MEIOSIS VOCABULARY

All of the DNA in an uncondensed (spaghetti-like) form

A double rod of condensed chromatin

ChromatinChromosomes

Sister Chromatids: the two halves of a chromosome; half original, half rebuilt

Homologous Chromosomes (pairs): chromosomes containing the same gene (possibly different alleles)one from mom, one from dadLine up together in tetrads during

meiosis

Centromeres: the region of DNA where 2 sister chromatids come together

Spindle Fibers: fibers that attach to sister chromatids and bring them to opposite poles during meiosis

TYPES OF CELLS

Cells that contain double the amount of chromosomes than haploid cells

Usually called the “normal” number of chromosomes

Two copies of each gene

Cells that contain half the amount of chromosomes than diploid cells

One copy of each gene

Diploid Haploid

TETRADSHow the chromosomes line up during Metaphase I of meiosis

Homologous chromosomes and their copies (sister chromatids) line up

SEGREGATIONHomologous chromosomes

randomly line up in tetrad formation during meiosis

Many possibilities for the combination of alleles in offspring

Two possibilities of lining up

CROSSING-OVERExchange of genes between

homologous chromosomes during meiosis

Adds more variation