is it an issue?
in sugar free gum and cannot be broken down so bacteria in gut feed on it causing bloating
39
What is Lactulose and what does it do?
fructose + galactose
given as a laxative to decrease intestinal production of ammonia
40
What is considered a complex carb?
3 or more sugars
41
Glucose enters cells via _________ transport
facilitated (passive) transport
42
What are 3 glucose transporters?
1. GLUT 1-3
2. GLUT 4
3. SGLT
43
Is GLUT 1-3 insulin sensitive or insensitive?
insensitive
44
Is GLUT 4 insulin sensitive or insensitive?
sensitive
45
Where is GLUT 4 found?
muscle and adipose cells
46
SGLT are driven by _____ gradient
Na2+
47
How is glucose retained in the cell?
hexokinase phosphorylates at position 6
48
Is the phosphorylation of glucose via hexokinase reversible or irreversible and why?
irreversible; coupled with ATP hydrolysis
49
Hexokinase I and III have ____________ kinetics
Michaelis-Menten kinetics (hyperbolic curve)
50
Why does Hexokinase I and III have Michaelis-Menten kinetics (hyperbolic curve)?
hexokinase in RBC are saturated with glucose so the [glucose] has little affect on hexokinase
- glucose-independent
51
Hexokinase IV is also known as ___________
glucokinase
52
Where is glucokinase found?
liver cells
53
Does glucokinase have high or low affinity for glucose and why?
low; glucokinase is almost never saturated with glucose so the [glucose] affects the activity a lot
54
What kind of kinetics does glucokinase have?
cooperatively kinetics
- glucose-dependent
55
What is the main signal to pancreas to secrete insulin?
glucose
56
Where is insulin stored?
granules in beta pancreas cells
57
How is insulin processed to become active?
C-peptide is cleaved off and B and A chain are connected
58
What is 2nM of glucose considered?
hypoglycemia (low)
59
What is >5mM of glucose considered?
hyperglycemia (high)
60
What secretes glucagon?
pancreatic alpha-cells
intestinal L-cells
61
What are the potentiators for insulin secretion?
amino acids
fatty acids
ketone bodies
62
What is the principal stimulus for glucagon production?
amino acids
63
What is the potentiator for glucagon secretion?
epinephrine
64
Insulin and glucagon secretion are __________ related
inversely
65
What is the glycemic index?
classifies how QUICKLY a food will affect the blood glucose level
66
How does constant consumption of high fructose corn syrup cause DMII?
pancreas becomes desensitized to glucose spikes and won't secrete insulin
67
What sodium-dependent glucose transporter does the intestine use?
SGLT-1
68
What is the ratio of Na : glucose for SGLT-1 in intestines?
2Na : 1 glucose
69
What controls the flux of sodium through SGLT-1 and 2?
Na/K ATPase
70
What sodium-dependent glucose transporter does the kidney use?
SGLT-2
71
What is the ratio of Na : glucose for SGLT-2 in kidney?
1:1
72
How do anti-SGLT-2 medications work?
prevent hyperglycemia by blocking SGLT-2 so glucose cannot be absorbed
73
What two tissues in the body are exclusively fueled by glucose?
brain
red blood cells
74
Why is glucose stored as a complex carb?
free glucose is osmotically active and will enter RBC and cause them to burst
75
What is the definition of glycolysis?
the breakdown of glucose to extract energy from thr C-C bonds
76
What form of glycolysis creates the most energy?
oxidative phosphorylation (O2 present)
77
What kind of cells preform anaerobic glycolysis?
red blood cells (no mitochondria)
78
What is the start and end product of glycolysis?
glucose (C6)
pyruvate (C3)
79
What are the 2 phases of glycolysis?
1. prep phase
2. pay-off phase
80
Which phase in glycolysis cost energy and which gains energy?
prep phase: loss E
pay off: gain E
81
What's the net cost of the prep phase of glycolysis?
2 ATP (2 dephosphorylation events)
82
What is the net gain of the pay-off phase of glycolysis?
4 ATP
2 NADH
2 H+
83
What enzymes in glycolysis perform DE-phosphorylations (ATP-->ADP)?
hexokinase
phosphofructokinase-1 (PFK-1)
84
What enzymes in glycolysis perform phosphorylations (ADP-->ATP)?
phosphoglycerokinase
pyruvate kinase
85
What enzyme in glycolysis converts NAD+ to NADH?
