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Genetics - Laboratory > Cell Division > Flashcards

Cell Division Flashcards

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1
Q

functions fo cell division

A

(1) growth and development (early embryonic development)
(2) repair of damaged tissues and organs
(3) formation of sex cells

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2
Q

sequence of phases in the life cycle of the cell

A

cell cycle; 90% preparation and 10% execution

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3
Q

what are the two phases of cell cycle?

A

(1) interphase (G1, S, G2)
(2) M phase

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4
Q

what is G0 phase?

A

resting phase

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5
Q

true or false: prokaryotes and eukaryotes undergo mitosis and meiosis.

A

false. prokaryotic cells are simpler structures and have different genetic materials and cellular organization from eukaryotes

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6
Q

decribe eukaryotic cells

A

has membrane-bound nucleus and organelles; structurally large and complex; larger genome; typically diploid

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6
Q

describe prokaryotic cells

A

no membrane-bound organelles; structurally small and simple; smaller genome; typically haploid

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7
Q

what are chromatids?

A

identical copies of a chromosome

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8
Q

what are chromatins?

A

DNA = histone proteins that condense to form chromatids

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9
Q

what are chromosomes?

A

highly condensed chromatin fibers carrying genes and are involved in cell division

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10
Q

chromosomes are composed of ___.

A

(1) chromosome arms (p and q arm)
(2) centromere
(3) kinetochore
(4) telomere

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11
Q

region of DNA where sister chromatids are joined

A

centromere

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12
Q

protein complex assembled on centromere and where spindle fibers attach

A

kinetochore

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13
Q

protects chromosome ends

A

telomere

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14
Q

number of complete sets of chromosomes in a cell is also known as ___.

A

ploidy level

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15
Q

differentiate haploid from diploid

A

haploid (n) : one set and a result of gamete formation
vs.
diploid (2n) : two sets and a result of fertilization

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16
Q

what cells are involved in mitosis? what is its result?

A

germ and somatic cells; two identical daughter cells (chromosome number is maintained)

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17
Q

mitosis in multicellular organsism vs unicellular organisms

A

for growth and development and replacement fo worn tissue
vs.
mode of reproduction

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18
Q

growth phase; cells increase in size

A

G1 phase

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19
Q

DNA replication phase

A

s phase

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20
Q

growth phase and preparation for mitosis; DNA repair

A

G2 phase

21
Q

what happens during prophase?

A

(1) chromatin fibers condense into chromatids
(2) nucleolus and nuclear membrane dissolve
(3) formation of spindle fibers
(4) centrosomes start to migrate to the poles

22
Q

what happens during metaphase?

A

(1) chromosomes align at the middle (metaphase plate) : most condensed state
(2) spindle fibers attach to the kinetochore

23
Q

what happens during anaphase?

A

(1) sister chromatids separate and migrate toward the opposite poles

24
Q

what component in the kinetochore pulls the sister chromatids causing separation?

A

motor protein

25
Q

what happens during telophase?

A

(1) chromatids arrive at the opposite poles, becoming less condensed
(2) spindle fibers dissolve
(3) nuclear envelope and nucleolus begin to reform
(4) cleavage furrow or cell plate begins to form

26
Q

cytoplasm is divided in half, forming two daughter cells

A

cytokinesis

27
Q

cytokinesis in animal cells vs plant cells

A

in animal cells, the cleavage furrow is pinched by a contractile ring from the periphery; in plant cells, the cell plate starts at the center and grows

28
Q

what cells are involved in meiosis?

A

germ cells (2n) > gametes (n)

29
Q

what type of division does meiosis follow? what si its result?

A

meiosis 1 : reductional division
meiosis 2 : equational division
results in four haploid daughter cells where the chromosome number is halved; key step in gametogenesis (oogenesis and spermatogenesis)

30
Q

key to genetic diversity; one round of DNA replication in interphase followed by two round of cell division

A

meiosis

31
Q

what happens in interphase I?

A

genetic material is replciated; ploidy: 2n

32
Q

what happens in prophase I?

