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Published byEustacia Bradley Modified over 6 years ago
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DNA (Deoxyribonucleic Acid): Structure and Function
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Where can you find it? Inside the cell
- nucleus, chloroplasts and mitochondria Chromosomes are made of DNA
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Parts of a Nucleotide Adenine is always paired with Thymine A + T
Phosphate Sugar Nitrogenous Bases: Adenine is always paired with Thymine A + T Guanine is always paired with Cytosine G + C
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Structure of DNA Discovery of Double Helix: 1962
James Watson, Francis Crick and Maurice Wilkins received a NOBEL PRIZE Watson, Crick and Wilkins used unpublished data from Rosalind Franklin’s research obtained without her knowledge and used without her consent. - She was misrepresented and unrecognized - She died of cancer in 1958 We know now: DNA is a double helix made of... - 4 nucleotides - A, T, G, C - in 2 polynucleotide strands - strands run antiparallel - [5'-----3'] - held together via weak H-Bonds & complimentary base pairing (A-T and C-G)
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DNA is double-stranded, with complementary base pairing
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A C T G G A T C
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DNA Structure To crack the genetic code found in DNA we need to look at the sequence of bases. The bases are arranged in triplets called codons. A G G - C T C - A A G - T C C - T A G T C C - G A G - T T C - A G G - A T C
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DNA Structure In eukaryotes it is always associated with proteins
NUCLEOSOMES = DNA wrapped around 8 histones (proteins) Help compact DNA Help control DNA transcription
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DNA’s job Stores information It has the code for all 20 amino acids
Mutation: changes in the base sequence primary structure of a protein is altered (changing its shape) Can be harmful, neutral or beneficial Important: create variation – basis of natural selection
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RNA Discovered after DNA Single strand shorter than DNA
Contains Uracil instead of Thymine A+U G+C Sugar = ribose (DNA contains deoxyribose) Types: mRNA: messenger blueprint for protein rRNA: ribosomal makes up ribosomes tRNA: transfer delivers the proper amino acid to the ribosome
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