What is the function of repetitive sequences?

Repetitive sequences accumulate variations in sequence and copy number during evolution, hence they are important tools for taxonomic and phylogenetic studies, and are known as “tuning knobs” in the evolution.

Why would it be beneficial for a chromosome to have repetitive sequences of DNA in regions bound by the centromere or the telomeres?

For example, repeated noncoding DNA sequences at the ends of chromosomes form telomeres . Telomeres protect the ends of chromosomes from being degraded during the copying of genetic material. Repetitive noncoding DNA sequences also form satellite DNA, which is a part of other structural elements.

What is meant by repetitive DNA?

Repetitive DNA: DNA sequences that are repeated in the genome. These sequences do not code for protein. One class termed highly repetitive DNA consists of short sequences, 5-100 nucleotides, repeated thousands of times in a single stretch and includes satellite DNA.

Why are repeated sequences prone to expansion?

4.1. Such repetitive sequences are prone to random expansions and deletions due to faulty replication or repair, or in the case of retrotransposons to mutagenesis by excision and integration. Transposable elements make a considerable fraction of the total genomic DNA sequence of humans.

What is telomerase and why is it important?

The enzyme telomerase adds TTAGGG repeats onto mammalian telomeres, which prevents their shortening. The activation of telomerase in malignant cancers seems to be an important step in tumorigenesis, whereby the cell gains the ability of indefinite proliferation to become immortal.

What are telomeres and why are they important how does telomerase play a role?

10 Telomere and Telomerase. Telomeres are repetitive nucleotide sequences at each end of chromosomes. Their function is to protect the ends of the chromosomes from deterioration or fusion to other chromosomes during cell division. With every cell division, telomeres shorten.

What is repetitive DNA What is the characteristic feature of such sequences Why is it considered as bulk DNA?

The term “repetitive sequences” (repeats, DNA repeats, repetitive DNA) refers to DNA fragments that are present in multiple copies in the genome. These sequences exhibit a high degree of polymorphism due to variation in the number of their repeat units caused by mutations involving several mechanisms (Tautz, 1989).

What is moderately repetitive DNA?

Repetitive DNA: DNA sequences that are repeated in the genome. These sequences do not code for protein. Another class termed moderately repetitive DNA consists of longer sequences, about 150-300 nucleotides, dispersed evenly throughout the genome, and includes what are called Alu sequences and transposons.

What is repeat expansion in genetics?

A trinucleotide repeat expansion, also known as a triplet repeat expansion, is the DNA mutation responsible for causing any type of disorder categorized as a trinucleotide repeat disorder. These are labelled in dynamical genetics as dynamic mutations.

What does telomerase do with the DNA?

Telomerase is a large ribonucleoprotein complex responsible for progressive synthesis of telomeric DNA repeats (TTAGGG) at the 3′ ends of linear chromosomes, thereby reversing the loss of DNA from each round of replication.

How does the telomerase help us stop gene erosion?

Telomeres serve as substrates for telomerase, the enzyme responsible for adding DNA to the ends of chromosomes, thus maintaining chromosome length [9, 16]. To compensate for the DNA erosion inherent in genetic stability, telomerase adds tandem array of simple-sequence repeats at the chromosome ends.

What is the importance of telomeres?

Telomeres, the specific DNA–protein structures found at both ends of each chromosome, protect genome from nucleolytic degradation, unnecessary recombination, repair, and interchromosomal fusion. Telomeres therefore play a vital role in preserving the information in our genome.

Why do we need repetitive DNA sequence elements?

Generic repeated signals in the DNA are necessary to format expression of unique coding sequence files and to organise additional functions essential for genome replication and accurate transmission to progeny cells. Repetitive DNA sequence elements are also fundamental to the cooperative molecular interactions forming nucleoprotein complexes.

What is repetitive DNA and transposons?

Repetitive DNA and Transposons. Repetitive DNA is composed of tandem, repeated sequences of from two to several thousand base pairs and is estimated to constitute about 30\% of the genome. Many of these sequences are localized in centromeres and telomeres, but they are also dispersed throughout the genome.

What is a satellite DNA sequence?

Satellite DNA is DNA sequences that contain highly repetitive DNA . Satellite DNA is a type of repetitive DNA and it classified into minisatellites, microsatellites and mini-variant repeats, based on the number of repetitive units, the number of base pairs in each unit and the base composition of the units.

What are the different types of repetitive DNA?

Satellite DNA, also known as tandemly repeated DNA, consists of clusters of repeated sequences and represents a diverse class of highly repetitive elements. size of an individual repeat: microsatellites, minisatellites, minisatellites, and microsatellites.