Cell Division and Meiosis Overview

Study Notes

Cell Division

Binary fission is DNA duplication followed by cell splitting in two.
Prokaryotes use this simple reproductive strategy.
The cell cycle has distinct phases.
Interphase consists of G1 (growth, checkpoint), S (DNA duplication), and G2 (preparation).
Mitosis is the nuclear division phase.
Checkpoints (G1, G2, M) regulate cell cycle progression.
G0 is the resting phase, where cells stop dividing (e.g., neurons).
Cytokinesis is the division of the cytoplasm; methods differ in organisms (plants, animals, fungi).
Density-dependent inhibition stops cells from dividing when crowded.
Anchorage dependence requires cell attachment for division.
Cancer cells lack density-dependent inhibition, exhibiting uncontrolled growth.
Transformation is the process of normal cells becoming cancerous.

Meiosis

Meiosis is crucial for sexual reproduction, generating gametes.
Diploid cells (full set) are crucial starting material.
Haploid cells (half set) form as a result of meiosis.
Meiosis I separates homologous chromosomes, including crossing over in Prophase I.
Random alignment of homologous pairs in Metaphase I increases diversity.
Meiosis II separates sister chromatids to make four haploid cells.
Gamete formation varies in males (4 sperm per diploid cell) and females (1 egg + polar bodies).
Crossing over in Prophase I exchanges genetic material between homologous pairs.
Nondisjunction results in abnormal chromosome numbers (e.g., Down syndrome).

Genetics

Genes are DNA sequences coding for proteins.
Locus is the specific location of a gene on a chromosome.
Sexual reproduction enhances adaptability.
Asexual reproduction produces clones efficiently but lacks diversity.
Homologous chromosomes have corresponding lengths, centromere positions, and gene types.
Autosomes are non-sex chromosomes (22 pairs).
Sex chromosomes determine sex (XX = female, XY = male).
X-linked traits are carried on the X chromosome (e.g., colorblindness).
Hemizygous refers to males having one X chromosome copy for traits on that chromosome.
Chromosomal mutations (deletions, translocations) are often severe or lethal.
Syndromes result from specific chromosomal mutations (e.g., Turner, Klinefelter syndromes).
XXY is Klinefelter syndrome, with male characteristics and some female traits.

Mendelian and Molecular Genetics

Linked genes are inherited together (due to proximity on the same chromosome).
Crossing over can separate linked genes.
Chi-Square Analysis is a statistical method to determine if observed data matches expected data. Formula ( \chi^2 = \sum \frac{(O - E)^2}{E} ).
Fruit flies (Drosophila) are widely used in genetic studies, due to rapid reproduction, easily observable traits, and simple genetic makeup.
XX and XY determine fruit fly sex.

Important Terms

Aneuploidy: Abnormal chromosome number (e.g., Down syndrome - trisomy 21).
Chiasmata: Crossover points during homologous chromosome pairing.
Barr body: Inactivated X chromosome in females.
Tetrad: Group of four chromatids during meiosis.

Description

This quiz covers essential concepts in cell division, including binary fission and the cell cycle phases such as interphase and mitosis. It also delves into meiosis, highlighting its role in sexual reproduction and gamete formation. Test your understanding of these fundamental biological processes!