Reminder-four main classes of large biomolecules Carbohydrates/polysaccharides Lipids Proteins/polypeptides Nucleic acids/polynucleotides-information storage, hard drives for living systems
Two Types Nucleic Acid DNA and RNA Function: Information Storage And Control DNA 1 Synthesis of mRNA Two Types Nucleic Acid DNA and RNA mRNA NUCLEUS CYTOPLASM mRNA 2 Movement of mRNA into cytoplasm Ribosome Figure 5.25 DNA → RNA → protein. 3 Synthesis of protein Amino acids Polypeptide
Components of nucleic acids Nucleic acids are polymers Nucleotides are the monomers Each nucleotide consists of a base, a sugar and a phosphate But the base plus the sugar without the phosphate is called a nucleoside Bases are purines (Pu) or pyrimidines (Pyr) Sugars are either ribose or 2-deoxyribose
Phosphodiester Bond Links nucleotides together Sugar and phosphate involved This example is a 3’-5’ bond Gives two distinct ends
Figure 5.26 Components of nucleic acids. Sugar-phosphate backbone 5 end Nitrogenous bases Pyrimidines 5C 3C Nucleoside Nitrogenous base Cytosine (C) Thymine (T, in DNA) Uracil (U, in RNA) Purines 5C 1C Phosphate group 3C 5C Sugar (pentose) Adenine (A) Guanine (G) 3C (b) Nucleotide Figure 5.26 Components of nucleic acids. Sugars 3 end (a) Polynucleotide, or nucleic acid Deoxyribose (in DNA) Ribose (in RNA) (c) Nucleoside components
RNA Structure Individual chains in cells Aka “single-stranded”: ssRNA Chains generally from 50-5000 nucleotides Distributed throughout the cell
RNA molecules fold up on themselves Secondary structure refers to folding pattern Confers unique shape Primary structure is the 5’ to 3’ sequence of bases 5’ 3’
DNA structure-different from RNA Two molecules interact to form double strand
Important features of the double helix Antiparallel strands Bases on the inside Chain held together by hydrogen bonds Watson-Crick base pairs AT and GC are the Watson-Crick base pairs Complementary
DNA Structure Almost always double helix Aka “double-stranded”: dsDNA Not as flexible as RNA Chains can be very long 120,000,000 nucleotides Distributed throughout the cell Sequestered DNA Structure
Individual nucleotides Mononucleotides Have different functions Energy carriers Help with enzyme reactions as cofactors Signalling