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James Watson and Francis Crick are credited with discovering the structure of DNA in April 1953 Nucleic Acids • Function: – genetic material • stores information – genes – blueprint for building proteins » DNA RNA proteins DNA • transfers information – blueprint for new cells – blueprint for next generation proteins Nucleic Acids • Examples: – RNA (ribonucleic acid) • single helix – DNA (deoxyribonucleic acid) • double helix • Structure: – monomers = nucleotides DNA RNA Nucleic Acids Function: carry hereditary info DNA •Double stranded helix • N-bases: A, G, C, Thymine •Stores hereditary info •Longer/larger •Sugar: deoxyribose RNA •Single stranded • N-bases: A, G, C, Uracil •Carry info from DNA to ribosomes •tRNA, rRNA, mRNA •Sugar: ribose Nucleic Acids • Two types – Deoxyribonucleic Acid (DNA) – Ribonucleic Acid (RNA) • DNA is the genetic material inherited from parent to offspring • The DNA molecule usually consists of hundreds or thousands of genes • DNA carries the information to make proteins How Does DNA Direct The Formation of Proteins? DNA → RNA → Protein 1. From the DNA Template, mRNA is made 2. mRNA then travels from the nucleus to the ribosome 3. At the ribosome, tRNA “reads” the code on the mRNA and assembles the amino acids 4. The long sequences of amino acids form polypeptides which form proteins Nucleotides • Nucleic Acids = polymers • Nucleotides = monomers • Nucleotides consist of a nitrogenous base, a pentose (5-carbon sugar), and a phosphate group • Two types of nitrogenous bases –Pyrimidines –Purines Pyrimidines • Six-membered ring of nitrogen and carbon atoms • Includes Cytosine (C), Thymine (T) – only in DNA, and Uracil (U) – only in RNA Purines • Six-membered ring fused to a Fivemembered ring. • Includes Adenine (A) and Guanine (G) Nucleotide • DNA’s sugar is deoxyribose • RNA’s sugar is ribose DNA Replication • DNA is two-stranded forming a double helix Nucleotide Phosphodiester bonds Hydrogen bonds Sugar-phosphate backbone Key Adenine (A) Thymine (T) Cytosine (C) Guanine (G) DNA Base Pairing Rules • Each "Rung" of the DNA "staircase" is formed by the linking of 2 Nucleotides through Hydrogen Bonds. • These Hydrogen bonds form only between specific Nucleotides. This is known as Base Pairing. The rules are as follows: – Adenine (A) will ONLY bond to Thymine (T) – Cytosine (C) will ONLY bond to Guanine (G) ATCGAGGTGCATGCTGATGCTGAT TAGCTCCACGTACGACTACGACTA DNA Replication Summary of DNA Structure Phophodiester bonds-linkage of OH group from 3’ Carbon to a phosphate of next group Hydrogen Bonds Is DNA a Measure of Evolution? Summary of DNA Structure Phophodiester bonds-linkage of OH group from 3’ Carbon to a phosphate of next group Hydrogen Bonds Review Questions 1. What substance varies within a nucleotide of DNA? A. B. C. D. E. Deoxyribose Nitrogenous Base Phosphate Group Ribose Sugar 2. All of the following bonds are correct EXCEPT: I. A Ξ T II. C Ξ G III. A Ξ U A. B. C. D. E. I only II only III only I and II only I and III only 3. A sample of double-stranded DNA has equal numbers of A. Adenine nucleotides and guanine nucleotides. B. Adenine nucleotides and cytosine nucleotides. C. Cytosine nucleotides and Thymine nucleotides. D. Purines and pyrimidines. E. Thymine and Uracil Molecules. Macromolecule Review 2006-2007 Carbohydrates • Structure / monomer – monosaccharide • Function – Short term energy – energy storage – structural compounds glycosidic bond • Examples – glucose, starch, cellulose, glycogen Lipids • Structure / building block – glycerol, fatty acid, cholesterol, H-C chains • Function – energy storage – membranes – hormones • Examples ester bond (in a fat) – fat, phospholipids, steroids Proteins • Structure / monomer – amino acids – levels of structure • Function – enzymes – transport – signals defense u structure u receptors u peptide bond • Examples – digestive enzymes, membrane channels, insulin hormone, actin Nucleic acids • Structure / monomer – nucleotide • Function – information storage & transfer • Examples – DNA, RNA phosphodiester bond Fig. 5-UN9