Chapter 15 Flashcards

1
Q

which of Mendel’s laws were supported by the behavior of chromosomes during meiosis

A

law of segregation and law of independent assortment

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2
Q

describe the chromosome theory of inheritance

A

mendelian genes have specific loci on chromosomes, chromosomes undergo segregation and independent assortment

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3
Q

who provided convincing evidence that chromosomes are the location of mendel’s heritable factors

A

Thomas Hunt Morgan

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4
Q

how did Morgan provide the first solid evidence that genes are associated with a specific chromosomes

A

during his breeding of fruit flies he came upon a gene that was only showing up in his male flies and not the females. This led him to believe that the Y chromosome did not have a copy of the gene.

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5
Q

what is a sex-linked gene

A

a gene located on either sex chromosome

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6
Q

how does the production of sex-linked proteins in females compare to that of males

A

they are at similar rates, as one of the two x chromosomes in each female cell is randomly inactivated during embryonic development

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7
Q

what happens if a female is heterozygous for a particular gene located on the x chromosome

A

she will be a mosaic for that character

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8
Q

What did Morgan conclude about how linkage affects the inheritance of different characters

A

genes that are close together on the same chromosome are inherited together, those on different chromosomes or further apart are inherited independently

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9
Q

what are offspring called that show new combinations of the parental traits

A

recombinant offspring

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10
Q

what percentage of offspring are recombinants

A

50%

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11
Q

how did Morgan explain a recombination of genes that were located close together

A

he theorized that there was a process that occasionally broke the physical connection between the genes, this was later discovered to be the crossing over of homologous chromosomes

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12
Q

what is a genetic map and how is it developed

A

it is an ordered list of the genetic loci along a particular chromosome, developed using recombination frequencies

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13
Q

what is a linkage map

A

an illustration of the relative locations of genes along a chromosome

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14
Q

what often results from large-scale chromosomal alterations

A

spontaneous abortions (miscarriages) or a variety of developmental disorders

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15
Q

what is nondisjunction

A

when pairs of homologous chromosomes do not separate normally during meiosis, causes gametes to form with two copies or no copies of a particular chromosome

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16
Q

what is aneuploidy

A

a condition in which offspring have an abnormal number of a particular chromosome

17
Q

what does it mean for a zygote to be trisomic

A

it has three copies of a particular chromosome

18
Q

what does it mean if a zygote is monosomic

A

it has only one copy of a particular chromosome

19
Q

what are the fours types of changes in chromosome structure

A

deletion, duplication, inversion, and translocation

20
Q

what causes down syndrome

A

trisomy 21

21
Q

what causes Klinefelter syndrome

A

extra chromosome in male (XXY)

22
Q

what causes Turner Syndrome

A

monosomy X (X0)

23
Q

what causes Cri du chat

A

a deletion in a chromosome

24
Q

what common disease is often caused by translocations of chromosomes

25
Describe genomic imprinting
the silencing of certain genes that are "stamped" with an imprint during gamete production (effect of the allele depends on which parent it was inherited from)
26
what are extranuclear genes
genes found in organelles in the cytoplasm
27
which parent controls the inheritance of traits controlled by genes present in the chloroplasts or mitochondria
mother - zygotes cytoplasm comes from the egg
28
what types of diseases are caused by defects in mitochondrial genes
diseases that affect the muscular and nervous systems - prevent cells from making enough ATP