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CYTOLOGY > chromosomal aberrations > Flashcards

chromosomal aberrations Flashcards

Aneuploidy

1
Q

an organism gains or loses one or more chromosomes but not a complete set

A

Aneuploidy

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2
Q
  • Monosomy (2n - 1) – l
    Trisomy (2n + 1)
A

Aneuploidy

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3
Q

loses of a single chromosome from an otherwise diploid genome

A

Monosomy

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4
Q

– gain of one chromosome

A

trisomy (2n + 1

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5
Q

complete haploid sets of chromosomes are present

A

Euploidy

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6
Q

more than two sets are present, the term ___ applies

A

polyploidy

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7
Q

three sets of chromosomes

A

Triploid (3n)

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8
Q

four sets of chromosomes

A

Tetraploid

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9
Q

These chromosomal variation
originates as a random error
during the production of
gametes, a phenomenon
referred to as ___,
whereby paired homologs fail
to disjoin during segregation

A

nondisjunction

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10
Q

does it Can happen during meiosis I or
meiosis II?

A

yes

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11
Q

Most common cause is nondisjunction (especially during meiosis)

A

Aneuploidy

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12
Q
  • The phenotypic effects range from minor physical symptoms to devastating
    and lethal deficiencies in major organ systems
A

Aneuploidy

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13
Q

Among survivors, phenotypic effects often include behavioral deficits and
mental retardation

A

Aneuploidy

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14
Q

It is the loss of one chromosome from a diploid complement

A

Monosomy

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15
Q

Although monosomy for the X chromosome occurs in humans, monosomy for any of the
autosomes is not usually )___ in humans or animals

A

tolerated

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16
Q

the failure of monosomic individuals to survive is first quite puzzling, since at least a
single copy of every gene is present in the remaining homolog

A

Monosomy

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17
Q

An explanation is that if just one of those genes is represented by a ___monosomy unmasks the recessive lethal allele

A

lethal allele,

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18
Q

In other cases, a single copy of a recessive gene may be insufficient to provide life
sustaining function (called ___)

A

haploinsufficiency

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19
Q

Addition of an extra chromosome produces somewhat more viable
individuals than does the loss of a chromosome

true or false

A

true

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20
Q

In animals, this is often true, provided that the chromosome involved is
relatively small

A

Trisomy

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21
Q
  • The addition of a large autosome to the diploid complement in humans has
    sever effects and is usually lethal during development
A

Trisomy

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22
Q

Describes instances in which more than two multiples of the haploid chromosome set
are found

A

Polyploidy

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23
Q

Infrequent in animal species but is well known in lizards, amphibians, and fish, and is
much more common in plants

A

Polyploidy

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24
Q
  • Classified as either Autopolyploidy or Allopolyploidy
A

Polyploidy

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25
Q

addition of one or
more extra sets of chromosomes
identical to the normal haploid
complement of the same species

A

Autopolyploidy

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26
Q

combination of
chromosome sets from different
species occurring as a consequence of
hybridization

A

Allopolyploidy

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27
Q
  • Polyploidy can arise in several ways
A
  1. Errors in meiosis during gamete formation
  2. Events at fertilization
  3. Errors in mitosis after fertilization
    * Polyploidy can result from errors in mitosis or meiosis
28
Q
  • If homologous chromosomes fail to separate during meiosis I, meiosis II will produce a
    diploid gamete.

Fusion of this diploid gamete with a normal haploid gamete will produce
a triploid zygote

A

polyploidy

29
Q

It can also be produced at fertilization by the simultaneous penetration of a haploid egg
by two haploid sperm (dispermy). The resulting zygote contains three haploid
chromosome sets and is triploid

A

Polyploidy

30
Q

The most common polyploidy
in humans, found in 15% to
18% of all spontaneous
abortions

A

Triploidy

31
Q
  • Approximately 75% of all
    cases of triploidy have two
    sets of paternal
    chromosomes
A

Triploidy

32
Q

Most triploid zygotes arise as
a result of

A

dispermy

33
Q

It can result from a failure of cytokinesis in the first mitotic division after fertilization

