Genetic Material

Question 1

What is DNA

Answer 1

-DNA (Deoxyribonucleic Acid) is an organic molecule carrying hereditary material.
-Found in all prokaryotic and eukaryotic cells.
-Responsible for genetic inheritance and protein production.

Question 2

How is bacterial DNA different from eukaryotic DNA

Answer 2

-Bacteria: Single circular DNA strand in the nucleoid region.
-Eukaryotes: DNA is membrane-bound in the nucleus

Question 3

Who discovered DNA and its structure?

Answer 3

-DNA was discovered by Friedrich Miescher in 1869.
-Double helix structure identified by Watson and Crick in 1953.

Question 4

What is the structure of DNA?

Answer 4

-Double helix, twisted ladder structure
-Made of nucleotides (sugar, phosphate group, nitrogen base).
-Bases pair as A-T and C-G.

Question 5

What are the components of DNA?

Answer 5

-Sugar (deoxyribose): Forms the backbone.
-Phosphate group: Links nucleotides.
-Nitrogen bases: Adenine (A), Thymine (T), Guanine (G), Cytosine (C).

Question 6

What are the nitrogen bases in DNA and their classifications?

Answer 6

-Purines: Adenine (A), Guanine (G).
-Pyrimidines: Cytosine (C), Thymine (T), Uracil(U)

Question 7

What are nucleotides and nucleosides?

Answer 7

-Nucleotides: Nitrogenous base + sugar + phosphate group.
-Nucleosides: Nitrogenous base + sugar (no phosphate group)

Question 8

What is the role of nucleotides in metabolism?

Answer 8

-Provide energy (e.g., ATP, GTP).
-Participate in cell signaling (e.g., cAMP, cGMP).
-Act as enzyme cofactors (e.g., NAD, FAD).

Question 9

DNA Polymerase

Answer 9

-Polymerase I: DNA repair.
-Polymerase II: Primer extension and proofreading.
-Polymerase III: In vivo DNA replication.

Question 10

Helicase

Answer 10

Unzips DNA by breaking hydrogen bonds.

Question 11

Ligase

Answer 11

Joins Okazaki fragments on discontinuous strands.

Question 12

Primase

Answer 12

This enzyme helps in the synthesis of RNA primer complementary to the DNA template strand.

Question 13

Endonucleases

Answer 13

These produce a single-stranded or a double-stranded cut in a DNA molecule.

Question 15

How does DNA coil and organize?

Answer 15

-DNA coils into chromosomes.
-Humans have 23 pairs of chromosomes.

Question 16

What is the genetic code?

Answer 16

A set of rules cells use to translate DNA or mRNA sequences into proteins with the help of ribosomes, tRNA, and codons.

Question 17

What is a codon?

Answer 17

A sequence of three nucleotides in DNA or RNA that specifies an amino acid or a stop signal.

Question 18

What does “non-ambiguous and universal” mean in the genetic code?

Answer 18

-Non-ambiguous: Each codon codes for only one amino acid.
-Universal: The code is the same across almost all organisms.

Question 19

What are start and stop codons?

Answer 19

Start codon: AUG (methionine).
Stop codons: UAG, UAA, UGA (do not code for amino acids).

Question 20

What does “commaless” mean in the genetic code?

Answer 20

Codons are read sequentially without spaces or punctuation between them.

Question 21

What does “nonoverlapping” mean in the genetic code?

Answer 21

Each nucleotide belongs to only one codon and is not reused in another codon.

Question 22

What is the polarity of the genetic code?

Answer 22

Codons are read in the 5′ → 3′ direction, determining the sequence of the encoded protein

Question 23

What is RNA?

Answer 23

RNA (ribonucleic acid) is a nucleic acid with a single helical strand that helps convert DNA instructions into functional proteins.

Question 24

How does RNA differ from DNA?

Answer 24

RNA has ribose sugar, uses uracil (U) instead of thymine (T), and forms a single helix.

Question 25

What are the three roles of RNA?

Answer 25

-Carries instructions from DNA to ribosomes.
-Delivers amino acids to ribosomes.
-Makes up ~50% of ribosome structure.

Question 26

What is mRNA and its function?

Answer 26

mRNA carries genetic instructions from DNA to ribosomes for protein synthesis and is small enough to pass through nuclear pores.

Question 27

What is rRNA and its role?

Answer 27

rRNA forms ~50% of ribosomes and facilitates protein synthesis by binding with proteins.

Question 28

What is tRNA and its function?

Answer 28

tRNA transports amino acids from the cytoplasm to ribosomes for protein assembly, as instructed by mRNA.

Question 29

What does RNA enable DNA to do?

Answer 29

RNA allows DNA to act as genetic instructions despite being confined to the nucleus.