Mitosis vs. Meiosis and Genetics

Key Differences between Mitosis and Meiosis

• Mitosis: Formation of somatic (body) cells
  • Produces two identical diploid cells
• Meiosis: Formation of reproductive cells (gametes)
  • Produces four genetically unique haploid cells (sperm and eggs)

Initial State of Cells

• Both processes start with a diploid cell (2N)
• Humans have 46 chromosomes (23 pairs)
• Interphase: Chromosomes replicate to prepare for division; not part of mitosis/meiosis but crucial for chromosome duplication

PMAT Stages (Prophase, Metaphase, Anaphase, Telophase)

• Mitosis:
  • Prophase: Chromosomes become visible
  • Metaphase: Chromosomes align in the center
  • Anaphase: Chromatids pulled apart
  • Telophase: New nuclear envelopes form, followed by cytokinesis
• Meiosis (two rounds of PMAT):
  • Meiosis I (crossing over occurs in Prophase 1, forming recombinant chromosomes)
  • Meiosis II (similar to mitosis but results in haploid cells)

Importance of Meiosis

• Results in four genetically diverse haploid gametes
• Crossing Over: Occurs in Prophase 1, contributing to genetic diversity
• Random Chromosome Assortment: In Anaphase 1, increases genetic variation
• Fusion of sperm and egg creates a zygote (diploid)

Genetics and Heredity

• Inheritance involves DNA, chromosomes, genes, and traits
• DNA is present in almost all cells, inherited from both parents

Structure of DNA

• DNA: Double helix, composed of nucleotides (sugar, phosphate, base)
• Four bases: Adenine (A), Thymine (T), Cytosine (C), Guanine (G)
  • Pairing: A-T, C-G

Gene Expression

• Genes: Segments of DNA coding for proteins
• Proteins determine traits and support various cellular functions
• Regulatory genes: Control expression of other genes

RNA and Protein Synthesis

• RNA Types:
  • mRNA (messenger RNA): Carries genetic information from DNA
  • rRNA (ribosomal RNA): Part of ribosomes
  • tRNA (transfer RNA): Transfers amino acids to ribosomes
• Transcription: DNA to mRNA
• Translation: mRNA to protein
  • mRNA sequence dictates tRNA and amino acid assembly

Practice Questions

• Crossing over occurs in Prophase 1 of Meiosis
• Mitosis results in two identical diploid cells; Meiosis results in four unique haploid cells
• Meiosis enhances genetic diversity through random assortment of chromosomes
• DNA forms genes and chromosomes; genes are specific segments coding for traits
• Regulatory genes regulate expression of other genes
• RNA polymerase initiates transcription; mRNA serves as a template for protein synthesis

Summary

• Understanding mitosis, meiosis, and genetics is crucial for comprehending cellular division and inheritance.
• The interplay of DNA, RNA, and proteins determine genetic expression and contribute to biological diversity and trait inheritance.