genetic material organized into
chromosomes
cell division(Fission) in prokaryotes
mother cell divides to produce two daughter cells
- mother cells chromosome duplicated prior to fission
- each daughter cell receives one copy of the chromosome
clone
a population of genetically identical cells
colony
a visible mass of cells
Steps in mitosis
(interphase)
1. Chromosomes duplicate to produce sister chromatids
2. Duplicated chromosomes condense(spindle inititiation)(Prophase)
//microtubules attach to kinetichores
3. Duplicated chromosomes migrate to the equatorial plane of the cell and the nuclear membrane breaks down
(metaphase)
4. Sister chromatids of each duplicated chromosomes move to opposite polls of the cell
(anaphase)
5. Chromosomes decondense and new nuclear membranes form
(telophase)
6. Membranes form between daughter cells(cytokinesis)
Meiosis Prophase 1(Leptonema)(thin threads)
Chromosomes condense and each chromosome has two sister chromatids
Meiosis Prophase 1(Zygonema)(paired threads
homologous chromosomes begin to pair
- synapsis of homologous chromosomes
- synaptonemal complex
Prophase 1:Pachynema
Thick threads
homologous chromosomes fully paired
- chromosomes condense further
- crossing over occurs
Meiosis
Prophase 1: Diplonema(Two threads)
Paired chromosomes separate slightly, are in contact at chiasmata
Meiosis
Prophase 1: movement through
Paired chromosomes condense further and become attached at spindle fibres
- nuclear envelope fragments
- spindle fibers attach to kinetichores
- chromosomes move to central plane in pairs
Metaphase 1
Paired chromosomes allign on the equatorial plane of the cell
- paired chromosomes are oriented towards opposite polls
- terminalization chiasmata move toward telomeres
Anaphase 1
Homologous chromosomes disjoin(seperation of paired chromosomes) and move to opposite polls of the cell
- seperated homologues move towards opposite polls
Telophase 1
Chromosome movement is completed and new nuclei begin to form
- chromosomes reach polls
- spindle apparatus is dissassembled
- daughter cells seperated by membranes
- chromosomes decondense
- each chromosome still has 2 sister chromatids
Prophase II
Chromsomes of 2 chromatids condense and become attached to spindle fibers(from opposite polls)
- chromsome condense
Metaphase II
Chromosomes allign on equatorial plane of each cell
Anaphase II
Sister chromatids disjoin and move to opposite polls in each cell
- centromeres split
Telophase II
Chromosome decondense and new nuclei begin to form
- chromatids now called chromasomes
- daughter nucleus haploid
- separated chromatids gather at polls
cytokinesis
haploid daughter cells seperated by cytoplasmic membrane
homologous chromosome exchange material by
crossing over
