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Lecture

BIOL 1602 Lecture Notes - Cytosine, Messenger Rna, Cell Nucleus


Department
Biology
Course Code
BIOL 1602
Professor
Rebecca Jubis

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Nucleic Acids - The Key to Life
Nucleic acids carry the genetic code that determines the order of amino acids in proteins
Genetic material stores information, can be replicated, and undergoes mutations
Differ from proteins as it has phosphorus and NO sulphur
Made up of several chains of nucleotides
DNA and RNA are types of nucleic acids
Nucleotide
Sugar-phosphate backbone (ensures stability of the molecule)
o Pentose sugar
Deoxyribose in DNA
Ribose in RNA
o Phosphate group
Organic bases
o Purines (double rings of C and N - bigger)
Adenine
Guanine
o Pyrimidines (single ring of C and N - smaller)
Thymine in DNA only
Uracil in RNA only
Cytosine
Deoxyribonucleic Acid (DNA)
Made up of 2 separate chains of nucleotides hold together by base pairing
o Connected by weak hydrogen bonds
o Can easily be opened for replication
o Adenine-Thymine has 2 H-bonds
o Cytosine-Guanine has 3 H-bonds
DNA normally twist into a helix (coil) / forms a double helix
o Makes the molecule compact (store a lot in small space)
o Protects from damage as base pairs are facing inwards
Both chains of DNA are
o Directional → according to the attachment between sugars and phosphate group
o Antiparallel → essential for gene coding and replication
Semi-Conservative Replication of DNA
Semi-conservative replication: each DNA strand acts as a template for the formation of a
new strand
Happens during interphase S of the cell cycle
Unwinding
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