Lab 7 Meiosis Flashcards
where does meiosis occur in animal cells
gonads
where does meiosis occur in plant cells
sporangia
what are the two nuclear division in meiosis
meiosis I and II
what happens when a cell is neither in meiosis I or II
cells do not grow and synthesis of DNA does not take place
what does meiosis result in
four, non-identical daughter cells with half the number of chromosomes as the original parent cell
haploid cells
- n
- cell with only one of each homologous pair of chromosomes
diploid cells
- 2n
- parent cells
- pairs of homologous chromosomes
what do the haploid cells become
eggs, sperm, or spores
what happens when the homologous chromosome pairs do not separate properly
- final nuclei may have either too many or too few chromosomes
- this can happen if sister chromatids don’t spilt as well
interphase
similar as when in mitosis
- occurs before meiosis
what happens within the first division in meiosis
chromosomes coil and condense
what occurs during the beginning of meiosis I
- nuclear envelope breaks down and spindles form
what happens in early prophase I
Synapsis
-each chromosome finds it homolog and pairs in a tight association
- genetic information begins to be shared
how are the synapsed homologous pairs held together
zipperlike protein called the synaptonemal complex
tetrad
each paired duplicated chromosome complex is made of four strands
crossing over
exchange between homologous non-sister chromatids
chiasmata
points of attachment where crossovers form
what happens to centromeres in metaphase 1
do not separate
where do tetrads lie in metaphase 1
move to the equator
anaphase 1
separation of each duplicated chromosome from its homolog and movement of one homolog towards each pole
what must meiosis II change
change duplicated chromosomes into single chromosomes
what occurs as meiosis II begins
two new spindles begin to form establishing the axes for the dispersal of chromosomes to each new nucleus
prophase II
- separation of centrioles
- two new spindles
- chromosomes in the center of each spindle
metaphase II
- chromosomes reach equator
- each duplicated chromosomes start to pull apart
anaphase II
- centromeres finally separate
- single chromosomes move to the poles
telophase II
-chromosomes arrive at the poles
- spindles break down
- nuclear envelopes form around each bunch of chromosomes as the chromosomes uncoil
what follows after meiosis II
cytokinesis
