Question

how are sister chromatids and homologous chromosomes different from each other?
○ homologous chromosomes are closely associated with each other in both mitosis and meiosis. sister chromatids are only associated with each other during mitosis.
○ they are not different. homologous chromosomes and sister chromatids are both identical copies of each other.
○ homologous chromosomes contain the same gene loci but may have different alleles of a particular gene. sister chromatids are identical copies of each other produced during dna replication.
○ homologous chromosomes are identical copies of each other. one sister chromatid comes from the father, and one comes from the mother.
○ sister chromatids are only formed during mitosis. homologous chromosomes are formed during meiosis.

Explanation:

1. Analyze Option 1: Homologous chromosomes pair in meiosis (synapsis) but not closely associated in mitosis; sister chromatids are associated in both mitosis (until anaphase) and meiosis (until anaphase II), so this is incorrect.
2. Analyze Option 2: Homologous chromosomes are not identical (they can have different alleles), while sister chromatids are identical copies, so this is wrong.
3. Analyze Option 3: Homologous chromosomes have the same gene loci (same genes) but can have different alleles (e.g., one from father, one from mother). Sister chromatids are formed by DNA replication, so they are identical copies. This matches the correct understanding.
4. Analyze Option 4: Homologous chromosomes are not identical copies (they are from different parents), and sister chromatids are both from the same parent (after replication of one chromosome), so this is incorrect.
5. Analyze Option 5: Sister chromatids are formed during S - phase (before both mitosis and meiosis), and homologous chromosomes are present in the cell (in diploid cells) throughout, not formed during meiosis. So this is wrong.

Answer:

C. Homologous chromosomes contain the same gene loci but may have different alleles of a particular gene. Sister chromatids are identical copies of each other produced during DNA replication.