M EIOSIS V OCABULARY

All of the DNA in an uncondensed (spaghetti- like) form A double rod of condensed chromatin Chromatin Chromosomes

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 dad Line 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

T Y PES OF C ELLS 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 DiploidHaploid

T ETRADS How the chromosomes line up during Metaphase I of meiosis Homologous chromosomes and their copies (sister chromatids) line up

S EGREGATION Homologous chromosomes randomly line up in tetrad formation during meiosis Many possibilities for the combination of alleles in offspring Two possibilities of lining up

C ROSSING -O VER Exchange of genes between homologous chromosomes during meiosis Adds more variation