Chapter 5: The Structure and Function of Large Biological Molecules

Essential Knowledge 3.a.1 – DNA, and in some cases RNA, is the primary source of heritable information (5.5). 4.a.1 – The subcomponents of biological molecules and their sequence determine the properties of that molecule ( ). 4.b.1 – Interactions between molecules affect their structure and function (5.4). 4.c.1 – Variation in molecular units provides cells with a wider range of functions ( ).

Macromolecules Large molecules formed by joining many subunits together. Macro = giant, large Also known as “polymers”. Ex: Carbs, proteins, lipids, nucleic acids

Polymers and Monomers Polymer—many units bonded together to make a larger macromolecule Poly = many Monomer - A building block of a polymer Mono = one

Condensation Synthesis or Dehydration Synthesis The chemical reaction that joins monomers into polymers Covalent bonds are formed by the removal of a water molecule between the monomers.

Hydrolysis Reverse of condensation synthesis Hydro - water Lysis - to split Breaks polymers into monomers by adding water

Four Main Types Of Macromolecules 1. Carbohydrates 2. Lipids 3. Proteins 4. Nucleic acids

Carbohydrates Used for fuel, building materials, and receptors. Made of C,H,O General formula is CH 2 O C:H:O ratio is 1:2:1 Monomers joined by glycosidic linkage (covalent bond)

Types Of Carbohydrates 1. Monosaccharides 2. Disaccharides 3. Polysaccharides

Monosaccharides Mono - single Saccharide - sugar Simple sugars 3 to 7 carbons Can be in linear or ring forms

Monosaccharides Can be “Aldoses” or “Ketoses” depending on the location of the carbonyl group. Aldose – end of chain Ketose – middle of chain Notice: names of end in -ose

Examples Glucose Galactose Ribose Fructose -ose Names u Word ending is common for many sugar/carbohydrates

Disaccharides Sugar formed by joining two monosaccharides through a “glycosidic linkage” Examples: Maltose = glucose + glucose Lactose = glucose + galactose Sucrose = glucose + fructose

Polysaccharides Many joined simple sugars Used for storage or structure Polymers made of glucose monomers (either  or  glucose) Examples: Starch Cellulose Glycogen Chitin

Starch Made of 1-4 linkages of  glucose Linkage makes the molecule form a helix Fuel storage in plants

Cellulose Made of 1-4 linkages of  glucose Linkage makes the molecule form a straight line Used for structure in plant cell walls

Comment Most organisms can digest starch (1- 4  linkage), but very few can digest cellulose (1- 4  linkage) Another example of the link between structure and function

Glycogen “Animal starch” Similar to starch, but has more 1-6 linkages or branches Found in the liver and muscle cells

Chitin Used by insects, spiders, crustaceans to build exoskeletons Also found in cell walls Differs from cellulose – chitin has nitrogen branch connected to glucose monomer

Monomer: Glucosamine Polymer: Chitin

Lipids – On Your Own First online.com/Objects/Vie wObject.aspx?ID=AP online.com/Objects/Vie wObject.aspx?ID=AP Visit this website and take notes over the material presented; we will go through the ppt after to catch anything missed!

Lipids Diverse hydrophobic molecules Made of C,H,O No general formula C:O ratio is very high in C

Lipid monomers Made of two kinds of smaller monomers. 1) Fatty Acids A long carbon chain (12-18 C) with a -COOH (acid) on one end and a -CH 3 (fat) at the other 2) Glycerol

AcidFat

Neutral Fats or Triacylglycerols Three fatty acids joined to one glycerol. Joined by an “ester” linkage between the - COOH of the fatty acid and the -OH of the alcohol.

Saturated vs. Unsaturated Fats Saturated - no double bonds. Unsaturated - one or more C=C bonds. Can accept more hydrogens Double bonds cause “kinks” in the molecule’s shape

Fats Differ in which fatty acids are used Used for energy storage, cushions for organs, insulation

Oils vs. Fats Oil = liquid Fats = solid Most animal fats are saturated FATS (like lard and butter.) Solids Most plant fats are unsaturated fats—we call these OILS (like olive, veggie oil) Liquids

Nutrition and Diet Diets high in saturated fats cause heart disease Hydrogenated vegetable oil is a product whose unsaturated fats have been converted to saturated fats by adding H

Question??? Which has more energy, a kg of fat (lipid) or a kg of starch (carb)? Fat !!!!! There are more C-H bonds which provide more energy per mass.

