What is the primary difference between sister chromatids and homologous chromosomes?

• A. Sister chromatids are involved in meiosis, while homologous chromosomes are involved in mitosis.
• B. Sister chromatids are identical copies of a single chromosome, while homologous chromosomes are pairs of chromosomes containing the same genes but may have different alleles.
• C. Sister chromatids are pairs of chromosomes containing different genes, while homologous chromosomes are identical copies of a single chromosome.
• D. Sister chromatids are found only in prokaryotic cells, while homologous chromosomes are found in eukaryotic cells.

Answer: (B)

Verified step by step guidance

1. Understand the definitions: Sister chromatids are identical copies of a single chromosome that are connected by a centromere. Homologous chromosomes are pairs of chromosomes that have the same genes at the same loci but may have different alleles.
2. Identify the context of occurrence: Sister chromatids are formed during DNA replication in both mitosis and meiosis, whereas homologous chromosomes are present in diploid organisms and are involved in meiosis.
3. Consider genetic composition: Sister chromatids are genetically identical, as they are copies of the same chromosome. Homologous chromosomes, however, can have different alleles for the same genes, contributing to genetic diversity.
4. Differentiate based on cellular processes: During mitosis, sister chromatids separate to ensure each daughter cell receives an identical set of chromosomes. In meiosis, homologous chromosomes pair up and can exchange genetic material through crossing over, leading to genetic variation.
5. Clarify the cell type: Both sister chromatids and homologous chromosomes are found in eukaryotic cells. Prokaryotic cells do not have homologous chromosomes as they typically have a single circular chromosome.