Final Exam Flashcards
(214 cards)
1
Q
What are the other names for Pentose Phosphate Pathway?
A
Hexose Monophosphate Pathway
Phosphogluconate Pathway
2
Q
What is the purpose of the PPP?
A
To generate NADPH + ribose
3
Q
The PPP generates NADPH. What do we need this for?
A
It’s an electron donor for biosynthesis, detoxification, respiratory bursts, and antioxidant regeneration
4
Q
The PPP produces ribose. Why do we need this?
A
For biosynthesis
- used to make nucleosides and nucleotides
- nucleosides and nucleotides are used to make ATP, coenzyme A, FAD, NAD, and NADP molecules
5
Q
Where does the PPP take place?
A
Cytosol
6
Q
What is the rate limiting enzyme of the PPP?
A
Glucose 6-Phosphate Dehydrogenase
7
Q
How much ATP is produced and consumed in the PPP?
A
0 consumed. 0 produced.
8
Q
What is a nucleoside?
A
Base + sugar
9
Q
What is a nucleotide?
A
Base + sugar + phosphate
10
Q
What are the purines?
A
Guanine and adenine
11
Q
What are the pyrimidines?
A
Cytosine and thymine. Uracil in RNA.
12
Q
The first part of the PPP is oxidative or non oxidative?
A
Oxidative
13
Q
The first part of the PPP is reversible or irreversible?
A
Irreversible
14
Q
What is the first step of the PPP called?
A
Dehydrogenation
15
Q
In the dehydrogenation step of the PPP, ______ is converted to ______?
A
Glucose 6-Phosphate is converted to 6-Phosphogluconodelta-lactone
16
Q
What enzyme is used in the dehydrogenation step of the PPP?
A
Glucose 6-phosphate dehydrogenase
17
Q
What is produced in the dehydrogenation step of the PPP?
A
NADPH
18
Q
What is the rate limiting step of the PPP?
A
Dehydrogenation (1st step)
19
Q
What is the rate limiting enzyme of the PPP?
A
Glucose 6-Phosphate Dehydrogenase
20
Q
What is the second step of the PPP called?
A
Hydrolysis
21
Q
________ is converted to ________ during hydrolysis?
A
6-phosphoglucono delta-lactone is converted to 6-phosphogluconate
22
Q
What enzyme is used during the hydrolysis step of PPP?
A
Lactonase
23
Q
Lactonase uses what to break a bond?
A
Water
24
Q
The third step of the PPP is called ________?
A
Oxidative Decarboxylation
25
__________ is converted to __________ during the oxidative decarboxylation step of PPP?
6-phosphogluconate is converted to ribulose 5-phosphate
26
What enzyme is used to turn 6-phosphogluconate into ribulose 5-phosphate?
6-phosphogluconate dehydrogenase
27
What are the products of the oxidative decarboxylation step of PPP?
NADPH and CO2
28
What is the name of the step that converts ribulose 5-phosphate to ribose 5-phosphate?
Isomerization
29
What enzyme is used when converting ribulose 5-phosphate into ribose 5-phosphate?
Isomerase
30
What is the step called when ribulose 5-phosphate is converted to xyulose 5-Phosphate?
Epimerization
31
What enzyme is used during epimerization?
Epimerase
32
During the isomerization step of the PPP, ________ is converted into _______?
Ribulose 5-phosphate is converted into ribose 5-phosphate
33
During the epimerization step of the PPP _______ is converted into _______?
Ribulose 5-phosphate is converted into xyulose 5-phosphate
34
Is the isomerization step of PPP oxidative?
No. It’s non-oxidative
35
Is the epimerization step of PPP reversible?
Yes. It’s non oxidative.
36
Is the oxidative decarboxylation step of PPP oxidative or non-oxidative?
Oxidative
37
The hydrolysis step of PPP is reversible or irreversible?
Irreversible. It’s oxidative.
38
Is the dehydrogenation step of PPP reversible?
No. It’s oxidative.
39
Is the oxidative decarboxylation step of PPP reversible?
No. It’s oxidative
40
The Transketolase 1 step uses what enzyme?
