MItosis Flashcards
1
Q
Define mitosis
A
- type of nuclear division
- production of 2 daughter nuclei, genetically identical to parent
- same no. of chromosomes as parent nucleus
2
Q
Chromosomes
A
- rod-like structure
- visible in nucleus during cell division
- contains 1 DNA molecule that is highly coiled and condensed arnd histones
- carries genes
3
Q
Homologous chromosomes
A
- exist pairs, one paternal, one maternal
- same gene loci, centromere position, length
- diff alleles
4
Q
Gene
A
- segment of DNA in a chromosome
- where specific genetic (hereditary) info is stored
- controls production of specific polypeptide/specific protein
5
Q
Alleles
A
- diff forms of same gene
- occupy same relative positions on a pair homologous chromosome
- letters used to represent alleles
6
Q
The cell cycle
A
- sequence of events frm when cell is formed till its division in to 2 daughter cells
- 3 stages
- interphase( resting stage), mitosis (nuclear division), cytokinesis (division of cytoplasm)
7
Q
Interphase
A
- resting/non-dividing stage
- cells absorb nutrients
- build up protoplasm
- synthesis new organelles
- replicate DNA
8
Q
What happens in interphase
A
- chromosomes appear as chromatin threads
- chromatin threads replicate
- centrioles replicate and divide (animal cells)
9
Q
Why must DNA replication and mitosis be precisely controlled
A
- ensures all daughter cells are genetically stable
- error during replication, new DNA formed diff frm original
- known as gene mutation and is passed to daughter cell
- gene mutation lead to uncontrolled division of cells (cancer), may be fatal
10
Q
Stages of mitosis (PMAT)
A
- Prophase
- Metaphase
- Anaphase
- Telophase
11
Q
Early prophase
A
- in animal cell, asters (short microtubules that grow out from centrioles) form arnd centrioles
- 2 pairs of centrioles move apart to opp poles of cell
- nucleolus disappears
- chromatin condense, coil and shorten to become chromosomes
- each chromosome, 2 sis chromatids attached to centromere (x-shaped)
12
Q
DNA replication
A
- chromatin threads replicate to produce 2 identical chromatin threads
- chromatin threads coil and shorten to form chromosomes
- each chromosome have 2 genetically identical DNA molecules (sis chromatids)
13
Q
Late prophase
A
- nuclear envelope breaks down
- spindle forms with spindle fibres, extending from one pole of cell to the other
14
Q
Metaphase
A
- line up singly along equator of spindle
- spindle fibre attached to centromere
- spindle fibres help to align chromosomes
15
Q
Anaphase
A
- each centromere divides
- spindle fibres shorten pull sis chromatids to opp poles of the cell
- once sis chromatids are separated, known as sis chromosomes