Cytogenetics

Question 0

Haploid

Answer 0

Having one copy of each chromosome (N=1) eg. Human gamete

Question 1

Karyotype

Answer 1

Display of chromosomes by their length

Question 2

Diploid

Answer 2

Having two copies of each chromosome (N=2) eg. Human somatic cell

Question 3

Aneuploid

Answer 3

Having one or more extra or missing chromosome

Question 4

Balanced chromosomal abnormality

Answer 4

No net gain or loss of chromosomal material

Question 5

Unbalanced chromosomal abnormality

Answer 5

Net gain or loss of chromosomal material

Question 6

Uniparental disomy

Answer 6

A chromosome pair is derived solely from one parent in the diploid offspring

Question 7

P and q arms of chromosomes

Answer 7

Short and long arms, respectively

Question 8

Metacentric chromosome

Answer 8

Both arms are appx equal in length

Question 9

Submetacentric chromsome

Answer 9

One arm is somewhat shorter than the other

Question 10

Acrocentric chromosome

Answer 10

One arm is much shorter than the other

Question 11

Autosome

Answer 11

Any of the chromosomes other than the sex determining chromosomes. In humans, X and Y are the sex chromosomes

Question 12

Euchromatin

Answer 12

Decondensed (active) form of a chromosomal region

Question 13

Heterochromatin

Answer 13

Condensed (inactive) form of chromosomal region. Constitutive heterochromatin is always condensed while facultative heterochromatin can become decondensed (active form) in certain circumstances

Question 14

Chromosome banding

Answer 14

Staining of bands, or chromosome segments, allowing the precise identification of individual chromosomes or parts of chromosomes

Question 15

Nondisjunction

Answer 15

The failure of the paired chromosome segments, allowing the precise identification of individual chromosomes or parts of chromosomes

Question 16

Reciprocal translocation

Answer 16

Segments from two different chromosomes have been exchanged

Question 17

Robertsonian translocation

Answer 17

Joining of two acrocentric chromosomes at the centromeres with loss of their short arms to form a single abnormal chromosome

Question 18

Inversion

Answer 18

A segment of the chromosome is flipped around and the genetic material is inverted

Question 19

Meiosis

Answer 19

Cell division by which germ cells are produced. Results in 50% reduction in the number of chromosomes present in gamete producing cells

Question 20

Mitosis

Answer 20

Type of cell division resulting in two cells with the same number of chromosomes as the parent cell

Question 21

Fluorescent in situ hybridization (FISH)

Answer 21

Allows distinct DNA segments > 40 kb in length to be visualized with probe DNA. Is used on parafinn embedded specimens. Commonly used to test for over expression of the HER2 gene is breast cancer tissue

Question 22

Spectral karyotype

Answer 22

Labeling each chromosome with a different dye combination, allowing one to track each chromosome on chromosome spreads. Important for cells with abnormal karyotypes. Requires live cells.

Question 23

Array CGH (array comparative hybridization)

Answer 23

Does not require living cells. Genomic DNA of interest is labeled with fluorescent dyes and hybridized to slides that have short DNA probes attached to them. Probes can represent virtually all areas of the genome. Based on pattern it is possible to identify insertions and deletions in the genome. Typically uses processed samples

Question 24

Congenital chromosomal abnormalities

Answer 24

Abnormal chromosome number in the developing fetus and is commonly associated with miscarriages

Question 25

Normal human karyotype

Answer 25

46, XX or 46, XY

Question 26

Turner syndrome

Answer 26

Known as monosomy X; 45, X

Question 27

Klinefelter syndrome

Answer 27

47, XXY

Question 28

Triple X syndrome

Answer 28

47, XXX

Question 29

47, XYY syndrome

Answer 29

47, XYY

Question 30

Common congenital autosomal chromosomal abnormalities

Answer 30

Down syndrome, Patau syndrome, Edwards syndrome

Question 31

Down syndrome

Answer 31

95% cases due to trisomy 21; 47, XX + 21 or 47, XY + 21

Question 32

Patau syndrome

Answer 32

Trisomy 13; 47, XX + 13 or 47, XY + 13

Question 33

Edwards syndrome

Answer 33

Trisomy 18; 47, XX + 18 or 47, XY + 18

Question 34

Autosomal deletion syndromes

Answer 34

A very large chromosomal segment tens of mega bases in size, such as an entire arm is deleted. Typically due to de novo mutation in gamete of parent or mitotic error early in development

Question 35

Haploinsufficiency

Answer 35

The remaining copy of the gene is insufficient for normal health

Question 36

Cri du chat syndrome

Answer 36

Deletion of the short arm of chromosome 5; distinct facial features and hypotonia, poor muscle tone

Question 37

Contiguous gene deletion syndromes

Answer 37

Small deleted genomic region containing two or more contiguous (located next to one another) genes. Involves maximum few mega bases
Deleted genomic region tends to be much smaller than that of an autosomal deletion syndrome

Question 38

DiGeorge syndrome

Answer 38

Patients have deletions in chromosome 22q11.2 genomic region;
Show cleft palate, learning difficulties and immune deficiency
Congenital heart disease in 74% of individuals