-make up chromosomes

-made of DNA and protein molecules

how do chromatin turn into chromosomes?

histones have the appearance of beads on a string

the "bead"s

consists of dna wound around a protein core of eight histone molecules

-the copies of the chromosomes

-contain identical genes

-joined by centromere

centromere

-the new chromosomes go to daughter cells after breaking apart

-receive a complete set of chromosomes

-an orderly sequence of events that extends  from time a cell first arises until it itself divides

-90% of the cells life is spent in this phase

-doubles everything in cytoplasm

-increases supply of proteins, organelles, and growth in size

-in middle of interphase when chromosomes are duplicated

G1 and G2 phase

before and after the s phase

g=gap

-in G2, each chromosome in the cell consists of two identical sister chromatids

-the cell is preparing to divide

-when the cell is actually dividing

-two processes: mitosis and cytokinesis

-the nucleus and its contents are evenly divided and distributed (form two daughter nuclei)

-

-the cytoplasm is divided into two

-usually begins before mitosis is completed

-produces two genetically identical daughter cells

-period of cell growth

-in G2, the cytoplasm contains two centrosomes

-chromosomes are duplicated in the nucleus

-cell is making ribsomes

-in the nucleus, chromatin fibers coil to turn to chromosomes

-the nucleoli disappear

-each chromosome appears as two identical sister chromatids joined together with a centromere

-mitotic spindle form as microtubules grow out from cnetromeres, that are moving away from each other

-nuclear envelope breaks up

-the spindle microtubules can now reach the chromosomes

-chromosomes are thick and have protein structure at their centromeres.

-spindle latches onto chromosomes and microtubules

-spindle moves chromo. to center

-the chromosomes are lined up

-spindle is fully formed

-the spindle microtubules attached to the two sister chromatids pull toward opposite poles to keep chromosomes in place

-when sister chromatids of each chromosomes separate

-motor proteins at the centromeres "walk" the daughter chromosomes to the poles

- microtubules shorten, except the ones that are not attached to chromosomes because those grow longer to elongate the cell

-when the two groups of chromosomes have reached the cell poles

-nucluer envelope forms

-chromosomes uncoil

-nucleoli reappear

-spindle disappears

-division of cytoplasm

-usually occurs with telophase

-in animals, a cleavage furrow pinches the cell in two...producing two daughter cells

-football shape of microtubules that guides separation of two sets of daughter chromosomes

-grow from two cetromsomes

-an indentation in the cytoplasm just under the plasma membrane is responsible for the cleavage

-the ring contracts like pulling a drawstring

-cell wall material is collected in the middle of the cell

-it fuses with the mebranous disk called the cell plate

-then the cell plate fuses with the plasma membrane and it split into two daughter cells

-one that remains in the original site in the body

-abnormal growth mass of body cells

cancer cells

-deranged cell cycles

-can divide excessively

-reproduction of cancer cells result in malignant tumors

-

-cancer in external parts of body

ex: skin

-in tissues that support the body

ex: bone and muscle

-cancers of blood forming tissues

ex: bone marrow and lymph nodes

-"burn"

-parts of the body are exposed to high radiation to disrupt cell division

-can cause nausea and hair loss

-removing tumor

-"poison"

-drugs that disrupt cell division

-ex: vinblastine and taxol