Transketolase
41
Transketolase removes how many carbons from xyulose 5-phosphate?
2 carbons
42
Xyulose 5-phosphate contains how many carbons?
5
43
When Transketolase removes 2 carbons from xyulose 5-phosphate, it becomes a 3 carbon structure called__________.
Glyceraldehyde 3-phosphate (G3P)
44
How many carbons does ribose 5-phosphate have?
5
45
When Transketolase adds 2 carbons to ribose 5-phosphate, it becomes what ______?
A 7 carbon molecule named sedoheptulose 7-phosphate
46
Explain what occurs in the Transketolase1 step of the PPP?
An enzyme called Transketolase takes 2 carbons from xyulose 5-phosphate (5C) making it a 3 carbon structure called glyceraldehyde 3-phosphate aka G3P. It then adds those 2 carbons to ribose 5-phosphate (5C) making it become a 7 carbon structure called sedoheptulose 7-phosphate.
47
Is the Transketolase 1 step of PPP reversible or irreversible?
Reversible. It’s non-oxidative
48
What enzyme is used during the transaldolase step of PPP?
Transaldolase
49
Transaldolase removes how many carbons?
3
50
Transaldolase removes carbons from what molecule?
Sedoheptulose 7-Phosphate
51
Transaldolase adds ___ carbons to _________.
3
G3P
52
When transaldolase removes 3 carbons from sedoheptulose 7-phosphate, it becomes what?
Erythrose 4-Phosphate
53
Erythrose 4-Phosphate has how many carbons?
4
54
When transaldolase adds 3 carbons to G3P, it becomes what?
Fructose 6-Phosphate
55
How many carbons does Fructose 6-Phosphate have?
6
56
Describe what transaldolase does
It takes 3 carbons from Sedoheptulose 7-Phosphate and adds them to G3P. Sedoheptulose 7-Phosphate becomes a 4 carbon structure called Erythrose 4-Phosphate. G3P becomes a 6 carbon structure called Fructose 6-Phosphate.
57
What enzyme is used in Transketolase 2?
Transketolase
58
T or F: Transketolase removes 2 carbons from xyulose 5-phosphate and adds them to ribose 5-phosphate during the Transketolase 2 step of PPP.
False. It does this in Transketolase 1. In Transketolase 2, the carbons are added to Erythrose 4-phosphate.
59
Describe what happens in the Transketolase 2 step of PPP.
Transketolase removes 2 carbons from xyulose 5-phosphate and adds them to Erythrose 4-phosphate making it fructose 6-phosphate. The xyulose 5-phosphate becomes G3P
60
How does the PPP connect to glycolysis?
PPP turns glucose 6-phosphate into ribose 5-phosphate. This can be turned into glycolysis intermediates such as fructose 6-phosphate and glyceraldehyde 3-phosphate.
61
3 ribulose 5-phosphates makes how many fructose 6-phosphates and glyceraldehyde 3-phosphates?
2 fructose 6-phosphates
1glyceraldehyde 3-phosphates
62
We make NADPH in the PPP. What can we synthesize using it?
Fat, cholesterol, steroid hormones, bile salts
63
Why do we use NADPH to synthesize things?
Because synthesis requires the addition of electrons. NADPH is the electron donor.
64
How do we use NADPH for detoxification?
We make toxins more water soluble by adding hydroxyl groups (OH) so we can excrete them in urine. This requires adding an electron from NADPH to oxygen to get H2O.
65
Where is NADPH used for detoxification?
The liver.
66
What enzyme is used to add electrons and oxygen to toxins to make them more water soluble for excretion?
Cytochrome P450
67
What is a respiratory burst?
The creation of “harsh chemistry” to kill pathogens
68
How do we make harsh chemistry?
We make it harsh by adding electrons from NADPH
69
Electrons + _______ =very reactive molecules
Oxygen
70
What are some examples or harsh chemistry formed in the body using NADPH?
Hydrogen peroxide
Myeloperoxidase
71
How is hydrogen peroxide used in the body?
