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mcdb1A > cell cycle and mitosis > Flashcards

cell cycle and mitosis Flashcards

(54 cards)

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1
Q

why do cells divide?

A

growth, repair, reproduce

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2
Q

prokaryotic cell division

A

cell division occurs through binary fission
dont require any signal
as long as there are nutrients in the environment they will divide
divide very rapidly, every 30 minutes
DNA in prokaryotes is usually a single chromosome that takes the form of a closed circle, so it must be extremely tightly folded

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3
Q

how do prokaryotes divide?

A

origin of replication (ori) is where replication starts
as replication starts there will be two copies of the origin of replication
these two origins will move away from each other and become tethered to the plasma membrane of the cell
origins will be pulled apart from one another in opposite directions
movement of origins of replication moving apart results in the one bacterial cell pinching in the middle to form two cells
fission results in two daughter cells

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4
Q

how is eukaryotic and prokaryotic division different

A

eukaryotes are larger and more complex with large numbers of chromosomes, many organelles, an endomembrane system, and a cytoskeleton that must be properly replicated and distributed equally to the daughter cells
cell division is rarely continuous and is regulated
need a signal to divide

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5
Q

why is it important to regulate cell division in multicellular organisms?

A

if you divide uncontrollably you can generate extra tissue or tumors

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6
Q

genome

A

collection of all dna blueprints of organism

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7
Q

how do we package 2m worth of DNA into a cell

A

package dna into chromosomes

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8
Q

chromosomes

A

linear DNA molecules with many proteins
contain hundreds to thousands of genes
humans have 46 chromosomes/ 23 pairs of them
somatic cells are diploid

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9
Q

somatic cells

A

all cells but sexual cells (gametes—> eggs/sperms)

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10
Q

having diploid chromosomes means what

A

we have two copies of each gene
one from male and one from female

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11
Q

centromere

A

waist that connects the chromatids of a paired chromatids
repetitive sequences of DNA bound by centromeric proteins

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12
Q

loci

A

specific location of a gene on a chromosome

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13
Q

alleles

A

versions of genes
same loci on a chromosome
difference in alleles changes the type of protein produced by the blueprint

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14
Q

what is constituted as a chromosome

A

I I is two chromosomes X is one chromosome

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15
Q

diploid

A

when you have two of the same version of chromosome

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16
Q

haploid

A

when u only have one subset of a pair of homologous chromosomes

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17
Q

cohesin

A

proteins that attach along the entire length of chromosomes to keep paired chromatids together

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18
Q

because we have very large genomes, packing them has to be a very precise, controlled process
thus we use

A

histones

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19
Q

histones charge

A

mostly positively charged in the point of contact with dna
important because dna is negatively charged due to its negatively charged phosphates

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20
Q

what connects histone clusters

A

linker dna

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21
Q

histone clusters are called

A

nucleosomes

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22
Q

what does the distance between nucleosomes change

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A

how accessible the dna is gonna be for transcription (more or less)

23
Q

chromatin

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A

dna-histone complex
come as either heterochromatin(tightly packed nucleosome complex) or euchromatin (relaxed fit of nucleeosomes)

