All of the following are correct about Troponin C EXCEPT –
ANSWER -B
Troponin C - contains an N lobe and a C lobe.
The C lobe can bind either Ca2+ or Mg2+.
The N lobe, which binds only Ca2+.
N lobe, which binds only Ca2+, is the regulatory lobe.
Cardiac troponin C (cTnC) is a 161-amino acid protein organized into two domains: the regulatory N-terminal domain (cNTnC, residues 1-86), the structural C-terminal domain (cCTnC, residues 93-161), and a flexible linker connecting the two domains (residues 87-92).
Point mutations in troponin C is seen in –
ANSWER -C
Point mutations can occur in troponin C inducing alterations to Ca2+ and Mg2+ binding and protein structure, leading to abnormalities in muscle contraction.
In cardiac muscle, they are related to dilated cardiomyopathy (DCM) and hypertrophic cardiomyopathy (HCM).
All of the following is true for Granzyme B EXCEPT –
ANSWER -A
Granzyme B - is a serine protease most commonly found in the granules of natural killer cells (NK cells) and cytotoxic T cells.
It is secreted by these cells along with the pore forming protein perforin to mediate apoptosis in target cells.
Which of the following is Most appropriate -
ANSWER -A
Norepinephrine activates α adrenergic receptors.
Epinephrine activates both α and β receptors.
Nitrergic neurons release NO, which relaxes vascular smooth-muscle cell by mediating action through –
ANSWER -D
Nitrergic neurons release
NO, which relaxes vascular smooth-muscle cell via the cyclic GMP dependent mechanism. It also acts in an independent mechanism.
All of the following are local paracrine modulators of vascular smooth-muscle cell tone EXCEPT -
ANSWER -C
Local paracrine modulators –
Mechanical -shear stress, cyclic strain
Biochemical - purinergic agonists, muscarinic agonists, peptidergic agonists.
Circulating modulators -
Norepinephrine and natriuretic peptides
Which of the following is FALSE regarding heparan sulfate –
ANSWER -B
Stable in a proteolytic environment.
Heparin, commonly known as an anticoagulant, is a highly sulfated form of heparan sulfate.
HS has also been shown to serve as cellular receptor for a number of viruses, including the respiratory syncytial virus.
Heparan sulfate is broken down in proteolytic environment like chronic wounds by heparanase.
Calmodulin's structure is very similar to the structure of –
ANSWER -C
Troponin C
Calmodulin's structure is very similar to the structure of troponin C (which is another calcium binding protein). They are both members of the EFh superfamily.
Which of the following is TRUE regarding Troponin C and Calmodulin –
ANSWER -B
Length of linker region
Troponin C, like calmodulin, has two globular domains that are connected by a linker region.
However, troponin C and calmodulin differ in the length of the linker region.
Linker region of calmodulin is smaller than that of troponin C.
All of the following are principal peptidergic neurotransmitters EXCEPT -
ANSWER -D
Sympathetic- epinephrine and norepinephrine.
Parasympathetic- acetylcholine.
Nonadrenergic/noncholinergic- which include two
subgroups—
Nitrergic, whose principal neurotransmitter is NO,
Peptidergic, whose principal neurotransmitters are
Substance P,
Vasoactive intestinal peptide,
Calcitonin gene-related peptide,
Non-peptide, adenosine triphosphate (ATP)
