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Download Chapter 3: Nucleic Acids, Proteins, and Enzymes
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CHAPTER 3: NUCLEIC ACIDS, PROTEINS, AND ENZYMES Unit 2: Macromolecules and Enzyme Function Introduction • Nucleic Acids • Polymers specialized for storage, transmission, and usage of genetic material • DNA – Deoxyribonucleic acid • RNA – Ribonucleic acid Nucleotides are the building blocks of Nucleic Acids • Monomer of nucleic acids are nucleotides • Consists of three components • Nitrogen containing base • Pentose Sugar • One of three Phosphate groups Nucleotides are the building blocks of Nucleic Acids • Nucleoside • Molecule made up of pentose sugar and nitrogenous base • Nucleoside monophosphate • Nucleotides that are composed of one phosphate group • These make up nucleic acids Nucleotides are the building blocks of Nucleic Acids • Bases of Nucleic Acids • Pyrimidine six-membered ring • Purine fused, double ring Nucleotides are the building blocks of Nucleic Acids • Formation of nucleic acids • Addition of nucleotides one at a time • Involves condensation reaction between hydroxyl groups of newly added nucleotides • Results in a phosphodiester linkage that bonds nucleotides • 5’ sugar of nucleotide binds with existing 3’ sugar of nucleotide Nucleotides are the building blocks of Nucleic Acids • Nucleotide Sizes • Oligonucleotides • Include RNA molecules that function as primers • Regulate expression of genes • Synthetic DNA used to amplify and analyze genomes Nucleotides are the building blocks of Nucleic Acids • Nucleotide Sizes • Polynucleotides • More commonly referred to as nucleic acids • Include DNA and RNA • Longest polymers in living world • Some DNA in humans contain hundreds of millions of nucleotides Base Pairing Occurs in Both DNA and RNA • Four bases of DNA • Adenine • Cytosine • Guanine • Thymine Base Pairing Occurs in Both DNA and RNA • Four bases of DNA • Adenine • Cytosine • Guanine • Thymine • Four Bases of RNA • Adenine • Cytosine • Guanine • Uracil Base Pairing Occurs in Both DNA and RNA • Sugars of DNA vs. RNA • Deoxyribose • Lack hydroxyl group at 2’ carbon • Not as flexible • Ribose • More –OH groups • More flexible • Forms variety of structures Base Pairing Occurs in Both DNA and RNA • Complementary Base Pairing • Rules: • Adenine and Thymine always pair • Cytosine and Guanine always pair • Polarity of bases contributes to formation of hydrogen bonds • Can break with a modest input of energy Base Pairing Occurs in Both DNA and RNA • RNA • Single-stranded • Can fold into 3-dimensional structures • Due to H-bonding and CBP • Structure is determined by particular order of bases Base Pairing Occurs in Both DNA and RNA • DNA • Double-stranded • Consists of two separate polynucleotide strands of the same length • Very uniform and stable • Carries Genetic information DNA Carries Information and Is Expressed Through RNA • DNA is purely an informational molecule • Carried in bases of its’ strands • Example: • TCAGCA will code for a different protein than CCAGCA DNA Carries Information and Is Expressed Through RNA • DNA has two functions 1. Can be reproduced exactly • DNA replication 2. Can be copied into RNA • Called DNA transcription • RNA will be translated into amino acid by process called Translation DNA Carries Information and Is Expressed Through RNA • Gene Expression Details • DNA replication and DNA transcription depend on base pairing • Processes are accomplished through complementary base pairing • Base pairing examples • DNA replication involves entire molecule • Entire molecule of DNA must be replicated completely DNA Carries Information and Is Expressed Through RNA • Genome • Complete set of DNA in a living organism • Not all information in the genome is needed at all times and in all tissues • Example: Keratin in skin cells • Sequences that encode specific proteins are called genes 3.2 Proteins Are Polymers with Important Structural and Metabolic Roles https://www.youtube.com/watch?v=zm-3kovWpNQ Introduction • Major functions of proteins • Enzymes • Defensive proteins • Hormonal and regulatory proteins • Receptor Proteins • Storage Proteins • Structural Proteins • Transport proteins • Genetic Regulatory proteins Amino Acids are the Building Blocks of Proteins • Polymers made up of amino acid monomers Amino Acids are the Building Blocks of Proteins • Contain two functional groups • Amino group • Ionizes to form H3N+ • Carboxyl group • Ionizes to form COO- Amino Acids are the Building Blocks of Proteins • Central Carbon is called the alpha carbon • Four available electrons for covalent bonding • R – group designates specific amino acid that is formed Amino Acids are the Building Blocks of Proteins • 20 amino acids occur extensively in proteins of all organisms • Grouped according to their properties • 5 electrically charged Amino Acids are the Building Blocks of Proteins • 20 amino acids occur extensively in proteins of all organisms • Grouped according to their properties • 5 electrically charged • 5 polar side chains Amino Acids are the Building Blocks of Proteins • 20 amino acids occur extensively in proteins of all organisms • Grouped according to their properties • 5 electrically charged • 5 polar side chains • 7 nonpolar side chain, hydrophobic Amino Acids are the Building Blocks of Proteins • 20 amino acids occur extensively in proteins of all organisms • Grouped according to their properties • 5 electrically charged • 5 polar side chains • 7 nonpolar side chain, hydrophobic • 3 Special cases Amino Acids are the Building Blocks of Proteins • Special Cases • Cysteine • Has terminal –SH group • Forms disulfide bridges • Glycine • R group is H atom • Small enough to fit in corners of interior protein molecules • Proline • Possesses modified amino group • Forms ring structure with amino group