It is used to create reactive oxygen species to destroy bacteria, viruses, and other pathogens
72
How is myeloperoxidase used in the body?
It’s an enzyme used to make hypochlorous acid (bleach) from hydrogen peroxide
73
Besides reactive oxygen species, what is the other reactice compound we talked about?
Reactive nitrogen species
74
What are free radicals?
Unpaired electrons
75
What makes free radicals extremely reactive?
They’re unpaired so they’re always trying to steal electrons
76
What are 3 common ROS?
Superoxide (free radical)
Hydrogen peroxide
Hydroxyl Radical
77
What is a superoxide radical?
A molecular oxygen with an extra electron. O2-
78
What are the 3 ways we get superoxide radicals?
1. Mitochondrial processes such as ETC
2. Cytochrome P450 reductive enzyme in the ER
3. White blood cells undergoing respiratory bursts
79
What is quenching?
Inactivation of reactive free radicals
80
What usually quenches a reactive free radical?
An antioxidant
81
How do we reduced free radicals?
By oxidizing antioxidants
82
What enzyme quenches superoxide?
Superoxide dismutase
83
What enzymes quench hydrogen peroxide?
Catalase
Glutathione peroxidase
84
What is superoxide dismitase and where is it found?
An enzyme that removes superoxide (quenches it) and produces hydrogen peroxide. It’s found everywhere.
85
What is catalase and where do we find it?
It removes hydrogen peroxide (quenches it) and is found mostly in peroxisomes but there is a small amount in cytoplasm, mitochondria, and microsomes.
86
What is glutathione peroxidase and where is it found?
An enzyme that gets rid of hydrogen peroxide (quenches it) and it is found in the Cytosol and mitochondria
87
How does glutathione peroxidase quench hydrogen peroxide?
It uses 2 glutathione molecules to turn hydrogen peroxide into water
88
Glutathione peroxidase is a tripepride made of what 3 molecules?
Glutamate
Cystein
Glycine
89
When glutathione peroxidase reduces hydrogen peroxide to make water, what does it lose?
An electron. Duh. It’s reducing it.
90
When glutathione peroxidase gets oxidized to make water from hydrogen peroxide, what happens to the molecular structure of the glutathione peroxidase?
A sulfur bridge forms between the 2 glutathione molecules
91
We know antioxidants quench reactive species but how do antioxidants get regenerated?
We add electrons back. They’re oxidized when quenching. Reduced when we need them.
92
What provides the electrons needed to regenerate antioxidant?
NADPH. Which comes from where? The PPP.
93
T or F: Alcohol is a CNS depressant
True
94
In what ways is alcohol a CNS depressant?
Extreme intoxication leads to sedation, depressed tendon flexes, low bp, low body temp, and decreased respiration.
95
What are some long term health risks of alcohol?
High blood pressure, heart disease, cancer, weakening of immune system, learning/memory problems
96
What is alcoholic acidosis?
Lactic acidosis
97
When is alcoholic ketoacidosis the most common?
After heavy drinking or in those with an alcohol use disorder
98
What is the molecular structure of alcohol?
Ethyl alcohol/ethanol
99
Alcohol is ___kcal/gram
7
100
T or F: Alcohol is less calories than carbs and proteins?
False
101
T or F: Alcohol is less calories than fat
True
102
T or F: Alcohol is easily absorbed through the entire GI tract?
True
103
T or F: alcohol is a volatile inorganic compound
False. It’s a volatile ORGANIC compound
104
What are the 3 enzymes systems for Ethanol Oxidation?
Alcohol dehydrogenase
Microsomal ethanol oxidizing system (MEOS) / Cytochrome P450
Catalase
105
Catalase oxidizes ethanol when _________ is present. Hint: what does catalase quench?
Hydrogen peroxide
106
Which of the 3 enzyme systems for ethanol oxidation is the least active system?
Catalase
107
How does alcohol dehydrogenase oxidize ethanol?
It reduces NAD + to turn the ethanol into acetaldehyde. Also giving us NADH.
108
When alcohol dehydrogenase (ADH) oxidizes ethanol, we get Acetaldehyde. What do we do with the acetaldehyde?
