Question

In my text book ,it is written that a chromosome has 1000s of genes and it is distributed throughout the chromatids except in the centromere. But we know that the chromosomes have DNAs inside them which have complementary base pairs. Then are these base pairs known as genes??

Answer 1

Genes are specific sequences of DNA on chromosomes that code for proteins, affecting an individual's genotype and phenotype. Not all DNA sequences are genes, and the centromere is typically gene-free. Different forms of a gene, called alleles, contribute to genetic diversity within homologous chromosomes.

Step-by-step explanation:

The human genome contains over 20,000 genes, which are specific sequences of DNA that code for functional products, such as proteins. These genes are distributed across the 23 pairs of chromosomes found in each human cell. While DNA consists of a double-stranded helix of nucleotides, where adenine (A) pairs with thymine (T) and cytosine (C) pairs with guanine (G), not all sequences of DNA are genes. Genes are particular sequences within the DNA that contain the instructions for building proteins necessary for the body's structure and function.

Each chromosome is composed of DNA and proteins, and though they contain thousands of genes, the centromere is typically not a location for genes. The role of the centromere is more structural, as it is a region that holds two sister chromatids together during cell division. The genotype of an individual is determined by the specific combination of genes inherited from both parents, while the phenotype is the observable characteristics that are expressed by these genes.

Alleles are different forms of a gene that can be found at the same locus on homologous chromosomes. These homologous chromosomes have the same genes with potentially different alleles, contributing to the genetic diversity seen in the offspring.