Phospholipids Similar to fats, but have only two fatty acids. The third -OH of glycerol is joined to a phosphate containing molecule. Phospholipids have a hydrophobic tail, but a hydrophilic head. Self-assembles into micells or bilayers, an important part of cell membranes.

Steroids Lipids with four fused rings. Differ in the functional groups attached to the rings. Examples: cholesterol sex hormones

Other Lipids… Soaps and detergents Waxes Certain pigments Cosmetics

Proteins The molecular tools of the cell Made of C,H,O,N, and sometimes S No general formula Polypeptide chains of Amino Acids linked by peptide bonds

Uses Of Proteins Structure Enzymes Antibodies Transport Movement Receptors Hormones

Protein monomers: 20 Amino Acids All have a Carbon with four attachments: -COOH (acid) -NH 2 (amine) -H -R (some other side group)

Amino acid “R” groups The properties of the R groups determine the properties of the protein. 20 different kinds: Nonpolar - 9 AA Polar - 6 AA Electrically Charged Acidic - 2 AA Basic - 3 AA

Polypeptide Chains Formed by dehydration synthesis between the carboxyl group of one AA and the amino group of the second AA. Produce an backbone of: (N-C-C) X

Levels of Protein Structure Organizing the polypeptide into its 3-D functional shape. Primary Secondary Tertiary Quaternary

Primary Sequence of amino acids in the polypeptide chain. Many different sequences are possible with 20 AAs.

Secondary 3-D structure formed by hydrogen bonding between parts of the peptide backbone. Two main structures:  helix pleated sheets

Tertiary Bonding between the R groups. Examples: hydrophobic interactions Hydrogen bonding ionic bonding Disulfide bridges (covalent bond)

Quaternary When two or more polypeptides unite to form a functional protein. Example: hemoglobin

Is Protein Structure Important?

Denaturing Of A Protein Events that cause a protein to lose structure (and function). Example: pH shifts (confuses chemical interactions) high salt concentrations (confuses chemical interactions) heat (usually renders proteins inactive)

Denaturing, cont. Ex: white of an egg turns “white” (denatured protein due to heat) Ex: why extreme temps are so deadly to people/animals

Nucleic Acids Informational polymers Pass genetic info from parent to offspring Made of C,H,O,N and P No general formula Examples: DNA and RNA

Nucleic Acids Polymers of nucleotides Called polynucleotides Nucleotides have three parts: nitrogenous base pentose sugar phosphate

Nitrogenous Bases Rings of C and N The N atoms tend to take up H + (base)-b/c of neg charge Two types: Pyrimidines (single ring)-C,T,U Purines (double rings)-A,G

Pentose Sugar 5-C sugar Ribose - RNA Deoxyribose – DNA RNA and DNA differ in an –OH group on the 3 rd carbon

DNA Deoxyribonucleic Acid Makes up genes Genetic information source for most life Found inside nucleus Copied during cell cycle (Interphase)

RNA Ribonucleic Acid. Structure and protein synthesis. Genetic information for a few viruses only. Found in Nucleus and near ribosomes in cytoplasm Three types Messenger (m) Ribosomal (r) Transfer (t) Contains: Uracil

MacromoleculeMonomerPolymer CarbohydrateMonosaccharideDisacc, Oligio, Polysacc ProteinAmino acidPolypeptide chain Nucleic acidNucleotide DNA, RNA (Polynucleotide) LipidsFatty acid, glycerolFats, waxes, oils, steroids

Summary Recognize how dehydration synthesis can be used to build polymers from monomers. Recognize how hydrolysis can be used to break down polymers into monomers. Identify the elemental composition, general formula, types and uses of carbohydrates. Identify the elemental composition, types and uses of lipids. Identify the elemental composition, levels of structure and uses of proteins. Identify the elemental composition and general uses of nucleic acids.