Module 31,32,33

Key Concepts of Gene Expression and Regulation

Introduction

• Classroom use only; contains copyrighted material.

Processes Involved

• DNA Replication: Parent DNA strand is a template for new strand synthesis.

• Transcription: DNA template leads to mRNA synthesis in the nucleus.

• Translation: mRNA is translated into polypeptides in the cytoplasm. Ribosomes and tRNA are involved.

Gene Expression Flow

• Sequence: DNA ➔ mRNA ➔ Protein.

Nucleic Acids

• Structure: Polymers of nucleotides (5-carbon sugar, nitrogenous base, phosphate group).

• Types: DNA (deoxyribose) and RNA (ribose).

• Nitrogenous Bases: Pyrimidines (C, T, U) and Purines (G, A).

DNA Structure

• Shape: Double helix with sugar-phosphate backbone.

• Replicati?on Mechanism: Semiconservative, each strand serves as a template.

Central Dogma

• Gene expression and regulation guiding processes.

DNA Replication Essentials

• Key Enzymes: DNA polymerase, helicase, topoisomerase, DNA ligase.

• Directionality: DNA synthesizes in the 5′ to 3′ direction.

Leading and Lagging Strands

• Leading Strand: Synthesized continuously; Lagging Strand: Synthesized in Okazaki fragments.

Telomeres

• Function: Prevent chromosome shortening and protect genetic data during replication.

• Role of Telomerase: Adds telomeric sequences.

Transcription Overview

• Begins at promoter, ends at terminator.

• Eukaryotic mRNA requires processing (5' cap, poly(A) tail, splicing).

Alternative Splicing

• Produces different proteins from the same transcript.