What are Chromosomes?
A chromosome is a thread-like structure made of DNA and proteins, located inside the nucleus of eukaryotic cells. It carries genetic information in the form of genes, acting as the organized package of genetic material essential for cell function and heredity.
Structure and Composition
Each chromosome consists of a single, long DNA molecule tightly coiled many times around proteins called histones. These histones provide structural support, helping to condense the long DNA into a compact form that fits within the cell nucleus. During cell division, chromosomes become even more condensed and visible, often appearing as an 'X' shape composed of two identical sister chromatids joined at a centromere.
Chromosomes in Heredity
Chromosomes are the vehicles for transmitting genetic traits from parents to offspring. Humans typically have 23 pairs of chromosomes (a total of 46) in most cells. One chromosome from each pair is inherited from the mother and the other from the father. This includes 22 pairs of autosomes and one pair of sex chromosomes (X and Y), which determine biological sex.
Importance in Cell Division
The organized structure of chromosomes is crucial for accurate cell division (mitosis for growth and repair, meiosis for reproduction). During these processes, chromosomes duplicate and then precisely divide, ensuring that each new daughter cell receives a complete and identical set of genetic instructions, vital for the survival and proper functioning of the organism.