chromosomal aberrations

Question 1

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

Answer 1

Aneuploidy

Question 2

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

Answer 2

Aneuploidy

Question 3

loses of a single chromosome from an otherwise diploid genome

Answer 3

Monosomy

Question 4

– gain of one chromosome

Answer 4

trisomy (2n + 1

Question 5

complete haploid sets of chromosomes are present

Answer 5

Euploidy

Question 6

more than two sets are present, the term ___ applies

Answer 6

polyploidy

Question 7

three sets of chromosomes

Answer 7

Triploid (3n)

Question 8

four sets of chromosomes

Answer 8

Tetraploid

Question 9

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

Answer 9

nondisjunction

Question 10

does it Can happen during meiosis I or
meiosis II?

Answer 10

yes

Question 11

Most common cause is nondisjunction (especially during meiosis)

Answer 11

Aneuploidy

Question 12

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

Answer 12

Aneuploidy

Question 13

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

Answer 13

Aneuploidy

Question 14

It is the loss of one chromosome from a diploid complement

Answer 14

Monosomy

Question 15

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

Answer 15

tolerated

Question 16

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

Answer 16

Monosomy

Question 17

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

Answer 17

lethal allele,

Question 18

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

Answer 18

haploinsufficiency

Question 19

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

true or false

Answer 19

true

Question 20

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

Answer 20

Trisomy

Question 21

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

Answer 21

Trisomy

Question 22

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

Answer 22

Polyploidy

Question 23

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

Answer 23

Polyploidy

Question 24

• Classified as either Autopolyploidy or Allopolyploidy

Answer 24

Polyploidy

Question 25

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

Answer 25

Autopolyploidy

Question 26

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

Answer 26

Allopolyploidy

Question 27

* Polyploidy can arise in several ways

Answer 27

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

Question 28

* 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

Answer 28

polyploidy

Question 29

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

Answer 29

Polyploidy

Question 30

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

Answer 30

Triploidy

Question 31

* Approximately 75% of all cases of triploidy have two sets of paternal chromosomes

Answer 31

Triploidy

Question 32

Most triploid zygotes arise as a result of

Answer 32

dispermy

Question 33

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

Answer 33

Tetraploidy

Question 34

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

Answer 34

normal diploid cells and tetraploid cells

Question 35

* 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

Answer 35

hays auko na

Question 36

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

Answer 36

translocations

Question 37

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

Answer 37

new learining lang

Question 38

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

Answer 38

sticky

Question 39

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 __

Answer 39

heritable

Question 40

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

Answer 40

heterozygous for the aberration

Question 41

* In such cases, unusual but characteristic pairing configurations are formed during _

Answer 41

meiotic synapsis

Question 42

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

Answer 42

deletion (deficiency

Question 43

* The ___ can occur either near one end (terminal deletion) or within the interior of the chromosome (intercalary deletion)

Answer 43

deletion

Question 44

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

Answer 44

buckle out

Question 45

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

Answer 45

survive

Question 46

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

Answer 46

duplication

Question 47

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

Answer 47

Inversions

Question 48

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

Answer 48

inversion

Question 49

– the centromere is not part of the rearranged chromosome segment

Answer 49

Paracentric inversion

Question 50

the centromere is part of the inverted segment

Answer 50

* Pericentric inversion

Question 51

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

Answer 51

heterozygotes

Question 52

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

Answer 52

t

Question 53

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

Answer 53

abnormal chromatids

Question 54

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

Answer 54

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

Question 55

Movement of chromosomal segment to a new location in the genome

Answer 55

Translocation

Question 56

Reciprocal translocation involves the exchange of segments between two nonhomologous chromosomes

Answer 56

Translocation

Question 57

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

Answer 57

Translocation

Question 58

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

Answer 58

Translocation

Question 59

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

Answer 59

Translocation

Question 60

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

Answer 60

Translocation

Question 61

the pairing results in a cross-like configuration

Answer 61

Translocation

Question 62

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

Answer 62

Translocation

Question 63

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

Answer 63

Robertsonian Translocation

Question 64

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

Answer 64

Robertsonian translocation