Which One of the Choices is Capable of Phosphorylating Key Proteins Involved in Regulating the Cell Cycle?

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Are you trying to complete a quiz or exercise about biology? One of the questions that you have may be which one of the options which can phosphorylating key proteins involved in regulating the cell cycle. If you have this quiz and you do not know the answer, let’s find out here.

The Answer of Which one of the choices is capable of phosphorylating key proteins involved in regulating the cell cycle

In the Quizlet website, there is a question which asks you about which one of the choices is capable of phosphorylating key proteins involved in regulating the cell cycle. Here is the question and the answer to this question.

Question: Which one of the options is capable of phosphorylating key proteins involved in regulating the cell cycle?

a. phosphatase
b. CDK
c. p53 protein
d. cyclin-CDK complex
e. cyclin

Answer: D. cyclin-CDK complex

The Other Questions in Quizlet

The question above can be found on the Quizlet website in Week 5 Study. There are still more questions in this Week 5 Study and you are able to see the questions and answers below.

  • Question: True or false, during meiosis, two rounds of DNA synthesis are required to form four gametes from one parent cell.
    Answer: False
  • Question: During meiosis I ….
    a. nonsister chromatids exchange maternal and paternal DNA.
    b. bivalents are formed during prophase I and are taken apart during anaphase I.
    c. chromosomes undergo reductional division.
    d. All of these choices are correct.
    e. Sister chromatids are not separated.
    Answer: d. All of these choices are correct.
  • Question: Most of the important changes in activities and functions that accompany passage through a cell cycle checkpoint are regulated by the…
    a. activation of kinase enzymes
    b. changes in membrane polarization
    c. activation of microtubules.
    d. activation of DNA polymerase.
    e. inhibition of cyclin proteins.
    Answer: a. activation of kinase enzymes
  • Question: Which of the following is not true about gametes?
    a. They fuse to shape a new organism during fertilization.
    b. Their names are eggs and sperm in animals.
    c. They own half as many chromosomes as a somatic cell of the similar individual.
    d. They are genetically the same to other gametes shaped during meiosis.
    e. They are formed by meiotic cell division.
    Answer: d. They are genetically the same to other gametes shaped during meiosis.
  • Question: When DNA replication is incomplete, which major checkpoint delays the cell cycle?
    a. G1 checkpoint
    b. M checkpoint
    c. G2 checkpoint
    d. G1, G2 and the M checkpoints
    e. When DNA replication is incomplete, none of the checkpoints delay the cell cycle.
    Answer: c. G2 checkpoint
  • Question: You have to consider a diploid organism (2n) with a haploid complement (n) of four chromosomes. At Prophase I, how many total chromosomes will be available in a cell?
    a. twelve, four pairs of homologous chromosomes and their haploid complement
    b. sixteen, four pairs of homologous chromosomes and two sister chromatids per chromosome
    c. eight, four pairs of homologous chromosomes
    d. four, one complete set of chromosomes
    Answer: c. eight, four pairs of homologous chromosomes
  • Question: Cell division is regulated by…
    a. signals that indicate a sufficient size of the cell.
    b. signals that indicate that DNA has been replicated.
    c. signals about the nutritional status of the cell.
    d. All of these choices are correct.
    e. growth factor signals.
    Answer: d. All of these choices are correct.
  • Question: The S cyclin-CDK complex…
    a. triggers initiation of DNA synthesis during the S phase.
    b. prevents initiation of DNA synthesis a second time during the S and G2 phases.
    c. All of these choices are correct.
    d. both controls the cell cycle during the S and G2 Phases, and triggers initiation of DNA synthesis during the S phase.
    e. controls the cell cycle during the S and G2 phases.
    Answer: c. All of these choices are correct.
  • Question: The second meiotic division resembles mitosis because…
    a. sister chromatids are separated during anaphase II to become the chromosomes of the daughter cells.
    b. chromosomes decondense during telophase II.
    c. microtubules attach from opposite directions to the centromere of each sister chromatid pair.
    d. the daughter cells have the same number of chromosomes as the parent cells.
    e. All of these choices are correct.
    Answer: e. All of these choices are correct.

About The Positive Regulation of the Cell Cycle

According to the Lumen Learning website, here is the explanation about control of the cell cycle, especially about the positive regulation of the cell cycle.

There are two groups of proteins and those are cyclins and cyclin-dependent kinases (Cdks). They have a responsibility to the progress of the cell through the various checkpoints. The levels of the four cyclin proteins undergo fluctuation throughout the cell cycle in a pattern which is predictable. There are increases in the concentration of cyclin proteins and those increases are triggered by both internal and external signals. Let’s say that the cell has moved to the next stage of the cell cycle. If so, the cyclins that were active in the prior stage are lowered.

The cell cycle is only regulated by cyclins when they are tightly bound to Cdks. To make it fully active, the Cdk/ cyclin needs to be phosphorylated in specific locations as well. Same as all kinases, Cdks are enzymes (kinases) which phosphorylate other proteins. The protein is activated by phosphorylation by changing its shape. The proteins which are phosphorylated by Cdks are involved in advancing the cell to the next phase. Throughout the cell cycle, Cdk protein levels are relatively stable. However, there is a fluctuation in the concentrations of cyclin and the concentrations determine when Cdk/cyclin complexes form. At specific points, the different cyclins and Cdks bind in the cell cycle and regulate checkpoints which are different.

Even though the cyclins are the primary regulatory molecules that determine the forward momentum of the cell cycle, there are some other mechanisms which fine tune the progress of the cycle with negative, rather than positive, effects. Essentially, these mechanisms block the progression of the cell cycle and it happens until problematic conditions are resolved. Cdk inhibitors are molecules which prevent the full activation of Cdks and there are many of these inhibitor molecules that directly or indirectly monitor a particular cell cycle event.

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