BIOL2050 W1 L3

Introduction

Thanks for coming and understanding lecture recordings.

Info about future lectures and assignments.

Housekeeping

  • First Assignment for Molecular Genetics: Bond somatic space assessment in tutorials 2 and 3.

    • We'll discuss context and examples in weeks 2 and 3.

    • This assignment is worth 20% and is available on Canvas.

  • Help Sessions: One-on-one help for assignments in week 5. Bring drafts for review.

  • First Genetics Quiz: Due at the end of week 5, worth 5%.

Today's Lecture

Topic: Nuclear Genome

  • Discussed how people thought genetic info was protein-based until the 1950s.

  • Key experiments from 1928-1950 showed DNA is genetic material.

    • This is important for assessments.

Structure of DNA

  • DNA has a double helix with antiparallel strands.

  • It's packed into the nucleus of eukaryotic cells.

  • The human genome has 3.2 billion base pairs, fitting into a 5-micron nucleus.

Cell Structure

Eukaryotic Cells

  • Comparison of plant and animal cells shows similarities and differences in organelles.

  • The nucleus has a nuclear envelope with pores for communication.

  • Ribosomes help in translating mRNA into proteins.

  • Nucleolus: Takes up 25% of the nucleus and is responsible for making RNA and ribosomes.

Key Organelles

  • Mitochondria: The powerhouse that creates ATP (energy).

  • Vacuole (in plants): Stores water and waste, helping keep the cell rigid.

DNA Packaging

  • DNA is condensed about 200,000 times in the human nucleus.

  • This is crucial for replication and transcription.

  • Histone proteins are important for DNA packing: they are positively charged and wrap negatively charged DNA.

  • Nucleosome cores form chromatin fibers that create chromosomes.

Chromatin Types

  • Heterochromatin: Highly compact form.

  • Euchromatin: Loosely packed allowing gene access.

Gene Organization and C Value Paradox

C Value Paradox

  • There's no link between genome size and the number of genes.

    • For example, Arabidopsis has fewer base pairs than humans but more genes.

Gene Structure

  • Genes are made of exons (coding) and introns (non-coding).

  • Alternative splicing can produce multiple protein products from a single gene.

Human Genome Project

  • This project sequenced the human genome (3.2 billion base pairs) for about $3 billion.

  • Many countries, institutes, and over 3,000 scientists contributed.

  • Initially thought to have more genes than it actually does (about 20,000 identified).

Genome Size Variation

  • This explains how gene density and repetitive DNA impact genome size.

  • Discusses different types of repetitive DNA and their effects on genome size.

DNA Profiling and Forensics

  • Using variable number of tandem repeats for DNA profiling.

  • Unique patterns show individual genetic variations.

Conclusion

  • Recap of key concepts for assessments.

  • Encouragement to ask questions in the next tutorial.