biolecture5 - Bio Lecture 5 Informational molecules Nucleic...

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Bio Lecture 5 Informational molecules: Nucleic acids and proteins U C A G U C A G Components of nucleic acids Keeping the strands together Amino acids Protein structure Nucleic Acids: polymers. Two types: DNA, RNA Each monomer – nucleotide – with three parts Nitrogenous base, pentose sugar = nucleoside Phosphate moiety Nitrogenous Bases: - purines – 2 rings: adenine, guanine : both DNA and RNA - pyrimidines – 1 ring cytosine, thymine, uracil Pentose Sugar: - ribose (in RNA - deoxyribose (in DNA) Phosphate Moiety: bonds to 5’ carbon of ribose sugar within a nucleotide (ester bond resulting from condensation reaction) DNA: X-ray diffraction data suggests helix Nucleotides are .34 nm apart H bonds hold the strands together Amino Acids: - asymmetrical Almost all biologically active are L isomers 20 AA form the proteins in living organisms Amino group, functional group, carboxyl group, α carbon Amino acid functional groups confer chemical properties Nonpolar amino acids: Alanine, valine, leucine, isoleucine
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Alanine most abundant Nonpolar series: Caline, Leucine, Isoleucine Others: Glycine, Methionine, Phenylalanine, Tryptophan, Proline Polar: serine, threonine, systeine, lysosine, Charged AA: hydrogen donors, hydrogen acceptors KNOW NAMES, WHICH KIND THEY ARE Amino Acids polymerize into proteins by condensation reactions Four levels of protein structure: 1. primary structure: AA sequence, starts from amino end goes on to the carboxyl end 2. secondary structure : repeating structure based on interactions in the peptide backbone 3. tertiary structure: shape of the molecule due to interactions of R groups 4. some have quarternary: if there are two or more subunits that come together to make the protein. Eg. Hemoglobin Primary structure: A single letter code is usually used to describe amino acid 1° structure Secondary structure: due to hydrogen bonds of the backbone, not R groups 2 principle forms (domains): 1. α helix 2. β pleated sheet Many proteins have mixtures of alpha helix and beta pleated sheet motifs
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biolecture5 - Bio Lecture 5 Informational molecules Nucleic...

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