Misc.
Name the five phases of mitosis in order.
1. Prophase
2. Prometaphase
3. Metaphase
4. Anaphase
5. Telophase (and Cytokinesis)
Spindle fibers attached to the kinetochores align the chromosomes (sister chromatids) along the middle of the cell.
What is metaphase?
The cell cycle phase in which cells, such as nerve or muscle cells, are dormant.
What is the G0 phase?
A partial hepatectomy, or the surgical removal of a section of the liver, is often performed to treat tumors or other abnormal growths in the liver. Following a partial hepatectomy, resting liver cells re-enter the cell cycle, duplicating until the excised portion of the liver has been regenerated.
According to the information above, performing a partial hepatectomy causes liver cells to
Exit G0 phase and enter G1 phase
In E. Coli, the sites in which DNA replication begins, which moves to opposite ends of the bacterium
or
The process of asexual reproduction where a single-celled organism grows to roughly twice its size and then splits into two cells.
What is origin of replication?
or
What is binary fission?
What happens during telophase and cytokinesis?
(Animal or plant cells)
Telophase: Daughter nuclei begin forming in the cell around the two ends of the cell to contain the newly split chromosomes, fibers are depolymerized, and chromosomes become less condensed
Cytokinesis (animals cells): Formation of a cleavage furrow where the cell splits in two.
Cytokinesis (plant cells): Vesicles along the metaphase plate create the cell plate.
Describe density-dependent inhibition
and/or
Describe anchorage dependence.
Density-Dependent Inhibition: Cells that are too crowded (not enough space) will stop dividing.
Anchorage Dependence: Cells must be attached to something (substratum) in order to divide
Human papillomavirus (HPV) is a viral infection that is transmitted mainly through skin-to-skin contact. Following transmission, HPV enters host cells and integrates into the host genome, eventually causing the cells to synthesize the viral protein E6. In turn, E6 inactivates the host protein p53, a tumor suppressor that arrests the cell cycle or induces apoptosis when DNA damage is detected.
Regarding cell division, what would happen to the infected cell?
HPV causes uncontrolled cell division in infected cells.
Briefly explain the two major steps of somatic cell division
(You don't need to explain the entire process of each, just give a basic summary)
1. Mitosis - The division of genetic material in the nucleus
2. Cytokinesis - The division of the cytoplasm
What happens during prophase? (At least 2)
Chromatin condense into chromosomes and into two sister chromatids.
The centrosomes begin to form the mitotic spindle and move away from each to the opposite ends of the cell.
The nucleolus disappears
What is the difference between a benign tumor and a malignant tumor?
Benign: Abnormal cells remain only at the site in which they grew because they have too few cellular changes to survive at other sites
Malignant: Abnormal cells that can spread to other sites through metastasis
A student is examining a whitefish blastula cell under a microscope. Based on his observations, the student proposes that the whitefish blastula cell is in interphase.
What observation about the cell would support the student's claim? (Hint: Talk about chromosomes)
The genetic content (chromosomes) of the cell exists as dispersed chromatin
If a cell has half as much DNA as other cells in mitotically active tissue, which cell cycle phase must it be in?
What is the G1 phase?
What happens during prometaphase?
Spindle fibers (kinetochore microtubules) attach to the kinetochores of the chromosomes. Fibers that don't attach to chromosomes overlap with each other
The fibers attached to both sides of a chromosomes begin to move the chromosomes to the middle of the cell through a sort of "shuffle"
You accidentally fall and scrape your knee on the concrete below you. As a result, some of your platelets release this type of protein to help stimulate the division of fibroblasts to help heal the wound.
What is a growth factor?
(Specifically a platelet-derived growth factor)
The formation of a cell plate is beginning across the middle of a cell and nuclei are re-forming at opposite ends of the cell. What kind of cell is this?
(Name both cell type and phase)
A plant cell undergoing telophase/cytokinesis
Explain how a chromosome moves along a mitotic spindle from the metaphase plate to the spindle pole (centrosome) occurs
Motor proteins on kinetochores move the chromosome down the spindle and motor proteins at the spindle pole reels then in
What happens during anaphase? (At least 2)
The cohesins, protein holding sister chromatids together, are removed by the enzyme separase
The newly made chromosomes are moved to the opposite ends of the cell by the depolymerization of the microtubules at the kinetochore ends.
Non-kinetochore microtubules lengthen and elongate the cell.
Describe what makes a cancer cell different from a regular cell
(At least 2 things)
Cancer cells don't need a growth factor from their culture to divide and can instead produce their own or convey a factor's signal in its absence.
Cancer cells stop dividing at random points in the cell cycle rather than at checkpoints.
Cancer cells can divide indefinitely if given a continuous supply of nutrients
Cancer cells can avoid apoptosis when something is wrong
Cyclin B is a mitotic cyclin that helps control the progression of cells into and out of mitosis during the cell cycle. During G22start subscript, 2, end subscript phase, cyclin B binds to and activates CDK1, a cyclin-dependent kinase. The resulting cyclin B/CDK1 complexes are then transferred into the nucleus, where they trigger entry into mitosis.
In order for cells to exit mitosis, the cyclin B/CDK1 complexes must be inactivated. This occurs through the selective degradation of cyclin B by specific enzymes (CDK1 remains intact). Once the levels of cyclin B are sufficiently reduced, cells transition out of mitosis and into G11start subscript, 1, end subscript phase, ready to undergo another cell cycle.
Based on the information above, describe the effect of a toxin that prevents the degradation of cyclin B during the cell cycle
Cells would be arrested in mitosis, and cell division would stop.