FISH, Comparative Genomic Hybridization, & CMA

Question 1

Which one of the following conditions is the most stringent for a DNA hybridization reaction?
A. 37 C
B. 45 C
C. 55 C
D. 65 C
E. 75 C

Answer 1

E. 75 C
The reaction temperature, along with other reaction conditions such as the ionic strength (usually determined by the Na+ concentration or the concentration of other denaturants), defines the stringency of a hybridization reaction. A more stringent set of reaction conditions is one under which only complementary DNA strands of higher affinity (i.e. high specificity) will associate. Likewise, lower stringency allows for association of complementary DNA strands with lower affinity (i.e. lower specificity) for each other.

higher temp = increased stringency

Question 2

The technique in which equal amounts of patient DNA and control DNA is used to compete for binding to a large number of DNA templates is called

Answer 2

comparative genomic hybridization

Question 3

Whcih one of the following cytogenic abnormalities is most readily detected by comparative genomic hybridization using chromosomal microarray?
A. 45,XX,-21,-21,+rob(21;21)
B. 46,XX/46,XY (ratio 5:95)
C. 46,XX,inv(8)
D. 46,XX,t(5;7)(q12;p22)
E. 48,XXYY

Answer 3

E. 48,XXYY

Question 4

Which of hte following best describes single-stranded DNA molecules of the same sequence?
A. They can be digested by restriction enzymes
B. They can form stemp loop structures
C. They can re-anneal to form double-stranded DNA
D. They exhibit hyperchromicity when heated
E. They obey the base composition rule of A=T, G=C

Answer 4

B. They can form stemp loop structures

Question 5

True or False?

DNA double helices are more stable than RNA double helices

Answer 5

True