PP9 Flashcards

Question

wHat are the 5 stages of mitosis in order?

Answer 1

``` prophase prometaphase metapahse anaphase telophase/cytoikenisis ```

Answer 2

- Chromatin condenses into chromosomes - Nucleus remains intact (but the nucleolus disintegrates) - Centrosomes separate and move around the nucleus. - Microtubule fibers extend between the centrosomes forming the mitotic spindle.

Answer 3

NOPE, only animals

Answer 4

Nuclear membrane breaks down Centrosomes are now positioned at opposite ends of the cell. Some microtubules attach to the kinetochores (centromere region) centromere: inside Motor proteins attach to microtubule tracks coming from the centrioles and the kinetochore/chromosome and move along the track, pulling the chromosome with it. The microtubules shorten by depolymerization at the end closer to the equator of the cell, i.e., the tubulin dimers forming the microtubules fall away from the end closest to the equator.

Answer 5

- Chromosomes become aligned along the cell midline (metaphase plate), also called equator. - For each chromosome, the kinetochores of the sister chromatids are attached to microtubules coming from opposite poles.

Answer 6

- Centromeres break and sister chromatids separate. - Chromosomes pulled to opposite ends of the cell, using microtubules as tracks. - Cells elongate - At the end of anaphase, each pole of the cell has a complete set of chromosomes.

Answer 7

- One copy of each chromosome is present at the opposite ends of the cell. - The chromatin fibers starts to loosen and become less coiled. - Spindle fibers disappear - Nuclear membrane forms around chromosomes.

Answer 8

Telophase marks the end of mitosis, even if cell division is not entirely complete. The formation of the cleavage furrow is the signal. Actin filaments are pinching the long cell in half.

Answer 9

- When the cytoplasm divides into two new daughter cells. - Cell gradually pinches in along the midline forming a cleave furrow - 2 new daughter cells are formed with identical genetic information - Cells may enter G1 of Interphase and repeat the cycle again! These cells would be blood forming cells, intestinal cells, skin cells, etc.

Answer 10

- Not all cells in your body actively participate in the cell cycle, since not all tissues require rapid replenishing of cells. - Many cells pause in the cell cycle somewhere between M phase and S phase for periods ranging from days to more than a year. - This period is called G0 phase and is distinguished from G1 phase by the absence of preparations for S phase. - Although cells in G0 phase have exited the cell cycle, they are still active in other ways, performing specialized functions

Answer 11

- Mitosis in plant cells is similar (but they have no centrioles) - Major difference is in cytokinesis: Cells can’t pinch in half like in animal cells Daughter cells in plants are separated by the cell plate which forms from vesicles from the Golgi. They move to the centre of the dividing cell and form a cell plate. The cell membrane will develop on either side of the plate.

Answer 12

- Cyclical operating set of molecules in the cell that both triggers and coordinates key events in the cell cycle. - At specific times, the cells checks itself to make an assessment if everything is ok. - For many mammalian cells, the G1 checkpoint (the “restriction point”) appears to be the most important. - If a cell receives a go-ahead signal at the G1 checkpoint then it usually goes through S, G2 and M phases. - If it does not, the cell goes to G0

Answer 13

These check points are controlled by special regulatory proteins. One of the most important regulatory proteins is called p53, which is classified as a tumor suppressor protein, also called Guardian of the Genome

Answer 14

1. It can pause the cell cycle and initiate cell DNA repair mechanisms that spot replication errors and fixes them. 2. If the DNA cannot be repaired it will induce cell death or apoptosis, which is programmed cell death

PP9 Flashcards

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