What is G-quadruplex telomere?
Telomeric DNA can fold into compact G-quadruplex structures involving the interaction of four guanine bases in a square planar arrangement stabilized by central cations10. G-quadruplexes can form from one, two or four strands of DNA in a parallel or antiparallel orientation11.
How are G-quadruplexes formed?
To form a G-tetrad, four guanines associate via eight hydrogen bonds from both the Watson–Crick and Hoogsteen faces of the base (Figure 2). Chemical structure of a GQ (G-quadruplex) tetrad. G-tetrads stack on top of one another giving rise to a GQ (Figure 3).
Where are G-quadruplexes found?
the transcriptome
The present study shows that rG4 are widely present in the transcriptome and in all known classes of transcripts, with 60% of transcripts having at least one pG4. Several studies have been performed in order to evaluate the number of pG4 sequences in genomes and transcriptomes.
What is an example of guanine?
Guanine is a purine nucleobase with a chemical formula of C5H5N5O. Purines are heterocyclic aromatic organic compounds. As a purine, adenine is comprised of two carbon rings: a pyrimidine ring and an imidazole ring. Guanine occurs in both DNA and RNA.
What color is guanine?
Figure 2: The four nitrogenous bases that compose DNA nucleotides are shown in bright colors: adenine (A, green), thymine (T, red), cytosine (C, orange), and guanine (G, blue).
What is a cruciform in biology?
Cruciform DNA is a form of non-B DNA, or an alternative DNA structure. The formation of cruciform DNA requires the presence of palindromes called inverted repeat sequences. These inverted repeats contain a sequence of DNA in one strand that is repeated in the opposite direction on the other strand.
What is the role of guanine?
A chemical compound that is used to make one of the building blocks of DNA and RNA. It is a type of purine. Structure of DNA.
Why is it called guanine?
The word guanine derives from the Spanish loanword guano (“bird/bat droppings”), which itself is from the Quechua word wanu, meaning “dung”. As the Oxford English Dictionary notes, guanine is “A white amorphous substance obtained abundantly from guano, forming a constituent of the excrement of birds”.
How is DNA cruciform formed?
What is the structure of guanine?
C5H5N5OGuanine / Formula
What is the uses of guanine?
In the cosmetics industry, crystalline guanine is used as an additive to various products (e.g., shampoos), where it provides a pearly iridescent effect. It is also used in metallic paints and simulated pearls and plastics. It provides shimmering luster to eye shadow and nail polish.
What is cruciform design?
Cruciform web design Cruciform web designs use a cross-shaped web page that expands to fill the width and height of the web browser window. There are a number of different approaches to implementing them.
What is cruciform section?
A cruciform section is otherwise known as open cross section. This can also be referred as doubly symmetric section. The section is formed with the help of two TEE section, in which one is inverted Tee – section appears to be a rectangular hollow section with extended flanges on its four sides.
What is cruciform structure?
Cruciform structures consist of a branch point, a stem and a loop, where the size of the loop is dependent on the length of the gap between inverted repeats (Figure 1). Direct inverted repeats lead to formation of a cruciform with a minimal single-stranded loop.
What are the functions of guanine?
Guanine is a nitrogenous base that makes up part of the nucleotides in DNA and RNA, but that’s not all. Nucleotides containing guanine can power chemical reactions and are involved in signaling inside the cell. Other forms of guanine can be found in bird droppings and even cosmetics.
Where is guanine found?
Adenine and guanine are found in RNA and DNA in terrestrial life, whereas thymine is only found in DNA and uracil only in RNA.
What are G-quadruplexes?
G-quadruplexes are higher-order DNA and RNA structures formed from G-rich sequences that are built around tetrads of hydrogen-bonded guanine bases. Potential quadruplex sequences have been identified in G-rich eukaryotic telomeres, and more recently in non-telomeric genomic DNA, e. g. in nuclease-hypersensitive promoter regions.
How are G quadruplex structures formed in DNA?
These G-quadruplex structures are said to be formed in the promoter regions of DNA through superhelicity, which favors the unwinding of the double helical structure of DNA and in turn loops the strands to form G-quadruplex structures in guanine rich regions.
How is the topology of the G-quadruplex determined?
The topology of the G-quadruplex structure can be determined by monitoring the positive or negative circular dichroism (CD) signals at specific wavelengths. Parallel G-quadruplexes have negative and positive CD signals at 240 and 262 nm, respectively, whereas antiparallel G-quadruplexes place these signals at 262 and 295 nm, respectively.
How do you classify quadruplex structures?
Quadruplex structures may be classified according to their strand polarities and the location of the loops that link the guanine strand (s) for quadruplexes formed either from a single-strand or from two strands. Adjacent linked parallel strands require a connecting loop to link the bottom G-tetrad with the top G-tetrad, leading to propeller typ…