DNA & RNA 0.0 / 5 ? BiologyBiological moleculesASAQA Created by: iloverevision:)Created on: 06-03-19 14:03 DNA & RNA Function both types of nucleic acid DNA stores genetic info RNA transfers genetic info from DNA to ribosomes ribosomes read RNA & make polypeptides - translation ribosomes are made from RNA & proteins 1 of 8 Nucleotide Structure molecules of DNA & Rna are polymers of nucleotides nucleotide is made from a pentose sugar, a nitrogen-containing base & a phosphate group they are monomers that make up DNA & RNA 2 of 8 Polynucleotide Structure many nucleotides join together to form polynucleotide chains/strands via condensation reaction between phosphate group of one & sugar of another forms phosphodiester bond chain of phosphates & sugar is known as sugar-phosphate backbone 3 of 8 DNA Structure double helix formed from 2 seperate strands which wind round eachother to form a spiral strands - polynucleotides made up of lots of nucleotides joined together in long chain really long & coiled up very tightly so lots of genetic info can fit in to small space in cell nucleus 4 of 8 DNA Nucleotide Structure made from a phospahte group, pentose sugar - deoxyribose & a nitrogen-containing organic base each has same sugar & phosphate bases on each can vary 4 possible bases adenine thymine cytosine guanine 5 of 8 Complementary Base Pairing 2 DNA polynucleotide strands join together by hydrogen bonds between bases each base can only join with1 particular partner complementary base paring adenine - thymine cytosine - guanine this means there are always equal amounts of adenine and thymine & cytosine and guanine 2 hydrogen bonds form between A & T 3 hydrogen bonds form between C & G 2 polynucleotide strands are antiparallel - run in opposite directions 2 antiparallel strands twist to form a DNA double helix 6 of 8 RNA structure RNA is made of nucleotides that contain a sugar, a phosphate group & 1 of 4 different bases nucleotides form polynucleotide strand with sugar-phosphate backbone pentose sugar - ribose sugar uracil replaces thymine as a base single polynucleotide strand RNA strands are much shorter than most DNA polynucleotides 7 of 8 DNA as Carrier of Genetic Code DNA first observed in 1800s - scientists doubted that it could carry genetic code - relatively simple chemical composition 1953 - experiments had shown that DNA was the carrier of the genetic code also the double helix structure was determined by Watson & Crick 8 of 8
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