BIOL110s05-08 - BIOL 110: Principles of Biology Spring 2005...

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Unformatted text preview: BIOL 110: Principles of Biology Spring 2005 Lecture 8, F 2/4/05 Dr. Nathan Staples (Ph.D., UCSB 2002) (Ph.D., http://www.smccd.net/accounts/staplesn/biol110/ • Don’t forget to read and prepare Pre-Lab writeups for Mon./Wed. Labs – (What? Why? & How? are we doing in the lab?) • Midterm #1: Next Friday, 2/11. (Ch. 1-3) • Study/Review Sheets available today. REVIEW: • Ch. 2: The Molecules of Life – chemistry – Acid/Base; pH Buffers – Organic molecules: Macromolecules – carbohydrates, lipids, • TODAY: • Ch. 2: The Molecules of Life – chemistry – Organic molecules: Macromolecules – – lipids, proteins, nucleic acids. • Ch. 3: How Cells Are Put Together – Cell Structure 1 4.) Sterols and Derivatives • No fatty acids • Rigid backbone of four fused-together carbon rings • Cholesterol: most common type in animals – Vitamin A, D, E, K – Estrogen, Testosterone Cholesterol 5.) Waxes • Long-chain fatty acids linked to longchain alcohols or carbon rings • Firm consistency, repel water • Important in waterproofing Structure Determines Function!!! 2 C. Proteins: Amino Acid Structure (charged, (charged, “protonated”, in protonated” aqueous solution) (charged, “dede• Properties: Determined protonated”, in protonated” aqueous solution) by the “R group” (remainder, or reactive) • Amino acids (R group / sidechains) may be: sidechains) Carboxyl Carboxyl group Amino group R group group 1. Non-polar 1. Non2. Uncharged, polar 3. Positively charged, polar 4. Negatively charged, polar tyrosine (tyr) lysine (lys) glutamate (glu) glycine (gly) UNCHARGED, POLAR AMINO ACID POSITIVELY CHARGED, POLAR AMINO ACID NEGATIVELY CHARGED, POLAR AMINO ACID valine (val) phenylalanine (phe) methionine (met) proline (pro) 3 Protein Synthesis • Protein is a chain of amino acids linked by peptide bonds – Sequence is “spelled-out” by DNA sequence!!! spelled- out” • Peptide bond (a type of covalent bond) (a – Condensation reaction links amino group of one amino acid with carboxyl group of next Water forms as a by-product by- Protein Shapes • Fibrous proteins – Polypeptide chains arranged as strands or sheets • Globular proteins – Polypeptide chains folded into compact, rounded shapes 4 1.) Primary Structure 1. Sequence of amino acids 2. Unique for each protein 3. Two linked amino acids = dipeptide 4. Three or more = polypeptide 5. Backbone of polypeptide has N atoms: -N-C-C-N-C-C-N-C-C-N- 2.) Second & 3.) Third Levels • Hydrogen bonding produces helix or sheet • Domain formation – Functional sub-region of a protein…. Tertiary structure Secondary Secondary structure 5 4.) Fourth-Level Structure (Quaternary structure) Some proteins are made up of more than one polypeptide chain alpha chain beta chain Tertiary (globin) globin) beta chain Hemoglobin alpha chain Primary Structure & Protein Shape 1. Primary structure influences shape in two main ways: 1. Allows hydrogen bonds to form between different amino acids along length of chain 2. Puts R groups in positions that allow them to interact 2. **** Sequence 3D shape / structure 3D biological / chemical function!!……. biological 3. STRUCTURE DETERMINES FUNCTION!! 6 One Wrong Amino Acid 1. A single amino acid change in beta chain of hemoglobin can cause sickle-cell anemia 2. Change causes Hb–S molecules to stick together if oxygen levels become low 3. Cell clumping has effects throughout the body Structure Determines Function!!! Denaturation • Disruption of three-dimensional shape • Breakage of weak bonds • Causes of denaturation: (extremes, high or low) (extremes, – pH – Temperature – Salt concentration • Destroying protein shape disrupts function 7 D. Nucleotide Structure & Function 1. Sugar (Deoxyribose, or Ribose) 2. At least one Phosphate group Phosphate 3. Nitrogen-containing Base Base • A, T (or U), G, or C ATP • FUNCTIONS: 1. Energy carriers 2. Coenzymes 3. Chemical messengers 4. Building blocks for nucleic acids ATP - A Nucleotide base three phosphate groups Adenine sugar ** Nucleotides are the monomers/subunits that assemble into Nucleic Acids (polymers) 8 1. DNA 1. 2. 3. 4. 5. Double-stranded (H-bonds!) Sugar-phosphate backbone Deoxyribose Sugar (stable!) Covalent bonds in backbone H-bonds between bases • 4 Nucleotides: ATGC • A=T • G≡C Structure Determines Function!!! 2. RNA 1. Usually single strands 2. Sug.-Phos. backbone Structure Determines Function!!! 3. RIBOSE sugar (less stable than deoxyrib.) 4. Four types of nucleotides (AUGC) 5. Unlike DNA, contains the base uracil in place of thymine (U, not T) 6. Three types are key players in protein synthesis (messenger, transfer, ribosomal). 9 How Cells Are Put Together Chapter 3 Early Cells • First cells appeared between 3.9 billion and 2.5 billion years ago • Earliest were prokaryotic and anaerobic – Photosynthetic pathway arose later and added oxygen to atmosphere!!!! • Over time cells became more complex with internal compartments and specialized structures 10 Cell Theory 1) Every organism is composed of one or more cells 2) Cell is smallest unit having properties of life 3) Continuity of life arises from growth and division of single cells -- Cells arise only from preexisting cells I. Cell 1. Smallest unit of life 2. Can survive on its own or has potential to do so 3. Is highly organized for metabolism 4. Senses and responds to environment 5. Has potential to reproduce….. 11 ...
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