SCYM Cell Cycle & DNA Content Analysis 2

Question 1

What is the primary reason RNase A is added to samples before propidium iodide staining for DNA content analysis?

Accepted Answer

To eliminate RNA that would otherwise contribute to PI fluorescence

Answer

To improve cell membrane permeabilization

Answer

To prevent cell clumping during staining

Answer

To stabilize nuclear DNA structure

Question 2

Which fixation method is most commonly used to prepare cells for propidium iodide-based DNA content analysis?

Accepted Answer

Ice-cold 70% ethanol

Answer

4% paraformaldehyde at room temperature

Answer

2.5% glutaraldehyde

Answer

10% neutral buffered formalin

Question 3

Aneuploid tumor cells are identified in DNA content analysis primarily by which characteristic?

Accepted Answer

DNA index significantly different from 1.0

Answer

CV greater than 10% on the G1 peak

Answer

Sub-G1 fraction exceeding 5%

Answer

S phase fraction above 20%

Question 4

The proliferation index in cell cycle analysis is calculated using which cell cycle compartments?

Accepted Answer

S and G2/M fractions relative to all cells

Answer

G0/G1 fraction only

Answer

G2/M fraction only

Answer

S phase fraction only

Question 5

EdU (5-ethynyl-2'-deoxyuridine) is preferred over BrdU for S phase detection because EdU detection:

Accepted Answer

Uses click chemistry that does not require DNA denaturation

Answer

Requires heat-induced DNA denaturation for antibody access

Answer

Produces significantly lower background fluorescence

Answer

Is incorporated into RNA rather than DNA

Question 6

DAPI (4',6-diamidino-2-phenylindole) binds preferentially to which type of DNA sequence?

Accepted Answer

AT-rich regions in the minor groove

Answer

GC-rich regions in the major groove

Answer

RNA secondary structures

Answer

Single-stranded DNA overhangs

Question 7

In a BrdU/PI dual-parameter assay, what two cell properties are simultaneously measured?

Accepted Answer

Active DNA synthesis and total DNA content

Answer

Cell viability and apoptosis

Answer

Mitochondrial membrane potential and cell size

Answer

Surface antigen expression and dead cell exclusion