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Physiology
Proteins
73
Biochemistry
Graduate
10/31/2012

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Cards

Term
What is physiological pH?
Definition
7.4
Term
At physiological pH, most amino acids exist as ________.
Definition
zwitterions
Term

True or False:

Histidine is hydrophilic.

Definition
True
Term

True or False:

Lysine is hydrophobic.

Definition
False
Term

True or False:

Arginine is hydrophilic.

Definition
True
Term

True or False:

Serine is hydrophilic.

Definition
True
Term

True or False:

Threonine is hydrophobic.

Definition
False
Term
List the aromatic amino acids.
Definition
tryptophan, phenylalanine, tyrosine
Term
Valine, leucine, and isoleucine are ____________.
Definition
branched chain amino acids
Term

True or False:

Branched chain amino acids are hydrophobic.

Definition
True
Term
Which amino acid is neither hydrophilic nor hydrophobic?
Definition
glycine
Term
Only the __ forms of amino acids are found in mammalian proteins.
Definition
L
Term
What can cause denaturation of proteins?
Definition
pH, temperature, mechanic
Term
Enzymes are ______________ that enhance reaction rates without themselves being used up in the process.
Definition
substrate-specific catalysts
Term
___________ are sometimes needed to activate enzymes.
Definition
Co-enzymes
Term
_________ degrade protein.
Definition
Proteases
Term
_____________ remove phosphate residues.
Definition
Phosphatases
Term
____________ transfer amino groups between substrates.
Definition
Aminotransferases
Term

True or False:

Enzyme concentrations are used to diagnose or treat disease.

Definition
True
Term
Km is the substrate concentration at which _________________________.
Definition
the reaction rate is 1/2 its maximal value
Term
An enzyme with low affinity for its substrate has a ___ Km.
Definition
high
Term
An enzyme with high affinity for its substrate has a ___ Km.
Definition
low
Term
__________ is reached when the enzyme becomes saturated with its substrate.
Definition
Maximal velocity (Vmax)
Term
___________ inhibitors can be reversed by increasing substrate concentrations.
Definition
Reversible competitive
Term
___________ inhibitors cannot be changed by increasing substrate concentrations.
Definition
Reversible noncompetitive
Term
_________ inhibitors form a stable complex.
Definition
Irreversible
Term
________ catalyze similar reactions but are slightly different in chemical structure and kinetic properties.
Definition
Isozymes
Term
Protein is digested in the stomach by ________.
Definition
pepsin
Term
Protein is digested in the intestine by __________.
Definition
proteases
Term

True or False:

Free amino acids can be absorbed intact.

Definition
True
Term

True or False:

Small di-and tripeptides can be absorbed intact.

Definition
True
Term
Larger peptides are digested further by ____________.
Definition
brush border peptidases
Term
During absorption in the small intestine, amino acids are transported from __________ to __________.
Definition
lumen, blood
Term
___________ can be absorbed intact in the neonate for 24-36 hours.
Definition
Immunoglobulins
Term
For how long can immunoglobulins be absorbed intact in the neonate?
Definition
24-36 hours
Term
Aromatic amino acids are metabolized in the ________.
Definition
liver
Term
Branched chain amino acids are oxidized by ________ and ________ tissue.
Definition
brain, muscle
Term
The brain and muscle tissues have high levels of ____________ that oxidizes branched chain amino acids.
Definition
BCAA transaminase
Term
In healthy animals, the BCAA:AAA ratio is approximately ______.
Definition
3:1
Term
In liver disease, the BCAA:AAA ratio is approximately ______.
Definition
1.5:1
Term
In liver disease, there is decreased hepatic clearance of _______ and increased utilization of ________ in muscle.
Definition
AAA, BCAA
Term
Catabolism of BCAA in skeletal muscle for energy purposes results in transfer of amino groups to _________ or _________.
Definition
pyruvate, glutamate
Term
The transfer of amino groups to pyruvavte forms _______.
Definition
alanine
Term
The transfer of amino groups to glutamate forms ____________.
Definition
glutamine
Term
__________ is the favored gluconeogenic substrate of liver cells.
Definition
Alanine
Term

True or False:

An amino acid must still have its amino group in order to be metabolized.

Definition
False: amino acids cannot be metabolized if they still have an amino group
Term
______ that is produced during amino acid metabolism is toxic to the body and must be removed.
Definition
NH3
Term
Pyruvate undergoes transamination to __________ by __________.
Definition
alanine, alanine transaminase
Term
After transamination of pyruvate to alanine, the alanine enters the blood and is transported to the ______.
Definition
liver
Term
Within the liver, alanine is converted back into _________ which is then used for ____________.
Definition
pyruvate, gluconeogenesis
Term
Once alanine is converted back to pyruvate in the liver, what happens to the NH3 group that was removed from alanine?
Definition
it enters the urea cycle and is excreted
Term
________ is the preferred substrate for amino acid oxidation in the brain.
Definition
Valine
Term
Valine can be deaminated to ___________ in the brain.
Definition
succinyl-CoA
Term
After valine is deaminated, the NH3 group is transferred to _________ to form __________.
Definition
gultamate, glutamine
Term

True or False:

The majority of amino acids are glucogenic.

Definition
True
Term
Glucogenic amino acids form ____________ and ___________ when metabolized.
Definition
TCA intermediates, pyruvate
Term
List the ketogenic amino acids.
Definition
leucine, isoleucine, tryptophan
Term
Ketogenic amino acids form __________ when metabolized.
Definition
acetyl-CoA
Term
Positive nitrogen balance occurs when _________ exceeds __________ of protein.
Definition
synthesis, degradation
Term
Negative nitrogen balance occurs when _______ exceeds _______ of protein.
Definition
loss, synthesis
Term
Urea synthesis occurs only in the _________.
Definition
liver
Term
Urea biosynthesis involves __ steps in the mitochondria and __ steps in the cytosol.
Definition
2, 3
Term
The main reason to form urea is to reduce levels of ___________.
Definition
ammonia
Term
What does BUN stand for?
Definition
blood urea nitrogen
Term
BUN is freely filtered by the __________.
Definition
kidneys
Term
About 25% of urea goes into the digestive tract, where __________ activity is high.
Definition
urease
Term
In cases of hyperammonemia, diffusion of NH3 out of the intestine needs to be minimized. This is achieved by __________ of the intestine with ___________.
Definition
acidification, lactulose
Term
In hyperammonemia, in order to trap NH3 in the intestinal tract so it can be excreted instead of absorbed, NH3 is acidified to _____. Why does this trap it in the intestine?
Definition
NH4+, NH4+ is a charged molecule, so it cannot travel through membranes and is therefore excreted instead of reabsorbed
Term
What is the normal range for total protein?
Definition
5 to 8 g/dL
Term
_________ is the most abundant plamsa protein.
Definition
Albumin
Term
________ acts as an osmotic agent by creating oncotic pressure.
Definition
Albumin
Term

True or False:

Albumin works as a Ca++ transport agent.

Definition
True
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