Term
| What percentage of amino acids are re-used to synthesize proteins during the cycle of protein synthesis and breakdown? |
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Definition
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Term
| In metabolism of ammonium in the fasted state, what product is formed, what organs are involved and what is secreted? |
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Definition
Forms: glutamine
Involves: kidneys
Secreted: ammonium |
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Term
| In metabolism of ammonium in the fed state, what product is formed, what organs are involved and what is excreted? |
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Definition
Forms: glutamine & alanine
Involves: kidneys & liver
Excretes: NH3 as urea |
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Term
| Why does a high consumption/catabolism of amino acids put upward pressure on pH? |
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Definition
-metabolism in Kreb's cycle produces bicarbonate (a weak base)
-bicarbonate reacts with H+, causing a trend towards alkalosis |
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Term
| Why don't we die form alkalosis when eating a high-protein diet? |
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Definition
-active urea cycle in fed state extracts the bicarbonate
-metabolism of sulfur-containing AA's produces some sulfuric acid to lower pH |
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Term
| What is the primary source of energy when the body is fully adapted to starvation? |
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Definition
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Term
| What is produced in the metabolism of triglycerides? When present in excess, what is the resulting physiological disease? |
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Definition
ketone bodies
ketoacidosis |
|
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Term
| Why don't we die of ketoacidosis when fasting? |
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Definition
-urea cycle is downregulated so that bicarbonate is not used up
-ammonium is produced in the kidneys & excreted in urine to clear H+ from body |
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Term
| What amino acids are of special importance in nitrogen metabolism? |
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Definition
glutamate
aspartate
alanine
glutamine |
|
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Term
| What is the role of glutamate in nitrogen metabolism? What is the alpha-ketoacid form? |
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Definition
| source of free NH3 end product of transamination reactions |
|
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Term
| What is the role of glutamine in nitrogen metabolism? |
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Definition
carries nitrogen between organs (goes to liver & kidneys)
source of free NH3 |
|
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Term
| What reactions move nitrogen from catabolized protein between organs for excretion? |
|
Definition
1. Transamination
2. Oxidative deamination
3. Glutamine/glutamate production
4. Urea cycle |
|
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Term
| What is transamination? What catalyzes this type of reaction? |
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Definition
the transfer of an amino group to an AA carbon skeleton (alpha ketoacid)
catalyzed by aminotransferases |
|
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Term
| What amino acids do not undergo transamination? (3) |
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Definition
|
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Term
| What enzymes transfer amino groups between alpha keto-acids? |
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Definition
|
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Term
| What are the two common aminotransferases? |
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Definition
GPT (glutamate pyruvate transaminase)
GOT (glutamate oxaloacetate transaminase) |
|
|
Term
True or False
Transamination is a undirectional reaction |
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Definition
|
|
Term
| What amino acid undergoes oxidative deamination? |
|
Definition
|
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Term
| What is oxidative deamination? What enzyme is involved? What is the reactant, what is the product? |
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Definition
release of NH3 from glutamate backbone using the enzyme glutamate dehydrogenase
Glutamate is converted to alpha-ketoglutarate, NH3 is released |
|
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Term
| What is free NH3 used for in each of the following: extrahepatic tisue, liver, kidneys |
|
Definition
EHT: glutamine synthesis
Liver: urea synthesis
Kidneys: becomes NH4, is excreted in urine |
|
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Term
| Where is 90% of glutamine synthesized? |
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Definition
|
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Term
| What enzyme is used in glutamine production? What are the reactants/products? |
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Definition
glutamine synthetase
Reactants: glutamate, NH3, ATP
Product: glutamine, ADP + Pi |
|
|
Term
True or False
Oxidative deamination is a unidirectional reaction |
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Definition
|
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Term
| What is glutamate production, and what enzyme is involved? |
|
Definition
| catabolism of glutamine, using glutaminase, to produce glutamate & free NH3 |
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Term
| Glutamate is active in the ______ during fed state and active in the ______ during fasting |
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Definition
Liver in fed state
Kidney during fasting |
|
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Term
|
Definition
| conversion of toxic NH3 to less toxic urea, which is transported to the kidney for excretion |
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Term
| GPT is involved with the conversion of ____ and ____ to ____ and ____ |
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Definition
| glutamate + pyruvate to alphaketoglutarate + alanine |
|
|
Term
| GOT is involved with the conversion of ____ and ____ to ____ and ____ |
|
Definition
glutamate + oxaloacetate to alphaketoglutarate + aspartate
(and vice versa!) |
|
|
Term
True or False
Arginine is produced in the urea cycle |
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Definition
|
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Term
| Defects in the enzymes involved in the urea cycle will lead to... |
|
Definition
| developmental neurotoxicity |
|
|
Term
| After amino groups have been removed, where do the resulting alphaketoacids go? |
|
Definition
| glucogenic or ketogenic pathways |
|
|
Term
| Which are the only 2 purely ketogenic AA's? |
|
Definition
|
|
Term
True or False
After Acetyl CoA has been formed, the remaining possible reactions are purely ketogenic |
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Definition
|
|
Term
| What is the function of pyruvate carboxylase? |
|
Definition
maintain TCA cycle intermediates
allow gluconeogenesis |
|
|
Term
| What cycle is involved with burning fat, and what compound is specifically required? |
|
Definition
TCA cycle
req's oxaloacetate |
|
|
Term
| How is blood glucose maintained after glycogen is delpeted? |
|
Definition
|
|
Term
| What hormone regulates blood glucose in the fed state? |
|
Definition
|
|
Term
| What hormone regulates blood glucose in the post-absorptive state? |
|
Definition
|
|
Term
| What hormone regulates blood glucose in the fasted state? |
|
Definition
| glucagon & glucocorticoids |
|
|
Term
| What hormone regulates blood glucose in a state of starvation? |
|
Definition
| glucagon & thyroid hormones |
|
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Term
| During acidosis, liver glutaminase, glutamate dehydrogenase, GOT and urea cycle enzymes are ______, and uptake of alanine and glutamine by the liver is ______ |
|
Definition
|
|
Term
| During acidosis, kidney glutaminase and glutamate dehydrogenase are _______, and uptake of glutamine and production of ammonium is _______ |
|
Definition
|
|
Term
True or False
During sustained aerobic exercise, ketone body production is not a significant concern |
|
Definition
| true, there is not enough time for these ketone bodies to be produced |
|
|
Term
| Describe the progressive mobilization of energy stores to maintain blood glucose during sustained aerobic exercise |
|
Definition
@ start: use existing ATP
5 seconds in: use creatine phophate
20 seconds in: use glycogen stores
20 minutes in: use triglycerides |
|
|
Term
| What is the role of epinephrine during sustained periods of exercise? |
|
Definition
-cardiac output
-bronchodilation
-glycogenolysis |
|
|
Term
| How can you extend your exercise capacity? |
|
Definition
Carbohydrate loading
-doubles muscle glycogen, delays failure of TCA cycle
Fasting 3h prior to start of exercise
-avoids insulin secretion
Supplementary CHO during the exercise
Caffeine
-earlier release of epinephrine, HSL will be activated sooner |
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