cell cycle quick flashcards

why do cells divide

growth & development - increase no. somatic cells

repair - replace cells lost through apoptosis

reproduction - asexual & sexual

what are some cells that don’t divide

mature red blood cells

neurons

difference in DNA between eukaryotes and prokaryotes

eukaryotes - a number of DNA molecules

prokaryotes - a single DNA molecule

eukaryotic chromosomes

DNA + protein (chromatin)

condense during cell division

what are somatic cells

have two sets of chromosomes

nonreproductive cells

what are gametes

have 1 set of chromosomes

reproductive cells

how are eukaryotic chromosomes organized

normally spread out in dispersed form (chromatin)

during interphase, DNA is replicated

during mitosis, chromosomes condense

what are sister chromatids

identical chromosomes

attached by cohesins

each duplicated chromosomes contains 2 identical DNA molecules. one in each chromatid

what is interphase

90% of the cycle

where most biogenesis and cell growth occurs

DNA replicates, centrosomes duplicate

G1 phase

S phase

G2 phase

what is cytokinesis

the cell divides into two daughter cells

genetically identical to each other and parent cell

how can be observe interphase as

intact nuclear envelope

dispersed chromatin - allow access to promoter regions

what is G1 phase

cell grows and makes organelles

what is the S phase

DNA is replicated - each chromosome is duplicated into two sister chromatids

what is the G2 phase

final preparations for cell division

centrosome duplication

what is the M phase

mitosis - division of genetic material

cytokinesis - division of cytoplasm

sister chromatids segregate into two cells and each daughter cell has one complete set of chromosomes

each daughter cell also recieves one centrosome

what is prophase

chromosomes condense

nuclear envelope intact

mitotic spindle forms

duplicated centrosomes separating to act as spindle poles

what is prometaphase

breakdown of nuclear envelope

chromosomes condense and sister chromatids start to “resolve” (cohesin digestion)

kinetochores are assembled at centromeres

spindle microtubules bind to kinetochores

what is metaphase

chromosomes align at metaphase plate

kinetochore microtubules attach sister chromatids to opposite poles of the spindle

cohesins along arms fully digested, cohesins only remain at centromeres

what is anaphase

shortest stage

chromosome segregation

cohesins at centromeres destroyed by separase

sister chromatids seperate and move to opposite poles

microtubules shorten to pull chromatids apart

what is telophase

chromosomes decondense, 2 new nuclear envelopes re-assemble

mitotic spindle disassembles

cytokinesis begins with contraction of the contractile ring

what happens in cytokinesis in animal cells

contractile rings of actin and myosin create cleavage furrow → pinches cell in two

fusion of intracellular vesicles with plasma membrane insert a new membrane

what happens in cytokinesis in plant cells

during telophase, vesicles derived for Golgi Apparatus move along microtubules to form cell plate

Cell plate enlarged until its surrounding membrane fuses with plasma membrane

results in 2 daughter cells with own plasma membrane

explain microtubules’ dynamic instability

they grow (rescue) and disassemble (catastrophe) alternatively

depending on the presence (rescue) or absence (catastrophe) of a GTP capping at their end

what are kinetochores

protein complexes that form a plaque on the surface of the centromere

in animal cells, each kinetochore binds 10-40 spindle microtubules

how do chromosomes move during mitosis

kinetochore proteins bind to sides of microtubules near plus end, with many labile bonds that ber

what is the result of mitosis

two genetically identical cells

each new cell has a full complement of chromosomes

each new cell has half the cytoplasm and organelle of the parental cell