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BIOL-2301 Final Exam > Chapter 4 > Flashcards

Chapter 4 Flashcards

1
Q

In mitosis, which plane do the two daughter cells divide one?

A

they divide longitudinally

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2
Q

When a cell is not dividing, it is in ___stage

A

interphase stage, g1

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3
Q

Mitosis produces:

A

2 daughter cells, both of whom receive identical diploid complements to the diploid complement of the cell.

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4
Q

What’re the three substages of interphase?

A

G1, S, G2

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5
Q

What is happening at G1?

A

cell growth, organelle replication, replication of centrosome

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6
Q

Which checkpoint determines if the cell can leave the G1 stage? What’re the conditions for the cell to proceed?

A

G1/S check point dictates whether or not the call can proceed to the S stage of interphase.

Conditions: large enough cell size must be obtained, sufficient time elapsed since last cell division.

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7
Q

What occurs in S stage?

A

DNA replication and chromosome duplication

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8
Q

Which checkpoint detemines if a cell can leave the S stage? What’re the the conditions for the cell to undergo mitosis?

A

after the dna is replicated, the cell goes into G2 phase, which is just a post DNA synthesis stage, where it continues to prep for cell division. the cell will not undergo mitosis unless all repair and DNA synthesis is complete (won’t leave the G2/M checkpoint

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9
Q

In proohase, chromatin starts to condense into threads of chromosomes with the help of ____protein complexes

A

condensin

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10
Q

how many centromere does each sister chromatid have?

A

each chromatid has one centromere that joins them together, therefore, in a sister chromatid pair, there are two centromeres.

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11
Q

What kind of protein holds the sister chromatids together until anaphase?

A

cohesin proteins

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12
Q

Summarize what happens in prophase.

A

the duplicated chromatin begin to condense with the help of condensin proteins. The sister chromatids then get held together by cohesin protein and are joined together at their centromeres. The nucleolus disappears and the nuclear membrane disintegrates.

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13
Q

What are the mitotic spindles made of? Where is polymerization of the spindle building blocks taking place?

A

mitotic spindles are made of tubulin proteins that make up microtubules. polymerization occurs at the centrosome: the organization centers at the poles.

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14
Q

How many centrosomes are at each pole?

A

there are two centrosomes at each pole in a duplicated cell. After mitosis, each daughter cell pocesses one pair of centrosomes.

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15
Q

At what stage of mitosis do the mitotic spindles begin to form?

A

in metaphase

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16
Q

what’re the three main types of microtubule spindles in a cell?

A

1) ones that anchor the centrosome to the cell membrane
2) ones that arch between the chromosomes
3) one that attach to chromosomes

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17
Q

Usually, microtubules are unstable. At what point to the microtubule spindles get stabilized?

A

spindles that do not attach to anything disintegrate (arch between the chromosomes). Only when the spindles attach to a kinetochore do they become stabilized.

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18
Q

What events all occur in metaphase?

A

spindle apparatus gets assembled via the polymerization of microtubules, and the spindles attach to the kinetochores and line the chromosomes on the metaphase plate.

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19
Q

Is there a checkpoint in metaphase?

A

yes

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20
Q

What conditions must be met in order for the cell to proceed past metaphase?

A

kinetochores must be perfectly aligned on the metaphase plate. when all the kinetochores are under tension, kinetochore-associated proteins get dephosphorylated, chemically signalling that metaphase is complete.

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21
Q

What happens in anaphase?

A

1) cohesins that were holding the two sister chromatids together disintegrate
2) Chromosomes separate and the sister chromosomes move to opposite poles as the microtubules that were connected to the kinetochore begin to depolymerize
3) cell elongates and the chromosomes are in 2 groups at opposite sides of the cell.

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22
Q

What happens in telophase?

A

the chromosomes begin to condense into the interphase form and the nuclear envelope reforms and the nucleolus reappears. The spindle apparatus disappear. Cytokinesis occurs in animal cells via cleavage furrow and cell plate formation occurs in plants.

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23
Q

Differences between mitosis and meiosis

A

1) synapsis and crossing over occurs in prophase I during meiosis
2) segregation of Homologous chromosomes in anaphase 1 instead of sister chromatids results in the daughter cells having half the original chromosomes
3) 2 nuclear divisions with no DNA replication between divisions
4) Meiosis produces 4 cells each genetically distince with half the amount of DNA of mitotic products.

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24
Q

What type of cells does meiosis take place in?

A

meiocyte cells.

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25
Q

In the female of animals and plants, only one of the ___ cell products develops into a functional cell, the rest ___

A

one of the four cell products develop into a functional cell, the rest disintegrate.

26
Q

In plants, products of meiosis form ____

A

haploid spores

27
Q

The spores undergo mitotic division to produce a haploid _____ generation

A

gametophyte generation organism

28
Q

the gametophyte generation produces ____ via mitosis or meiosis?

