Cell Cycle

why cell cycle

prevents cell from becoming too large; helps cell reproduce

what does cell division look like in an unicellular organism

reproduces the entire organism

what do multicellular cell depend on cell division for

development from fertilized cell; growth; reproduction

what does most cell division result in

daughter cells with identical genetic information

genome

contains all of the DNA of a cell

DNA molecules in a cell are packaged into ____

chromosomes

somatic (nonreproductive) cells

two sets of chromosomes (diploid)

gametes (reproductive) cells

has half as many chromosomes as somatic cells (haploid)

chromatin

a mixture of DNA and protein that condenses during cell division to form chromosomes

what happens in preparation for cell division

dna is replicated and chromosomes condense

each duplicated chromosomes has ____ chromatids

two

centromere

narrow “waist” of duplicated chromosome, where two chromatids are most closely attached

the first phase of interphase (g1)

cell is growing; carry out normal functions; preparing to replicate dna

what happens during interphase

chromosomes are copied (# doubles)

second stage of interphase (s)

cell copies its dna in prep for cell division

third stage of interphase (g2)

cell prepares for the division of its nucleus

steps in mitosis

1. prophase

2. prometaphase

3. metaphase

4. anaphase

5. telophase

what step does mitosis begin

prophase

prophase

chromosomes condense and become visible; spindle fibers emerge from centrosome; centrioles appear and begin to to move to opposite end of cell; nuclear envelope breaks down

prometaphase

kinetochores appear at centromeres; mitotic spindle attack to kinetochores; centrosomes move towards opposite poles

mitotic spindle

apparatus of microtubules that control chromosome movement during mitosis

metaphase

mitotic spindle fully develops; centrosomes are at opposite poles of cell; each sister chromatid is attached to a spindle fiber originating from opposite poles

anaphase

cohesion proteins that bind sister chromatids together break down; chromosomes are pulled towards opposite poles; non-kinetochore spindle fibers lengthen, elongating the cell

sister chromatids are called ____ during anaphase

chromosome

telophase

chromosomes arrive at opposite poles and begin to decondense; nuclear envelope starts to form around each set of chromosome; mitosis end

at what stage does mitosis end

telophase

cytokinesis

cell membrane moves inward to create two daughter cells