How Traits Are Passed From One Generation to the Next

Introduction

• DNA controls traits such as hair color, and eye color
• It's essential to understand how DNA does this
• Lecture by Roshni from Lano Hub

Genetics Journey

• Most organisms' genetic material is DNA
• DNA is found in chromosomes, and chromosomes are inside the nucleus

Questions to Understand

• How does DNA control traits?
• The relation of protein synthesis and DNA
• What is the role of RNA?

DNA and RNA

• DNA (Deoxyribonucleic Acid) and RNA (Ribonucleic Acid) are present
• DNA: Double-stranded helix, Deoxyribonucleotide
• RNA: Single-stranded, Ribose sugar
• Examination of the structure of both DNA and RNA

Monomers of DNA

• DNA monomers: Deoxyribonucleotide
• RNA monomer: Ribonucleotide
• Composed of phosphate group, pentose sugar, nitrogenous base

Nitrogenous Bases

• All bases: Purines and Pyrimidines
• Purines: Adenine (A) and Guanine (G)
• Pyrimidines: Cytosine (C), Thymine (T) (in DNA), and Uracil (U) (in RNA)
• Bases form nucleosides

Formation of Nucleotide

• Nucleoside + phosphate group = Nucleotide
• To form polynucleotide chain, nucleotides connect via 3’-5’ phosphodiester bond

Packaging of DNA

• In E. coli, DNA is looped, held by proteins
• In eukaryotes, DNA is wrapped around histone proteins
• Chromatin has two forms: Euchromatin and Heterochromatin

Molecular Basis of DNA Inheritance

• Discovery of transforming principle:
  • Griffith's experiment (using S strain, R strain)
  • Various scientists' experiments
• Ultimately, transforming principle was identified as DNA
• Hershey-Chase experiment: Showed that DNA is the genetic material using radioactive phosphorus and sulfur

Proteins and DNA

• Use of enzymes during DNA replication license
• DNA Polymerase and its role
• DNA Polymerase has proofreading and error-correcting ability

Energy and Replication

• Deoxyribonucleoside triphosphates as energy producers
• DNA replication means Xeroxing of DNA

Replication Process

1. Separation of DNA (using Helicase enzyme)
2. Leading strand: Continuous synthesis (uses DNA polymerase)
3. Lagging strand: Discontinuous synthesis (Primase enzyme, DNA Ligase enzyme)

RNA and Its Importance

• Transcription: Making RNA from DNA (uses RNA Polymerase)
• Transcription unit: Promoter, structural gene, and terminator
• Types of RNA: mRNA, tRNA, rRNA, and their functions
• Importance of exons and introns (protein coding)

In Summary

• DNA controls the molecular basis of life
• From Griffith's transformation principle to today's Hershey-Chase experiment
• Importance of DNA and RNA
• Essential pathways of transcription and replication