Chapter 3: Cell division and chromosome heredity Flashcards

1
Q

What are the characteristics of mitosis

A

One DIPLOID parent cell produces 2 DIPLOID daughter cells

occurs in somatic cells (no egg/sperm) and spores of ASEXUALLY reproducing species

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2
Q

What are the stages of mitosis

A

Interphase
prophase
prometaphase
metaphase
anaphase
telophase + cytokinesis

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3
Q

What occurs in mitosis interphase?

A

Chromosomes are unwound and begin duplicating… centrosomes are on one side of the cell

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4
Q

What occurs in mitosis prophase?

A

Centrosomes begin to move apart, microtubules begin to grow, chromatids condense

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5
Q

What occurs in mitosis prometaphase?

A

Nuclear envelope breaks down
nucleolus disappears
microtubules begin to expand/contract, pulling chromatids to central part of cell

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6
Q

What is a kinetochore?

A

Protein structure near centromere where microtubules attach

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7
Q

What is a nonkinetochore microtubule?

A

Makes the cell elongate during division

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8
Q

What are the negative and positive (+) ends of the microtubules from the centrosomes?

A

negative (-) : the end closest to the centriole
positive (+) : growing end of the microtubule

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9
Q

Describe the process of a growing motor protein???????

A
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10
Q

What occurs in mitosis metaphase?

A

Chromatids are pulled to the center and lined up single file
spindle and metaphase plates form

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11
Q

What occurs in mitosis anaphase?

A

The chromatids are pulled apart, forming daughter chromosomes at either spindle pole

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12
Q

What occurs in mitosis telophase/cytokinesis?

A

Nucleolus reforms
nuclear envelope reforms
chromosomes unwind
cytokinesis occurs (cell membrane divide)

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13
Q

Describe the process of chromatids being pulled apart?

A

Prophase: chromatids held together with cohesin protein

Metaphase: Kinetochore and microtubule attaches, kinetochore movement pulls is pulling the chromatids in opposite direction

Anaphase: Separase dissolves cohesin to let the chromatids be pulled apart

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14
Q

What are the characteristics of Meiosis 1 and 2?

A

2 rounds of cell division produces two HAPLOID gametes
——–one copy of each chromosome = one half of each homologous pair

Occurs in the gametes (egg/sperm) as well as spores of sexually-reproducing species

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15
Q

What are the stages of Meiosis 1 during prophase I?

A

Leptotene
Zygotene
Pachytene
Diplotene

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16
Q

What occurs in prophase Iduring leptotene?

A

-chromosomes begin to condense
-centriole gets ready to migrate

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17
Q

What occurs in Prophase I during Zygotene?

A

-homologs align precisely and pair up with each other (four sets of chromosomes in three pairs), knwon as bivalents

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18
Q

Describe the formation of the Synaptonemal complex?

A
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19
Q

What is the purpose of meiosis I?

A

Separate homologous chromosomes

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20
Q

What occurs in prophase I during pachytene?

A

Further condensation of chromosomes
synaptonemal complex is formed
crossing over occurs
nodules appear

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21
Q

What are PARs and where do they play a role in meiosis I, prophase I?

A

Pseudo autosomal regions
where crossing over occurs during pachytene phase of meiosis I

22
Q

What occurs in meiosis I, prophase I, during diplotene?

A

-nuclear envelope dissolves
-centrosomes moved to opposite sides
-microtubules are formed
-crossing over complete
-chromosomes begin to move apart

23
Q

What is the chiasma?

A

Where crossing over has occurred in prophase I

24
Q

What occurs during meiosis I during metaphase I?

A

-homologs pair and line up, 2 by 2 (2 pairs of chromosomes and three sets lined up at the spindle)

25
Q

What occurs during Meiosis I during anaphase?

A

Homologs separate (both members of pairs are separated)
3/6 chromosomes move to each pole, sister chromatids remain attached

26
Q

What occurs during Telophase I and cytokinesis during meiosis I?

A

nuclear envelope reforms
cleavage furrow –> cells divide

27
Q

Explain the process of chromosome separation in Meiosis I?

