Genetic

Genetics Study Notes

1. Key Definitions

• Haploid: A cell with one set of chromosomes (e.g., gametes).

• Diploid: A cell with two sets of chromosomes (e.g., somatic cells).

• Spindle: Microtubule structure that separates chromosomes during cell division.

• Synapsis: Pairing of homologous chromosomes during meiosis.

• Gamete: Sex cell (e.g., sperm or egg) containing half the genetic material.

• Zygote: A fertilized egg cell resulting from the union of two gametes.

• Dominant: An allele that masks the effect of a recessive allele.

• Recessive: An allele whose effect is masked by a dominant allele.

2. Process of Mitosis and Cell Cycle

• Purpose: To create identical somatic cells for growth, repair, or replacement.

• Phases of the Cell Cycle:

  1. Interphase: Cell grows, performs normal functions, duplicates DNA.

  2. Mitosis:

     • Prophase: Chromosomes condense, spindle forms, nuclear envelope dissolves.

     • Metaphase: Chromosomes align at the cell’s equator.

     • Anaphase: Sister chromatids are pulled apart to opposite poles.

     • Telophase: Nuclear envelope reforms; chromosomes de-condense.

  3. Cytokinesis: Cytoplasm divides, forming two identical cells.

3. Process of Meiosis

• Purpose: To create gametes with half the chromosome number for sexual reproduction.

• Steps:

  1. Meiosis I (Reduction Division):

     • Homologous chromosomes separate.

     • Crossing over occurs during prophase I (increases genetic diversity).

     • Results in two haploid cells.

  2. Meiosis II:

     • Similar to mitosis; sister chromatids separate.

     • Results in four haploid gametes.

4. Compare Mitosis & Meiosis