ch 8 variation in chromosome structure & number Flashcards

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1
Q

genetic variation

A

genetic differences among members of the same species or among different species

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2
Q

allelic variation

A

genetic variation in a population that involves the occurrence of two or more different alleles for a particular gene

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3
Q

cytogeneticist

A

a scientist who studies chromosomes under the microscope

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4
Q

metacentric

A

describes a chromosome with the centromere near the middle

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5
Q

submetacentric

A

describes a chromosome in which the centromere is slightly off the center

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6
Q

acrocentric

A

describes a chromosome with the centromere significantly off center, but not at the end

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7
Q

telocentric

A

describes a chromosome with its centromere at one end

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8
Q

G bands

A

the chromosomal banding pattern that is observed when the chromosomes have been treated with the chemical called Giemsa stain

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9
Q

deletion

A

condition in which a segment of DNA is missing

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10
Q

deficiency

A

condition in which a segment of chromosomal material is missing

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11
Q

duplication

A

the repetition of a segment of DNA more than once within a chromosome and/or within a genome

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12
Q

inversion

A

a change in the orientation of genetic material along a chromosome such that a segment is flipped or reversed from the normal order

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13
Q

translocation

A
  1. rearrangement in which one segment of a chromosome breaks off and becomes attached to a different part of the same chromosome
  2. event that occurs when a ribosome moves from one codon in an mRNA to the next codon
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14
Q

simple translocation

A

rearrangement in which one piece of a chromosome becomes attached to a different chromosome

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15
Q

reciprocal translocation

A

rearrangement in which two different chromosomes exchange pieces

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16
Q

terminal deletion

A

(also called see terminal deficiency) deletion in which a segment is lost from the end of a linear chromosome

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17
Q

interstitial deletion

A

(also called interstitial deficiency) deletion in which an internal segment is lost from a linear chromosome

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18
Q

repetitive sequences

A

short DNA sequences that occur many times within a species’ genome

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19
Q

nonallelic homologous recombination

A

recombination that occurs at homologous sites within chromosomes, where the sites are not alleles of the same gene; such misaligned crossovers are often due to the occurrence of repetitive spequences

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20
Q

gene duplication

A

an increase in the copy number of a gene; can lead to the evolution of gene families

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21
Q

gene family

A

two or more genes within a single species that are similar to each other because they were derived from the same ancestral gene

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22
Q

copy number variation (CNV)

A

a type of structural variation in which a segment of DNA that is 1000 bp or more in length commonly exhibits copy number differences among members of the same species

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23
Q

segmental duplication

A

a duplication in which a small segment of a chromosome has more than one copy if the same gene

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24
Q

comparative genomic hybridization (CGH)

A

a hybridization technique to determine if cells have changes in chromosome structure, such as deletions or duplications

25
Q

pericentric inversion

A

an inversion in which the centromere is located within the inverted region of the chromosome

26
Q

paracentric inversion

A

an inversion in which the centromere is found outside the inverted region

27
Q

position effect

A

a change in phenotype that occurs when the location of a gene changes from one chromosomal site to a different one

28
Q

inversion heterozygote

A

a diploid individual that carries one normal chromosome and a homologous chromosome with an inversion

29
Q

inversion loop

A

the loop structure that is formed when the homologous chromosomes of an inversion heterozygote attempt to align themselves

30
Q

acentric fragment

A

a fragment of chromosomes that lacks a centromere

31
Q

dicentric

A

describes a chromosome with two centromeres

32
Q

dicentric bridge

A

the region between the two centromeres in a dicentric chromosomes

33
Q

telomeres

A

specialized repeated sequences found at the ends of eukaryotic chromosomes

34
Q

balanced translocation

A

a translocation, such as a reciprocal translocation, in which the total amount of genetic material remains normal or nearly normal

35
Q

unbalanced translocation

A

a translocation in which a cell has too much or too little genetic material compared with a normal cell

36
Q

robertsonian translocation

A

the structure produced when two telocentric chromosomes fuse at their short arms

37
Q

translocation cross

A

the structure that is formed when chromosomes that have undergone a reciprocal translocation attempt to synapse during meiosis; this structure contains two normal chromosomes and two translocated chromosome; eight total chromatids are found within the cross

38
Q

semisterility

A

condition in which an individual has lowered fertility

39
Q

euploid

A

describes an organism in which the chromosome number is an exact multiple of a chromosome set

40
Q

triploid

A

describes an organism or cell with three sets of chromosomes

41
Q

tetraploid

A

describes an organism with four sets of chromosomes (4n)

42
Q

polyploid

A

describes an organism or cell with three or more sets of chromosomes

43
Q

aneuploid

A

not euploid; refers to a variation in chromosome number so that the total number of chromosomes is not an exact multiple of a set (or of the number n)

44
Q

trisomic

A

describes a diploid cell or organism with one extra chromosome (ie 2n + 1)

45
Q

monosomic

A

describe a diploid cell or organism that is missing a chromosome (ie 2n – 1)

46
Q

nondisjunction

A

event in which chromosomes do not segregate properly during mitosis or meiosis

47
Q

haplodiploid

A

describes a species, like certain bees, in which one sec is haploid (ie male) and the other sex is diploid (ie females)

48
Q

endopolyploidy

A

in a diploid individual, the phenomenon in which certain cells of the body are polyploid

49
Q

polytene chromosome

A

aggregation of chromosomes found in certain cells, such as drosophila salivary cells, in which homologous chromosomes have synapsed and replicated many times and the copies lie side by side

50
Q

chromocenter

A

the central point where the chromosomes of a polytene chromosome aggregate

51
Q

meiotic nondisjunction

A

the event in which chromosomes do not segregate properly during meiosis

52
Q

mitotic nondisjunction

A

an event in which chromosomes do not separate properly during mitosis

53
Q

alloploid

A

describes an organism that contains sets of chromosomes from two or more different species

54
Q

complete nondisjunction

A

event in which all the chromosomes fail to segregate properly during meiosis or mitosis and remain in one of the two daughter cells

55
Q

mosaicism

A

condition in which the cells of part of an organism differ genetically from those of the rest of the organism

56
Q

autopolyploid

A

a polyploid produced within a single species due to nondisjunction

57
Q

allodiploid

A

describes an organism that contains one set of chromosomes from two different species

58
Q

allopolyploid

A

describes an organism that contains two (or more) sets of chromosomes from two (or more) species

59
Q

allotetraploid

A

describes an organism that contains two sets of chromosomes from two different species