During mitosis, what is the primary difference between sister chromatids and homologous chromosomes?

• A. Sister chromatids are found only in prokaryotes, while homologous chromosomes are found only in eukaryotes.
• B. Sister chromatids are identical copies of a single chromosome connected by a centromere, while homologous chromosomes are pairs of chromosomes with the same genes but possibly different alleles.
• C. Sister chromatids are formed during meiosis, while homologous chromosomes are formed during mitosis.
• D. Sister chromatids have different genes, while homologous chromosomes are genetically identical.

Answer: (B)

Verified step by step guidance

1. Step 1: Understand the definitions of sister chromatids and homologous chromosomes. Sister chromatids are two identical copies of a single chromosome that are connected by a centromere after DNA replication.
2. Step 2: Recognize that homologous chromosomes are pairs of chromosomes, one inherited from each parent, that have the same genes arranged in the same order but may carry different alleles (variations of a gene).
3. Step 3: Note that sister chromatids are formed during the S phase of the cell cycle (before mitosis), while homologous chromosomes exist as pairs throughout the cell cycle in diploid organisms.
4. Step 4: Differentiate their roles during cell division: sister chromatids separate during mitosis to ensure each daughter cell receives an identical set of chromosomes, whereas homologous chromosomes pair and separate during meiosis to reduce chromosome number.
5. Step 5: Summarize the primary difference: sister chromatids are identical copies of one chromosome connected by a centromere, while homologous chromosomes are similar but not identical pairs of chromosomes with the same genes but potentially different alleles.