POM summative prep QS Flashcards
How is the rate of glycolysis controlled?
A) Phosphoglucose isomerase is an allosteric enzyme
B) Glucose-6-phosphate inhibits hexokinase
C) Pyruvate saturation within the cytoplasm
D) Phosphofructokinase activityis controlled by ATP, ATP is an inhibitor
Answer: D
A:Phosphoglucose isomerase is not an
allosteric enzyme, however
phosphofructokinase is
B: This is partly true; however not the best
answer since glucose-6-phosphate
concentrations are reliant on
phosphofructokinase activity
C: Pyruvate saturation does not inhibit
glycolysis (anaerobic respiration, conversion
to lactate or enter into mitochondria)
D: Phosphofructokinase is an allosteric
enzyme, therefore ATP concentrations that are
elevated express an inhibitory effect on the
enzyme → Reduction in activity.
Which enzyme can be used as a diagnostic tool for a myocardial infarction?
A) Hexokinase-IV
B) Pyruvate dehydrogenase
C) Lactate dehydrogenase
D) Creatine phosphatase
Explain Why?
Answer: C
Lactate dehydrogenase is present predominantly in heart, liver, kidneys, skeletal muscles, blood and lungs. Cell necrosis → LDH released into circulation, influencing LDH serum levels.
What are the 7 molecules that arise from degradation of all 20 AAs?
Pyruvate, Acetyl CoA, Acetoacetyl CoA, Oxaloacetate, alpha-ketoglutarate, Succinyl CoA, fumarate
What is incorrect regarding the glycerol-phosphate shuttle?
A) Dihydroxyacetone phosphate→ Glycerol-3-phosphate
B) Reduced FAD transfers electrons to coenzyme Q
C) Inner mitochondrial membrane is impermeable to NADH & NAD+
D) Mitochondrial glycerol dehydrogenase uses FAD
Answer: B
A: Dihydroxyacetone phosphate (DHAP) is
reduced to form glycerol-3-phosphate by
reduced cytosolic NADH
B: Reduced FAD directly transfers electron to
complex II within the ETC → Coenzyme Q
C: True
D: Mithoncrial glycerol dehydrogenase is a
transmembrane protein that used FAD as an
electron carrier; to shuttle electrons into the
electron transport chain.
What type of inhibitor does orlistat behave?
Potent inhibitor of gastric and pancreatic lipases, behaving as competitive inhibitor
Why can’t acetyl CoA be used as a substrate for gluconeogenesis?
This is because it cannot be recovered back into pyruvate effectively
Why is hexokinase IV effective?
Hexokinase IV found in the liver is less sensitive to blood glucose concentrations, therefore less susceptible to the inhibitory effect of glucose-6-phosphate
Which substrate is most suitable for
the brain during prolonged fasting?
A) Glucose
B) Ketone bodies
C) Fatty acids
D) Amino acids
Answer: A
Which does not increase erythropoiesis?
A) Chronic bronchitis
B) Increased serum iron inhereditary haemochromatosis
C) Renal cell carcinoma
D) Polycystic ovarian syndrome
Answer: B
A: Chronic bronchitis is associated with
anoxia due to reduced oxygenation of the
blood, this results in hypoxic conditions →
Increased hypoxia inducible factor
B: Hereditary haemochromatosis causes a
reduction in hepcidin therefore increased iron
enterocyte absorption through ferroportin into
circulation → This causes increased iron
levels; ion overload and damage kidneys
reducing epo synthesis
C: Increases epo synthesis and secretion
influencing the rate of erythropoiesis
D: Increased testosterone stimulates the
release of erythropoietin, PCOS is associated
with elevated testosterone levels.
How are excess iron levels regulated?
Increased ferritin iron sequestration
Increased iron levels suppress ferroportin integration into enterocyte basolateral membrane, therefore increasing sequestration of iron as storage as ferritin → shed across
epithelium into lumen
Why does inflammation cause anaemia?
Inflammation causes hepcidin production this led to a decreased ferroportin expression in enterocytes and thus decreases iron entry into plasma.
Which molecules’ internal shape is
independent of the external
environment?
A) Glucose
B) NaCl
C) Insulin ligand receptor
D) Phosphoglucose isomerase
Answer:A
Glucose consists of covalent bonding,
therefore its configuration does not dissociate
into ions.
B: Sodium chloride is an ionic compound
dissociating into ions when in solution
C: Insulin receptor ligand gated hence changes
domain of tyrosine kinases and undergoes
conformational change
D: Enzyme undergoes conformational change
upon substrate binding at active site; also can
be denatured depending on temperature & pH
of external environments
Receptors and enzymes are proteins →
Denatured
Which is the correct function of
FOXP3?
