AP BIOLOGY

CELL DIVISION

THE CELL CYCLE

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
DEFINE:What is a chromosome?
A
an organelle found only in a plant cell
B
process in which DNA is copied
C
regular sequence of growth and division that cells undergo
D
doubled rod of condensed chromatin
Explanation: 

Detailed explanation-1: -chromosome – A double rod of condensed chromatin.

Detailed explanation-2: -Chromatin in the nucleus condenses to form double-rod structures called chromosomes. Looks like an “X”. Each chromosome has two rods because the cell’s DNA has replicated, and each rod in a chromosome is an exact copy of the other.

Detailed explanation-3: -The condensation of chromatin is characterized by a reduction of volume due to a spatial organization into densely packed higher-order structures (8). Specific histone modifications, e.g., histone H1 and H3 phosphorylation, occur at mitosis and contribute to the individualization and condensation of chromosomes.

Detailed explanation-4: -During prophase, the threadlike chromatin in the cell’s nucleus begins to condense into tiny rods. Scientists call each doubled rod of condensed chromatin a chromosome. Each identical rod, or strand, of the chromosome is called a chromatid.

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