booster vids CELL DIVISION

haploid vs diploid

gametes (n) (23 chromes)

zygotes (2n) (2×23 = 36 chromes)

what are MTOCs and their function?

they are centrosomes which are made of 2 centrioles

spindle fibers are made here to attach to kinetochores (anchor)

what type of cells in our body go through mitosis and meisosis?

mitosis = somatic (nerve, skin, muscle, etc.)

meiosis = germ cells (reproduction)

what phase of mitosis/meiosis can you do karyotyping ?

metaphase/m1

what goes on in prophase and prometaphase of mitosis?

prophase = chromatin condenses to chromosomes, mitotic spindle

prometaphase = nuclear envelope disappears + chromatids attach to kinetochore

what cytokinesis is and how it differs bw animals and plant cells?

cytokinesis = division of cytoplasm

in animal cells = cleavage furrow

in plant cells = cell plate

purpose of meiosis 1 and meiosis 2?

meiosis 1 = diploid to 2 haploid daughter cells;

• separate homo chromes and do genetic recombination

meiosis 2 = separate sis chromatids

what happens at chiasmata?

chromes trade segments

what is synapsis?

homo chromes form into tetrads

diff bw Pro I and Pro II of meiosis ?

Pro I = homo chromes pair up and form tetrads to crossover at chiasmata

Pro II = no crossing over

diff bw Ana I and Ana II of meiosis ?

Ana I = disjunction —> homo pairs separate)

Ana II = sis chromatids separate (not homo pairs)

3 ways that genetic variation/recombination occurs?

1) crossing over

2) independent assortment

3) random joining of gametes

role of M phase, G1, S, G2

M phase = mitosis/cytokinesis

G1 = cell growth and incrs in protein synthesis

S = DNA rep + check for errors

G2 = protein synthesis — organelles rep + cell ensures everything’s ok

what is the role of G0 phase?

G0 = the resting phase

• temporary aka quiescent = memory T cells

• permanent = nerve, muscle, senescent = cell too old/dmged to rep

what phases does interphase of the cell cycle consist of?

G1, S, G2

what’s the longest phase of the cell cycle?

Interphase

when is S:V ratio good?

when is G:V ratio good?

incrs SA : V = : ) (cellular exchange can happen)

incr Genome : V = : ) (cell can sustain itself)

why can’t skeletal muscle divide but can grow instead?

growing = many nuclei = long + cylindrical = SA : ) = more effective

what are 3 specific regulations of the cell cycle ?

1) Checkpoints

2) Density-dependent inhibition (too many cells = stop dividing bc no room )

3) anchorage dependency = cells divide ONLY if they’re anchored to a surface

how many checkpoints are there in the cell cycle and what are their roles?

Restriction point = end of G1 = favorable condns?

G2/M checkpt = end of G2 = is DNA repped properly?

spindle checkpoint = metaphase = are sis chromatids attached to spindle fiber?