Lecture Notes: Mitosis vs Meiosis and Genetics

Introduction

• Focus on differences between mitosis and meiosis
• Mitosis: formation of somatic (body) cells
• Meiosis: formation of reproductive cells (gametes - sperm and egg)

Mitosis vs Meiosis

• Start as diploid cells (2N): 46 chromosomes (23 from each parent)
• Interphase: Chromosome replication, crucial for cell division
  • Chromatids double, but chromosome count remains at 46
• Acronym PMAT for stages: Prophase, Metaphase, Anaphase, Telophase
  • Meiosis stages repeat twice (e.g., Prophase 1, Metaphase 1)

Mitosis Stages

• Prophase: Chromosomes condense
• Metaphase: Chromosomes align in the center
• Anaphase: Chromatids separated to opposite cell ends
• Telophase: New nuclear envelopes form, leading to two identical diploid cells (46 chromosomes each)

Meiosis Stages

• Prophase 1: Chromosomes pair, crossing over for genetic diversity

• Metaphase 1: Paired homologous chromosomes align

• Anaphase 1: Homologous chromosomes separate

• Telophase 1: New cells with diverse chromosomes

• Prophase 2: Chromosomes condense again

• Metaphase 2: Chromosomes align in a single line

• Anaphase 2: Chromatids separate

• Telophase 2: Resulting in four genetically distinct haploid cells (23 chromosomes each)

Practice Questions

1. Crossing over occurs during Prophase 1 of meiosis.
2. Mitosis results in two genetically identical diploid cells; meiosis results in four genetically unique haploid cells.
3. Random assortment of chromosomes during Anaphase 1 contributes to genetic diversity.

Heredity and Genetics

• DNA, Chromosomes, and Genes: Key Components
  • DNA: genetic code present in most cells
  • Chromosomes: structures organizing DNA
  • Genes: DNA segments that code for traits
• Inherited traits: Influenced by both DNA and environmental factors

DNA Structure

• Composed of nucleotides (deoxyribose sugar, phosphate, base)
• Bases: Adenine (A), Thymine (T), Cytosine (C), Guanine (G)
  • A-T and C-G pairing
• DNA's double helix structure

Gene and Protein Synthesis

• Proteins: Influence traits, structural support, enzymatic activity
• Gene regulation: Controls gene activation

RNA's Role

• RNA assists in translating DNA into proteins
• Types:
  • mRNA: Messenger RNA conveys genetic instructions
  • rRNA: Ribosomal RNA, part of ribosome structure
  • tRNA: Transfer RNA, carries amino acids

Transcription and Translation

• Transcription: DNA to mRNA in the nucleus
  • RNA polymerase synthesizes mRNA
• Translation: mRNA to proteins at ribosomes
  • tRNA brings amino acids, matches mRNA codons

Practice Questions

1. RNA polymerase initiates transcription of a gene into mRNA.
2. mRNA serves as a template for assembling amino acids into proteins.

Conclusion

• Understanding the differences between mitosis and meiosis is crucial for comprehending genetics.
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Note: Always cross-verify with updated sources and textbooks for detailed understanding and exam preparation.