5.1 Cellular Reproduction

• Growth Phases:

  • G1 Phase: Normal metabolic roles and growth.

  • S Phase: DNA replication occurs.

  • G2 Phase: Preparation for mitosis.

• Types of Reproduction:

  • Sexual Reproduction: Combination of genetic information from two individuals, creating genetically unique offspring.

  • Asexual Reproduction: Offspring produced by a single parent, genetically identical to the parent and each other.

• Prokaryotic Reproduction:

  • Bacteria reproduce asexually via binary fission.

  • Involves one circular chromosome, sometimes a plasmid (small circular DNA).

  • Plasmids can alter metabolism or provide additional genes for survival.

  • DNA Replication: Enzyme DNA Polymerase synthesizes new strands from the original DNA template.

5.2 Genetic Variation in Bacteria

• Bacteria increase genetic diversity through:

  • Conjugation: DNA transferred between bacteria using pili.

  • Transduction: DNA from viruses is inserted into bacteria.

  • Transformation: DNA fragments acquired from the environment.

5.3 Eukaryotic Cell Cycle

• Division Mechanisms:

  • Mitosis: Division in somatic cells, producing two identical cells.

    • Somatic cells are diploid (2 sets of chromosomes).

  • Meiosis: Division in germ cells, producing four haploid cells (1 set of chromosomes).

• Eukaryotic Cell Cycle Phases:

  • Interphase: G1, S, G2 phases; majority of cell life.

  • M Phase: Mitosis occurs.

  • C Phase: Cytokinesis: cytoplasm divides,

• Chromosomes in Humans:

  • 46 total (23 pairs): 22 autosomal pairs, 1 pair of sex chromosomes.

5.4 Stages of Mitosis

• Phases of Mitosis:

  1. Prophase: Chromosomes condense, nuclear envelope disintegrates, spindle fibers form.

  2. Metaphase: Chromosomes align at the cell's equatorial plane.

  3. Anaphase: Sister chromatids separate and move toward poles.

  4. Telophase: Nuclear envelope reforms, chromosomes decondense.

• Cytokinesis: Division of the cytoplasm, cleavage furrow in animal cells.