BLGY1232 Mutation
Chemistry
Nucleic acids are polymeric molecules
Nucleotides are made up of a sugar, a “base” and phosphate
The sugars are RIBOSE and DEOXYRIBOSE:
These contain 5 carbon atoms, labelled 1’ 2’ 3’ 4’ and 5’
The ‘ symbol is known as a “prime”, so you will hear these positions referred to
as “one-prime”, “two-prime”, “three-prime” etc
Ribose carries an -OH group on both the 2’ and the 3’ carbon
Deoxyribose carries an -OH group, only on its 3’ carbon
Ribose is the constituent sugar of RNA, deoxyribose is the constituent sugar of
DNA
The 1’-C atom is linked to a base; Adenine (A), Cytosine (C), Guanine (G),
Thymine (T),Uracil (U) Thymine is found only in DNA and is replaced by Uracil
in RNA
A sugar linked to a base is called a nucleoside or a deoxynucleoside (depending on
whether the sugar is ribose or deoxyribose)
Nucleoside phosphates or nucleotides have 1, 2 or 3 phosphate groups attached to
the 5’ carbon atom. (As in adenosine mono-, di- or tri-phosphate)
The polynucleotide chains (the nucleic acids) consist of chains of nucleotides which
are linked by the formation of bonds between the phosphate on the 5’ carbon of one
nucleotide, to the oxygen on the 3’ carbon of the next nucleotide The bond is
known as a 3’ 5’ phosphodiester bond: O-P-O
DNA and RNA chains have POLARITY; At one end there will always be a free 5’-
phosphate, at the other there will always be a free 3’-hydroxyl group “five-prime
end” and the "three-prime end”
If it’s a complementary chain they can form a double stranded molecule; RNA and
DNA
Central dogma; DNA can be copied to make DNA, it can also be copied into RNA via
transcription and RNA is transformed into a protein via translation RNA can be
transferred back to DNA via reverse transcription
DNA replication
DNA is copied by semi-conservative replication
Involves; DNA-unwinding enzymes, primase, DNA polymerase and DNA ligase
DNA polymerase – one enzyme, 3 activities;
Polymerase activity extends new chain 5’-3’ by copying template strand from
3’-5’ by extending an RNA primer annealed to the template
5’-3’ exonuclease activity chews way ahead of polymerase
3’-5’ exonuclease checks for mismatches and removes them
Transcription – the copying of DNA sequence into RNA by the enzyme RNA
polymerase
Translation – the RNA copy of the DNA sequence (mRNA) is decoded by the protein
synthetic machinery to synthesize polypeptides (proteins) the proteins have
enzymatic and structural properties in the cell and carry out all the cellular functions
that characterize living organisms
Chemistry
Nucleic acids are polymeric molecules
Nucleotides are made up of a sugar, a “base” and phosphate
The sugars are RIBOSE and DEOXYRIBOSE:
These contain 5 carbon atoms, labelled 1’ 2’ 3’ 4’ and 5’
The ‘ symbol is known as a “prime”, so you will hear these positions referred to
as “one-prime”, “two-prime”, “three-prime” etc
Ribose carries an -OH group on both the 2’ and the 3’ carbon
Deoxyribose carries an -OH group, only on its 3’ carbon
Ribose is the constituent sugar of RNA, deoxyribose is the constituent sugar of
DNA
The 1’-C atom is linked to a base; Adenine (A), Cytosine (C), Guanine (G),
Thymine (T),Uracil (U) Thymine is found only in DNA and is replaced by Uracil
in RNA
A sugar linked to a base is called a nucleoside or a deoxynucleoside (depending on
whether the sugar is ribose or deoxyribose)
Nucleoside phosphates or nucleotides have 1, 2 or 3 phosphate groups attached to
the 5’ carbon atom. (As in adenosine mono-, di- or tri-phosphate)
The polynucleotide chains (the nucleic acids) consist of chains of nucleotides which
are linked by the formation of bonds between the phosphate on the 5’ carbon of one
nucleotide, to the oxygen on the 3’ carbon of the next nucleotide The bond is
known as a 3’ 5’ phosphodiester bond: O-P-O
DNA and RNA chains have POLARITY; At one end there will always be a free 5’-
phosphate, at the other there will always be a free 3’-hydroxyl group “five-prime
end” and the "three-prime end”
If it’s a complementary chain they can form a double stranded molecule; RNA and
DNA
Central dogma; DNA can be copied to make DNA, it can also be copied into RNA via
transcription and RNA is transformed into a protein via translation RNA can be
transferred back to DNA via reverse transcription
DNA replication
DNA is copied by semi-conservative replication
Involves; DNA-unwinding enzymes, primase, DNA polymerase and DNA ligase
DNA polymerase – one enzyme, 3 activities;
Polymerase activity extends new chain 5’-3’ by copying template strand from
3’-5’ by extending an RNA primer annealed to the template
5’-3’ exonuclease activity chews way ahead of polymerase
3’-5’ exonuclease checks for mismatches and removes them
Transcription – the copying of DNA sequence into RNA by the enzyme RNA
polymerase
Translation – the RNA copy of the DNA sequence (mRNA) is decoded by the protein
synthetic machinery to synthesize polypeptides (proteins) the proteins have
enzymatic and structural properties in the cell and carry out all the cellular functions
that characterize living organisms
