Question

Consider a cross between two individuals with genotypes AaBb. Match the chromosomes as they would appear in a cell at G1, G2, and metaphase of mitosis.

A) G1: AB; G2: Ab, aB; Metaphase: AB
B) G1: AB; G2: AB, ab, Ab, aB; Metaphase: AB, Ab, aB, ab
C) G1: Ab, aB; G2: AB, Ab, aB, ab; Metaphase: AB
D) G1: AB, Ab, aB, ab; G2: AB; Metaphase: AB

Answer 1

At G1 of the cell cycle, chromosomes are in a single form (Ab, aB). In G2 phase, chromosomes have replicated into sister chromatids (AB, Ab, aB, ab). During metaphase, these align at the equatorial plane also as (AB, Ab, aB, ab).

Step-by-step explanation:

When considering a cross between two individuals with genotypes AaBb, you can track the chromosomes and their alleles through the phases of the cell cycle to identify what genotypes would be present at specific stages - G1, G2, and metaphase of mitosis. At the G1 phase, each chromosome has not yet replicated, so they are still in single form, like Ab and aB.

During G2 phase, after DNA replication, each chromosome is duplicated into sister chromatids that remain attached - these appear as AB, Ab, aB, and ab. At the metaphase of mitosis, the chromosomes will align at the cell's equatorial plane as sister chromatids, still in pairs, represented as AB, Ab, aB, and ab, prepared for segregation into daughter cells.