A) Exclusively found in Treg
cells
B) Promotes cellular division
C) Exerts local suppressor
effects during immune
response
D) Synthesized only in the
thymus
E) Found in Th3, Tr1, Treg cells
Answer: E
Which is not a cause of pernicious
anaemia?
A) Achlorhydria
B) Veganism
C) Autoimmune disorder on
gastric chief cells
D) Atrophic gastritis
Answer: C
Pernicious anaemia concerns a B12
deficiency
A: Achlorhydria refers to insufficient
secretion of hydrochloric acid from parietal
cells → Inability to liberate B12, to bind onto
intrinsic factor.
B:Vegan leads to an inadequate intake of
sources containing the compound
C: Gastric cells do not secrete intrinsic factor
of HCl, parietal cells do
D: Atrophy of parietal cells causes a reduction
in intrinsic factor secretion, reduced B12-IF
complex formation reduces serum
transportation to enterocyte.
How are erythrocytes recycled?
Splenic reticuloendothelial macrophages hydrolyse erythrocytes within the spleen
Which one provides a more reliable count: polychromasia or reticulocyte count?
Reticulocyte count is less subjective and more reliable
What is used to stain reticulocyte and why are they a suitable choice?
Methylene blue
Reticulocytes in general young cells have a higher RNA content so hence it binds to methylene blue causing a blue tinge on the cytoplasm
Target cells, elliptocytes and spherocytes are examples of what?
A) Anisocytosis
B) Poikilocytosis
C) Spherocytosis
D) Microcytosis
Answer: B
Poikilocytosis: Erythrocytes illustrate more variation in shape than is normal. Poikilocytes can exist as spherocytes, irregularly contracted cells, sickle cells, target
cells, elliptocytes, and as fragments.
Why do white cells stain blue?
A) Application of H&E stain
B) Application of Giemsa stain
C) Application of Ziehl-Neelson
stain
D) Application of Leischman’s
stain
Answer: D
A: Used to stain basophilic structures with
purplish blue colour
B: Giemsa stains binds to chromosomes and is
responsible for lighter and darker regions
C: Binds to acid fast bacteria (TB)
D: Red cells look red, white cells look blue
What are the four main fluid compartments are there in your body? (In order from highest to lowest and include the percentages).
Intracellular fluid (55%)
Interstitial fluid (36%)
Blood plasma (7% )
Transmembrane fluid (2%)
Where does lipogenesis and beta-oxidation occur respectively?
Lipogenesis - Cytoplasm
Beta-Oxidation - Mitochondrial matrix
How does increased iron in hereditary haemochromatosis led to a reduce in erythropoiesis?
Hereditary haemochromatosis causes a reduction in hepcidin therefore increased iron enterocyte absorption through ferroportin into circulation → This causes increased iron levels; ion overload and damage kidneys reducing erythropoietin synthesis
What is the definition in terms of tumour of:
a) differentiation
b) growth pattern
a) Differentiation refers to how much of the cells of the tumour resemble of the cells of the tissue it derived from.
b) Growth pattern refers to how much the architecture of the tumour resemble the architecture of the tissues it derived from
Where do erythropoietin synthesis occur?
Kidney
How does symptoms of scurvy develop due to vitamin C deficiency?
Vitamin C is a co-factor for the enzymes Prolyl hydroxylase and Lysyl Hydroxylase.
These enzymes hydroxylate the proline and lysine residues of collagens for cross-linking which is needed for stability.
Thus deficiency of Vitamin C would eventually led to an impaired hydroxylation between collagens thus leading to symptoms of scurvy
A patient is suspected to be
experiencing a Hypersensitivity
reaction. If the reaction is Type III,
which of the following would NOT
be seen?
A. Elevated IgG antibodies
B. Inflammation of joints
C. Lowered Haptoglobin levels
D. Neutrophilia
Answer: C
Type III Hypersensitivity is characterized by
failure to clear immune complexes made of
IgG and/or IgM antibodies.
This failure to clear can cause deposition of
the immune complexes in various tissues such
as the joints, which leads to inflammation via
complement activation.
Neutrophils are therefore rapidly recruited to
the area of inflammation via chemotaxis.
Haptoglobin is an alpha-2 globulin found in
plasma. It forms complexes with haemoglobin
which can be used to diagnose a haemeolytic
anaemia, a probable result of a type II
hypersensitivity reaction where RBCs are
destroyed faster than they are produced.
What is the therapeutic use of haptoglobin in plasma?
Haptoglobin is an alpha-2 globulin found in
plasma. It forms complexes with haemoglobin
which can be used to diagnose a haemeolytic
anaemia
