Question

how is dna organized in the nucleus when the cell is prepared for division? how is dna organized in the nucleus when the cell is not dividing? (figure 3-11)

tightly coiled as chromosomes; loosely coiled as chromatin

loosely coiled as chromosomes; tightly coiled as chromatin

loosely coiled as chromatin; tightly coiled as chromosomes

tightly coiled as chromatin; loosely coiled as chromosomes

Explanation:

To solve this, we recall the organization of DNA:

• When a cell is preparing for division (mitosis/meiosis), DNA is tightly coiled into chromosomes to facilitate proper segregation.
• When the cell is not dividing, DNA is in a more relaxed, loosely coiled form called chromatin, which allows for processes like transcription.

Now, analyze the options:

• Option 1: "tightly coiled as chromosomes; loosely coiled as chromatin" matches the correct organization (dividing: chromosomes, non - dividing: chromatin).
• Option 2: Reverses the coiling states for chromosomes and chromatin, so it's incorrect.
• Option 3: Reverses the states (non - dividing as chromatin is correct, but dividing as chromosomes is correct here? Wait no, the first part is "loosely coiled as chromatin" (non - dividing) and second "tightly coiled as chromosomes" (dividing)? Wait no, the question is first "when cell is prepared for division" then "when not dividing". So the first part of the option should be division state, second non - division. So option 3 has first part as non - division (chromatin) and second as division (chromosomes) which is reversed.
• Option 4: Also reverses the coiling states, incorrect.

Answer:

A. tightly coiled as chromosomes; loosely coiled as chromatin