Structural Aberrations

Question 1

The 5 types of structural aberrations

Answer 1

Duplication, deletion, inversion, translocation, fragile sites

Question 2

This usually arises from breaks in the chromosome

Answer 2

Structural aberrations

Question 3

This is where a part of the genetic material is present more than once in the genome

Answer 3

Duplication

Question 4

Give a cause of duplication

Answer 4

Unequal crossing over or errors during replication

Question 5

What is the cause of the bar-eyed (bar-shaped eyes) mutation in drosophila?

Answer 5

Due to x-linked duplication in the bar gene

Question 6

This reduces the number of facets in the eye of the drosophila

Answer 6

Bar mutation

Question 7

This is the phenomenon where the chromosomal environment can have an effect on the expression of the specific gene

Answer 7

Position effect

Question 8

This is where the phenotype of a gene is altered by changes in the position or chromosomal environment of the gene

Answer 8

Position effect

Question 9

What do you call the normal gene in drosophila?

Answer 9

Wild type

Question 10

______ crossing over produces bar and double-bar mutations

Answer 10

Unequal

Question 11

What are the 2 types of deletion?

Answer 11

Terminal, interstitial

Question 12

In prophase 1 during structural aberrations, the normal chromosome must ____ in order for the homologous sequences to align

Answer 12

Loop out

Question 13

This is a disorder due to the deletion of a p-arm at chromosome 5, characterized by a high pitch cat-like cry, intellectual disability, delayed development, microcephaly, hypotonia, widely set eyes, low set ears, small jaw, rounded face, and a heart defect

Answer 13

Cri du chat syndrome

Question 14

This is caused by a deletion of a section on the p-arm at chromosome 4 and is characterized by broad flat nasal bridge, high forehead, short philtrum, microgmathia, poorly formed ears, eyes are spaced and may be protruding, asymmetrical facial features and microcephaly, delayed growth, intellectual disability, and seizures

Answer 14

Wolf-hirschhorn syndrome

Question 15

Deletion on the long arm at chromosome 15, feeding difficulty at early age, but becoming obese after 1 yr, mild to moderate mental retardation

Answer 15

Prader-willi syndrome

Question 16

This is an aberration where it is turned 180 degrees within the chromosome

Answer 16

Inversions

Question 17

What are the types of inversion?

Answer 17

Paracentric, pericentric

Question 18

What does inversions result to?

Answer 18

Reduced fertility

Question 19

In _______, the chromosomes form an inversion loop which allows the homologous sequences to align

Answer 19

Prophase 1

Question 20

A type of inversion where the centromere is not included

Answer 20

Paracentric

Question 21

A type of inversion where the centromere is included

Answer 21

Pericentric

Question 22

What is present in a paracentric inversion?

Answer 22

Bridge formation and breakage effect

Question 23

1 normal gene sequence, 1 inverted segment

Answer 23

Inversion heterozygote

Question 24

Movement of a chromosome segment into a new location in the genome

Answer 24

Translocation

Question 25

3 types of translocation

Answer 25

Nonreciprocal intrachromosomal translocation, nonreciprocal interchromosomal translocation, reciprocal interchromosomal translocation

Question 26

Translocation that occurs in the same chromosome

Answer 26

Nonreciprocal intrachromosomal translocation

Question 27

Translocation occurs between one of the chromatid of non homologous chromosomes

Answer 27

Nonreciprocal interchromosomal translocation

Question 28

Translocation where a pair of non homologous chromosomes are both affected

Answer 28

Reciprocal interchromosomal translocation

Question 29

Non-homologous chromosomes are not suppose to _____ genes

Answer 29

Share

Question 30

This results from a reciprocal translocation where the configuration forms a tetravalent

Answer 30

Tetravalent configuration

Question 31

2 types of disjunction in reciprocal translocation

Answer 31

Adjacent and alternate

Question 32

This is defined by the fusion of the long arms of 2 acrocentric chromosomes near their centromeric region

Answer 32

Robertsonian chromosome translocation

Question 33

This occurs because of robertsonian translocation

Answer 33

Translocation down syndrome

Question 34

These are chromosomal regions susceptible to gaps or breaks

Answer 34

Fragile sites

Question 35

How many fragile sites in the human genome?

Answer 35

120 and is associated with mental retardation

Question 36

This is a common form of mental retardation, affects 1/1250 males and 1/2500 females, behaves as a dominant trait, shows variable expressibility, males show long and narrow faces with protruding chins, enlarged ears, increase in testicular size

Answer 36

Fragile-x syndrome/martin bell syndrome

Question 37

What is variable expressibility?

Answer 37

Only 30% of fragile x females are retarded but 80% of males are retarded

Question 38

What gene spans the fragile site?

Answer 38

FMR-1 gene

Question 39

What sequence of three nucleotides is repeated many times in the fragile-x syndrome gene?

Answer 39

CGG

Question 40

(Fragile-x syndrome) 6-54 cgg repeats

Answer 40

Normal

Question 41

(Fragile-x syndrome) more than 200 cgg repeats

Answer 41

Affected

Question 42

(Fragile-x syndrome) 55-200 cgg repeats

Answer 42

Carrier

Question 43

This is when heritable disorders exhibit a progressively early age of onset and increased severity of disorder in each successive generation

Answer 43

Genetic anticipation

Question 44

Fragile-x syndrome is more common in?

Answer 44

Men

Question 45

This is characterized by long face, large jaw, large prominent ears, high arched palate, microcephaly, autism, adhd, prader-willi phenotype, intellectual disability, broad forehead

Answer 45

Fragile-x syndrome