A

Tetraploidy

34
Q
  • If tetraploidy arises sometime after the first mitotic division, two different cell types are
    present in the embryo: ___
A

normal diploid cells and tetraploid cells

35
Q
  • Included in this broad category are deletions and duplications of genes or part of a
    chromosome and rearrangements of genetic material in which a chromosome segment
    is inverted, exchanged with a segment of a nonhomologous chromosome, or merely
    transferred to another chromosome
A

hays auko na

36
Q

Exchange and transfers are called _, in which the locations of genes are
altered within the genome

A

translocations

37
Q

In most instances, these structural changes are due to one or more breaks
along the axis of a chromosome, followed by either the loss or
rearrangement of genetic material

A

new learining lang

38
Q

The ends produced at points of breakage are “___” and can rejoin other
broken ends

A

sticky

39
Q

If the breakage and rejoining do not reestablish the original relationship
and if the alteration occurs in germ plasm, the gametes will contain the
structural rearrangement, which is __

A

heritable

40
Q

If the aberration is found in one homolog but not the other, the individual is said to be
__

A

heterozygous for the aberration

41
Q
  • In such cases, unusual but characteristic pairing configurations are formed during _
A

meiotic
synapsis

42
Q

When a chromosome breaks in one
or more places and a portion of it is
lost, the missing piece is called a
_

A

deletion (deficiency

43
Q
  • The ___ can occur either near
    one end (terminal deletion) or
    within the interior of the
    chromosome (intercalary deletion)
A

deletion

44
Q

For synapsis to occur between a
chromosome with a large intercalary
deletion and a normal homolog, the
unpaired region of the normal homolog
must “___” into a deletion or
compensation loop

A

buckle out

45
Q

If only a small part of a chromosome is
deleted, the organism might ___

A

survive

46
Q

When any part of the genetic material,
either a single locus or a large piece of a
chromosome, is present more then once in
the genome, it is called a duplication

A

duplication

47
Q

A type of chromosomal aberration in which a segment of a chromosome is turned
around 180 degrees within a chromosome

A

Inversions

48
Q

An __ requires breaks at two points along the length of the chromosome and
subsequence reinsertion of the inverted segment

A

inversion

49
Q

– the centromere is not part of the rearranged chromosome
segment

A

Paracentric inversion

50
Q

the centromere is part of the inverted segment

A
  • Pericentric inversion
51
Q

Organisms with one inverted
chromosome and one noninverted
homolog are called inversion
____

A

heterozygotes

52
Q

Pairing between two such
chromosomes in meiosis is
accomplished only if they form an
inversion loop

t or f

A

t

53
Q

If crossing over occur within the
inversion loop,___
are produced

A

abnormal chromatids

54
Q

When crossover occurs within a
paracentric inversion, one
recombinant ____ are produced

A

dicentric chromatid
(two centromeres) and one
recombinant acentric chromatid
(lacking a centromere)

55
Q

Movement of chromosomal segment to a new
location in the genome

A

Translocation

56
Q

Reciprocal translocation involves the exchange of
segments between two nonhomologous
chromosomes

A

Translocation

57
Q

The genetic consequences of reciprocal
translocations are similar to those of inversions

A

Translocation

58
Q

Genetic information is not lost or gained, there is
only a rearrangement of the genetic material

A

Translocation

59
Q

The presence of a translocation does not directly
alter the viability of individuals bearing it

A

Translocation

60
Q

Homologs that are heterozygous for
a reciprocal translocation undergo
unorthodox synapsis during meiosis

A

Translocation

61
Q

the pairing results in a cross-like
configuration

A

Translocation

62
Q

As with inversions, genetically
unbalanced gametes are also
produced as a result of this unusual
alignment during meiosis

A

Translocation

63
Q

When breaks at the extreme ends
of the short arms of two
nonhomologous acrocentric
chromosomes occur, the small
segments are lost and the larger
segments fuse at their centromeric
region

A

Robertsonian
Translocation

64
Q

This type of translocation
produces a new, large,
submetacentric or metacentric
chromosome, often called a
____

A

Robertsonian translocation

65
Q
A

CYTOLOGY (10 decks)

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