Aldehyde dehydrogenase (ALDH) oxidizes it by reducing NAD+ giving us Acetate and NADH
109
How does catalase oxidize ethanol?
It pairs the oxidation of ethanol with the reduction of hydrogen peroxide to make water. This makes sense bc catalase quenches hydrogen peroxide.
110
When catalase reduces hydrogen peroxide to make water, ethanol becomes _________.
Acetaldehyde. Then ALDH will convert that to acetate.
111
MEOS/ Cytochrome P450 is associated with what organelle?
Endoplasmic reticulum
112
When do we use the MEOS system to oxidize ethanol?
When ADH is completely saturated the MEOS catches the spill over
113
How does MEOS oxidize ethanol?
It does not use NAD+ like ADH did. It’s taking ethanol and making it into Acetaldehyde. The acetaldehyde is then broken down to acetate by ALDH (which produces an NADH).
114
Are MEOS enzymes inducible?
Yes. High concentrations of ethanol induced synthesis of MEOS enzymes which allows for more effective metabolism of ethanol in hepatocytes.
115
We know we produce NADH and acetate when oxidizing ethanol. Where does that NADH and Acetate go?
NADH: enters the ETC to produce ATP
Acetate: gets converted to acetyl CoA to enter the TCA/Krebs cycle
116
When we oxidize ethanol, what pathways are inhibited?
Krebs/TCA
Fat burning (Beta Oxidation)
TCA prep step
Gluconeogenesis
117
When we oxidize ethanol, what pathways are stimulated?
Fatty Acid and TAG synthesis
Lactate production
Ketone production
118
Ethanol oxidation reduces gluconeogenesis and fat burning. What does this cause?
Hypoglycemia (low bp)
119
How is the TCA cycle inhibited by ethanol oxidation?
NADH inhibits the TCA bc 3 steps of TCA (3, 4, 8) produce NADH using NAD+.
120
How is the TCA prep step inhibited by ethanol oxidation?
It’s inhibited by high concentrations of NADH. Ethanol oxidation uses up the NAD+ which prevents pyruvate dehydrogenase from making NADH from NAD+.
121
What are the coenzymes needed for TCA prep step (Pyruvate Dehydrogenase Complex)
Thiamine pyrophosphate
Lipoamide
Coenzyme A
FAD
NAD+
122
Why is there a fat accumulation when ethanol gets oxidized?
There is increased lipid synthesis and decreases lipid removal
123
How does ethanol oxidation stimulate lactate production?
We have a lot of pyruvate due to increased energy state and NADH which is inhibiting the TCA. This shifts the reaction of pyruvate to make more lactate.
124
Ethanol oxidation stimulates lactate production. What happens when we have high lactate production?
Lactic acidosis
125
How does ethanol oxidation stimulate malate production?
When malate dehydrogenase converts oxaloactetatw to malate, it produces more NAD+ to use for ethanol oxidation
126
Low oxaloacetate leads to more or less ketone production?
More
127
Why does low oxaloacetate lead to more ketone production?
Because we’re using acetyl CoA for ketone production instead of making citrate for the TCA cycle bc TCA is inhibited.
128
How does ethanol oxidation increase ketone synthesis?
3-hydroxybutyrate dehydrogenase converts 3 hydroxybutyrate to acetoacetate. This conversion produces NAD+ to use for ethanol oxidation.
*it also uses excess acetyl CoA because TCA is inhibited
129
What must an amino acid lose to become an alpha-ketoacid?
An amino group (NH3)
130
Why would we want amino acids to become alpha-ketoacids?
Ketoacids can be used for other metabolic pathways (TCA, fatty acid synthesis, etc)
131
What 4 things determine the destination of a ketoacid?
Energy charge (ATP)
Hormones (glucagon/insulin)
Glucose concentration
Tissue (muscle vs liver)
132
Alanine=amino acid. What alpha-ketoacid does it become?
Pyruvate
133
What amino acid forms alpha-ketoglutarate?
Glutamate
134
What amino acid forms oxaloacetate?
