Meiosis: A special type of cell division By: Crystal Carroll

WHY IS MEIOSIS IMPORTANT? Sexual reproduction begins with Meiosis Zygote grow through Mitosis--resulting in an organism Evolutionary change Overview of Meiosis

INTERPHASE I Longest phase Chromosomes replicate

PROPHASE I Homologus chromosomes begin to condense Synapsis occurs Crossing over occurs

METAPHASE I Tetrads line up Spindle fibers attach

ANAPHASE I Tetrads separate Centromeres remain in tact

TELOPHASE I Two haploid cells form at each pole Each chromosome has two sister chromatids

CYTOKINESIS Division of the cytoplasm Cleavage furrows form No further replication of the genetic material

INTERKINESIS Transistion period

PROPHASE II New spindles form No crossing over

METAPHASE II Chromosomes line up on metaphase plate

ANAPHASE II Centromeres split

TELOPHASE II & CYTOKINESIS Nuclei form Cytokinesis occurs Mitosis occurs

MEIOSOS IS NOT FLAWLESS The most common cause of pregnancy failure Arise from mistakes During egg formation More frequent as women age Gain or loss of whole chromosomes

Meiosis