Meiosis and Mitosis Flashcards
What are the 4 parts?
Prophase
Metaphase
Anaphase
Telophase
Describe prophase:
Chromatin becomes condensed
chromosomes become visible
nucleolus disappears
centrioles move to opposite poles
Describe metaphase:
chromosomes are aligned along the equator
spindle fibres attach to centromeres
Describe anaphase:
centromeres attach two chromosomes of each split chromosome
Spindle fibres pull chromatids apart
Describe telophase:
Sister chromatids at opposite poles
now chromosomes again
Describe 3 differences between mitosis and meiosis:
Meiosis only takes place in reproductive organs
Meiosis has 2 divisions and 4 daughter cells
daughter cells are different from each other and the parent cell
Describe the difference between meiosis I and II
Meiosis I - chromosomes in two sets, one from each homologous pairs
Meiosis II - two chromatids from each chromosome split - two new daughter cells formed
Describe prophase I:
Homologous pair up to form bivalents
chromosomes condense and become visible
nucleolus disappears
2 non-sister chromatids exchange sections with each other (crossing over)
Describe metaphase I:
Homologous pairs align along the equator
Spindle fibres attach to centromeres
Describe anaphase 1:
spindle contract, pull chromosomes to opposite poles
(difference between mitosis is chromatids are pulled apart)
Two chromosomes in age bivalent pair pulled apart
Describe telophase I:
chromosomes pulled to opposite ends of the cell
Each chromosome still consists of two chromatids
Nuclear membrane reforms
What are homologous pairs?
Pairs of chromosomes that are similar in shape and size
Where does meiosis occur?
In diploid cells
Gives rise to the gametes
Prophase 1
Chromosomes condense and become visible as 2 chromatids
Spindle fibres form, nucleolus disappears and the nuclear membrane breaks down.
Homologous pairs join to form bivalents
Metaphase 1:
Homologous pairs line up on the equator
Spindle fibres attach to the centromere of each chromosome
Anaphase 1
Microtubules of spindle fibres contract and pull chromosomes pairs apart to opposite poles of the cell
Separation of cells lead to daughter cells becoming haploid
Telophase 1
Chromosomes are at opposite ends of the cell
Spindle fibres disappear, nuclear membrane reforms, nucleolus reforms & chromosomes unwind
Prophase 2
Chromosomes condense , 2 chromatids become visible
Spindle fibres form, nucleolus disappears and nuclear membrane breaks down
Metaphase 2
Chromosomes line up on the equator of the cell
Spindle fibres attach to the centromeres of each cell
Anaphase 2
Spindle fibres contract
Pull sister chromatids apart to opposite poles of the cell
Telophase 2
2 cells produced by meiosis 1 divide to form 4 haploid daughter cells
Chromosomes reach opposite ends of the cell
Cytokinesis occurs
Differences between mitosis and meiosis
Mitosis - Produce 2 daughter cells Meiosis - produce 4 daughter cells Mitosis - has 1 division Meiosis - has 2 divisions Mitosis - occurs in all cells Meiosis - only occurs in sex cells Mitosis - produce identical daughter cells Meiosis - produce non-identical daughter cells Mitosis - produce haploid cells Meiosis - produce diploid cells