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BIOL 322 Genetics > Exam 2 - Chapter 6: Meiosis and Mitosis > Flashcards

Exam 2 - Chapter 6: Meiosis and Mitosis Flashcards

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1
Q

Who first accurately described down syndrome and?

A

John Langdon Down

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2
Q

Who identified Down syndrome as a chromosome condition?

A

Jérôme Lejeune identifie 47 chromosomes in individuals with Down syndrome

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3
Q

What is trisomy 21?

A

A extra partial or whole copy of chromosome 21 that is associated with causing Down Syndrome

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4
Q

What are two causes of trisomy 21?

A

1) No chiasmata forms and both homologs move to the same pole during meiosis I
2) Chiasmata forms too close to end and doesn’t provide enough resistance to the spindle fiber causing a break

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5
Q

Why are older mother more likely to produce offspring with trisomy 21?

A

Because their primary oocytes have been arrested in prophase I for a longer period of time which may increase frequency of nondisjunction

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6
Q

What is mitosis?

A

a cell divides into two daughter cells

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7
Q

What is meiosis?

A

When cell division occurs twice to produce four, haploid daughter cells

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8
Q

What is the order of the cell cycle

A

G1 > S > G2 > M

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9
Q

What occurs during G1 phase?

A

Regular cell growth and commitment to cell division

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10
Q

What 4 things occur during S phase?

A

1) DNA replication
2) chromosomes condense
3) centromers replicate
4) cohesions are cleaved, except at centromeres

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11
Q

What are centrosomes?

A

the microtubule organizing center that extends microtubules during DNA replication

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12
Q

What are asters?

A

star shaped formations that centromeres form when extending spindle apparatus

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13
Q

What centrioles?

A

Barrel shaped organelles that contribute to microtubule organizing

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14
Q

What are centromeres?

A

Where spindle fibers attach to chromatids

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15
Q

What are cohesions?

A

Protein structures that hold sister chromatids together during cell division

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16
Q

What is the structure and function of tubulin?

A

composed of alpha and beta dimers; make up microtubules and give them a positive and negative end

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17
Q

Which charged ends of a microtubule attach where?

A

The positive end attaches to the kinetochore of chromatin and the negative end is at the centrosome

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18
Q

What is the purpose of G2 phase?

A

Growth to prepare for cell division

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19
Q

What is M phase?

A

the division of a cell into two (mitosis)

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20
Q

What 2 things occur during prophase?

A

1) centrosomes are at the poles
2) microtubules grow from centrosomes to form spindles

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21
Q

What 2 things occur during metaphase?

A

1) Spindles attach at the centromere
2) Spindle tension aligns chromosomes at equator

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22
Q

What are kinetochores?

A

protein complex on a sister chromatid that a spindle binds to

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23
Q

What direction do sister chromatid kinetochore poles face during meiosis I?

A

the same

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24
Q

What direction do sister chromatid kinetochore poles face during meiosis II?

A

opposite

25
Q

What 2 things occur during anaphase?

A

1) chromatids are unbound from each other by separate by cleaving cohesions
2) Chromosomes segregate to poles rapidly by shortening of spindles

26
Q

What occurs during telophase?

A

the physical separation of cells

27
Q

In what three ways does meiosis I differ from mitosis?

A

1) Homologous chromosomes are separated in meiosis I and sister chromatids are separated in mitosis
2) Synaptonemal complex holds homologous chromosomes together during meiosis I, cohesions in meiosis II
3) cross over does not occur in meiosis II

28
Q

When does crossing over occur?

A

during prophase I

29
Q

What is crossing over?

A

homologous chromosomes forms chiasmatas and swap DNA segments

30
Q

How does bouquet formation occur?

A

One end of the each chromosome attaches to the nuclear membrane and the nuclear membrane rearranges with the help of pairing centers to form a bouquet and pair homologs

31
Q

What is the synaptonemal complex?

A

a protein structure that forms during meiosis I to hold homologous chromosomes together

32
Q

What is a chiasmata?

A

Point of contact between non-sister chromatids of homologous chromosomes where crossing over occurs

33
Q

Two causes of recombination in meiosis?

A

crossing over and independent assortment?
between homologs or sister chromatids?

34
Q

What does SPO11 do?

A

make double stranded breaks to facilitate crossing over

35
Q

What is oogenesis?

A

production of a haploid secondary oocyte via meiosis

36
Q

What is a polar body and its function?

A

A nonfunctional cell produces during oogenesis that essentially serves to discard chromosomes

37
Q

What stage are female oocytes arrested at when they are born?

A

Prophase I

38
Q

What stages does a primary oocyte go through and arrest at during ovulation?

A

meiosis I and arrests at metaphase II as a secondary oocyte

39
Q

What stages does a secondary oocyte go through after fertilization?

A

completes meiosis II

40
Q

What is non disjunction?

A

When chromosomes fail to separate properly during cell division resulting in an abnormal amount of chromosomes in daughter cells

41
Q

What is aneuploidy and a common cause?

A

condition of having an abnormal number of chromosomes in haploid set; disjunction

42
Q

What is euploidy?

A

variation in the number of sets of chromosomes

43
Q

What is monosomy?

A

When one chromosome in a haploid set is missing

44
Q

What is trisomy?

A

an extra chromosome exists in a haploid set

45
Q

what is tetrasomy?

A

four copies of chromosomes in a set

46
Q

What is alloploidy?

A

two or more sets of chromosomes come from two different species

47
Q

What is an allodiploid?

A

There are only 1 homolog of each chromosome and chromosomes come from two different species

48
Q

What is mosaicism?

A

Organism contains a subset of cells that are genetically different from the rest and results in genetic abnormalities after fertilization

49
Q

What is a bilateral gynandromorph?

A

half of the body develops as male and the other as female

50
Q

How does a bilateral gynandromorph result?

A

An XX female loses an X during development

51
Q

What is autoploidy?

A

When nondisjunction results in an individual having more or extra chromosomes in each set

52
Q

What is translocation?

A

When a segment of one chromosome is attached to another chromosome

53
Q

What are reciprocal translocations?

A

two non-homologous chromosomes exchange genetic material

54
Q

What are 2 causes of reciprocal translocation?

A

1) chromosomal breakage and DNA repair
2) Abnormal crossovers

55
Q

What is a balanced translocation?

A

translocation where equal amount of genetic material is exchanged

56
Q

Is a reciprocal translocation balanced or unbalanced?

A

balanced

57
Q

What is a simple translocation?

A

translocation of genetic material in one direction and is often associated with phenotypic abnormalities or lethality

58
Q

What is a roberstonian translocation?

A

break occurs near centromeres of two non-homologous chromosomes and larger fragment fuse at centromeres regions to form one large chromosome and smaller segments are lost or form small chromosome

59
Q

What genera is robertsonian translocation associated with?

A

Transition from great apes to humans

BIOL 322 Genetics (9 decks)

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