Outline The Differenc Between Meiosis And Mitosis Flashcards
Mitosis
- overview
Creates daughter diploid cells
Cell cycle is heavily involved (G1, S, G2 and M phases)
Interphase
-overview
G1: Cell increases in size and the organelles are copied
S: cell synthesises a complete copy of DNA in its nucleus. it also duplicated the centrosome (aids during mitosis)
G2: the cell increase even more in size, making proteins and organelles and begins to reorganise in preparation for mitosis
Mitosis:
- overview
Cell divides the copies DNA and cytoplasm making 2 new cells (mitosis and cytokinesis)
Prophase: mitosis spindles begin to form, and the nucleus condenses its chromosomes, breaking the nuclear envelope
Prometaphase: centromeres and kinetochore attach to the individual chromatin and mitotic spindles form
Metaphase: chromosomes align on the metaphase plate (equator) (still attached to the kinetochore microtubules)
Anaphase: cohesion dissolved and is broken down and the microtubules pull the chromosome apart (equally)
Telophase: microtubules are in opposite polar direction, overlapping in the centre,
Pushes cell apart, narrowing the cell and the new nuclei start to form around the chromosomes
Cytokines: cells get pinched together and start to seperate into 2 cells, 2 nuclei form and chromosomes decondense, movement of chromosomes driven by microtubules (split the cell) cleavage furrow with contractile ring
Meiosis:
- overview
Forms 4 haploid gamete cells
Only consists of 1 set of chromosomes
Alternates between diploid and haploid
Haploid life cycles:
- overview
Mitotically divide to haploid gametes
Zygote formation (forming diploid)
Meiosis to form haploid and mitosis to form more haploid cells
Diploid life cycle:
- overview
Diploid adult meiosis to haploid gametes
Zygote formation to diploid, mitosis to diploid adult
Mitosis vs meiosis
- differences
Mitosis:
- ch make convenient packages to replicate DNA,
- the chromatids remain attached to the same centromere
- metaphase they align, and then pass 2 new daughter cells inheriting a complete ch set
Meiosis:
- DNA replicated, chromatids remain attached at centromeres
- genetic exchange takes place
- 2 divisions forming four daughter cells each only containing half of the chromosomes (haploid)
Meiosis I proces
Prophase I:
- homologous ch pair, synapsid and crossing over occur (4x chs)
Metaphase I:
- pairs homologous ch align at metaphase plate
Anaphase I:
- microtubles pull chromatids apart forming 2 daughter cells (with diploid chs)
Telophase I:
- homologous chromosomes separate, sister chromatids remain together
Crossing over at prophase I
Generic recombinebtween non-sister chromatids at the chiasmata
Allows homologues to exchange chromosomal material
Alleles of genes on separate homologues now found on same homologue
Independent alignment at Metaphase I
Terminal chiasmata hold homologues together following crossing over
Microtubules from opposite poles attach to each homologue
Homologues are aligned at metaphase plate
Orientation of each pair of homologues on the spindle is random
Unequal recombination
Ch line up incorrectly resulting in deletion or duplication
LINEs
Long intersperses nuclear elements
About 5kb, look like retro, encore reverse transcriptase
Self mobile
SINEs
Short interspersed Nuclear elements
300 no, small events like pseudo genes, not encode reverse transcriptase, not self mobile
