GB1 - Meiosis Ch. 13 Vocab

sex chromosomes

X and Y chromosomes

associated w/ individual’s sex

autosomes

any chromosome other than sex chromosomes

homologous chromosomes / homologs

chromosomes that are the same size & shape

same genes, diff alleles

homologous pair

pair of homologous chromosomes

gene

segment of DNA, found at specific place on chromosome, that influences trait

allele

particular version of gene

karyotype

The distinctive appearance of all the metaphase or prometaphase chromosomes in an individual, including the number of chromosomes, their length, and their banding patterns.

diploid

organisms that have two versions (homologs) of ea. type of chromosome

2n

haploid

organism containing just one type of chromosome

haploid number

n

number of distinct types of chromosomes in a given cell

maternal chromosome

chromosome from mother

paternal chromosome

chromosome from father

ploidy

number of haploid chromosome sets in cell

polyploid

3+ of ea. type of chromosome in ea. cell

3n, 4n, 5n…

unreplicated chromosome

chromosome consisting of 1 double helix molecule of DNA wrapped around a histone

replicated chromosome

chromosome after DNA replication

consists of 2 identical sister chromatids, ea. containing 1 double helix DNA molecule wrapped around a histone

sister chromatids

two identical chromatids in replicated chromosome

non-sister chromatids

chromatids on diff members of a homologous chromosome pair

not identical

meiosis I

The first cell division of meiosis, in which synapsis, crossing over, and independent assortment occur. It separates homologous chromosomes from each other, producing daughter cells with half as many chromosomes as the parent cell.

meiosis II

The second cell division of meiosis, in which sister chromatids are separated from each other. Meiosis II does not reduce chromosome number and is similar to mitosis.

spindle apparatus

The array of microtubules responsible for moving chromosomes

kinetochores

protein complex that forms on a chromosome during M phase.

Forms at the centromere and serves as a site for microtubule attachment.

Contains motor proteins and microtubule-binding proteins that are involved in chromosome segregation

centromere

region of a replicated chromosome where the two sister chromatids are joined

gametogenesis

The production of gametes (eggs or sperm).

zygote

The cell formed by the union/fertilization of two gametes.

bivalent

4 chromatids from 2 homologous chromosomes

paired, replicated

prophase I, metaphase I

synapsis

pairing of homologous chromosomes

chiasmata

crossing over point

cohesins

proteins that hold sister chromatids together along full length

synaptonemal complex

homologs are held together by a network of proteins

crossing over

chromosome exchange in late prophase I

new combination of alleles

independent alignment/assortment

the alignment of bivalent is independent from others in Metaphase I

new combinations of chromosomes

asexual reproduction

any mechanism of producing offspring that does not involve the production and fusion of gametes

basis of mitosis in eukaryotes

clone

offspring with exact genetic copy

sexual reproduction

any mechanism of producing offspring that does not involve the production and fusion of gametes

variation in offspring

genetic recombination

creation of new combinations of alleles

random fertilization

sperm and egg from different individuals come together without regard for any particular alleles they carry

down syndrome

A human developmental disorder caused by trisomy (3 copies) of chromosome 21.

trisomy

3 copies of a chromosome

2n+1

nondisjunction

homologs or sister chromatids fail to separate during meiosis

monosomy

2n-1

only 1 copy of one of the chromosomes

aneuploid

too many/few of chromosomes of particular type

oogenesis

human egg development

primary oocytes

diploid precursors to eggs