GAP DH
86
Everything in the pay off stage of glycolysis is x____ because??
2
b/c 2 GAP is made per glucose
87
What are the enzymes that catalyze irreversible reactions in glycolysis?
hexokinase
PFK-1
pyruvate kinase
88
What is the net gain of degradation of 1 glucose in glycolysis?
2 NADH
2 ATP
2 pyruvate
89
What is the overall reaction of glycolysis?
glucose + 2ADP + 2Pi + 2NAD --> 2 pyruvate + 2ATP + 2NADH + 2H + 2H2O
90
What is the limiting reactant in glycolysis?
NAD+ (does not come from diet, must be made in cells)
91
What is the purpose of NAD+/NADH?
electron carrier
92
Which is oxidized and which is reduced form? NAD/NADH
NAD+: oxidized
NADH: reduced (extra H)
93
What is the ratio of NAD+/NADH?
Large (much more NAD+ because cells are always ready to use it)
94
How do you treat Pellagra?
Vitamin B3 supplement
95
How can NADH be oxidized back into NAD+?
Lactate DH can reduce pyruvate into lactate which puts of NAD+ back into glycolysis for GAP DH
96
How does the total glycolytic pathway change when NAD+ is made from lactate?
instead of 2 pyruvate as a product there is 2 lactate instead
97
What is the advantage and disadvantage of anaerobic glycolysis?
advantage: very quick way to replenish glycolysis
disadvantage: acidifies blood (lactate and H+)
98
How is the acidification of blood by anaerobic glycolysis fixed?
HCO3- (carbonate) neutralizes
99
Glycolysis with or with out O2 results in much smaller production of H+
with O2
100
How many ATP are made in O2 present glycolysis vs. anaerobic glycolysis?
regular: 36/38ATP
anaerobic: 2 ATP
101
What are 2 ways of controlling glycolysis?
1. control access to blood/cells via GLUTs
2. AMP/ATP regulation of PFK
102
In the presence of AMP there is a ____________ relationship to PFK activity
hyperbolic (lowers Km)
103
In the presence of ATP there is a ____________ relationship to PFK activity
sigmoidal (high Km)
104
Why is AMP used as a signaling molecule over ADP?
changes in [AMP] are much larger than ADP
105
How is PFK activity controlled allosterically?
by ATP and AMP
106
How is PFK activity controlled by hormones?
controlled by insulin, glucagon/epi, F2,6-BP
107
How can the liver control the speed of glycolysis?
by controlling the [insulin] put out
108
What is the purpose of the Pentose Phosphate Shunt?
produce NADPH and GSH for protection/repair again radicals
109
Where does the oxidative branch come off of glycolysis?
G6P
110
Where does the pentose-P branch come off and feed back into glycolysis?
in: F6P
out: GAP
111
What is produced in the oxidative branch of PPP?
2 NADPH
ribulose-5-phosphate
112
0
0
113
What are the 3 enzymes involved in the oxidative branch?
1. G6PD
2. glucono lactonase
2. 6-phospho Gluconate DH
114
How many oxidations are there in the oxidative branch of PPP?
2 (2 dehydrogenases)
115
What enzyme in PPP is highly regulated?
G6PDH
116
What enzyme catalyzes the unregulated irreversible reaction in PPP oxidative branch?
6-phospho Gluconate DH
117
Is flux through the sugar phosphate branch of PPP regulated?
no
118
If only the oxidative branch of PPP happened, what is produced?
NADPH and Ribulose-5P
(feds back into glycolysis)
119
If only the sugar phosphate branch of PPP happened, what is produced?
ribose 5-phosphate
120
If both branches of PPP happened, what is produced?
NADPH and ribose-5-P
121
Why does most of the NADPH made in the PPP go to the liver?
fatty acid synthesis
122
For red blood cells, what is the only way to make NADPH?
