33 terms

ch 10 meiosis


Terms in this set (...)

asexual reproduction
single individual passes genes to its offspring without fusion of gamete
genetically identical individuals from same parent
sexual reproduction
2 parents give rise to offspring that have unique combination of genes inherited from 2 parents
gametes are required
life cycle
generation-to-generation sequence of stages in reproductive history of organism
ordered display of pairs of chr from cell
homologous chr/ homologs
2 chr in each pair
same length, shape, and carry genes controlling same inherited characters
sex chr
determine sex of individual
X and Y
remaining 22 pairs of chr
code for general body characteristics
reduces # of chr sets from diploid to haploid
consists of 2 division meiosis 1 and meiosis 2
DNA replication occurs only once
2 cell division result in 4 daughter cells
unfertilized egg
sex chr is X
sperm cell
sex chr X or Y
prophase 1
events similar in mitotic prophase
homologs pair up (synapse)
cross over if homolog arms touch
homologs pair up
point which arms touch
metaphase 1
homologous pairs line up at equatorial plate
orientation of homologs is random
anaphase 1
homologous pairs separate
if crossover occured chiasmata separate
telophase 1
homologs move to opposite ends of cell
meiosis 1 puts 1/2 org # of chr in each new cell
each daughter cell has one of each homolog
meiosis 2
events identical to mitosis excepts sister chromatids are not identical
cuts # of chromatids in 1/2
total of 4 daughter cells each with 1/2 # of parental chr form
egg formation
to max amt of cytoplasm in egg 1 is formed instead of 4
no cytoplasm conservation
4 cells formed
union of gametes
fertilized egg
has 1 set of chr from each parent
produces somatic cells by mitosis
cell death
constant in living things
necrosis, apoptosis
cells are poisoned or starved due to low O2 or low ATP cell burst cause inflammation
genetically programmed
occurs if cells are no longer necessary (webbing between feet)
lessens cancer in exposed cells (blood, intestional epithelia)
cells isolates, chromatin breaks up, cell fragments living cells ingest remainder
changes in organisms DNA
org source of genetic diversity
create alleles
reshuffling of alleles during sexual reproduction produces genetic variation
different versions of genes created by mutations
contribute to genetic variation
independent assortment of chr
crossing over
random fertilization
independent assortment of chr
homologous pairs of chr orient randomly at metaphase 1 of meiosis
each pair of chr sorts maternal and paternal homologs into daughter cells independently of the other parts
random fertilization
adds to genetic variation bc any sperm can fuse with any ovum
crossing over
adds even more variation
each zygote has unique genetic identity