Centromeres are indicated by the dark, gray regions separating the short (p) arms from the long (q) arms. There are several other staining techniques used for more specialized purposes. One, called Q-banding, stains chromosomes with quinacrine mustard and views them fluorescently.
What are the bands on chromosomes called?
The ends of the chromosome are called telomeres. Each chromosome arm is divided into regions, or cytogenetic bands, that can be seen using a microscope and special stains. The cytogenetic bands are labeled p1, p2, p3, q1, q2, q3, etc., counting from the centromere out toward the telomeres.
What do the colored bands on the chromosome represent?
The pattern of bands are numbered on each arm of the chromosome from the centromere to the telomere. … Banding can be used to identify chromosomal abnormalities, such as translocations, because there is a unique pattern of light and dark bands for each chromosome.
What causes a dark band around the chromosome?
A karyotype analysis usually involves blocking cells in mitosis and staining the condensed chromosomes with Giemsa dye. The dye stains regions of chromosomes that are rich in the base pairs Adenine (A) and Thymine (T) producing a dark band.
What are bands in karyotype?
Most conventional cytogenetic analyses depend on the karyotyping of banded metaphase chromosomes. A band is defined as that part of a chromosome which is clearly distinguishable from its adjacent segments by appearing darker or brighter with one or more banding techniques.
What is Exon?
Exons are coding sections of an RNA transcript, or the DNA encoding it, that are translated into protein. Exons can be separated by intervening sections of DNA that do not code for proteins, known as introns. … Splicing produces a mature messenger RNA molecule that is then translated into a protein.
What is the name for banding patterns?
The different types of banding are G-banding, reverse-banding, C-banding, Q-banding, NOR-banding, and T-banding. Giemsa stain is used in G-banding whereas quinacrine is used in Q-banding.
What is the purpose of G-banding?
G-banding allows each chromosome to be identified by its characteristic banding pattern. The banding pattern can distinguish chromosomal abnormalities or structural rearrangements, such as translocations, deletions, insertions, and inversions. G-banding has been divided into regions, bands, and subbands.
What is the difference between G-banding and C banding?
G-banding involves the staining of trypsin-treated chromosomes and R-banding involves denaturing in hot acidic saline followed by Giemsa staining. C-banding is specifically used for identifying heterochromatin by denaturing chromosomes in a saturated alkaline solution followed by Giemsa staining.
What are karyotypes used for?
Karyotype is a test to identify and evaluate the size, shape, and number of chromosomes in a sample of body cells. Extra or missing chromosomes, or abnormal positions of chromosome pieces, can cause problems with a person’s growth, development, and body functions.
What is a centromere do?
The primary function of the centromere is to provide the foundation for assembly of the kinetochore, which is a protein complex essential to proper chromosomal segregation during mitosis.
What is trisomy syndrome?
A trisomy is a chromosomal condition characterised by an additional chromosome. A person with a trisomy has 47 chromosomes instead of 46. Down syndrome, Edward syndrome and Patau syndrome are the most common forms of trisomy.
How do you do karyotypes?
To observe a karyotype, cells are collected from a blood or tissue sample and stimulated to begin dividing; the chromosomes are arrested in metaphase, preserved in a fixative and applied to a slide where they are stained with a dye to visualize the distinct banding patterns of each chromosome pair.
How do you read a chromosome band?
The bands are visible under a microscope when the chromosome is suitably stained. Each of the bands is numbered, beginning with 1 for the band nearest the centromere. Sub-bands and sub-sub-bands are visible at higher resolution. A range of loci is specified in a similar way.
What is N banding?
The N-banding technique, so named for staining the nucleolus organizer regions of animal and plant chro- mosomes (Funaki et al. 1975), was shown by Gerlach (1977) to also stain specific heterochromatic regions of chromosomes in wheat. … Moreover, it revealed the heterogeneity of heterochrornatin in wheat chromosomes.
Why do chromosomes have different bands?
Chromosome banding allows the identification of chromosome deletions, duplications, translocations, inversions, and other less common chromosome abnormalities.