QUESTIONS Flashcards
What coenzyme is required in the mechanism
of a transamination reaction?
Active Vitamin B6
Which of the following statements is
INCORRECT
a. Decarboxylation of glutamine
forms the inhibitory
neurotransmitter GABA.
b. Serotonin and melatonin are
metabolites of tryptophan.
c. The concentration of histamine in the
brain hypothalamus exhibits a
circadian rhythm.
d. Histamine arises from the
decarboxylation of histidine.
a. Decarboxylation of glutamine
forms the inhibitory
neurotransmitter GABA.
What amino acid is made from pyruvate via
transamination?
Alanine
Hydroxylation of tyrosine by the enzyme
tyrosine hydroxylase yields ___________.
Subsequent decarboxylation of the said
product yields _____________.
5-hydroxytryptophan; serotonin
Which of the following reactions is highly
active in the liver when large amounts of
amino acids are moving from extrahepatic
tissue to the liver?
oxidation of glutamate by
glutamate dehydrogenase
The following enzymes in the urea cycle are
found in the cytosol, EXCEPT:
a) Argininosuccinate lyase
b) None of the above
c) Arginase
d) Ornithine transcarbamoylase
Ornithine transcarbamoylase
SITUATION: There are low amounts of
glucose in the body.
Under such conditions, muscle tissue would
be broken down providing a large amount of
ALANINE to the liver. Once the above amino
acid entered the liver, it would undergo
transamination to _____ which would then
undergo ______ to ______ to
enter ________.
pyruvate
carboxylation
oxaloacetate
gluconeogenesis
The replication of DNA is made possible by
the presence of _____ strands in the double
helix of DNA.
complementary
In DNA, the ribose derivative lacks an _____
on C-_____.
alcohol; 2
Nucleotides play a central role in living
organisms because ______.
they function as building blocks for
nucleic acids
What is the name of the molecule that is
composed of guanine linked to the C-1ꞌ of
ribose with three phosphate group at C5’?
: guanosine triphosphate
The pyrimidine found in both DNA and RNA is
_____.
Cytosine
What is the name of the molecule that is
composed of adenine linked to the C-1ꞌ of
ribose with one phosphate group at C5’?
adenosine monophosphate
Genomic DNA is _____, resulting in the
production of _____.
transcribed; mRNA
What is the name of the molecule that is
composed of adenine linked to the C-1ꞌ of
ribose?
adenosine
The triplet code allows many amino acids to
be specified by more than one codon. Such a
code is said to be _____.
degenerate
The amino acid would be attached to this
structure at
5
Which of the following represents a DNA
mutation in the template strand that would
convert serine to cysteine?
5’-GCT-3’ to 5’-GCA-3’
The codon is found _____ while the anticodon
is found _____.
in the mRNA; on the tRNA
. The term rRNA refers to ______ RNA.
ribosomal
Codons that do not specify amino acids but
signal the ribosome to terminate polypeptide
chain elongation are called
stop codons
There is/are ___ start codon(s) and ___ stop
codon(s).
b. 1;3
Which of the following best describes a new
strand of DNA relative to the template strand
used to synthesize it?
a negative copy of the template
Which lipoprotein carries triacylglycerols
synthesized by the liver during the fasting
state?
VLDL
Which enzyme is activated during the fasting
state to catalyze the release of free fatty acids
from adipose tissue triglycerides?
Hormone-sensitive lipase
What is the priority for substrate exchange
among tissues during fasting?
Maintaining plasma levels of
glucose
What is the primary fate of amino acids
released during protein degradation in
muscles during fasting?
Converted to glucose through
gluconeogenesis
What does the pancreas secrete in response
to elevated glucose and amino acid levels
during the absorptive state?
Epinephrine
From late fasting into starvation, what key
roles do the kidneys play?
Proton excretion as NH4+
Which of the following hormones stimulates
glucagon secretion?
Low blood glucose
What is the significance of C-peptide in
insulin synthesis?
It serves as a marker of
endogenous insulin production
What is a characteristic symptom of
hypoglycemia in the central nervous system?
. Confusion and coma
allows processive unwinding of
DNA
Helicase
initiates synthesis of
RNA primers
Primase
initiates
daughter strand synthesis
DNA polymerase
bind to ssDNA to
prevent premature
reannealing of ssDNA to
dsDNA
SSBs
Prevent extreme
supercoiling of the
parental helix
Topoisomerases
Carboxypeptidase _____ is an enzyme that cleaves
aromatic amino acids at the C terminal end of peptides.
On the other had Carboxypeptidase ______ cleaves
basic amino acids at the same end of the chain. Both
enzymes are called ______________.
A; B; Exopeptidase
One of the primary routes of ammonia uptake in
mammals is
Amination of glutamate to form glutamine
Which of the following reactions is highly active in the
liver when large amounts of amino acids are moving
from extrahepatic tissue to the liver?
oxidation of glutamate by glutamate
dehydrogenase
What is the primary role of pyridoxal phosphate (PLP)
in transamination reactions?
It acts as a carrier of amino groups.
The following are purely glucogenic amino acids,
EXCEPT:
a) Alanine
b) Proline
c) Glycine
d) Phenylalanine
d) Phenylalanine
Match the following with their correct specialized
conversion product:
a) Tryptophan =
b) Tyrosine =
c) Histidine =
d) Glutamine =
Tryptophan = Serotonin
b) Tyrosine = Epinephrine
c) Histidine = Histamine
d) Glutamine = None of the choices
The DNA strand that serves as the template for the
synthesis of RNA is often called the _____.
noncoding strand
RNA occurs primarily as single-stranded molecules
that can give rise to _______ structures.
stem-loop
Nucleotides contain one or more phosphate groups
that are usually attached to the ______.
C-5ꞌ atoms
What type of bond is made between nucleotides?
Phosphodiester
In most organisms, replication proceeds in a _____
manner from the _____.
bidirectional; replication origin
Which strand of DNA is replicated exclusively in a
discontinuous fashion?
lagging strand
Transfer RNA molecules are involved in ______.
translation
The correct amino acid is covalently attached to a
tRNA by the corresponding ______ which is specific
for each ______.
aminoacyl-tRNA synthetase (aaRS); amino
acid
Which lipoprotein carries triacylglycerols synthesized
by the intestinal mucosal cells during the absorptive
state?
Chylomicron
What is the primary focus of regulatory mechanisms
during the absorptive state?
Storage of nutrients as glycogen,
triacylglycerol, and protein
What does the pancreas secrete in response to
elevated glucose and amino acid levels during the
absorptive state?
Insulin
What is the sequential order of the cleavage events
that convert preproinsulin into insulin?
Cleavage at preproinsulin, then at
proinsulin
Which cellular organelle is primarily responsible for the
synthesis of insulin in pancreatic β-cells?
Rough endoplasmic reticulum
In the context of insulin action, what is the primary
function of insulinase?
Degradation of insulin
What is the primary stimulus for increased insulin
secretion?
Glucose
How does insulin affect glucose uptake?
Stimulates glucose uptake by muscle and
adipose tissue
Which hormone opposes the actions of insulin during
“survival crises” situations?
Epinephrine
During prolonged fasting, which hormone opposes the
actions of insulin and promotes lipolysis and
ketogenesis?
Growth hormone
If you add phosphate group to your nucleoside, it’ll become ___?
Nucleotide
