Answer 1) The G2 checkpoint exists before the M phase. It checks for DNA damage as well as DNA replication. If the DNA has incorrect replication it will pause at the G2 phase and allow for repair. If the repair is unable to be complete it results in the cell entering the apoptosis pathway of programmed cell death.
Thus the answer is C) A and B only.
Answer 2) Deamination is the loss of ammonia by a hydrolysis reaction resulting in the conversion of a cytosine into a uracil this often occurs spontaneously. This is a replacement of the base, not a loss.
When depurination occurs with DNA, it leads to the formation of apurinic site and results in an alteration of the structure. This results in information loss in the form of bass loss.
Thymine dimers are formed by the dimerization of to pyrimidine molecules. This results in the formation of molecular lesions. This is not a type of base loss.
Insertion is addition of a base in the genome. This is not a type of base loss.
Thus the answer here is B) Depurination.
Answer 3) DNA ligase is the enzyme used to join fragments of DNA together. Thus the answer is A) Ligase.
In order for a cell to move past the G2 checkpoint and into M phase, the...
6.) Mitogens are (b) transcription factors important for cyclin production (c) kinases that cause cells to grow in size (a) extracellular signals that stimulate cell division. d) produced by mitotic cells to keep nearby neighboring cells from dividing 7.) Which of the following cyclins is most active during mitosis? (a) cyclin A (b) cyclin B (c) cyclin C (d) cyclin D 8) Which molecule inactivate itotic cyclin-CDK complexes using phosphorylation? (a) Cdc25 (b) Cdc6 (c) Weel (d) Helicase 9.) What...
Dynamic phosphorylation/dephosphorylation is key to proper cell cycle control in that: (select all answers that apply) A. CAKs phosphorylate (and activate) CDK subunits. B. Wee1 kinase phosphorylates (and activates) CDK subunits. C. Cdc25 kinase phosphorylates (and activates) CDK subunits. D. Phosphorylation of the CKI Sic1 directs its subsequent ubiquitination and proteasomal degradation. E. Kinases phosphorylate (and activate) SCF, the ubiquitin ligase responsible for degradation of G1/S phase cyclins.
Which of the following is NOT a checkpoint that controls the progression of the cell cycle? 0 Cyclins and cyclin-dependent kinases are proteins that are responsible for advancing a cell through the phases of the cell cycle. The G2 checkpoint checks for DNA damage and determines if all of the DNA is replicated. The metaphase checkpoint determines if all chromosomes are attached to the spindle apparatus. Cytokinesis involves the formation of cleavage furrow to separate the cells. The restriction point...
2. Cyclin B plus CDC2 are necessary for a checkpoint at the G2->M transition that makes sure chromosomes are intact before mitosis begins. If you irradiate cells in G2 phase with gamma rays, which damages the DNA that was successfully replicated in S-phase, cells delay entry into mitosis until the DNA damage is repaired. If you inactivated that Cyclin B/ CDC2 checkpoint with the drug wortmannin and irradiated cells in G2, what would happen? a) Cells would never enter mitosis...
1 You are a studying the progression of cells through the cell cycle. You are particularly interested in the cyclins E and A, both of which contribute sequentially to the same cell cycle transition. In this case one cyclin initiates the transition and the other completes the process. In these images you see cell extracts from Hela Cells. A) shows the levels of various proteins, while B) shows the amount of DNA in the cells, more DNA shifts this graph...
9. In human cells four different cyclins drive the cell cycle (see picture). Please, note that the cyclins overlap (the picture shows the concentration of each cyclin protein in the cytoplasm). Write a short essay or outline of an experiment to test the following things: How can you figure out how much cyclin protein is present in the cytoplasm at different phases of the cell cycle? B. How can you figure out if there is overlap between the cyclins? For...
QUESTION 1 causes de-activation of M phase cyclin/CDK complexes, which triggers exit from mitc O A. APCIC-directed degradation of mitotic cyclins O B-SCF-directed degradation of mitotic cyclins ° C. Inactivation of Cdc14 OD. Phosphorylation of Sic1 OE Inactivation of separase
In most cells, where do all microtubules originate? What is the difference between a kinetochore and a centromere? During mitosis, the breakdown of the nuclear envelope depends on the: a. disassembly following proteasomal degradation of intermediate filaments. b. disassembly of lamin filaments following phosphorylation by mitotic cyclin/cdk complexes. c. ubiquitination of mitotic cyclin proteins. d. lamin filament dephosphorylation by cdc14. Which of the following occurs during anaphase A? a. The spindle elongates. b. Kinetochores remain attached to shortening kinetochore microtubules....
4. Short response (2 sentences max, 6pts each) A. Many yeast species have only one cyclin-dependent kinase (Cdk), which activates protein targets that drive events in multiple phases of the cell cycle. Why doesn't this Cdk activate G1-, S-, G2-, and M-phase proteins all at the same time? B. Please describe how cell death by apoptosis can play a beneficial role in the body's healthy growth. C. For a cell starting in G1, place the following cell cycle events in...
4. Short response (2 sentences max, 6pts each) A. Many yeast species have only one cyclin-dependent kinase (Cdk), which activates protein targets that drive events in multiple phases of the cell cycle. Why doesn't this Cdk activate G1-, S-, G2-, and M-phase proteins all at the same time? B. Please describe how cell death by apoptosis can play a beneficial role in the body's healthy growth. C. For a cell starting in G1, place the following cell cycle events in...