PPP
123
How can the liver make NADPH other than PPP?
malate --> pyruvate (via malate DH)
124
What is the oxidized and reduced form? (NADP+/NADPH)
NADP+: oxidized
NADPH: reduced
125
What is the NADP+/NADPH ratio?
smaller (much more NADPH b.c used for repairs)
126
What enzyme catalyzes NADP+/GSSG-->NADPH/GSH?
glutathione reductase
127
What does glutathione do? (GSH)
protects against free radicals and peroxides
128
What is the GSH/GSSG ratio?
large (reduced form favored)
129
What 3 enzymes are involved in GSH detoxifying hydrogen peroxide and superoxide?
superoxide dismutase
catalase
GSH reductase (regenerates GSH)
130
What happens if G6PD is deficient?
increases oxidative stress b/c oxidative branch of PPP is affected = less NADPH for RBC
131
How can G6PD deficiency be useful?
oxidative stress helps protect against malaria
132
________ men and _________ G6PD deficient are protected against malaria
hemizygous men
heterozygous
133
What is hemoglobinuria in G6PD deficiencies?
bursting of RBC because of oxidative stress (not enough NADPH) causing dark urine
134
What is the reducing end of glycogen and the non-reducing end?
reducing: 1'OH
non-reducing: 4' OH
135
Where is glycogenin located in glycogen?
center (tier zero)
136
Glycogen is a polymer of glucose designed for .....
rapid mobilization of metabolic fuel
137
Where is most of the glycogen stored?
kidneys
138
In glycogenesis, is G6P turned into glucose and sent to other tissues?
No (you are storing glucose not breaking it down)
139
Is glycogenesis endergonic or exergonic?
endergonic (requires E)
140
What are the 4 steps of glycogenesis?
1. activation of glucose
2. priming of UDP-glucose
3. extension of chain
4. branching of chain
141
How is glucose activated in glycogenesis?
UDP-glucose pyrophosphorylase forms UDP-glucose
142
What enzyme primes UDP-glucose for glycogenesis?
glycogenin
143
What enzyme extends the a(1-4) chain in glycogenesis?
glycogen synthase
144
What enzyme branches glucose polymers with a 1,6-bond in glycogenesis?
branching enzyme
145
What is process in essential for solubility of glycogen?
branching
146
How many glucose are required for glycogen synthase?
4
147
Is the reducing or non-reducing end of glycogen brokenoff and added to the position 6 of carbon for brnahcing?
non-reducing
148
What is different about glycogenolysis in the liver v. muscles?
in muscles G6P is not broken down into glucose to send to other tissues while in the liver it sends broken down glucose to feed other tissues
149
___________ feeds muscle contractions
glycogen
150
Does the liver or muscles release glucose into the blood stream and why?
lover b/c it has an insulin and glucagon receptor while muscles have only insulin receptors
151
__________ does not release glucose from glycogen while the liver does
muscles
152
What is the only organ that can dephosphorylate glucose and send it into the blood?
liver
153
Is glycogenolysis exergonic or endergonic?
exergonic (release energy)
154
What are the 3 steps of glycogenolysis?
1. removal of glucose units
2. debranching
3. isomerization of G1P
155
What enzyme removes alpha(1-4) glucose during glycogenolysis?
glycogen phosphorylase
156
What enzyme is responsible for debranching glucose in glycogenolysis?
glycogen debranching enzyme
157
Glycogen debranching enyzme cannot remove all of the branch leaving a ____________ branch
limit branch
158
What enzyme isomerizes G1P --> G6P in glycogenolysis?
phosphoglucomutase
159
What happens during the isomerization stage of glycogenolysis?
G1P converted into G6P (which further breaks down to glucose)
160
What 2 ways is glycogenolysis regulated?
1. allosteric (intracellular)
2. hormonal (extracellular)
161
What are 2 key enzymes that regulate glycogen metabolism?
glycogen phosphorylase
glycogen synthase
162
How is glycogen regulated by hormones?
insulin and epinepherine/glucagon regulate the phosphorylation of glycogen synthase and phosphorylase
163
What are the 3 main substrates glucose can be synthesized (as a carbon scaffolding) from in gluconeogenesis?
glycerol
lactate
alanine
164
Does gluconeogenesis require energy?
yes (from FA oxidation)
165
What organs do gluconeogenesis?
kidney
liver
166
What is the rate of preference for carbon skeletons of gluconeogenesis?
lactate > alanine > glycerol
167
Is acetyl-coA a carbon input option for gluconeogenesis?
