DNA
Full form of DNA
Full form of DNA is Deoxyribonucleic acid and Full form of RNA is Ribonucleic acid. Both DNA and RNA are nucleic acids present in cells. Now, lets come to our question- The two strands of dna are held together by
The three things that make up each strand of DNA and RNA are:
1. Nitrogenous Base (A,G,C,T)
2. Pentose sugar
3. Phosphate Group
Nitrogenous bases in DNA
The DNA is made up of four kinds of nitrogenous bases which are :
Guanine (G) Cytosine (C) Adenine (A) Thymine (T)
Two of the bases are purines, which are adenine and guanine. Pyrimidines bases are thymine and cytosine.
The two strands of DNA are held together by
The two strands of dna are held together by hydrogen bonds. In a dna strand the nucleotides are linked together by hydrogen bonds.
These two strands are formed by complementary pairs of nitrogen bases — Adenine pair with thymine by two hydrogen bonds. Guanine pair with Cytosine by three hydrogen bonds. This is known as the “Base-Pair Rule”. In a double stranded DNA, because of this base pairing , an adenine always pair with thymine and a guanine always pair with cytosine. This is called complementarity of DNA.
Stability of DNA is due to
Stability of dna is due to hydrogen bonds between the bases. Adenine pair with thymine by two hydrogen bonds in DNA and to Uracil in RNA. Guanine pair with cytosine by three hydrogen bonds. Therefore, G-C pairing is stronger than A-T pairing.
Role of Hydrogen bonds in DNA
Hydrogen bonds are non-covalent and weak bonds. More bonding means more stability to the DNA structure. Hydrogen bonds are involved in between two strands, which means in between bases of complementary strand pairing.
Covalent bonds in DNA
Nucleotides are linked together by covalent bonds and forms a single strand. Nucleotides are linked together means sugar of one nucleotide and phospahte of another nucleotide. Therefore, there is hydrogen bonding (weaker bonds) in two strands and within one strand there is covalent bonding(stronger bonds).
DNA strands are separated by
Helicases are enzymes that are essential for DNA replication as they unwind or separate double-stranded DNA into single strands and thus allow each strand to be copied.
During DNA replication, helicase binds to and breaks apart the hydrogen bonds between the bases on the DNA strands that pull apart the two strands.
Hope you like the answer- The two strands of dna are held together by. Now comment in comment box – what are complementary strands?
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