Mitosis Flashcards
What are the two types of cell division?
Mitosis and Meiosis.
What is mitosis?
produces 2 daughter cells that have the same number of chromosomes as the parent cell and each other.
What is meiosis?
Produces 4 daughter cells with half the number of chromosomes of the parent cell.
What is the process preceding mitosis where the cell is not dividing?
Interphase which is a period of considerable cellular activity which includes the replication of DNA.
What happens in prophase, STAGE 1 of mitosis?
Chromosomes become visible. Centrioles move to opposite ends (poles) of the cell and spindle fibres develop. Nucleolus disappears and nuclear envelope breaks down, leaving the chromosomes free in the cell. Chromosomes are drawn to equator of cell by spindle fibres attached to the centromere.
What are the collective spindle fibres known as?
The spindle apparatus
What happens in metaphase, STAGE 2 of mitosis?
Chromosomes are seen to be made up of two chromatids, each an identical copy of DNA from parent cell. Chromatids are joined by centromere. Microtubules from poles attach to centromere and chromosomes are pulled along spindle apparatus and arrange themselves across the equator of cell.
What happens in anaphase, STAGE 3 of mitosis?
Centromeres divide in two and spindle fibres pull chromatids apart, chromatids move to opposite poles, now referred to as chromosomes. Energy for this process is provided by mitochondria, which gather round the spindle fibres.
What happens if chromosomes are treated with chemicals that destroy the spindle?
Chromosomes remain at the equator, unable to reach poles, preventing anaphase.
What happens in telophase, the FINAL stage of mitosis?
Chromosomes reach respective poles and become longer and thinner, finally disappearing altogether, leaving only chromatin. Spindle fibres disintegrate and nucleolus and nuclear envelop reform.
What occurs during cytokinesis?
Cytoplasm divides.
What is the cell division process in prokaryotic cells called?
Binary Fission
What is the process of binary fission?
- DNA molecule replicates and both copies attach to cell membrane.
- Plasmids also replicate.
- Cell membrane begins to grow between two DNA molecules, pinching inwards, dividing cytoplasm in 2.
- New cell wall forms between two molecules of DNA, dividing cell into 2 identical daughter cells with a single copy of circular DNA and variable number of plasmid copies.
What occurs during the replication of viruses?
Viruses are non-living so cannot undergo cell division. They attach to their host cell with attachment surface proteins, inject their nucleic acid into host cell which provides instructions for host cell’s metabolic processes to start producing viral components, via the genetic information. Components such as the nucleic acid, enzymes, and structural proteins are then assembled into new viruses.
How does mitosis aid growth?
Haploid cells fuse to form a diploid cell, which contains genetic information to form the new organism. Mitosis ensures that all cells growing from the original cell are identical to resemble its parents.