24
Q

example of heterochromatin

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A

chromosomes
tightly packed

25
karyotype
the number and size and shape of chromosomes
26
chromosome duplication
process called mitosis chromosome replicates, creating two copies of each of its genes —> results in paired chromatids connected by cohesin proteins mitosis separates the two paired chromatids from one another into two chromosomes in different daughter cells results in two daughter cells that are genetically identical copies of the original cell no genetic variation between daughter cells and parent cell
27
eukaryotic cell cycle 4 phases
G1 phase S phase G2 phase m phase
28
interphase
every phase other than m phase
29
m phase general descriotion
mitosis division of DNA inside the cell (division of nucelus) cytokinesis also occurs (division of daughter cells)
30
G1 phase
gap 1 period between M phase and S phase phase where cell carries out its function until something signals it to divide
31
S phase
dna synthesis phase replication occurs -- > replicated chromosomes replicated DNA
32
G2 phase
replicate everything other than DNA - ER, organelles, cytoskeleton, etc
33
how is the cell cycle regulated
checkpoints G1, G2 M checkpoints
34
G1 checkpoint
after signal is received to replicate, the cell ensures it is in the right shape to do so ensure that all the genes are in the right place and shape —> so that they are functional
35
G2 checkpoint
ensure copies are correct and everything has been replicated
36
M checkpoint
ensure dna is going to be properly divided
37
experiment where cells in one phase of cell cycle are fused with a cell in a different phase
fusing cells allows the cells to move to a different phase of cell cycle (dependent on what phase the other cell was in) Sharing cytoplasm allowed for this change in phase, due to CDKs presence
38
kinases
a protein that adds a phosphate group to a protein (phosphorylate)
39
Cyclin dependent kinases
a kinase that requires cyclin to work CDK will phosphorylate many proteins and activate or inhibit their activity Covalently add phosphate to proteins and regulate how they work CDK is always there but its active site is not always exposed Cyclin is made when the cell must move to the next phase/ when it is required Cyclin binding to cdk changes its conformation, exposing its active site A protein substrate and ATP bind to cdk and protein is phosphorylated
40
How cdk governs the cell cycle
Many pairs of cyclin and cdk Work as checkpoint of cell cycle
41
example of cdk
Maturation promoting factor (MPF) Exists between G2 and M phase at a checkpoint Allows for cell to go into mitosis Cyclin concentration goes down after M phase, so MPF activity also goes down
42
Checkpoint triggers
G1 Dna damage S Incomplete replication or DNA damage G2 Dna damage M Chromosome unattached to spindle
43
Mitosis Goal:
Separate duplicated DNA in the chromosome to the 2 daughter cells The daughter cells are genetically identical
44
5 phases of mitosis
Prophase Prometaphase Metaphase Anaphase Telophase
45
mitosis interphase
Pre-mitosis stages Nuclear envelope encloses nucleus Nucleus still maintains nucleolus Two centrosomes(make spindle fibers) have formed by duplication Chromosomes are duplicated during S-phase but have yet to condense
46
mitosis prophase
Chromatin fibers become tightly coiled and condense into discrete chromosomes Nucleoli disappear ( nucleolus) Each duplicated chromosome appears as two identical paired chromatids joined at the centromere Mitotic spindle begins to form Centromeres move away from one another (waist of chromosomes) Want to center in the cell
47
mitosis prometaphase
Nuclear envelope fragments Microtubules extend from each centrosome, invading ex-nuclear space Kinetochores. A specialized protein structure, forms at the centromere of each chromatid
48
metaphase
Centrosomes(type of mtoc) are now at opposite poles of the cell Chromosomes have arrived at metaphase plate (center of ell) Plane that is equidistant between spindles two poles The kinetochores of paired chromatids attach to kinetochore microtubules coming from each pole
49
Mitotic spindle
assembly of microtubules and their associated proteins that move chromatids around Kinetochore microtubules attach to chromatids at their centromeres
50
Polar microtubules
Microtubules that don’t attach to kinetochores but serve to center the spindle
51
Aster
Serve to center spindle in the cell
52
anaphase mitosis
Cohesin protein degrades, allowing sister chromatids to part Each chromatid is now an independent chromosome Daughter chromosomes move towards opposite ends of cell as kinetochore microtubules shorten Polar microtubules extend, pushing cell apart
53
mitosis telophase
Two daughter nuc;lei form in the cell, nuclear envelope arise from fragments of parent cell’s nucleus Nucleoli reappear Chromosomes decondense Spindle microtubules depolymerase
54
Cytokinesis
Break two cells apart In animals You develop a contractual ring of microfilaments (pinch) In plant cells Vesicles form cell plate creating a new cell wall/cell plate

mcdb1A (11 decks)

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