Structure and Components of Chromosomes

Structure of Chromosomes

• A chromosome is a thread-like structure made up of DNA and proteins that carry genetic information in the nucleus of eukaryotic cells.
• Chromosomes are found in the nucleus of eukaryotic cells and in the nucleoid region of prokaryotic cells.

Components of Chromosomes

• Centromere: a specialized region near the center of the chromosome that plays a crucial role in the separation of chromosomes during cell division.
• Telomeres: repetitive DNA sequences (TTAGGG in humans) that cap the ends of chromosomes, protecting them from deterioration and fusion.
• Origins of replication: regions where DNA replication is initiated.

Types of Chromosomes

• Autosomes: non-sex chromosomes that are identical in both males and females.
• Sex chromosomes: X and Y chromosomes that determine the sex of an individual (XX for females and XY for males).

Number of Chromosomes

• Humans have 23 pairs of chromosomes, for a total of 46 chromosomes per cell.
• The number of chromosomes can vary between species.

Chromosomal Abnormalities

• Aneuploidy: a condition where a cell has an abnormal number of chromosomes, which can lead to genetic disorders.
• Translocation: a type of chromosomal abnormality where a segment of a chromosome breaks off and attaches to a non-homologous chromosome.
• Deletion: a type of chromosomal abnormality where a segment of a chromosome is missing.
• Duplication: a type of chromosomal abnormality where a segment of a chromosome is copied and attached to the same chromosome.