KARYOTYPING

Karyotype

number ad appearance of chromosomes in the nucleus of a eukaryotic cells

Karyotype

it analyzes presence or absence of individual chromosomes.
Nature or extent of chromosomal aberrations
Sex chromosome content

Genetic counseling

allows the parents for an opportunity to determine the genetics odds that their offspring may carry a particular negative or lethal trait.

Blood, Bone marrow, skin

if px is adult, what is the sample

Amniotic fluid, extraembryonic cells

sample used if px is an unborn child

Lec

lectins

mitogenic agents that stimulates mitosis

Colchicine

mitotic inhibitor because it mainly arrests mitosis and metaphase

Hypotonic solution

used as the cell enlarges, this will provide more room for chromosomes to spread out

Karyogram or Idiogram

is a way to depict chromosomes, the way chromosomes are organized in the image makes them easy to visualize

KARYOLOGY

study whole sets of chromosomes

Deletion

part of chromosome is deleted

Duplication

segment of chromosome breaks off and attaches to homologous chromosome

Inversion

segment of chromosome is excised and reintegrated at 180-degree orientation

Translocation

segment of chromosome breaks off and attaches to non-homologs chromosome. Change in chromosome segment location.

Euploidy

complete set of chromosome is present

Aneuploidy

gaining or losing one chromosome (< or > 46)

Monosomy

loss of single chromosome

Trisomy

gain of single chromosome

Polyploidy

more than two set of chromosome is present

Tetraploid

4 sets (92 chromosomes)

2n+ x chromosome

Aneuploidy

2n-1

Monosomy

2n

Disomy

2n+1

Trisomy

2n+2,2n+3,etc.

Tetrasomy, pentasomy, etc.

Euploidy

multiples of n

Nondisjunction

error during the production of gametes where pair of homologs failed to dishoint during segregation .

barr body

is the inactive X chromosome in a female somatic cell

Lyonization

inactivation of sex chromosome, transforming it into a Barr body

Group A

1-3; largest and have median centromere

Group B

4-5; large but smallet than group A; have submedian centromere

Group C

6-12; medium size with submedian centromereG

Group D

13-15; medium sized and acrocentric centromere

Group E

16-18; short; can be median or submedian

Group F

19 and 20; median centromere

Group G

21 and 22; very short having acrocentric centromere

Chromosome X

similar to Group C

Chromosome Y

similar to Group G

Translocation

chromosomal abnormalities which occur when chromosomes break and the fragments rejoin to other chromosomes

Heterochromatin

stains darker than euchromatin, indicating tighter packing, and mainly consists of genetically inactive repetitive DNA sequences.

G Banding

is obtained with Giensa stain following digestion of chromosomes with trypsin.

dark regions

tend to be heterochromatic, late replicating and AT rich

light regions

tend to be euchromatic, early replicating and GC rich

Q- BANDING

less frequently Quinacrine, is used to stain bands on the chromosomes
- binds to AT rich regions

R- BANDING

is the reverse of G-banding
the dark regions are euchromatic (GC rich regions) and bright regions are heterochromatic (AT rich)
often used together with G-banding on human karyotype to determine whether there are deletions

C- BANDING
C= Centromeric

Giensa binds t constitutive heterochromatin, so it stains centromeres
use alkali solution (bariun hydroxide)

Q- BANDING

is a fluorescent pattern obtained using quinacrine for staining
first chromosome banding to be reported

T-BANDING

To visualize telomeres

Silver Staining

silver nitrate stains the nucleolar organization region-associated protein.

SPECTRAL KARYOTYPING

aka sky
is a molecular cytogenetic technique used to simultaneously visualize all the pairs of chromosomes in an organism in different colors.

Fluorescently labeled probes

for each chromosome are made by labeling chromososme- specific DNA with different fluorophores.

combinatorial labeling method

because there are limited number of spectrally distinc fluorophores, it is used to generate many different colors.

Digital Karyotyping

a technique used to quantify DNA copy number on a genomic scale
D

Digital karyotyping

short sequences of DNA in specific loci to different genome are isolated and enumerated here

• also known as virtual karyotyping

Fluorescent In SITU HYBRIDIZATION

is a powerful technique that labels a known chromosome sequence with DNA probes attached to fluorescent dyes, thus enabling visualization of specific regions of chromosomes by fluorescnt microscopy.

Chromosome specific probes
painting probes

types of FISH PROBES

Chromosome specific probe

for detection of chromosome number abnormalities

Painting probes

good for detecting translocations

Philadelphia chromosome (Ph1)

and there’s translocaion in chromosome in q34 and q11.2