Aspartate
135
What ways do we metabolically use amino acids?
Protein synthesis
Oxidation to make ATP
Glucose production
Fat production
136
What are amino acids initially used for?
Protein synthesis. However if we have an excess, we use them for fat synthesis
137
What do we do with amino acids when we have low energy?
We oxidize them to make ATP
138
When there is low glucose in the body, what do we do with amino acids?
Turn them into glucose and send them to the liver for gluconeogenesis
139
When we have a high energy charge and lots of glucose, what do we with the left over amino acids?
We turn them into fat
140
What are the BCAAs?
LIV
Leucine, isoleucine, valine
141
What amino acids are glucogenic and ketogenic?
PITTT
Phenylalanine, isoleucine, tryptophan, threonine, tyrosine
142
What amino acids are ketogenic only?
Leucine and lysine
143
Each amino acid has its own _________to enter the aerobic system
Pathway
144
What does amino acid oxidation mean?
It means we’re using them in the aerobic system (TCA cycle and ETC) to produce ATP
145
When do we oxidize amino acids?
When the cell has low energy
146
T or F: The liver can oxidize most of the 20 different amino acids?
True
147
T or F: Muscle can oxidize most of the 20 different amino acids?
False
148
What amino acids can muscle oxidize?
LIVGAA
Leucine, isoleucine, valine, glutamate, aspartate, asparagine
149
Alanine has how many amine groups?
1
150
Glutamine has how many amine groups?
2
151
Asparagine has how many amine groups?
2
152
Glutamate has how many amine groups?
1
153
Aspartate has how many amine groups?
1
154
Is the conversion of alanine to pyruvate direct? (Meaning does alanine have to be converted to something else before it becomes pyruvate?)
Yes it is direct
155
Is glutamine to alpha ketoglutarate a direct conversion?
No.
Glutamine > glutamate > alpha ketoglutarate
156
Is asparagine to oxaloacetate a direct conversion?
No.
Asparagine > Aspartate > oxaloacetate
157
Where do we turn amino acids into glucose?
The liver via gluconeogenesis
158
When do we turn amino acids into glucose?
When blood glucose is low.
Starvation, low carb intake, exercise
159
What amino acids do we use when we need glucose?
Amino acids that are glucogenic so any except lysine and leucine.
160
During exercise, muscle releases _________.
Alanine
161
What do we do with the alanine released from muscle during exercise?
Take it to liver to make glucose
162
When the liver makes glucose from alanine released from the muscle during exercise, what is the main product?
Urea waste
163
What happens to glutamate concentrations in the blood during exercise?
They decrease bc it’s taken into muscle and gives up an NH3
164
What happens to alanine concentrations in the blood during exercise?
They increase bc alanine is released from muscle and is traveling (in the blood) to liver for gluconeogenesis.
165
Muscles can donate nitrogen to other tissues for what?
Building amino acids
Building nitrogenous bases and nucleotides
- which is needed for building new cells
166
What must muscles produce to export nitrogen out of the muscle?
Glutamine
167
What other systems rely on glutamine?
Immune system
Digestive system
168
What role does glutamine have in the immune system?
It is an immunonutrient. It supplies nitrogen to the immune system for important processes.
169
What does glutamine do for the digestive tract?
It prevents leaky gut by preserving the gut barrier function and tight junction integrity
170
What is step 1 of the glutamine-glutamate cycle?
Muscle imports glutamate from blood
171
What is step 2 of the glutamine-Glutamate cycle? What enzyme is used?
Muscle takes a nitrogen from an amino acid (LIVGAA) and adds it to glutamate to produce glutamine.
Enzyme used- glutamine synthetase
Requires ATP
172
What is step 3 of the glutamine-Glutamate cycle?
Glutamine is release from the muscle into the blood and travels to other cells that need nitrogen (digestive and immune)
173
What is step 5 of the glutamine-Glutamate cycle? What enzyme is used?
Glutamine drops off the nitrogen which means it turns back into glutamate.
