5136947
Description
Flashcards by Bee Brittain, updated more than 1 year ago
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Created by Bee Brittain
over 8 years ago
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| Question | Answer |
| How many daughter cells does mitosis produce? What are special about these daughter cells and their parent cells? | 2 and the daughter cells are genetically identical to their parent cells |
| What is the event called where a daughter cell might not end up being genetically identical to its parent cell? | Mutation |
| What is mitosis always proceeded by? | Interphase |
| The first stage of mitosis | Prophase |
| Prophase ( C, S.f) | - Chromosomes first become visible as long thin threads. They then condense and shorten. - Centrioles move to opposite ends (poles) of the cell - Spindle fibres develop from each centriole (spindle apparatus) |
| Prophase (N, C, S.f) | -The nucleus disappears - Nuclear Envelope breaks down - Chromosomes free in the cell - Chromosomes are drawn towards the equator of the cell by the spindle fibres attached to the centromere |
| Second stage of mitosis | Metaphase |
| Metaphase | - Chromosomes are seen to be made up of two chromatids each of which is an identical copy of DNA from the parent cell. - Chromatids are joined by the centromere - It is to this centromere that som emicrotubules from the poles are attached and the chromosomes are pulled along the spindle apparatus and arrange themselves on the equator of the cell. |
| What is the 3rd stage of mitosis? | Anaphase |
| Anaphase | - Centromeres divide into two and the spindle fibres pull the single chromatids, that make up the chromosomes, apart - Chromatids move to opposite ends of cell -Energy for the process is provided by mitochondria |
| Telophase | - Chromosomes reach poles - Chromosomes become longer and thinner, finally disappearing altogether, leaving only widely spread chromatin - Spindle Fibres disintegrate - Nucleolus and nuclear envelope re-form |
| Cytokinesis | Cytoplasm divides into two |
| Bacterium divide by what process? | Binary fission |
| State what happens during binary fission | - replication of the circular DNA and of plasmids - division of the cytoplasm to produce two daughter cells, each with a single copy of the circular DNA and a variable number of copies of plasmids. |
| Viruses are a-cellular and non-living and so cannot divide via mitosis, instead, how do they divide? | They attach to a host cell with attachment proteins on its surface. They then inject their nucleic acid into the host cell. The genetic information in the nucleic acid tells the cells metabolic processes to start producing viral components which then form a new virus. |
| Why is it essential to make exact copies of cells? | Repair - New cells have to have the same structure and function to the one they are replacing. Reproduction - single-celled organisms divide by mitosis Growth - 2 haploid cells fuse to form a diploid cell, if this cell is to resemble its parents all the cells that grow from that one cell has to be genetically identical |
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