A

gametes via mitosis. it is already haploid

29
Q

The haploid gametes fuse to create a ____

A

diploid zygote

30
Q

the zygote then forms the ___generation

A

sporophyte

31
Q

How are plant spores produced?

A

the sporophyte generation undergoes meiosis.

32
Q

Meiosis 1= _____ division

A

reductional division, it reduces the amount of chromosomes in half

33
Q

Meiosis II= ____ division

A

equatorial division. mitotic like division, producing cells with single stranded chromosomes.

34
Q

How does meiosis create genetic diversity?

A

1) crossing over

2) independent assortment of homologous chromosomes during prophase one

35
Q

How many alignments are possible on the metaphase plate?

A

a diploid organism with 2N chromosomes will have a 2n possible combination of arranging its chromosomes during metaphase 1

36
Q

Prophase 1 of meiosis is divided into ___ substages

A

5

37
Q

What happens in leptotene?

A

chromosomes appears as thread-like structures and begins to condense.

2) telomeres are associated with regions in the membrane– aids in pairing of homologous chromosomes.
3) synaptomenal complex of homologous chromosomes form, separated by a central element.

38
Q

Does synapsis occur in leptotene stage?

A

no

39
Q

What is the lateral element?

A

chromomers that aid in the condensing process during leptotene stage.

40
Q

At what stage do the homologous chromosomes pair up to form the synaptomenal complex?

A

leptotene stage.

41
Q

At what stage does true synapsis of homologous chromosomes occur?

A

zygotene stage.

42
Q

What is the synaptonemal complex?

A

lateral element protein structure that helps hold homologous chromosomes together.

43
Q

What happens to the chromosomal appearance at zygotene stage?

A

appears like “pairs threads” that are slightly thicker.

44
Q

What happens at pachytene stage of prophase 1?

A

1) chromosomes appear thickened
2) all four chromatids (2 homologous pairs) are apparent
3) crossing over occurs.
4) chiasmata visible

45
Q

At what stage does crossing over occur in prophase 1?

A

pachytene stage

46
Q

At what stage does the synaptomenal complex breaks down? What else happens at this stage? How is this stage characterized?

A

diplotene stage. chromosomes begin to separate, and the homologous chromosomes remain together only at the points of crossing over. (chiasmata)

Nuclear membrane disappears.

47
Q

What stage can sex cells stay in for the majority of the human life?

A

diplotene stage. diplotene stage is completed at 7th month of development and then remains in diplotene until puberty. in females, one cell progresses out of diplotene and gets released for fertilization.

48
Q

At what stage do the homologous chromosomes almost fully separate except at one chiasmata?

A

diakinesis. one chiasmata stays until anaphase 1. chromosomes attain maximum condensation.

49
Q

T/F In anaphase 1: centromere separation between chromosomes occur.

A

False. In anaphase one, homologous chromosomes separate from one another and proceed to opposite poles. In anaphase 2, the centromere separation between chromatids then occur.

50
Q

What a centrioles composed of?

A

9 triplets of microtubules.

51
Q

What are centrioles meant for daughter cells to have?

A

they are meant to ensure that daughter cells receive a pair of centrioles so that progeny can produce basal bodies.

52
Q

T/F: Cilia is sel replicating

A

true. if a cell loses its centrioles because a copy was not passed down from its parent, it can never make basal bodies/cilia or flagella ever again.

53
Q

What are spindle fibers composed of?

A

individual microtubules.

54
Q

What’re three main functions of spindle fibers? (think of three a’s)

A

1) attach to chromosomes via kinetochore
2) arch between chromosomes and help with cell exploration and expansion
3) anchor the centrosome to cell membrane.

55
Q

What is sexual dimorphism?

A

the difference in appearance between males and females of the same species.

56
Q

T/F: the X chromosome contains genes related to sexual dimorphism

A

false. genes involved in sexual differentiation are located throughout the genome.

57
Q

Which sex is the homogametic sex?

A

female. XX

58
Q

How did thomas morgan determine that the white eye trait in drosophila was X linked?

A

he did reciprocal crosses. Cross 1: affected female x normal male =1;1 white males and females and 1;1 red males and females.

Cross 2: normal female x affected male. F2= all red females, and 1;1 red to white males.

non mendelian genetics concluded that there was possible sex linkage.

59
Q

When looking at a pedigree, what’re some general attributes that allow you to determine that a trait is X-Linked Recessive?

A

1) grandfather to grandson transmission through daughters
2) more males than females affected
3) never see male to male transmission

60
Q

When looking at a pedigree, what’re some general attributes that allow you to determine that a trait is X-Linked Dominant?

A

1) more females than males affected
2) females transmit to both females and males
3) all daughters of affected males are affected
4) never see male to male transmission (becuase they donate the Y and not the mutant X to their sons)
5) apparent in every generation.

61
Q

What is non-disjunction?

A

the failure of one or more pairs of homologous chromosomes or sister chromatids to separate normally during nuclear division.

BIOL-2301 Final Exam (6 decks)

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