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Biochem Midterm Exam 2024 Bio Chem Exam Latest 2024 Questions and Correct Answers Rated A+
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Biochem Midterm Exam 2024 Bio Chem Exam Latest 2024 Questions and Correct Answers Rated A+
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Biochem Midterm Exam 2024 Bio ChemExam Latest 2024 Questions and Correct
Answers Rated A+
Which of the following intermediates is an allosteric activator of
pyruvate kinase? -ANSWER-fructose-1,6-bisphosphate
An individual is deficient in Vitamin B 12. In this individual, which of
the following reactions would be compromised? -ANSWER-
Conversion of methylmalonyl co A to succinyl coA
Phenylkentonuria can be caused by a deficiency in the enyzyme
phenylalanine hydroxylase or it can present due to a deficiency in
which of the following required metabolic cofactors? -ANSWER-
tetrahydrobiopterin
An individual is autosomal recessive for a branched chain keto acid
dehydrogenase deficiency. This deficiency may result in the elevation
of all of the following the following amino acids except: -ANSWER-
homocysteine
Maple syrup urine disease (branched chain amino acids; tie in with
pyruvate dehydrogenase complex and alpha-ketoglutarate
dehydrogenase complex, and the requirement for thiamine, lipoic acid,
niacin, riboflavin and pantothenate).
An allosteric activator will increase enzyme activity through which of
the following mechanisms? -ANSWER-Binding the enzyme, and
keeping it in the "R" conformation
,The reduction of NAD+ is often coupled to the oxidation of an alcohol.
In this reaction, NAD+ obtains which of the following from the oxidized
compound? -ANSWER-two electrons as a hydride ion
One of the differences in pro vs. eukaryotic protein translation is in the
process of initiation. In eukaryotes, translational initiation starts with
the small ribosomal subunit associating with the 5' cap on the mRNA.
In prokaryotes, translational initiation starts with the ribsomal
recognition of which of the following sequences? -ANSWER-The
Shine-Dalgarno sequence
The folate cycle is directly involved in which of the following amino
acid metabolic pathways? -ANSWER-Remethylation of homocysteine
to methionine
The steroid hormone receptor regulates expression of genes at the
level of: -ANSWER-transcription
Ca2+ influx thru a channel that is activated by a change in the
membrane potential across the plasma membrane is an example of
a(n): -ANSWER-Voltage-gated channel
In eukaryotes, pre-mRNA must undergo a series of modifications
leading to a mature mRNA. These include all of the following
processes except: -ANSWER-The addition of a 3' CCA
Order the following statements to illustrate the correct cascade of
events that occurs after ligand binding of G-protein coupled receptor
(heptahelical receptor)
1. Degradation of cAMP by phosphodiesterase
2. Dissociation of Gbeta and Ggamma subunits
3. Exchange of GDP for GTP in the G-alpha subunit
,4. Activation of adenyly cyclase to generate cAMP -ANSWER-3, 2, 4,
1
All of the following stimulate the release of insulin except -ANSWER-
epinephrine
Under conditions when glucose is high, hexokinase will be more active
then glucokinase kinase. This is due to which of the following
rationales? -ANSWER-Glucokinase has a higher Km than hexokinase
Platelet-derived growth factor is secreted from platelets aggregated at
the site of an injury. This growth factor stimulates nearby smooth
muscle cells to proliferate. This type of signaling is best described as
which of the following? -ANSWER-paracrine
The major regulatory step of the pentose phosphate pathway is
catalyzed by which enzyme? -ANSWER-Glucose 6-phosphate
dehydrogenase
The regulation of PRPP synthetase is critical in the production of both
purines and pyrimidines. This enzyme is inhibited under which of the
following conditions? -ANSWER-When both GTP and ATP are
elevated
Which of the following allosterically activates mammalian isocitrate
dehydrogenase? -ANSWER-Ca2+ / AMP / ADP
Regulation of the Lac operon is critical to bacteria. If glucose is
absent, which of the following statements is true with regards to the
lac operon? -ANSWER-RNA polymerase is bound to the promoter and
the operon is transcribed
, Complex II (Succinate dehydrogenase) is not considered to be part of
the process of oxidative phosphorylation because it is unable to do
which of the following activities? -ANSWER-Pump protons from the
mitochondrial matrix to the intermembrane space
Under low energy conditions, AMP will bind to phosphofructokinase I
and glycogen phosphorylase. This is an example of which of the follow
types of enzyme regulation? -ANSWER-allosteric activation
SMAD proteins are downstream targets of serine threonine receptors.
Phosphorylation of the SMAD proteins by the receptor is required for
translocation to the nucleus. This type of covalent modification is
referred to as -ANSWER-alpha ketogluterate to succinyl CoA
Which of the following would occur in the liver under levels of high
glucose (think insulin is elevated)? -ANSWER-Generation of glucose
1-phosphate to be used for glycogen synthesis
Glucagon binds a G-Protein coupled receptor. Which of the following
second messengers is generated by this cascade of events ? -
ANSWER-cAMP
A deficiency in the enzyme fructokinase will lead to all of the following
clinical presentations except -ANSWER-hypoglycemia
Starting at the level of the receptor, order the list of activities (given
below) to illustrate the sequence of events that occurs following ligand
binding of a tyrosine kinase receptor.
1. Activation of Ras-GTP
2. Recruitment of SOS (GEF)
3. Autophosphorylation of the intracellular domain of the receptor
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