Post on 12-Nov-2014
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Nucleic AcidsNucleic Acids
• DNA= • Deoxyribonucleic AcidDeoxyribonucleic Acid• The structure of DNA was not discovered
until 19531953 when WatsonWatson and Crick Crick proposed the structure below.
• DNA is made up of two strands of nucleotidesnucleotides.
• These two strands wind around each other in a double helixdouble helix.
• Each nucleotide is made up of three different parts:
• 1) Phosphate1) Phosphate
• 2) Sugar2) Sugar
• 3) nitrogenous base3) nitrogenous base
• The sugarsugar and phosphatephosphate make chains, and the basesbases connect the two strands of DNA together.
• Draw the structure of DNA below and circle the nucleotides.
• There are 4 different nitrogen bases called:
• 1) AAdenine• 2) GGuanine• 3) CCytosine• 4) TThymine• A purinepurine always pairs with a ppyrimidineyrimidine• AA with TT• CC with GG• Weak hydrogen bondshydrogen bonds hold the nitrogen
bases together.
PurinePurine
pyrimidinepyrimidine
• RNA =• Ribonucleic AcidRibonucleic Acid• RNA is very similar to DNA. RNA nucleotides
are also made up of three parts: sugar, phosphate, and one of four nitrogen bases.
• RNA DNA• riboseribose (sugar) instead of deoxyribose deoxyribose• UracilUracil (bases) instead of ThyamineThyamine and• Single strandSingle strand instead of double stranddouble strand
• now Purine pyrimidine
• AdenineAdenine pairs with UracilUracil
• GuanineGuanine pairs with CytosineCytosine
• RNA has three different functions in the cell, depending on its structure. All RNA is single stranded
• Messenger RNA (mRNA) – carries DNA carries DNA code from nucleus to the cytoplasmcode from nucleus to the cytoplasm
• Transfer RNA (tRNA) – brings amino acids brings amino acids to the ribosometo the ribosome
• Ribosomal RNA (rRNA) – puts amino puts amino acids togetheracids together