Advanced Concepts in Cell Division and Genetics

This page delves into more complex terms and processes related to cell division, chromosomal behavior, and genetic variation. It covers important structures and events that occur during mitosis and meiosis.

Definition: Gametes are reproductive cells, such as sperm and egg cells, while somatic cells are any body cells that are not germ cells (reproductive cells).

Key structures and concepts:

• Spindle fibres: Protein structures that move chromosomes to opposite poles during cell division
• Centrioles: Structures in the cytoplasm where spindle fibres form, part of the cytoskeleton
• Chromatids: One half of a replicated chromosome, joined to the other half at the centromere
• Sister chromatids: Two identical copies of a parent chromosome attached at the centromere

Highlight: Replicated chromosomes contain two identical sister chromatids, while unreplicated chromosomes consist of only one double strand.

Genetic terms and processes:

• Allele: One variant of a particular gene, e.g., for eye color
• Gene: A section of a chromosome that codes for a product (protein or RNA)
• Homologous chromosomes: Chromosomes that are identical in terms of size, shape, banding pattern, and array of genes

Vocabulary: A bivalent chromosome is one pair of chromosomes (sister chromatids) in a tetrad, formed in prophase I of meiosis.

Important processes in genetic variation:

1. Independent assortment: The process in metaphase I where alleles of genes swap into different chromosomes, resulting in unique chromosome combinations
2. Crossing over: The exchange of DNA sections between homologous chromosomes, taking place in prophase I of meiosis

Example: Crossing over and independent assortment contribute to genetic diversity in offspring, which is crucial for evolution and adaptation.

These advanced concepts build upon the basic understanding of mitosis and cell division, providing a comprehensive view of the complex processes involved in cellular reproduction and genetic inheritance.