Nucleic acids and Mitosis

Question 1

What are the three components of nucleotides?

Answer 1

• Pentose sugar
• Phosphate group
• Nucleotide base

Nucleotides are the building blocks of nucleic acids, which include DNA and RNA.

Question 2

What type of pentose sugar is found in DNA?

Answer 2

Deoxyribose

This distinguishes DNA from RNA, which contains ribose.

Question 3

What type of pentose sugar is found in RNA?

Answer 3

Ribose

Ribose has one more oxygen atom than deoxyribose.

Question 4

What are the two main types of nitrogenous bases?

Answer 4

• Purines
• Pyrimidines

Purines have two rings, while pyrimidines have one ring.

Question 5

List the nitrogenous bases found in DNA.

Answer 5

• Adenine (A)
• Guanine (G)
• Cytosine (C)
• Thymine (T)

These bases pair specifically in the double helix structure.

Question 6

List the nitrogenous bases found in RNA.

Answer 6

• Adenine (A)
• Guanine (G)
• Cytosine (C)
• Uracil (U)

Uracil replaces thymine in RNA.

Question 7

What is the structure of DNA?

Answer 7

A double helix

DNA consists of two strands that are antiparallel and held together by hydrogen bonds between nitrogenous bases.

Question 8

In prokaryotes, how is DNA organized?

Answer 8

As a circular chromosome

Prokaryotes may also contain plasmids, which are smaller loops of DNA.

Question 9

In eukaryotes, how is DNA organized?

Answer 9

Into several linear chromosomes

Eukaryotic DNA is associated with histone proteins.

Question 10

What type of bond connects the sugar and phosphate groups in the DNA backbone?

Answer 10

Phosphodiester bond

These bonds link nucleotides together in a strand.

Question 11

What is complementary base pairing?

Answer 11

A purine always pairs with a pyrimidine

For example, adenine pairs with thymine (or uracil in RNA) and guanine pairs with cytosine.

Question 12

What are the types of RNA involved in transcription and translation?

Answer 12

• mRNA (messenger RNA)
• tRNA (transfer RNA)
• rRNA (ribosomal RNA)

These RNA types play critical roles in protein synthesis.

Question 13

What is the role of siRNA?

Answer 13

Regulates gene expression

siRNA stands for small interfering RNA and is typically 20-30 nucleotides long.

Question 14

Fill in the blank: RNA is a _______ polynucleotide.

Answer 14

Single-stranded

This is a key distinction from DNA, which is double-stranded.

Question 15

What discovery did James Watson and Francis Crick make about DNA?

Answer 15

The double helix structure

Their model was based on X-ray diffraction data from Rosalind Franklin.

Question 16

True or False: In DNA, thymine pairs with adenine.

Answer 16

True

This is essential for the complementary base pairing in the double helix.

Question 17

What is the significance of the antiparallel orientation of DNA strands?

Answer 17

It allows for complementary base pairing

The strands run in opposite directions (3’ to 5’ and 5’ to 3’).