What is a satellite chromosome Class 11?

Answer: The chromosomes may have additional constriction or secondary constriction at their endsas distal part of the arm formed by chromatin thread are known satellite chromosome. These constriction gives appearance of an outgrowth or small fragment. Chromosome 13, 14,15, 16, 21 and 22 are satellite chromosomes.

What is the use of the satellite chromosomes?

Thus, satellite DNAs serve as critical regions of eukaryotic chromosomes ensuring correct encapsulation of all chromosomes in the interphase nucleus. It is essential that satellite DNAs with different sequences are bound by proteins capable of bundling multiple chromosomes.

What is a satellite DNA?

A satellite DNA is a portion of the DNA consisting of tandem repeats of non-coding nucleotide sequences that occur in the genome. The length of a satellite DNA ranges from 1 to several base pairs. For instance, in humans, an alpoid DNA is a satellite DNA found in all chromosomes and consists of 170 base pairs.

What is satellite DNA and its function?

Satellite DNA consists of very large arrays of tandemly repeating, non-coding DNA. Satellite DNA is the main component of functional centromeres, and form the main structural constituent of heterochromatin.

What is the full form of SAT chromosome?

With time, the term “SAT-chromosome” simply became a synonym and also an abbreviation for satellite chromosome. The satellite at metaphase appears to be attached to the chromosomes by a thread of chromatin.

What are secondary constriction and satellite chromosomes?

Due to secondary constriction, a knob-like structure is formed at the end called a satellite chromosome (SAT chromosome). DNA in a secondary constriction which forms rRNA is called rDNA.. NORs occur in SAT chromosomes (13,14,15,21,22).

What is the difference between repetitive DNA and satellite DNA?

DNA is the genetic material present in the nucleus of the eukaryotic cells. A DNA sequence that is present multiple times in a haploid genome is called repetitive DNA….

Repetitive DNA	Satellite DNA
It includes both highly repetitive andmiddle repetitive DNA.	It represents the highly repetitive DNA.

Where are chromosomes in satellites?

These chromosomes are called satellite chromosomes. In humans it is usually associated with the short arm of an acrocentric chromosome, such as in the chromosomes 13, 14, 15, 21, & 22. The Y chromosome can also contain satellites, although these are thought to be translocations from autosomes.

What is satellite DNA How are they classified?

Classification of Satellite DNA : It is classified into two categories based on base composition, length of segment and number of repetitive units : VNTRs- Variable Number of Tandem repeats or minisatellites surrounded by conserved restriction site. Small DNA sequence is arranged tandemly in many copy numbers.

Is satellite DNA repetitive DNA?

Satellite DNA (satDNA) is the highly repetitive DNA consisting of short sequences repeated a large number of times. It carries a variable AT-rich repeat unit that often forms arrays up to 100 Mb. The monomer length of satDNA sequences ranges from 150 to 400 bp in the majority of plants and animals.

Do satellite chromosomes have primary constriction?

Satellite chromosomes have secondary constrictions. They have one or more secondary constrictions. Primary constriction refers to the region of centromere.

What are the 4 types of chromosomes?

Chromosomes can be classified into 4 types based on the length of the chromosomal arms and the position of the centromere.

• Sub metacentric chromosomes.
• Acrocentric chromosomes.
• Telocentric chromosomes.
• Metacentric chromosomes.

What are satellite bodies in chromosomes?

Satellite bodies/ Trabant are the round elongated or knob-like structures exhibited by some chromosomes beyond the secondary constriction (NOR) which remains connected with the rest of the chromosome by a thin chromatin filament. It is the region between the secondary constriction and the nearest telomere of the chromosome.

What are nucleolar SAT-chromosomes?

The satellite at metaphase appears to be attached to the chromosomes by a thread of chromatin. SAT-chromosomes whose secondary constriction is associated with the formation of the nucleolus are referred to as nucleolar SAT-chromosomes.

Does the Y chromosome have satellites?

The Y chromosome can also contain satellites, although these are thought to be translocations from autosomes. The secondary constriction always keeps its position, so it can be used as markers to identify specific chromosomes.

What is the significance of Secondary constrictions in chromosomes?

The secondary constrictions are always constant in their positions and hence can be used as markers to identify these particular chromosomes. The Y chromosome can also contain satellites, although these are thought to be translocations from autosomes. Chromosomes containing satellites are called SAT Chromosomes.

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