week 3 thursday

Question 1

cytoskeleton

Answer 1

intricate network of protein fillaments:

microtubules
microfiliments
intermediate filliments

Question 2

organize protein filaments of cytoskeleton in order of size (small to big)

Answer 2

microfiliments
intermediate filaments
microtubules

Question 3

organize protein filaments of cytoskeleton in order of rigidity (least to most rigid)

Answer 3

microfiliments - flexible
intermediate fillaments - rigid

microtubules - neither, transports items in tubes

Question 4

microfiliments

Answer 4

maintain cell shape, involved in muscle contractions and more

atp added to + end (has directionality, turns to adp (looses phosphate) the longer it is a part of the filament

Question 5

intermediate filiments

Answer 5

made of coiled monomers that wrap around eachother, stacking these coiled monomers creates strong ropelike structure

provide tensile strength + IFs make up nuclear lamina

Question 6

nuclear lamina

Answer 6

underlay of nuclear envelope that provides structure to nuclear envelope

Question 7

tensile strength

Answer 7

how cells stay together and connected when under physical pressure (ex. being pulled apart)

Question 8

microtubule structure

Answer 8

stacked alpha and beta heterodimers create a protofiliment, protofiliments combine to form the tube shape (microtubule)

Question 9

centresome

Answer 9

made of microtubules. 9 groups of 3 microtubules make up larger tube (centriole) two of these purpendicuraly aligned make up the full centrosome

Question 10

microtubules

Answer 10

have directionality due to alpha and beta alternation. all microtubules are synthesized in the centrosome.

vesicles travel through microtubules (movement driven by motor proteins)

Question 11

kinesin

Answer 11

microtubule motor protein. + end directed (moves towards + end)

Question 12

dynein

Answer 12

microtubule motor protein. - end directed (moves towards - end)

Question 13

first phase of the cell cycle

Answer 13

1. G1/G0

monitor internal + external environent, are there enough nutrients to grow and devide?
- if enough: G1 starts (cell growth, continued monitoring)
- not enough: G0 nothing happens

Question 14

second phase of the cell cycle

Answer 14

2. synthesis/S-phase

replicate chromosomes (DNA replication)

Question 15

third phase of the cell cycle

Answer 15

3. G2

monitor internal and external environments + cell growth (sort of like second G1)

Question 16

fourth phase of the cell cycle

Answer 16

4. mitosis

seperate chromosomes, nuclear devision, cytoplasmic devision (cytokenesis)

Question 17

flow cytrometry

Answer 17

way of scientifically monotering the cell cycle

dye DNA in cells and run cells through laser cell-by-cell to read flourecense and create graph

Question 18

cyclin-dependend kinases (Cdks)

Answer 18

tell/decide when/if cell moves to next phase of cell cycle

(catalytic subunit, phosphorilizes substances to trigger cell cycle events, can only phosphorilate when bonded w/cyclin)

Question 19

cyclin

Answer 19

regulatory subunit, expression occilates (concentration of cyclin changes/is regulated)

Question 20

what is cyclin concentration regulated by

Answer 20

transcription (slow increase) and proteolysis (fast decrease due to cell distruction)

Question 21

what does phosphorilation to the cyclin-Cdk complex do

Answer 21

can either activate or inhibit, depends on which site is phosphorylated (inhibiting or activating site)

Question 22

Cdk inhibitors (CKIs)

Answer 22

act as cell cycle brake.

blocks active site in cyclin-Cdk, causing inhibition

Question 23

DNA damage checkpoints

Answer 23

block cell progression, places where cell stops + checks steps of the cell cycle

Question 24

M-Cdk

Answer 24

active M-Cdk drives transition to mitosis/signals for mitosis to comence

regulates its own activity through positive feedback loop

Question 25

how are mitotic spindles formed

Answer 25

M-Cdk reorganizes chromosomes by phosphorylating cohesion (which form sister chromatids)

mitotic spindles are assembled using microtubles, M-Cdk phosphorilates microtubule associated proteins (MAPs) and microtubule motor proteins (kenisin + dynein) to assemble spindles

Question 26

prometaphase

Answer 26

M-Cdk phosphorilizes nuclear lamins (structure of nuclear envelope) which causes breakdown of the nuclear envelope

Question 27

prometaphase/metaphase

Answer 27

connect chromosomes to mitotic spindle through keneticore

Question 28

keneticore

Answer 28

massive protein complex at the centromere of a chromosome to which the microtubules bind (stabalises microtubules)

Question 29

structure of mitotic spindle

Answer 29

the 3 types of microtubules (from cytoskeleton)

motor proteins attach spindles to chromosomes, connect to eachother for structure, radiate outwards (individually) for structure

Question 30

metaphase

Answer 30

chromosomes continue to be organized by spindles + motor proteins

Question 31

anaphase

Answer 31

seperation of chromosomes by spindles

seperatase (enzyme) cuts cohesions which cuts the tension + allows chromosomes to quickely seperate

Question 32

anaphase A

Answer 32

chromosomes are pulled towards poles

Question 33

anaphase B

Answer 33

spindle poles move away from eachother (cell elongates)

Question 34

telophase

Answer 34

wrapping up, exit from mitosis

new nuclear envelopes formed for new daughter cells

Question 35

cytokenesis

Answer 35

contractile ring forms out of actin microfilliments and cytoplasm devides into two new cells