A

(1) chromatin fibers condense into chromatids
(2) nuclear envelope and nucleolus dissolve
(3) homologous chromosomes align via synapsis, held together by synaptonemal complexes
(3) crossing over may occur in the chiasmata
note: ploidy : 2n

33
Q

chromosomes that have the same DNA length, genes present (tho sequence can vary
between maternal and paternal genes), and centromeres in the precise location

A

homologous chromosomes

34
Q

what si the ploidy level fo homologous chromsomes?

A

2n or diploid

35
Q

when homologous chromosomes align, they are called ___.

A

tetrads

36
Q

what is crossing over? where do they occur?

A

exchange of genetic sequence or recombination; may occur between the middle chromatids

37
Q

what happens in metaphase I?

A

(1) tetrads randomly align, enabling genetic variation
(2) spindle fibers attach to both the kinetochores of teh sister chromatids
note : ploidy is 2n

38
Q

what happens in anaphase I?

A

(1) chiasmata separate
(2) each member of the homologous pair moves toward the opposite poles
(3) sister chromatids remain attached
ploidy : 2n

39
Q

what happens in telophase I + cytokinesis?

A

two daughter cells with sisters chromatids attached to each other are formed; ploidy : n

40
Q

what happens in prophase II?

A

(1) similar to mitotic prophase
note : ploidy is n; no pairing of homologous chromosomes and no crossing over

41
Q

what happens in metaphase II?

A

(1) alignment of the sister chromatids at the metaphase plate
(2) spindle fibers attach to the kinetochore
note: ploidy is n

42
Q

what happens in anaphase II?

A

sister chromatids separate and move toward opposite poles
note : ploidy is n

43
Q

what happens in telophase II + cytokinesis?

A

(1) complete meiotic cell division
(2) results into four haploid daughter cells

44
Q

explain how genetic variation ahppens

A

(1) crossing over and recombination, wherein there is an exchange of genetic sequence, occur during prophase I. this results in new combinations of genes on each chromosome.
(2) the random arrangement of homologous pairs in metaphase I also contributes to variation since the daughter cells receive a mix of maternal and paternal chromosomes during this event
(3) fusion of genetically diverse gametes (fertilization) : each gamete carries a unique set of genetic information due to crossing over and independent assortment

45
Q

applications : cells that can replicate itself or differentiate into various cell types; used in disease modeling, tehrapy, transplants, skin grafts

A

stem cells

46
Q

application : how does cell cycle affect stem cells?

A

cell cycle affects the dissolution of pluripotency (the ability to become any cell type) and differentiation into specific cell types.
cell cycle is important in maintaining pluripotency and differentiation. disruptions lead to the loss of plurip. and affect the differentiation process

47
Q

applications : cell cycle and cancer

A

cell cycle’s regulation is important for maintaining healthy cell growth. when this regulation fails, cancer may develop. cancer cells often bypass the cell cycle checkpoints that normally prevent uncontrolled growth. when cancer cells ignore these checkpoints, they grow and divide uncontrollably, forming tumors

48
Q

a suppressor gene that causes cell cycle arrest or apoptosis

A

p53 tumor suppressor gene

49
Q

how was the onion root tip prepared?

A

(1) onion bulb was placed in a bottle filled with water and was left to sit overnight (encourage root growth since root tips are regions of active cell division)
(2) onion root tips were cut to ~5mm between 11 am and 2 pm (ensures that cells are collected during their peak mitotic activty)
(3) root tips were transferred to a farmer’s solution for 24 hours (fixes the cells and preserve their structure; halt any further cell division)
(4) root tips were stored in 70% ethanol at 4 degrees C (helps dehydrate tissue)
(5) root tips were placed in a petri dish with 1 N HCl for 8-10 mins (helps soften the cell walls to easily squash the root tip and spread cells on the slide; helps break down middle lamella which holds plant cells together)
(6) place the transparent part of the onion root tip on a clean glass slide
(7) add a drop of acetocarmine and squash the root tip (acetocarmine acts as a stain)
(8) place a coverslip on the slide. remove excess stain. gently press down using the eraser end to spread the cells into a single layer for easier observation.
(9) fix the slide over the flame for 3 - 4 times
(10) observe the slide (meiosis)

Genetics - Laboratory (2 decks)

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