chapter2 bio chromosomes

What are Chromosomes?

Thread-like structures in the nucleus made of DNA and proteins, carrying genetic information in the form of genes.

What is DNA?

Deoxyribonucleic acid, the genetic material present in chromosomes containing instructions for an organism's development and function.

What is a Gene?

A specific sequence of nucleotides in DNA that encodes for a particular protein or RNA molecule.

What is Chromatin?

The complex of DNA and proteins (histones) that make up chromosomes.

What is the Cell Cycle?

The sequence of growth, DNA replication, and division that a cell goes through during its life.

What are the main phases of the Cell Cycle?

Interphase (G1, S, G2) and M phase (Mitosis or Meiosis).

What happens during Interphase?

The cell grows (G1), replicates its DNA (S), and prepares for division (G2).

What is Mitosis?

A type of cell division that results in two daughter cells each having the same number and kind of chromosomes as the parent nucleus, typical of ordinary tissue growth.

What are the phases of Mitosis?

Prophase, Metaphase, Anaphase, and Telophase.

What occurs during Prophase?

Chromatin condenses into visible chromosomes, the nuclear envelope breaks down, and the spindle fibers form.

What occurs during Metaphase?

Chromosomes align along the metaphase plate (equator) of the cell driven by spindle fibers.

What occurs during Anaphase?

Sister chromatids separate and move to opposite poles of the cell.

What occurs during Telophase?

Chromosomes arrive at the poles, the nuclear envelope reforms, and chromosomes decondense.

What is Cytokinesis?

The division of the cytoplasm to form two separate daughter cells, usually occurring immediately after mitosis.

What is the significance of Mitosis?

Growth, repair, and asexual reproduction in organisms; ensures genetic consistency.

What is Meiosis?

A type of cell division that results in four daughter cells each with half the number of chromosomes of the parent cell, as in the production of gametes and plant spores.

Where does Meiosis occur?

In reproductive cells to produce gametes (sperm and egg cells).

What is the significance of Meiosis?

Produces genetic variation through crossing over and independent assortment, and ensures the chromosome number remains constant across generations.

What are Homologous Chromosomes?

Pairs of chromosomes that have the same genes but may have different alleles (versions of those genes).

What is Crossing Over in Meiosis?

The exchange of genetic material between homologous chromosomes during prophase I of meiosis.