7.3a. Explain what CDK proteins are and how they contribute to the passage of ce

Question

7.3a. Explain what CDK proteins are and how they contribute to the passage of cells through successive parts of the cell cycle. Also, the experiment that discovered them.

7.4.a Explain why two steps are necessary in meiosis

7.4b. Describe the process of crossing over and the consequences it yields at the completion of meiosis.

7.4.d. Describe how independent assortment works and how it can lead to genetic variation

7.5a. Compare and contrast the processes of necrosis and apoptosis, as well as their consequences for an organism.

Explanation / Answer

Since you have posted multiple questions, I am going to answer some parts of it. I hope it helps. Thanks

7.4a: Meiosis occurs twice because instead of creating two new cells with equal numbers of chromosomes, the cell does a second division soon after the firs one. That second division divides the number of chromosomes in half. When you have half the number of chromosomes, you are called a haploid cell.

7.4b: Crossing over occurs between prophase1 and metaphase1. It is the process where homologous chromosomes pair up with each other and exchange different segments of their genetic material to form recombinant chromosomes. Crossing over occurs in the first division of meiosis. At that stage each chromosome has replicated into two strands called sister chromatids. The major consequence of crosiing over is the formation of chiasma, which occurs at least once per chromosome pair. Thus, following crossing over, at least two of the four chromatids become unique, unlike those of the parent.

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