genetic information is copied and passed on to daughter cells Flashcards
differences in mitosis and meiosis
mitosis
- one division = 2 daughter cells
- same number chromosomes (diploid)
- no crossing over
- homologous chromosomes do not associate in pairs
- genetically identical
meiosis
- 2 divisions, 4 daughter cells
- haploid, half number of chromosomes
- pair up into bivalents
- genetically different
what happens in interphase (not part of mitosis)
- replication of DNA
- making new organelles
- ATP synthesis
- protein synthesis
what happens in prophase in mitosis
- DNA condenses forming chromosomes.
- chromatids become visible
- the centrioles move to opposite poles
- the spindle begins
- nuclear membrane disintegrates
what happens in metaphase during mitosis
- chromosomes arrange themselves at equator of spindle
- centromere attach to spindle fibres
what happens to anaphase during mitosis
- centromere splits
- spindle fibers contracts
- chromatids separate and pull to opposite poles
what happens to telophase during mitosis
- chromatids reached poles
- chromosomes uncoil and lengthen
- spindle breaks down and nucleolus reappears and membrane reforms
uses for mitosis
used for growth and repair of tissue or replace old cells
what is the mitotic index
number of cells in p+m+a+t/ total number of cells X 100
what happens in prophase 1 in meiosis
- DNA condenses forming chromosomes.
- chromatids become visible
- the centrioles move to opposite poles
- the spindle begins
- nuclear membrane disintegrates
- crossing over
what happens in metaphase 1 in meiosis
bivalents migrate to the equator of cell in a random assortment
what happens in anaphase 1 in meiosis
- centromere splits
- spindle fibers contracts
- chromatids separate and pull to opposite poles
what happens in telophase 1 in meiosis
- chromatids reached poles
- chromosomes uncoil and lengthen
- spindle breaks down and nucleolus reappears and membrane reforms
- diploid
what happens in prophase 2 in meiosis
- DNA condenses forming chromosomes.
- chromatids become visible
- the centrioles move to opposite poles
- the spindle begins
- nuclear membrane disintegrates
what happens in metaphase 2 in meiosis
- chromosomes arrange themselves at equator of spindle
- centromere attach to spindle fibres
- chromatids are not identical
what happens in anaphase 2 in meiosis
- centromere splits
- spindle fibers contracts
- chromatids separate and pull to opposite poles
what happens in telophase in meiosis
- chromatids reached poles
- chromosomes uncoil and lengthen
- spindle breaks down and nucleolus reappears and membrane reforms
where does mitosis take place in a plant
meristems
