meiosis

two ways/processes genes are passed on

mitosis, meiosis

mitosis is ___ reproduction

asexual

meiosis is involved with ___ reproduction

sexual

____ can be advantageous and adaptive

variation

meiosis reduces chromosome number from __ to __

2n, 1n

meiosis prevents build-up of…

DNA

what type of cell does meiosis start with?

diploid germ-line cell

do homologous chromosomes interact in mitosis or meiosis?

meiosis

meiosis consists of __ consecutive cell _______

2, divisions

overall description of meiosis I

homologous chromosomes pair up then split, halving chromosome #

synapsis

homologous chromosomes pair up, forming tetrads

tetrad

4 chromatids from homologous chromosomes

overall description of meiosis II

sister chromatids split exactly like mitosis

tetrads are connected by…

chiasma

what 3 things happen in prophase I?

homologs pair up to form tetrads, chiasma form, crossing over occurs

what happens in metaphase I?

tetrads move as units to middle of cell

what happens in anaphase I?

homologs separate to each side of cell, but chromatids stay together

another term for telophase I and cell division I

reduction division

in terms of ploidy, what type of cells are the daughter cells from telophase and division I?

haploid

are the daughter cells from meiosis identical to each other or parent cells?

no

what phase is in between meiosis I and II?

interkinesis

interkinesis

like interphase, but without DNA replication

another term for telophase II and cell division II

equational division

final daughter cells from meiosis II go on to become…

gametes

how is 2n zygote formed?

combination of two 1n gametes

meiosis I daughter cells are ____ with ____ chromosomes

haploid, replicated

meiosis II daughter cells are ____ with ____ chromosomes

haploid, unreplicated

interkinesis, including interphase II and prophase II, are…

variable

in what phase do sister chromatids finally separate?

anaphase II

mendel’s 1st law

law of segregation

law of segregation

each parent gives exactly one of their two alleles to offspring

mendel’s 2nd law

law of independent inheritance

law of independent inheritance

any allele from one gene can pair up with any allele from another gene when being sorted into gametes

all chances for allele combinations occur ____ in the gametes

equally

law of segregation in action during meiosis

each gamete gets exactly one allele for each gene

law of independent assortment in action during metaphase I

chromosomes line up randomly, so each gamete has a different allele combination

recombination

shuffles genetic variation, produces different allele combinations

chiasma form at ___ during ____

random, prophase I

what must occur before crossing over happens?

synapsis

what happens during the crossing over process?

homologous chromosomes exchange some genetic info

products of crossing over

recombinant chromosomes

nondisjunction

chromosomes don’t split during anaphase

nondisjunction results in…

one cell has too many chromosomes, one cell doesn’t have enough chromosomes

trisomy 21 (down syndrome)

3 copies of chromosome 21

aneuploidy

wrong number of chromosomes