STP Biomedical Sciences 5

Question 1

In a CRISPR-Cas9 experiment, what determines the sequence specificity of the cut?

Accepted Answer

The guide RNA sequence complementary to the target DNA

Answer

The ~20-nucleotide guide RNA spacer sequence base-pairs with the target DNA strand, directing Cas9 to the correct genomic locus adjacent to a PAM.

Question 2

Which immunoglobulin class is the most abundant in human serum and is capable of crossing the placenta?

Accepted Answer

IgG

Answer

IgG is the predominant serum immunoglobulin and is actively transported across the placenta via FcRn receptors, conferring passive immunity to the fetus.

Question 3

A researcher measures increased lactate production in cancer cells even in the presence of oxygen. This phenomenon is known as:

Accepted Answer

The Warburg effect

Answer

The Warburg effect describes aerobic glycolysis in cancer cells, where glucose is preferentially converted to lactate despite sufficient oxygen.

Question 4

Which assay directly measures the affinity (Kd) of a protein-ligand interaction in real time without labeling?

Accepted Answer

Surface plasmon resonance (SPR)

Answer

SPR measures changes in refractive index as molecules bind to an immobilized ligand on a sensor chip, providing real-time, label-free kinetic data.

Question 5

What is the function of signal recognition particle (SRP) in protein targeting?

Accepted Answer

It recognizes signal sequences and arrests translation until the ribosome docks with the ER

Answer

SRP binds the emerging signal peptide and pauses translation, then delivers the ribosome-mRNA-nascent chain complex to the ER translocon.

(STP) Scientist Training Programme Practice Test

(STP) Scientist Training Programme Practice Test

STP Biomedical Sciences 5