mitosis and meiosis Flashcards
why do cells divide?
growth ,repair ,and reproduction
what is mitosis and cytokinesis ?
mitosis is nuclear division while cytokines is cytoplasm division
what is the difference between mitosis and meiosis ?
mitosis is the division of somatic or body cells.
replicates chromosome and produces 2 identical uncle in preparation for cell division. immideiatly followed by cell division producting 2 daughter cells . (present in all organisms except viruses )
while meiosis is the division of gametes or sex cells. it involves 2 rounds of divisions that result in 4 cells with only 1 copy of each parental chromosome . daughter cells are genetically different
what are the phases go mitosis ?
interphase
prophase
metaphase
anaphase
telophase: chromosomes uncoil (chromatin is formed )
spindle fibers disintegrate
nuclear membrane forms
describe interphase .
interphase :genetic material is doubled in preparation for division
is divided into 3 distinctive phases :
G1 : when all organelles and cytoplasmic content replicate
S phase : when DNA replicates
G2 all enzymes necessary for division are produced
( cell spends most of its time in interphase)
describe prophase .
:( first stage of cell division )
. DNA replicated in interphase in condensed
.microtubules form
nuclear envelope will start to break down but they stay intact
nucleolus disappears
describe metaphase
chromosomes meet in the middle
centrosomes from opposite poles produce spindle fibers that are attached to sister chromatids
describe anaphase
chromosomes are pulled apart to opposite sides by contracting spindle fibers
describe telophase
chromosomes uncoil (chromatin is formed )
spindle fibers disintegrate
nuclear membrane forms
what are homologous chromosomes?
they are chromosome pairs (one from each parent ) that are similar in length , gene position , and centromere location .
what is a tetrad ?
two chromosomes or 4 chromatids (sister and non sister chromatids)
what is cross over ?
process in which DNA is exchanged
describe metaphase 1
homologous chromosomes line up next to each other along the center of the cell
describe anaphase 1
homologous chromosomes are pulled to opposite poles but sister chromatids remain attached by centromere
describe telophase 1
chromosomes arrive at opposite walls of cell . usually occurs at same time and 2 haploid daughter cells are formed. cell goes from meiosis 1 to meiosis 2 without interphase in between them
