MODULE 4:
GENE EXPRESSION & REGULATION –
BEGINNER-FRIENDLY COMPREHENSIVE NOTES
OBJECTIVE
Learn how genes control cellular functions, how cells make proteins, and how gene activity is
regulated.
TABLE OF CONTENTS
• Introduction
• Key Definitions
• The Genetic Code
◦ Codons, Start/Stop codons, Degeneracy, Wobble Hypothesis
◦ Example Codon Table
• Protein Synthesis
◦ Transcription (DNA → RNA)
◦ Translation (RNA → Protein)
• Gene Regulation
◦ Prokaryotic: Operons (Lac operon example)
◦ Eukaryotic: Epigenetics
• Genetic Technologies
◦ PCR, Gel Electrophoresis, CRISPR
• Exam-Oriented Questions
◦ MCQs, SAQs, Long Answer Questions
• Cheat Sheet
• Suggested Reading
, 1. INTRODUCTION
Genes are the instructions for building proteins, which perform almost all functions in the cell.
Gene expression is the process of reading these instructions and making functional products.
Regulation of gene expression ensures proteins are made at the right time, in the right cell, and in
the right amount.
Understanding gene expression is essential for biology, medicine, and biotechnology.
Example: Muscle cells express genes for actin and myosin; liver cells express genes for enzymes
involved in metabolism.
2. KEY DEFINITIONS
Term Definition Simple Explanation
Segment of DNA that codes for a functional DNA instruction for making
Gene
product (protein or RNA) something useful
Genome Complete DNA of an organism All the genes in a cell
Messenger RNA; carries genetic code from DNA
mRNA The “message” copy of a gene
to ribosome
The “delivery truck” for amino
tRNA Transfer RNA; brings amino acids to ribosome
acids
The “factory” where proteins are
rRNA Ribosomal RNA; forms ribosome structure
made
Three nucleotides in mRNA coding for one amino
Codon 3-letter code for an amino acid
acid
Start codon AUG, signals start of translation “Begin reading here”
Stop codon UAA, UAG, UGA; signals end of translation “Stop reading”
Operon Group of genes controlled together (prokaryotes) Genes working as a team
Promoter DNA region where RNA polymerase binds Start signal for transcription
GENE EXPRESSION & REGULATION –
BEGINNER-FRIENDLY COMPREHENSIVE NOTES
OBJECTIVE
Learn how genes control cellular functions, how cells make proteins, and how gene activity is
regulated.
TABLE OF CONTENTS
• Introduction
• Key Definitions
• The Genetic Code
◦ Codons, Start/Stop codons, Degeneracy, Wobble Hypothesis
◦ Example Codon Table
• Protein Synthesis
◦ Transcription (DNA → RNA)
◦ Translation (RNA → Protein)
• Gene Regulation
◦ Prokaryotic: Operons (Lac operon example)
◦ Eukaryotic: Epigenetics
• Genetic Technologies
◦ PCR, Gel Electrophoresis, CRISPR
• Exam-Oriented Questions
◦ MCQs, SAQs, Long Answer Questions
• Cheat Sheet
• Suggested Reading
, 1. INTRODUCTION
Genes are the instructions for building proteins, which perform almost all functions in the cell.
Gene expression is the process of reading these instructions and making functional products.
Regulation of gene expression ensures proteins are made at the right time, in the right cell, and in
the right amount.
Understanding gene expression is essential for biology, medicine, and biotechnology.
Example: Muscle cells express genes for actin and myosin; liver cells express genes for enzymes
involved in metabolism.
2. KEY DEFINITIONS
Term Definition Simple Explanation
Segment of DNA that codes for a functional DNA instruction for making
Gene
product (protein or RNA) something useful
Genome Complete DNA of an organism All the genes in a cell
Messenger RNA; carries genetic code from DNA
mRNA The “message” copy of a gene
to ribosome
The “delivery truck” for amino
tRNA Transfer RNA; brings amino acids to ribosome
acids
The “factory” where proteins are
rRNA Ribosomal RNA; forms ribosome structure
made
Three nucleotides in mRNA coding for one amino
Codon 3-letter code for an amino acid
acid
Start codon AUG, signals start of translation “Begin reading here”
Stop codon UAA, UAG, UGA; signals end of translation “Stop reading”
Operon Group of genes controlled together (prokaryotes) Genes working as a team
Promoter DNA region where RNA polymerase binds Start signal for transcription
