What term describes pairs of chromosomes that have the same genes but different alleles?

The term that describes pairs of chromosomes that have the same genes but different alleles is homologous chromosomes. Homologous chromosomes are pairs of chromosomes, one inherited from each parent, that contain the same sequence of genes at the same loci but may differ in the alleles they carry. For example, one homolog may carry a gene for brown eyes while the other may carry a gene for blue eyes.

In contrast, sister chromatids refer to the two identical copies of a chromosome that are formed by the replication of a single chromosome, and they are genetically identical to each other until they are separated during cell division. Centromeres are the specialized regions on chromosomes where the two sister chromatids are joined together and where spindle fibers attach during cell division. Telomeres are repetitive nucleotide sequences at the ends of chromosomes that protect them from degradation and are not involved in the genetic content of the chromosomes.

Thus, the concept of homologous chromosomes is essential in understanding genetic variation and inheritance, emphasizing how different alleles of the same gene can contribute to diversity within a population.