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General Bio I > Chapter 15 (Chromosomal Theory) > Flashcards

Chapter 15 (Chromosomal Theory) Flashcards

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1
Q

What are Mendel’s “factors”?

A

segments of DNA located along

chromosomes

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2
Q

What is the chromosomal theory of inheritance?

A

Mendelian genes have specific loci (positions) along

chromosomes, and it is the chromosomes that undergo segregation and independent assortment

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3
Q

Who is Thomas Hunt Morgan?

A

provided evidence that a specific gene with a specific chromosome existed

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4
Q

What did Thomas Hunt experiment on?

A

fruit flies (Drosophila melanogaster)

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5
Q

Why were fruit flies a good choice for Thomas Hunt to experiment on?

A

production of hundreds of offspring, new-generation forms every two weeks, easily distinguishable chromosomes

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6
Q

What is the wild type?

A

dominant (most abundant)

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7
Q

What is mutant type?

A

recessive (alt. form of wild type)

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8
Q

What change was significant in Hunt’s experiment and what did it explain?

A

only male had white eyes instead of the usual red, suggesting that mutation was sex-linked and it supported the theory of chromosomal inheritance

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9
Q

What is the notation for white eyes?

A

w

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10
Q

What is the notation for red eyes?

A

w+

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11
Q

What is a sex-linked gene?

A

gene located on sex chromosome

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12
Q

What are X-linked genes?

A

gene on X chromosome

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13
Q

What are Y-linked genes?

A

genes located on Y chromosome

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14
Q

What is a parental type?

A

looks like parent

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15
Q

What is a recombinant type?

A

looks like a mix of parents

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16
Q

What is the distance between genes if they are to be inherited together?

A

they have to be close together (unit wise)

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17
Q

What are serious x-linked diseases?

A

Duchenne muscular dystrophy and hemophilia (blood clotting gone)

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18
Q

What do dominant x genes affect?

A

physical

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19
Q

What do recessive genes affect?

A

enzymatic level

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20
Q

How can linked genes be inherited together?

A

they are located near each other on the same chromosome, they don’t sort independently and can affect the inheritance of two traits

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21
Q

Do linked genes deviate from Mendel?

A

yes

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22
Q

What is genetic recombination?

A

production of offspring with combinations of traits that differ from those found in either P generation parent

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23
Q

What does a 50% frequency of recombination suggest?

A

genes located on a different chromosomes or can be very far apart

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24
Q

What does a frequency of recombination lower than 50% suggest?

A

genes are located closely on chromosome

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25
Q

What is genetic recombination based on?

A

Based on crossing over of homologous chromosomes during prophase I of meiosis – exchange of DNA

26
Q

What did Alfred Sturtevant do?

A

construct the first genetic map that has ordered list of loci along a particular chromosome

27
Q

What is a linkage map?

A

A genetic map based on recombination frequencies

28
Q

What are map units for a linkage map?

A

distance between genes for every 1% of genetic recombination frequency

29
Q

When is the physical connection of genes contributing to the idea of unlinked genes?

A

Despite being on the same chromosome and thus being physically connected, the genes are genetically unlinked; alleles of such genes assort independently, as if they were on different chromosomes

30
Q

What does a linkage map not portray?

A

physical location of a gene, only shows recombination frequencies

31
Q

What can a large scale chromosomal alteration lead to?

A

miscarriage or developmental issues

32
Q

What structure is supposed to distribute chromosomes to daughter cells without error?

A

mitotic spindle

33
Q

What is nondisjunction?

A

members of a pair of homologous chromosomes do not move apart properly during meiosis I or sister chromatids fail to separate during meiosis I (aka one gamete receives both pairs whereas the other game doesn’t receive anything)

34
Q

What is aneuploidy?

A

zygote has an abnormal number of a chromosome (think a for abnormal)

35
Q

What is monosomic?

A

the aneuploid zygote that is missing a chromosome (2n-1) (mono for one less)

36
Q

What is trisomic?

A

aneuploid zygote that has one extra chromosome (2n+1) (tri for 3, 1 extra)

37
Q

When does monosomic and trisomic occur?

A

in fertilization

38
Q

What is polyploidy?

A

an organism has more than two complete sets of chromosomes

39
Q

Which one has a more detrimental affect, aneuploidy or polyploidy?

A

aneuploidy

40
Q

What are the different types of changes in chromosomes from errors in meiosis crossing over?

A

deletion, duplication, inversion, translocation

41
Q

What is deletion?

A

the chromosomal fragment is lost

42
Q

What is duplication?

A

“deleted” fragment may become attached as an extra segment to a sister or non-sister chromatid

43
Q

What is an inversion?

A

A chromosomal fragment may also reattach to the original chromosome but in the reverse orientation

44
Q

What is translocation?

A

fragment to join a nonhomologous chromosome

45
Q

How are deletion and duplication related?

A

nonsister chromatids sometimes exchange unequal-sized segments of DNA, so that one partner
gives up more genes than it receives
products of such an unequal crossover are one chromosome with a deletion and one chromosome with a duplication

46
Q

What is an aneuploid condition?

A

Down syndrome

47
Q

What causes Down syndrome?

A

three copies of chromosome 21 (become trisomic)

48
Q

What does Down Syndrome affect?

A

facial features, short stature, correctable heart defects, and developmental delays

49
Q

In the mother, how does down syndrome frequency increase?

A

with age

50
Q

What does nondisjunction in meiosis result in?

A

aneuploidy

51
Q

What happens in the aneuploidy of sex chromosomes?

A

Y chromosome carries relatively few genes or extra copies of the X chromosome

52
Q

What is Klinefelter syndrome?

A

an extra inactive X chromosome in a male (XXY) and it affect reproductive organs, Males can also display an extra Y chromosome (XYY)

53
Q

Are females with XXX healthy or no?

A

healthy because the X is inactive

54
Q

What is Turner syndrome?

A

only one X chromosome, are sterile because

their sex organs do not mature

55
Q

How does a female and male have the same level of protein production?

A

female’s extra X is inactivated so one X in both male and female work

56
Q

What is a Barr body?

A

inactive X chromosome in each cell of a female condenses into a compact object

57
Q

When are Barr bodies reactivated?

A

to make eggs

58
Q

Is the determination of which X chromosome get’s inactivated in females random or not?

A

it is random and independent (1 of the X in XX will get deactivated, but which one?)

59
Q

What are mosaic cells and where are they found?

A

found in females, e with the active X derived
from the father and those with the active X derived from the mother, when a person has 2 or more genetically different sets of cells in his or her body.

60
Q

If a female is heterozygous, what happens to her mosaic cells?

A

half of her cells will express one allele, while the others will express the alternate allele (ex: recessive mutation can lead to some patches of skin will have sweat glands while others will not)

General Bio I (18 decks)

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