1.6 Cell Division Flashcards
What is the cell cycle?
Starts with interphase then to mitosis then cytokinesis.
What are the stages of Mitosis?
- early prophase
- late prophase
- metaphase
- anaphase
- early telephase
- late telephase
What happens in interphase?
There are three stages G1, S phase, G2.
Mitochondria and chloroplast numbers increase.
S phase is where all genetic material in nucleus replicates.
What happens in Early prophase?
Chromosomes are becoming shorter and fatter by supercoiling
spindle microtubules are growing.
What happens in late prophase?
Spindle microtubules extend from each pole to the equator.
Each chromosome has two identical chromatids formed by DNA held together by a centromere.
What happens in Metaphase?
Nuclear membrane has broken down and chromosomes have moved to the equator.
Spindle microtubules from both poles are attached each centromere on opposite sides.
*At the end of metaphase the centromeres replicate and chromatids separate.
What happens in anaphase?
The centromeres have divided and the chromatids have become chromosomes.
spindle microtubules pull the genetically identical chromosomes to opposite poles.
What happens in early telephase?
Spindle fibres break down
chromosomes have reached the poles and the nuclear membrane is formed around them.
What happens in late telephase?
Chromosomes uncoil and are no longer individually visible.
cell divides to form two cells with same nuke by cytokinesis.
DNA uncoils, nuclear membrane forms, membrane splits.
What is oncogenesis?
The formation of tumours.
What is oncogenes?
Mutated genes that start tumours.
What are the chemicals called that cause mutations?
mutagens
What is metastasis?
The spreading of tumours to a different part of the body.
What is the haploid number?
Gametes - n - nuclei that only has one pair of homotogous chromosomes.
What is the diploid number?
Somatic cells - 2n - has pairs of chromosomes.
What is tetraploid?
2n X 2 = 4n
What is a chromatin?
Each portion of DNA
What is a chromosome?
Threadlike structure of nuclei made from DNA and stretched out during interphase.
What is super coiling?
Process by which long/thin chromatins transform into short/fat chromosomes. This is where chromatins wrap around a histone protein.
What is a chromatid?
On of the two copies of DNA in a chromosome held to another one by a centromere.
What is a centromere?
Portion of DNA that did not replicate during s phase of interphase but instead at the end of metaphase.
What are centriols?
related to the production of spindle fibres . 2 centromeres = 1 centriol.
What is equational division?
When the nucleus divides so that each chromosome divides into equal longitudinal halves.
What is a tumour?
IT is the over production of cells - can be cancerous.
What does mallegent mean?
Being able to spread.
What is the mitotic index and what is it used for?
It is the number of cells in mitosis over total number of cells. used to predict how fast a tumour will grow.