A

Diplotene/diakinesis: Kinetochore/nonkinetochore microtubules attach to kinetochore near centromere

Metaphase: Kinetochore movement pulls the chromosomes in opposite directions

Anaphase I: homologs are moved to separate poles

28
Q

What is the purpose of meiosis II?

A

Separate sister chromatids

29
Q

What happens in meiosis II during prophase II?

A

nuclear envelope breaks down
centrosomes begin to migrate

30
Q

What happens in meiosis II during metaphase II?

A

Metaphase plate forms… chromosomes line up at spindle
haploid number of chromosomes (3 instead of 6)

31
Q

What happens in meiosis II during Anaphase?

A

Chromatids separate

32
Q

What happens in meiosis II during telophase II and cytokinesis?

A

Nuclear envelope reforms
cleavage furrow causes the cells to split
they are not genetically identical

33
Q

Compare meiosis I with Meiosis II?

A

Meiosis I: separation of homologs
Meiosis II: separation of sister chromatids

34
Q

compare the outcome of mitosis with meiosis?

A

mitosis: 2 diploid cells
meiosis: 4 haploid cells

35
Q

Describe the law of segregation?

A

When an organism makes gametes, each gamete receives just one gene copy, which is selected randomly.

36
Q

Describe the law of independent assortment?

A

alleles of two (or more) different genes get sorted into gametes independently of one another.

37
Q

How many pairs of chromosomes do drosophilia have? what is the difference between the male and female?

A

three pairs of autosomes (non sex)…. one pair of sex chromo
Female - identical sex chromo
male- non identical sex chromo

38
Q

What occurred in crosses A and B of Morgans fly experiment?

A

Cross A - Red female, white male… F1 = all red, F2 = 3:1 red and white

Cross B - White female, red male… F1 = red and white 1:1…. F2 = 1:1 ratio of red to white eyes

39
Q

What happens to results when testing reciprocal crosses?

A
  • the results will differ, difference in phenotypic frequencies show up in F1 or F2
40
Q

describe HOW you get the results from cross A? (3:1 F2)

A

Male white carries only ONE X gene that has the mutation, so it not expressed in the first generation, as the female has both dominant genes…. will be expressed in the second generation because the female of F1 is now a carrier… only one of the males will express the gene

41
Q

Describe how sex is determined as a fetus is developing?

A

-presence of SRY (sex determining region)
- SRY –> codes for TDF –> TDF causes wolffian duct to grow (MALE) –> MIH causes mullarian ducts to regress

42
Q

What is the gene system used for birds and another animals ?

A

Z/W
Females : WZ
Males : ZZ

43
Q

Describe the Cross A and B of chickens?

A

Cross A:
female (Zb W) x male (ZB ZB)
F1 = female (ZB W) + Male (ZB Zb)
(all progeny are barred)

Cross B:
female (ZB W) x male (Zb Zb)
F1 = female (Zb W) + male (ZB Zb)
(Hens are white and roosters are barred)

44
Q

Heterozygous FEMALES transmit each X-linked allele to approximately ____ daughters and _____ son.

A

1/2, 1/2

45
Q

Affected MALES transmit X-linked allele to _____ daughters and _____ sons?

A

100%. daughters, no sons

46
Q

Would you expect males that inherit an X-linked recessive allele to always express the trait?

A

Yes, they only have one X allele

47
Q

Would you expect females that inherit an X-linked recessive allele to always express the trait?

A

No, it depends on the other X allele

48
Q

Describe a Y-linked inheritance

A

all sons of affected males express traits
no females express the trait

49
Q

What is the term for a gene carried on the Y chromosome?

A

Holandric

50
Q

Describe Lyonization

A

One chromosome is randomly inactivated in each cell of a female…can cause female mammals to be mosaic

51
Q

how do you determine how many barr body’s are present in a cell?

A

Number of X chromosomes above 1.
(ex: 3 chromosomes = 2 barr bodies)

52
Q

What are some examples of lyonization?

A

Anhidrotic ectodermal dysplasia (patches on skin with no sweat glands).
Calico and tortoiseshell cats
males = rare (XXY)