Chromosome Analysis

Question 1

Chromosomes are most conveniently studied in what type of cells?

Answer 1

Peripheral blood lymphocytes

Question 2

Sample that is most ideal for chromosome analysis.

Answer 2

5-10mL of heparinised venous blood.

Question 2

In chromosome analysis, this reagent prevents coagulation that would otherwise interfere with the later separation of the lymphocytes.

Answer 2

Heparin

Question 3

In culturing blood cells, _____ is added to cultures set up from each blood sample and this stimulates the T lymphocytes to transform and divide.

Answer 3

phytohaemagglutinin

Question 3

After a 48–72h incubation, cell division is arrested at metaphase by the addition of ____ , and a ____ is added to cause the cells to swell and to separate the individual chromosomes before fixation.

Answer 3

colchicine; hypotonic solution

Question 3

T/F. With G-banding, the light bands appear to contain relatively few active genes, to be AT-rich and to replicate late in S phase.

Answer 3

False. Dark bands = little genes = AT rich = replicate late in S phase

Question 4

T/F. In G banding, light bands contain about 80% of the active genes, including all housekeeping genes, are relatively GC-rich and replicate early in S phase.

Answer 4

True.

Question 5

Q-banding is achieved by staining chromosomes with?

Answer 5

Quinacrine (and examining under ultra- violet light)

Question 5

Modern banding allows precise identification and visualization of?

Answer 5

each chromosome; missing or additional material of 4, 000 kb or more

Question 5

G banding is achieved by staining chromosomes with?

Answer 5

Giemsa stain

Question 6

In chromosome analysis, improved resolution of smaller defects is possible by?

Answer 6

Prometaphase banding (earlier arrest of the dividing cell)
Fluorescence in situ hybridisation
Flow cytometry
Analysis of DNA (e.g., aCGH)

Question 7

Analysis of highly repetitive macrosatellite repeat DNA in heterochromatin at the centromeres, especially in chromosomes 1, 9 and 16, and the long arm of Y can be made using?

Answer 7

C banding

Question 7

Analysis of active nucleolus organiser regions (NORs), which contain the ribosomal RNA genes in the satellite stalks of the acrocentrics can be made using?

Answer 7

silver NOR staining

Question 7

Analysis of the late-replicating X chromosome can be made using?

Answer 7

5-bromodeoxyuridine (BrdU) staining with incorporation towards the end of DNA synthesis

Question 7

Analysis of the centromeric heterochromatin of 1, 9 and 16 together with distal Yq and proximal 15p can be used using?

Answer 7

DAPI/distamycin A staining

Question 8

Some laboratories routinely use ____, in which the bands stain in the opposite fashion from that seen with G-banding; this is achieved by heating the chromosomes in a saline buffer before staining with Giemsa and may be useful if the telomeres are involved in aberrations.

Answer 8

R-banding (reverse banding)