$$T_m = 2 \times (A+T) + 4 \times (G+C)$$

Question 1

Which experimental technique was crucial in revealing the helical structure of DNA by showing a 3.4 Å periodicity?

Accepted Answer

X-ray diffraction analysis

Question 2

According to the Watson–Crick model, how many base pairs are present in one complete turn of the DNA double helix?

Accepted Answer

10

Question 3

Which of the following best describes the chemical affinity that allows complementary base pairing in DNA?

Accepted Answer

Hydrogen bonds between paired bases

Question 4

What is the primary structural difference between DNA and RNA?

Accepted Answer

RNA contains ribose and uracil, while DNA contains deoxyribose and thymine

Question 5

Which class of RNA acts as a template for protein synthesis by carrying genetic information from the gene to the ribosome?

Accepted Answer

Messenger RNA (mRNA)

Question 6

During DNA denaturation, what happens to the absorption of UV light at 260 nm?

Accepted Answer

It increases due to hyperchromic shift

Question 7

Which analytical technique uses fluorescent probes to monitor hybridization and identify specific chromosomal areas?

Accepted Answer

Fluorescent in situ hybridization (FISH)

Question 8

In nucleic acid electrophoresis, why do smaller DNA fragments migrate faster through the agarose gel?

Accepted Answer

The porous matrix restricts larger molecules more

Question 9

Which RNA type is directly involved in carrying amino acids to the ribosome during translation?

Accepted Answer

Transfer RNA (tRNA)

Question 10

A DNA molecule with a higher melting temperature is likely to have which characteristic?

Accepted Answer

Higher guanine-cytosine content

Question 11

Which equation best represents the relationship between melting temperature ($$T_m) $$and GC content in DNA?

Accepted Answer

$$T_m = 2 	imes (A+T) + 4 	imes (G+C)$$

Question 12

Which scenario best illustrates molecular hybridization?

Accepted Answer

Single-stranded DNA from two different organisms forming a duplex

Question 13

Which RNA type is involved in gene regulation and can silence gene expression?

Accepted Answer

Micro RNA (miRNA)

Question 14

If you heated a sample of double-stranded DNA from 30°C to 100°C while measuring $$A_{260}$$, which graph would you expect to see?

Accepted Answer

A graph showing a hyperchromic shift (increase in $$A_{260})$$

Question 15

Which of the following is NOT a major class of cellular RNA involved in gene expression?

Accepted Answer

Telomerase RNA

Question 16

What is the function of small nuclear RNA (snRNA)?

Accepted Answer

Processes mRNA

Question 17

Which property of DNA is exploited in agarose gel electrophoresis for fragment separation?

Accepted Answer

DNA's size-dependent migration through a porous matrix

Question 18

Which of the following statements about RNA is correct?

Accepted Answer

RNA contains ribose as its sugar

Question 19

Which of the following is a plausible consequence of DNA denaturation in a laboratory setting?

Accepted Answer

Decrease in viscosity and increase in UV absorption

Question 20

Which RNA molecule is involved in DNA replication at chromosome ends (telomeres)?

Accepted Answer

Telomerase RNA

Ch 9 P2 DNA Structure and Analysis – Study Notes

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