Biology Exam Notes

Mitosis

• Two cells produced.
• Each cell has the same number of chromosomes as the parent cell (e.g., 36 chromosomes).

Meiosis vs. Mitosis

• Meiosis: Produces four cells; two rounds of division; haploid; daughter cells are different from each other and the parent.
• Mitosis: Produces two cells; one round of division; diploid; daughter cells are identical to the parent and each other.

Cell Division

• Cytokinesis: Division of cytoplasm.

Chromosome Number

• Humans have 46 chromosomes.

Cell Types

• Diploid (2N): Somatic cells, homologous pairs, not gametes.
• Haploid: Sex cells (gametes), formed by meiosis, half the number of chromosomes compared to somatic cells.

Cell Cycle

• Steps: Growth Phase 1, Synthesis, Growth Phase 2, Mitosis, Cytokinesis.
• Cells spend most of their life in Interphase.

Genetics

• Gene: A segment of DNA that codes for a particular trait.
• Genetics: The study of heredity.
• Crossing over in Meiosis occurs in Prophase 1.

Reproduction

• Asexual: Unicellular, mitosis, no change in chromosome numbers, offspring is identical.
• Sexual: Two parents, multicellular, meiosis.

Sex Determination

• Female: XX
• Male: XY
• Human zygote develops into a male if it receives a Y chromosome from sperm.