Cell Division; biology

growing and getting ready to divide

cells dividing

-precisely replicates its DNA

-allocates the 2 copies f DNA to opposite ends of cell

-seperates into 2 daughter cells that are same

-normal cell operation and growth

-12 hrs

DNA is replicated

• cell growth and preparation for cell division
• -5.5 hours

-DNA double helix unwinds

- protein wraps around DNA to make chromatin

-chromatin condenses forming 2 chromatids.

-well defined nucleous bounded by nuclear envelope

-one or more nucleoli

-chromosomes that are loosely packed with chromatin fibers

-splitting of cytoplasm

-DNA begins to condense or thicken becoming more visible

-nuclear membrane and nucleoli start to disappear

-sister chromatids join togehter by centromeres

-centrioles migrate to opposite ends of cell

-Telomeres

-centromere

-heterochromatin

-Euchromatin

chromosome tips

-Consists of repeating sequence TTAGGG

-protects chromosomes from breaking

-part where spindle fibers attach when cell divides

-replicated toward the end of S stage

-mostly structural role, maintain chromosome together

dark areas of a chromosome

-highly repetitive DNA sequences

light areas of chromosome

-more protein-encoding sequences

-genes

bridge gap between gene-rich regions and telomeres

specialized region formed right before mitosis where spindle fibers can attach.

spindle fibers extend from the poles toward the cells equator

-microtubules become attached to the centromere on the chromosomes

-early in this stage chromosomes develop kinetochores

method of displaying matching of homologous chromosomes

-only visible if chromosomes are condense during replication

-humans 22 pairs of autosomes, 1 pair of sex

-spindle fibers begin to shorten seperating sister chromatids

-seperated chromatids now called chromosomes

-motor proteins move chromatids along microtubules

-nuclear envelope appears to form

-spindle fibers disappear

-chromosomes decondense

-2 daughter cells.

in animals, it occurs by a process called cleavage

in plants, it occurs by the formation of cell plate