Question

Which of the following statements are true? Select one or more: a. Two sister chromatides arise by replication of the DNA of the same chromosome and remain paired as they line up on the metaphase plate b. Microtubule polymerization and depolymerization and microtubule motor proteins are all required for DNA replication during 5 Phase X C. Centrosomes are duplicated before M Phase begins d. Microtubules nucleate at the centromeres and then connect to the kinetochores, which are structures at the centromere regions of chromosomes e. Interpolar microtubules attach end-to-end and are therefore continuous from one spindle pole to the other Which of the following statements is correct? Select one or more: a. Cells do not part from G1 into 5 phase of the cell cycle unless there are sufficient nutrients to complete an entire cell cycle b. The enzymatic activity of a Cdk protein is determined both by the presence of a bound cyclin and by the phosphorylation state of the Cdk Some vertebrate cell-cycle control proteins function when expressed in yeast cells d. The period between one M phase and the next is called Gap phase (G1 and G2) e. The 'M phase of cell cycle stands for 'Mitosis' X

Answer 1

1. a) true. Sister chromatids arise from the same chromosome repication. They remain bound at metaphase plate equator.

b) False. During S phase we dont need polymerisation and depolymerisation of the microtubules. Actually they are in need during anaphase while pulling the chromosome to the opposite pole.

c) True. All the cenrioles have to duplicated before Mphase.

d) True. Microtubules bind to the the kinetochore at the centromere region

e)Yes. Both interpolar microtubules arise from opposite opposite spindle pole and overlap each other. then they slide each other to separate chromosome.

2. a) True. Cell cycle proceeds after clearing the check points in each phase of the cycle.

b) true. Phosphorylation and bound cyclin proteins are important for activation.

c) False. Different types of eukaryotic cells contain different types and numbers of CdKs. Yeast has only one Cdk and vertebrate contai four.

d) False. The period between one M phase to another M phase is called cell cycle. The cell cycle contains G1, S, G2. and M phase.Gap phase comes in between M phase and S phase. So answer is false.

e) True. The M phase stands for Mitosis.