Enzyme used- glutaminase
174
Process of turning Amino acid into fat
Amino acid > ___________
Alpha-ketoacid
175
Process of turning Amino acid into fat
__________> acetyl CoA
Alpha-ketoacid
176
Process of turning Amino acid into fat
Acetyl CoA> __________
Malonyl CoA
177
Process of turning Amino acid into fat
What enzyme is used to convert Acetyl CoA to malonyl CoA?
Acetyl CoA carboxylase
178
Process of turning Amino acid into fat
Malonyl CoA > _________
Fatty acid
179
Process of turning Amino acid into fat
Malonyl CoA to fatty acid uses what enzyme?
Fatty acid synthase
180
Nitrogen excretion is also called what ______
Urea cycle
181
Why must we excrete nitrogen from the body?
We can’t store it
182
If you eat too much protein meaning you have extra amino acids, what happens to them?
They get sent to the liver where they’re degraded to be excreted as urea (pee)
183
How are excess amino acids degraded?
Transamination: amino groups are transferred to alpha ketoglutarate
Deamination: amino group is removed
184
Every amino acid is degraded using transamination except 2. These 2 used deamination instead. What 2 amino acids are they?
Lysine and threonine
185
Where does the urea cycle take place?
Liver. Partially in the mitochondrial matrix and partially in the Cytosol
186
What is the purpose of the urea cycle?
To eliminate ammonia by producing urea
187
How many ATP is used to make urea from ammonia?
3
188
There are 2 ways glutamate can enter the urea cycle. What is the first one?
Glutamate dehydrogenase.
It removes the nitrogen (amino group) from glutamate.
189
There are 2 ways glutamate can enter the urea cycle. What is the second way?
Aspartate aminotransferase aka glutamate oxaloacetate transaminase
Transfers the amino group from glutamate to oxaloacetate making Aspartate.
190
What are the reactants of the rate limiting step of the urea cycle?
This is a pre step
HCO3 and NH3 and 2 ATP
Aka
Bicarbonate and an amino group
191
What are the products of the rate limiting step of the urea cycle?
This is a pre step
Carbamoyl Phosphate
2 ADP
192
What enzyme is used in the rate limiting step of the urea cycle?
This is a pre step
Carbamoyl Phosphate Synthetase-1
193
What are the reactants of step 1 of the urea cycle?
Carbamoyl phosphate + ornithine
194
What is the product of step 1 of the urea cycle?
Citrulline
195
What is the enzyme used in step 1 of the urea cycle?
Ornithine transcarbamoylase
196
What are the reactants of step 2 of the urea cycle?
Citrulline + Aspartate
And ATP
197
What is the product of step 2 of the urea cycle?
argininosuccinate
And AMP and pyrophosphate
198
What enzyme is used in step 2 of the urea cycle?
Argininosuccinate synthetase
199
What is the reactant of step 3 of the urea cycle?
Argininosuccinate - fumarate
200
What is the product of step 3 of the urea cycle?
Arginine
201
What enzyme is used for step 3 of the urea cycle
Argininosuccinate lyase
202
What are the reactants of step 4 of the urea cycle?
Arginine and water
203
What are the products of step 4 of the urea cycle?
Ornithine and urea
204
What makes up urea?
2 amino groups
-1 comes from free ammonia
- 1 comes from Aspartate
1 carboxyl group
- comes from CO2
205
How is the urea cycle regulated?
N-acetylglutaminate activates carbamoyl phosphate synthetase-1 (CPS-1)
206
Do purines have 1 ring or 2?
2
207
Do pyramidines have 1 ring or 2?
1
208
What are the purines?
Adenine and guanine
209
What are the pyrimidines?
Cytosine, thymine, uracil (RNA)
210
What are examples of nucleosides?
Adenosine, guanosine, inosine, uridine, cytidine, and thymidine
211
What are examples of nucleotides?
AMP, GDP, CTP, etc…
212
What are the 2 methods for nucleotide synthesis?
De Novo Synthesis
Salvage Pathway
213
T or F: We need ATP for nucleotide synthesis?
True
214
What do we start with when making nucleotides?
Ribose 5-phosphate
*We get this from PPP
