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NUCLEIC ACIDS RNA and DNA
Nucleic Acids
A nucleic acid is a macromolecule composed of chains of monomeric nucleotides. In biochemistry
these molecules carry genetic information or form structures within cells.
The most common nucleic acids are deoxyribonucleic acid (DNA) and ribonucleic acid (RNA).
Nucleic acids are universal in living things, as they are found in all cells and viruses. Nucleic acids were first discovered by Friedrich Miescher.
Nucleotide
Nucleic acids consist of nucleotides that have a sugar, nitrogen base, and phosphate
Nitrogen-Containing Bases
Pentose (5 –Carbon) Sugars
Deoxyribonucleotide
Ribonucleotide
ATP (Adensosine triphosphate)
NAD+ + ATP -> NADP+ + ADP catalyzed by NAD+ kinase
Polynucleotides
DNA and RNA Structures
Difference between DNA and RNA structures
Characters DNA RNA
1. Molecule Double stranded, helical Single stranded, straight or variously folded and twisted.
2. Pentose sugar Deoxyribose Ribose
3. Pyrimidine base Thymine Uracil
4. Complementary base pairing
Always present and exists between A = T and G = C
Normally absent, but may be present in twisted segments of a molecule. If present, pairing is between A = U and G = C
5. Ratio of Purines: Pyrimidines
Always 1:1 Not necessarily 1:1
Double-helical structure of DNA
Double-helical structure of DNA
DNA Replication
Semiconservative Replication
DNA Polymerization
PlasmidsA plasmid is an extra-chromosomal DNA molecule separate from the chromosomal DNA which is capable of replicating independently of the chromosomal DNA.
In many cases, it is circular and double-stranded. Plasmids usually occur naturally in bacteria, but are sometimes found in eukaryotic organisms.
Classification of RNA
m- RNA
Messenger or mRNA
is a copy of the
information carried by
a gene on the DNA.
The role of mRNA is to
move the information
contained in DNA to
the translation
machinery.
t –RNA
tRNA is the information
adapter molecule.
It is the direct interface
between amino-acid
sequence of a protein and
the information in DNA.
Therefore it decodes the
information in DNA.
There are > 20 different
tRNA molecules.
r-RNA Ribosomal RNA (rRNA) is the central component of the
ribosome, the protein manufacturing machinery of all living cells.
The function of the
rRNA is to provide
a mechanism for
decoding mRNA
into amino acids
and to interact with
the tRNAs during
translation by
providing peptidyl
transferase activity.
REFERENCES
Michael L. Shuler and Fikret Kargı, Bioprocess Engineering: Basic Concepts (2 nd Edition),Prentice Hall, New York, 2002.
1. James E. Bailey and David F. Ollis, Biochemical Engineering Fundementals (2 nd Edition), McGraw-Hill, New York, 1986.
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fig.cox.miami.edu
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nanobiologynotes.blogspot.com
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http://www.diffen.com/difference/Dna_vs_Rna
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http://www.johnkyrk.com/DNAanatomy.html
http://www.johnkyrk.com/DNAreplication.html
http://207.207.4.198/pub/flash/26/
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