IMS Flashcards
Which of the following modifications is common in secretory proteins but does not occur in eukaryotic mRNA?
a) addition of poly-A tail
b) capping with 7-methylguanine
c) glycolysation
d) splicic) ng
Explain
Glycolysation
Explain:
a, b and d are all examples of post transcription modifications in mRNA
Glycolysation is the controlled enzymatic modification of an organic molecule, especially a protein, by addition of a sugar molecule
What kind of secretion is based on vacuole-based exocytosis (as seen in salivary glands or the pancreas)?
a) Apocrine
b) Eccrine
c) Holocrine
d) Merocrine
Explain
Merocrine
Merocrine glands secrete product through exocytosis of secretory vacuoles - no part of cell is lost in process
Which of the following hormones is essential for stimulating the production of platelets?
a) Erythropoietin
b) Granulocyte colony stimulating factor
c) Thrombopoietin
d) Thyroid hormone
Thrombopoietin
Thrombopoietin is a glycoprotein hormone produced by the liver and kidney which regulates the production of platelets. It stimulates the production and differentiation of megakaryocytes, the bone marrow cells that bud off large numbers of platelets.
What does Prasugrel block in order to inhibit platelet aggregation?
ADP binding to P2Y receptor
Prasugrel is a drug used to prevent formation of blood clots. It is a platelet inhibitor and an irreversible antagonist of P2Y₁₂ ADP receptors.
Which characteristic of a drug predicts that it will be easily absorbed across a cell membrane?
Lipophilic, unionised
Which of the following antibiotics targets bacterial ribosomes?
a) Chloramphenicol
b) Penicillin
c) Rifampin
d) Trimethoprim
Explain
Chloramphenicol
Chloramphenicol: targets bacterial ribosomes to inhibit protein synthesis
Penicillin: prevents new cell wall formation so bacteria dies
Rifampin: inhibits bacterial RNA polymerase, the enzyme responsible for DNA transcription
Trimethoprim: antibiotic that prevents bacteria producing folate so bacteria cannot produce DNA
During an ART (assisted reproductive technology) treatment cycle, hCG (human Chorionic Gonadotropin) by subcutaneous injection is used for:
a) induction of ovulation
b) luteal phase support
c) ovarian stimulation
d) pituitary down regulation
Luteal phase support
Providing hormonal supplementation during the luteal phase with either progesterone itself, or human chorionic gonadotropin (hCG), which stimulates progesterone production, may improve implantation. Due to similar structure, hCG binds to same receptor as LH.
Which of these events occur during the second meiotic division?
a) DNA replication
b) Pairing between chromosomal homologues
c) Recombination between chromosomal homologues
d) Separation of sister chromatids
Separation of sister chromatids
The first meiotic division separates pairs of homologous chromosomes to halve the chromosome number (diploid → haploid)
The second meiotic division separates sister chromatids (created by the replication of DNA during interphase).
Which statement best describes how viral antigens are displayed on the cell surface of an infected cell? Viral peptides are loaded onto:
a) CD4+ receptors
b) CD8+ receptors
c) MHC class I molecules
d) MHC class II molecules
?
Skeletal muscle fibres are repaired by which of the following cells?
a) fibroblasts
b) myocytes
c) myotubes
d) satellite cells
Satellite cells
Paraxial mesodermal cells adjacent to the neural tube form blocks of cells called somites. Skeletal muscles, excluding those of the head and limbs, develop from mesodermal somites. Somites give rise to myoblasts.
A myoblast is a muscle-forming stem cell that migrates to different regions in the body and then fuses to form a myotube.
A myotube is formed from many different myoblast cells so it contains many nuclei, but has a continuous cytoplasm. This is why skeletal muscle cells are multinucleate (cardiac and smooth muscle cells are not).
A satellite cell is similar to a myoblast because it is a type of stem cell; however, satellite cells are incorporated into muscle cells and facilitate the protein synthesis required for repair and growth.
Fibroblasts: are the major cells responsible for the production of collagen
During replication of DNA, the synthesis of DNA on the lagging strand takes place in segments. What are these segments called?
Okazaki fragments
Which of the following controls the binding of oxygen to haemoglobin?
a) At high altitude, levels of bisphosphoglycerate (BPG) in red blood cells rise, decreasing the affinity of Hb for oxygen
b) Decreased pH of blood increases the affinity of Hb for oxygen
c) High levels of carbon monoxide in blood increase the affinity of Hb for oxygen
d) Increased lactic acid concentration in blood increases the affinity of Hb for oxygen
At high altitude, levels of bisphosphoglycerate (BPG) in red blood cells rise, decreasing the affinity of Hb for oxygen
Which of the following is a feature of the primary structure of collagen?
a) every other amino acid residue is glycine
b) It contains a high proportion of hydrophobic amino acid residues
c) It contains hydroxylated proline and lysine residues
d) It is abnormal in patients with low vitamin D levels
?
Which of the following is a glycerophospholipid?
a) Galactocerebroside
b) Ganglioside GM2
c) Phosphatidylserine
d) Sphingomyelin
Phosphatidylserine
Phosphatidylserine is a phospholipid—more specifically a glycerophospholipid—which consists of two fatty acids attached in ester linkage to the first and second carbon of glycerol and serine attached through a phosphodiester linkage to the third carbon of the glycerol
Which of the following procedures is used as a common technique for karyotyping using light microscopy?
a) C-banding
b) FISH
c) G banding
d) Q banding
FISH
