Chapter 12 Flashcards
what makes up chromatin
- one long DNA molecule
- proteins that maintain chromosome structure & control activity of genes
what do chromatin eventually break down into
chromosomes
what is the purpose of the centromere
join sister chromatids by the waist
what are the two parts of the cell cycle
interphase (non-dividing)
mitotic phase
what are the stages within interphase
G1
S
G2
G1 phase
growth & increase in cytoplasm
S phase
duplication of chromosomes
G2 phase
growth & preparation for division
what are the two stages of the mitotic phase
mitosis and cytokinesis
mitosis
division of nucleus
cytokinesis
division of cytoplasm and end up with 2 daughter cells
what are the 5 subphases of mitotic phase
prophase
prometaphase
metaphase
anaphase
telophase
what does “n” represent
how many different ones you get from mom and dad
what is involved in prophase
centrosomes
centrioles
spindles
interphase
- prep
- two centrosomes form
chromosomes duplicate - nucleoli form
- cytoplasmic contents double
prophase
-microtubules begin to emerge
- form spindle
- nucleoli disappear
- chromosomes condense
what is a mitotic spindle
organize microtubule arrangement
- produced by centrosomes
- required to divide chromosomes
prometaphase
move chromosomes to center of cell
- spindle microtubules reach chromosomes
- nuclear envelop disappears
metaphase
- mitotic spindle formed
- chromosomes align at middle
- face opposite poles
anaphase
- sister chromatids separate
- daughter chromosomes moved to opposite poles
- cell elongates
telophase
- nuclear envelope forms around each chromosome
- chromatin uncoils
- spindle disappears
- cytokinesis
cytokinesis in animal cells
- cleavage furrow forms
cleavage furrow deepens to separate contents
cytokinesis in plant cells
cell plate forms in the middle from vesicles containing cell wall material
- cell plate grows outward to reach edges to divide cell
- each cell would now posses plasma membrane and cell wall
how do bacteria divide
binary fission
binary fission
- bacterial chromosomes replicate
- proteins attach to chromosomes & separate them
- proteins divide cytoplasm
why does cell cycle length vary
due to variation of length of G1 phase
what do rapidly dividing cells do to the G1 phase
eliminate it
what happen to nondividing cells
get permanently stuck in G1 phase (G0)
what can affect division rate
response to changing environment
how is cell cycle regulated
through variation in length of cycle and division rates
cell cycle checkpoints
allow for cycle to be regulated
how do the cell cycle checkpoints work
Regulatory molecules at each checkpoint allow a cell
to “decide” whether to proceed with division
what happens if a cell cycle checkpoint fails
cancer and tumors
cancer
- grow rapidly and uncontrolled
- invade nearby tissues & spread rapidly
- caused by defective cell cycle checkpoints
what does mitosis start with and produce
- starts with diploid somatic cells
- produce genetically identical daughter cells
metaphase plate
during metaphase, chromosomes will line up on this plate at the center of the cell
what is the purpose of the kinetochore
protein structure where the spindle fibers attach during division to pull the sister chromatids apart
