Tutorial 14 — Nucleic Acids

Note: This tutorial PDF consists primarily of scanned images. The questions below are reconstructed based on typical FAD1018 Tutorial 14 content on Nucleic Acids.

Tutorial Information

Extracted note: "Dr. Danial" — possibly the lecturer's name

Learning Outcomes

Understand the structure of nucleotides
Learn the structure of DNA and RNA
Understand base pairing and the double helix
Learn about DNA replication, transcription, and translation
Understand mutations and their effects

Part A: Nucleotides and Nucleosides

Question 1

a) What are the three components of a nucleotide?

b) Draw the structure of a nucleotide showing:

Nitrogenous base
Pentose sugar (ribose or deoxyribose)
Phosphate group

c) What is the difference between a nucleoside and a nucleotide?

Question 2

a) Classify nitrogenous bases into purines and pyrimidines.

b) Draw the structures of:

Adenine (purine)
Guanine (purine)
Cytosine (pyrimidine)
Thymine (pyrimidine)
Uracil (pyrimidine)

c) Which bases are found in DNA? Which in RNA?

Question 3

a) Draw the Haworth structure of:

β-D-ribofuranose (in RNA)
β-D-2-deoxyribofuranose (in DNA)

b) What is the structural difference between ribose and deoxyribose?

c) Why is this difference important for the stability of DNA?

Part B: DNA Structure

Question 4

a) Describe the primary structure of DNA.

b) What type of bond links nucleotides together?

c) Draw a dinucleotide showing the phosphodiester linkage.

Question 5

a) Describe the secondary structure of DNA (Watson-Crick double helix).

b) Explain complementary base pairing:

A pairs with T (how many hydrogen bonds?)
G pairs with C (how many hydrogen bonds?)

c) Why is A-T pairing different from G-C pairing in terms of stability?

Question 6

a) Distinguish between the major and minor grooves of DNA.

b) What is the approximate distance between base pairs along the helix axis?

c) How many base pairs are there per turn of the helix?

d) Compare A-DNA, B-DNA, and Z-DNA.

Part C: RNA Structure

Question 7

a) List the major types of RNA and their functions:

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

b) Why is RNA typically single-stranded while DNA is double-stranded?

c) Can RNA form double-stranded structures? Give examples.

Question 8

a) Draw the cloverleaf structure of tRNA and label:

Acceptor stem
Anticodon loop
D loop
TΨC loop

b) What is the function of the anticodon?

c) What is the role of the 3'-CCA end?

Part D: DNA Replication

Question 9

a) Describe the process of DNA replication.

b) Explain the roles of:

DNA helicase
DNA polymerase
DNA ligase
Primase

c) Why is DNA replication semi-conservative?

Question 10

a) Distinguish between leading and lagging strand synthesis.

b) What are Okazaki fragments?

c) Why does DNA polymerase only work in the 5'→3' direction?

Part E: Transcription and Translation

Question 11

a) What is transcription? Where does it occur?

b) Compare DNA replication and transcription.

c) What is the genetic code? What are its characteristics?

Question 12

a) What is translation? Where does it occur?

b) Describe the steps of translation:

Initiation
Elongation
Termination

c) Explain the role of ribosomes in protein synthesis.

Part F: Mutations

Question 13

a) Define mutation. List different types of mutations.

b) Distinguish between:

Point mutation (substitution)
Insertion
Deletion
Frameshift mutation

c) What is a silent mutation? Give an example.

Question 14

a) What are the causes of mutations?

Spontaneous mutations
Induced mutations (mutagens)

b) Give examples of mutagens:

Chemical mutagens
Physical mutagens (radiation)

c) How can mutations be beneficial, neutral, or harmful?

Key Concepts

Nucleotide — Building block of nucleic acids (base + sugar + phosphate)
Nucleoside — Base + sugar (no phosphate)
DNA — Deoxyribonucleic acid (double-stranded)
RNA — Ribonucleic acid (typically single-stranded)
Base Pairing — A-T, G-C complementary pairing
Double Helix — Secondary structure of DNA
Replication — Copying of DNA
Transcription — Synthesis of RNA from DNA
Translation — Protein synthesis from mRNA
Mutation — Change in DNA sequence
Genetic Code — Codon-amino acid correspondence

Summary: DNA vs RNA

Feature	DNA	RNA
Sugar	Deoxyribose	Ribose
Bases	A, T, G, C	A, U, G, C
Structure	Double-stranded	Single-stranded
Location	Nucleus	Nucleus and cytoplasm
Functions	Storage of genetic info	Protein synthesis
Stability	More stable	Less stable

FAD1018 Tutorial 14 — Nucleic Acids