meiosis Flashcards
karotype
complete set of persons chromosmes in homologous pairs (paternal on left side and maternal on right side). chromosomes are numbered
centromere
binds sister chromatids (still one chromosome but now two chromatids)
asexual reproduction (4 types)
1.budding- buds off parent and falls off to grow exactly like parent
- fragmentation-part falls off and grows into clone of parent eg) sea stars
- vegitative propagation-ends of plant fall of and if in soil and growing conditions will grow into adult plant (identical to parent)
4.parthenogenesis- egg laid and grows without fertilization eg) bees
diploid vs haploid
2n=2 sets of chromosomes (one from each parent)
n- no homologous pairs 1 set of chromosmes
karyogram
visual of karyotypes
ploidy
number of chromosomal pairs. each numbered pair (diploid or haploid)
chiasma
a point of crossing over (site of exchange)
crossing over
Exchange of corresponding segments
of DNA by non-sister chromatids in a
tetrad during prophase I
synapsis
pairing of homologous chromosomes (zipping up)
2n=8
8 chromosomes total
4 from mother and 4 from father
4 homologous pairs
gametes would have 4 chromosomes
n=4 (n= #of homologous pairs)
domestic cats have 18 autosomes and a pair of sex chromosomes
2(19)=38
tetrad/bivalent
and seen in which phase and due to what
a pair of chromosomes refers to 4 chromatids (chromosome replication in interphase leads to tetrad in prophase 1)
endonucleases
creates nicks in non-sister chromatids so exchange can occur at chiasma
genetic variation in meiosis
1.crossing over (recombiant)
2. independent assortment (random alignment of homologous chromosomes)
3. random fertilization
possible gamete outcomes due to random alignment (law of independent assortment)
calculated by 2^n (n= # of homologous pairs)
eg) 2n=8 therefore possible outcomes is 2^4=16 possible outcomes