Q: Which equation represents the condensation reaction that forms a phosphodiester bond between two nucleotides?

$$\text{Nucleotide}_1 + \text{Nucleotide}_2 \rightarrow \text{Nucleotide}_1\text{-}\text{Nucleotide}_2 + H_2O$$

Question 1

Which of the following best describes the three components of a nucleotide found in nucleic acids?

Accepted Answer

A phosphate group, a five-carbon sugar, and a nitrogenous base

Question 2

What is the key difference between the sugars in DNA and RNA nucleotides?

Accepted Answer

DNA contains deoxyribose, which has an H at the 2' carbon; RNA contains ribose, which has an OH at the 2' carbon

Question 3

Which nitrogenous base is found only in RNA and not in DNA?

Accepted Answer

Uracil

Question 4

What type of bond forms between the phosphate group on the 5' carbon of one nucleotide and the OH group on the 3' carbon of another nucleotide during nucleic acid polymerization?

Accepted Answer

Phosphodiester linkage

Question 5

Which of the following statements about the directionality of nucleic acid strands is correct?

Accepted Answer

Nucleic acid strands have a 5' end with a phosphate group and a 3' end with a hydroxyl group

Question 6

Which equation represents the condensation reaction that forms a phosphodiester bond between two nucleotides?

Accepted Answer

$$	ext{Nucleotide}_1 + 	ext{Nucleotide}_2 ightarrow 	ext{Nucleotide}_1	ext{-}	ext{Nucleotide}_2 + H_2O$$

Question 7

Why is DNA considered a highly stable molecule compared to RNA?

Accepted Answer

DNA lacks the 2' OH group, making it less reactive and more resistant to degradation

Question 8

Which of the following best explains the antiparallel nature of DNA strands in the double helix?

Accepted Answer

One strand runs 5' to 3', while the other runs 3' to 5'

Question 9

Which base pairing occurs in DNA according to the Watson-Crick model?

Accepted Answer

A pairs with T, and G pairs with C

Question 10

What is the role of activated nucleotides, such as ATP, in nucleic acid polymerization?

Accepted Answer

They provide the energy required to make the polymerization reaction spontaneous

Question 11

During DNA replication, what is the function of complementary base pairing?

Accepted Answer

It ensures that each new DNA strand is an exact copy of the original

Question 12

Which of the following is a unique property of RNA compared to DNA?

Accepted Answer

RNA can act as a catalyst (ribozyme)

Question 13

In the context of the RNA world hypothesis, why is RNA considered a likely candidate for the first self-replicating molecule?

Accepted Answer

RNA can both store genetic information and catalyze its own replication

Question 14

Which of the following best describes the secondary structure of RNA?

Accepted Answer

RNA folds into hairpin structures due to complementary base pairing within the same strand

Question 15

Which equation best represents the base pairing in DNA?

Accepted Answer

$$[A] = [T]$$ and $$[G] = [C]$$

Question 16

Which of the following is NOT a function of ribozymes in the RNA world hypothesis?

Accepted Answer

Stabilizing the DNA double helix

Question 17

A researcher isolates a nucleic acid molecule that is single-stranded, contains uracil, and is capable of folding into complex three-dimensional shapes. What is the most likely identity of this molecule?

Accepted Answer

RNA

Question 18

Which of the following statements about the tertiary structure of DNA is correct?

Accepted Answer

DNA can form supercoils and wrap around histone proteins for compaction

Question 19

Which of the following is a real-world application of understanding ribozymes and the RNA world hypothesis?

Accepted Answer

Designing algorithms to model evolutionary changes in catalytic RNA molecules

Question 20

Which of the following characteristics is shared by both DNA and RNA?

Accepted Answer

Both have a sugar-phosphate backbone

Nucleic Acids and the RNA World: Structure, Function, and Evolution chapter 4

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