NO
168
Energy in the form of ATP, GTP, and NADH are provided for gluconeogenesis by...?
fatty acid beta oxidation
169
What are the 3 bypasses for gluconeogenesis to get around irreversible reactions?
glucokinase bypass
phosphofructokinase bypass
pyruvate kinase bypass
170
What enzyme is for the glucokinase bypass
in gluconeogenesis?
glucose-6-phosphatase
171
What enzyme is for the phosphofructokinase bypass
in gluconeogenesis?
fructose-1,6-bisphosphatase
172
What 2 enzymes are for the pyruvate bypass in gluconeogenesis?
PEP carboxylase
pyruvate carboxylase
173
What gluconeogensis bypass uses 2 enzymes?
pyruvate kinase bypass
174
GTPase for gluconeogenesis is present in what organs but absent in _________
present: liver, kidney
absent: muscles
175
What is the net cost of gluconeogenesis?
4 ATP
2 GTP
2 NADH
176
What is the overall equation of gluconeogenesis?
2 pyruvate + 4 ATP + 2 GTP + 2 NADH --> glucose + 4 ADP + 2 GDP + 2 NAD
177
Excessive gluconeogenesis causes ______glycemia
hyperglycemia
178
insufficient gluconeogenesis causes ______glycemia
hypoglycemia
179
People who have a diabetes have ___excessive/insufficient____ gluconeogenesis?
excessive
180
What medication is used to treat hyperglycemia for diabetes?
metformin
181
Insufficient gluconeogenesis can be caused from excess ________
insulin
182
what enzyme helps pyruvate enter the mitochondria for CAC?
pyruvate translocase
183
What has to happen so that pyruvate can be retained in the mitochondria and enter the CAC?
oxidized and decarboxylated into acetyl coA
184
What enzyme catalyzes pyruvate turning into acetyl coA?
pyruvate DH
185
What are the inputs and outputs of pyruvate DH?
input: CoA and NAD+
output: CO2 and NADH
186
What vitamim is in CoA?
Vitamin B5
187
What are two ways to regulate pyruvate DH?
DIRECTLY: acetyl coA and NADH inhibit
INDIRECTLY: acetly coA and NADH activate Pyruvate DH kinase which then inhibits
188
How may oxidations are there in the CAC (releases energy)?
4
189
What are the 4 products of oxidations in the CAC?
3 NADH
1 FADH
1 GTP
190
What 2 enzymes release CO2 in the CAC?
isocitrate DH
a-ketogluterate DH
191
What do all the enzymes that perform oxidations in CAC end in?
dehydrogenase
192
What is the overall reaction of the CAC?
acetyl-coA + NAD + FAD + GDP + Pi + H2O --> CO2 + NADH + FADH2 + GTP(ATP) + H + CoA
193
___ molecules of CO2 are released from CAC?
2
194
___ NADH and ___ FADH2 are generated from the CAC?
3 NADH
1 FADH2
195
___GDP/ADP are phosphorylated in the CAC?
1
196
What is FAD made of?
flavin mononucleotide (FMN)
adenosine monophosphate (AMP)
197
FMN in FAD is derived from vitamin _____
Vitamin B2
198
What 4 reactions drain the CAC?
1. FA synthesis
2. glutamin from a-ketogluterate
3. amino acids from succinate
4. gluconeogeneisis from oxaloacetate
199
What 2 reactions feed the CAC?
1. glutamine from a-ketogluterate
2. pyruvate carboxylase
200
pyruvate carboxylase is _________ dependent
biotin
201
what does pyruvate carboxylase do?
converts pyruvate directly into oxaloacetate
202
What is the purpose of pyruvate carboxylase converting pyruvate directly into oxaloacetate?
replenishes CAC intermediates
203
What vitamin is a cofactor for biotin?
vitamin B7
204
Where is biotin synthesized from?
from intestinal microorganisms (fed by diet)
205
What does biotinidase do?
recycles biotin
206
What vitamin is essential for pyruvate DH?
vitamin B1
207
What 3 reaction require Vitamin B1?
1. pyruvate ----> acetyl coA (via PDH)
2. a-ketogluterate ---> succinyl coA (via a-ketogluterate DH)
3. GAP -----> R5P (via transketolase)
208
There are 3 reactions that require Vitamin B1, which 2 of the 3 actually impairs ATP production?
pyruvate ----> acetyl coA (via PDH)
a-ketogluterate ---> succinyl coA (via a-ketogluterate DH)
