PA-CAT BIOCHEM I
(PHYSICIAN ASSISTANT
EXAM PRE-HEALTH
BIOCHEMISTRY SUMMATIVE
EXAM 1) QUESTIONS WITH
100% SOLVED ANSWERS!!
PA-CAT
Evatee 9/12/24 PA-CAT
,PA-CAT BIOCHEM I (PHYSICIAN ASSISTANT
EXAM PRE-HEALTH BIOCHEMISTRY
SUMMATIVE EXAM 1) QUESTIONS WITH
100% SOLVED ANSWERS!!
A ligand binds to an external domain, causes a conformational change to a
protein, and enables calcium to pass through. Which type of receptor facilitates
this process? Answer - Ionotropic receptors (ligand-gated ion channels) are
transmembrane ion channel proteins. Binding of a ligand causes a
conformational change that opens a channel and allows ions to pass through.
Enzyme-linked receptors are transmembrane receptors that receive messages
from chemical messengers and then function as enzymes.
G-protein-coupled receptors are transmembrane receptors that bind a ligand
extracellularly. A conformational change then allows effector molecules to bind
G-proteins intracellularly and elicit various responses.
Intranuclear receptors are located inside the nucleus and have lipophilic
messenger molecules.
The Michaelis-Menten equation for enzyme kinetics determines the velocity of
an enzymatic reaction. What must be assumed in the reaction for this equation
to be accurate? Answer - For the Michaelis-Menten equation to be accurate,
there must be only one product of the reaction. There needs to be one
substrate. There cannot be an intermediate. There cannot be a cofactor in the
reaction for the equation to be accurate.
The pH of biochemical systems is regulated by buffers. In the
bicarbonate/carbonic acid system, what molecule represents the weak base?
Answer - Bicarbonate acts as the weak base in the biochemical system. It
interacts with the hydronium ion to make carbonic acid, which is in equilibrium
, with carbon dioxide, both of which are considered weak acids in a biochemical
system.
A patient presents with a disease caused by the destruction of beta-cells of the
pancreas and hyperglycemia. What outcome is likely to result as a direct
consequence of the beta-cell impairment? Answer - A patient with type I
diabetes typically has absent or very low levels of insulin secretion due to the
destruction of pancreatic beta-cells.
The level of glucagon secretion may increase due to loss of insulin-mediated
suppression, but glucagon is secreted by pancreatic alpha-cells.
What process involves carcinogenesis and new blood vessel growth from
existing blood vessels, inherent to protooncogenes? Answer - Angiogenesis is
the formation of new blood vessels from old blood vessels. Intravasation is the
process where cancer cells squeeze into blood vessels. Metastasis is when
cancer cells spread from the original site to another secondary site.
Proliferation is a rapid reproduction of a cell.
Allosteric moderators influence the oxygen affinity of hemoglobin. A decrease
of which regulator results in a shift towards T-state (tense state) and oxygen
release? Answer - pH
Bisphosphoglycerate, carbon dioxide, and pH are allosteric modulators of
hemoglobin.
As pH decreases, proton concentration is increased. This increase shifts more
hemoglobin into the T-state, which increases oxygen release.
The same phenomenon is observed when carbon dioxide levels increase.
Binding of bisphosphoglycerate stabilizes the T-state, and oxygen affinity is
decreased.
Temperature also affects the oxygen affinity of hemoglobin. A decrease in
temperature increases the oxygen affinity of hemoglobin.
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