G1 is associated with which of the following cellular events? break down of the nuclear membrane DNA replication the beginning of mitosis all of the responses are correct normal cell growth and function Question 2 1 pts In comparing somatic cells and gametes, somatic cells are diploid with half the number of chromosomes. diploid with twice the number of chromosomes. haploid with half the number of chromosomes. none of the responses are correct. haploid with twice the number of chromosomes.
The Correct Answer and Explanation is :
Question 1: G1 is associated with which of the following cellular events?
The correct answer is: normal cell growth and function.
Explanation:
The G1 phase (Gap 1) is the first phase of the cell cycle, occurring right after a cell finishes mitosis (M phase) and cytokinesis. During G1, the cell grows in size, synthesizes RNA, and produces proteins necessary for cell function. It also prepares for DNA replication, which will occur in the subsequent S phase (Synthesis phase). Unlike other phases, such as G2 or M phase, G1 does not directly involve DNA replication or the breakdown of the nuclear membrane. It is primarily a phase of normal cell growth and function, where the cell carries out its routine metabolic activities and ensures it is ready for the next steps in the cell cycle.
Importantly, there is a checkpoint at the end of G1 (called the G1/S checkpoint), which assesses whether the cell has grown enough and if the environment is suitable for DNA replication. If conditions are not favorable, the cell may enter a resting phase called G0.
Question 2: In comparing somatic cells and gametes, somatic cells are:
The correct answer is: diploid with twice the number of chromosomes.
Explanation:
- Somatic cells are any cells that make up the body (except for gametes) and are diploid, meaning they have two sets of chromosomes, one from each parent. In humans, somatic cells have 46 chromosomes (23 pairs). These cells go through the full cell cycle and divide by mitosis to produce two genetically identical daughter cells.
- Gametes, on the other hand, are reproductive cells (sperm and egg in animals), and they are haploid. This means they have only one set of chromosomes, containing 23 chromosomes in humans (half the number found in somatic cells). The purpose of gametes is to combine during fertilization, restoring the diploid number of chromosomes in the zygote.
In conclusion, somatic cells are diploid with twice the number of chromosomes compared to gametes, which are haploid. The process of gametogenesis (the formation of gametes) reduces the chromosome number by half, ensuring that when sperm and egg unite, the resulting zygote will have the correct diploid number of chromosomes.