BIOLOGY CONCEPTS & CONNECTIONS Fourth Edition Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Neil A. Campbell Jane B. Reece Lawrence G. Mitchell Martha R. Taylor From PowerPoint ® Lectures for Biology: Concepts & Connections CHAPTER 6 Macromolecules Modules 3.11 – 3.20

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Proteins are involved in –cellular structure –movement –defense –transport –communication Mammalian hair is composed of structural proteins Enzymes regulate chemical reactions PROTEINS 3.11 Proteins are essential to the structures and activities of life Figure 3.11

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Proteins are the most structurally and functionally diverse of life’s molecules –Their diversity is based on different arrangements of amino acids (monomer of proteins) –There are only 20 amino acids 3.12 Proteins are made from just 20 kinds of amino acids

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Each amino acid contains: –an amino group –a carboxyl group –an R group, which distinguishes each of the 20 different amino acids Amino group Carboxyl (acid) group Figure 3.12A

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Each amino acid has specific properties because of its R group Leucine (Leu) Figure 3.12B Serine (Ser)Cysteine (Cys) HYDROPHOBICHYDROPHILIC

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Cells link amino acids together by dehydration synthesis The bonds between amino acid monomers are called peptide bonds 3.13 Amino acids can be linked by peptide bonds Amino acid Dipeptide Dehydration synthesis Carboxyl group Amino group PEPTIDE BOND Figure 3.13

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings A protein consists of polypeptide chains folded into a unique shape –The shape determines the protein’s function 3.14 Overview: A protein’s specific shape determines its function Figure 3.14AFigure 3.14B

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings 3.15 A protein’s primary structure is its amino acid sequence (linked by peptide bonds) 3.16 Secondary structure is polypeptide coiling or folding produced by hydrogen bonding Figure 3.15, 16 Amino acid Hydrogen bond Alpha helix Pleated sheet Primary structure Secondary structure

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings 3.17 Tertiary structure is the overall shape of a polypeptide (linked by hydrogen and ionic bonds) 3.18 Quaternary structure is the relationship among multiple polypeptides of a protein (linked by hydrogen and ionic bonds) Figure 3.17, 18 Polypeptide (single subunit of transthyretin) Transthyretin, with four identical polypeptide subunits Tertiary structure Quaternary structure

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Review of proteins Many uses in the human body, including enzymes Monomer=amino acids, linked together by peptide bonds Polymer=polypeptide Examples: meat, beans, nuts, dairy

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The polymers of nucleic acids are DNA and RNA DNA is our genetic material RNA is instructions for making proteins NUCLEIC ACIDS 3.20

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The monomers of nucleic acids are nucleotides Phosphate group Sugar Figure 3.20A –Each nucleotide is composed of a sugar, phosphate, and nitrogenous base Nitrogenous base (A)

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings The sugar and phosphate form the backbone for the nucleic acid Sugar-phosphate backbone Nucleotide Figure 3.20B

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings DNA is a double helix There are 4 nucleotides: –A and T –C and G –They form base pairs Figure 3.20C Nitrogenous base (A) Base pair

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Review of Nucleic Acids Polymers include DNA and RNA Monomers are nucleotides (which are made of sugar, phosphate, and nitrogen base) Carry genetic information and instructions for making proteins Examples: DNA and RNA

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Indicators Indicators are chemicals or techniques used to identify unknown solutions of macromolecules

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Starch (polysaccharide) The indicator for starch (polysaccharide) is iodine –it changes from a yellow/orange color to a blue/black color in the presence of starch

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Protein The indicator for proteins is Biuret’s reagent. –It changes from light blue to purple in the presence of protein

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Glucose (monosaccharide) The indicator for glucose is Benedict’s solution AND heat –When heated, a solution with glucose will change from blue to a red/orange color if it has glucose

Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings Lipids, fats, oils To test for the presence of lipids, we use test for translucence. –The unknown liquid is applied to a piece of paper. If it becomes translucent, lipids are present.