Summary of Transcription, Translation & Cell Division

Generalized Cell Components

• Contains plasma membrane, cytoplasm, and nucleus

Nucleus Details

• Components: Nucleolus, chromatin, nuclear envelope, nuclear pore
• DNA double helix wraps around histones to form chromatin

Transcription

• Activation of specific genes to synthesize mRNA
• Occurs in the nucleus; involves RNA polymerase
• Pre-mRNA is synthesized and then processed to functional mRNA

Translation

• Takes place at ribosomes (rRNA and proteins)
• mRNA serves as a template to match tRNA (anticodon) with amino acids
• Translation phases: A-site, P-site, and E-site on ribosome
• Initiator tRNA brings methionine to the start codon
• Protein synthesis proceeds by forming peptide bonds

Protein Structure

• Levels of organization: Primary, Secondary (alpha helix, beta pleated sheet), Tertiary, and Quaternary structure
• Chaperones assist in correct folding of proteins

Cell Division

• Types of division:
  • Somatic: Mitosis (nuclear division) + Cytokinesis (cytoplasmic division)
  • Reproductive: Meiosis (gamete formation)

Mitosis Overview

• Cell cycle phases: Interphase (G1, S, G2) and Mitotic phase
• Mitosis stages: Prophase, Metaphase, Anaphase, Telophase
• Identical diploid daughter cells are produced

Meiosis Overview

• Two stages: Meiosis I and II
• Reduces chromosome number from diploid (2n) to haploid (n)
• Introduces genetic diversity via crossing over and independent assortment

Genetic Recombination

• Exchanging genetic material during meiosis enhances variability
• Mechanism essential for evolution and adaptation in populations

Control of Cell Division

• Maturation Promoting Factor (MPF) regulates the cell cycle
• Signals determine when to replicate DNA or enter mitosis
• Homeostasis involves balance between cell division and programmed cell death (apoptosis) or necrosis

Locations of Meiosis

• Occurs in gonads: testes in males, ovaries in females
• Results in ova and sperm, each with haploid number following meiosis.