Your Homework Review the following slides and record information that is unfamiliar to you as well as questions you have. The expectation is that you have learned Biomolecules in Biology and read chapter 2. We will not be spending a lot of time in class on this topic.

You Must Know The role of dehydration synthesis and hydrolysis How to recognize the 4 organic compounds (carbs, lipids, proteins, nucleic acids) by structural formulas. The cellular functions of all four organic compounds. The 4 structural levels of proteins Protein denaturing and range of activity of enzymes

Dehydration Synthesis (Condensation Reaction) Hydrolysis Make polymers Breakdown polymers Monomers  Polymers Polymers  Monomers A + B  AB AB  A + B + H2O + + H2O +

Categories, functions and examples Biomolecule type Monomers Categories, functions and examples Carbohydrates Proteins Nucleic Acids Lipids

Carbohydrates Energy and Structure Monomers – CH2O (ratio of 1C:2H:1O) Monomers – C6H12O6 (monosaccharides) - used as energy source (glucose, fructose, galactose) Dimers – C12H22O11 (disaccharides) – also energy source (sucrose, lactose, maltose) Polymers – CH2O taken many times = Cn(H20)(n-1) – these are storage and structural

Carbohydrates Monosaccharides = monomers (eg. glucose, ribose) Polysaccharides: Storage (plants-starch, animals-glycogen) Structure (plant-cellulose, arthropod-chitin)

The structure and classification of some monosaccharides

Linear and ring forms of glucose

Carbohydrate synthesis

Cellulose vs. Starch Two Forms of Glucose:  glucose &  glucose

Cellulose vs. Starch Starch =  glucose monomers Cellulose =  glucose monomers

Storage polysaccharides of plants (starch) and animals (glycogen)

Structural polysaccharides: cellulose & chitin (exoskeleton)

Proteins “Proteios” = first or primary 50% dry weight of cells Contains: C, H, O, N, S Myoglobin protein

Protein Functions (+ examples) Enzymes (lactase) Defense (antibodies) Storage (milk protein = casein) Transport (hemoglobin) Hormones (insulin) Receptors Movement (motor proteins) Structure (keratin)

Overview of protein functions

Overview of protein functions

Four Levels of Protein Structure Primary Amino acid (AA) sequence 20 different AA’s peptide bonds link AA’s

Amino Acid R group = side chains “amino” : -NH2 “acid” : -COOH Properties: hydrophobic hydrophilic ionic (acids & bases) “amino” : -NH2 “acid” : -COOH

Four Levels of Protein Structure (continued) Secondary Gains 3-D shape (folds, coils) by H-bonding Alpha (α) helix, Beta (β) pleated sheet

Basic Principles of Protein Folding Hydrophobic AA buried in interior of protein (hydrophobic interactions) Hydrophilic AA exposed on surface of protein (hydrogen bonds) Acidic + Basic AA form salt bridges (ionic bonds). Cysteines can form disulfide bonds.

Four Levels of Protein Structure (continued) Tertiary Bonding between side chains (R groups) of amino acids H bonds, ionic bonds, disulfide bridges, van der Waals interactions

Four Levels of Protein Structure (continued) Quaternary 2+ polypeptides bond together

amino acids  polypeptides  protein Bonding (ionic & H) can create asymmetrical attractions

Chaperonins assist in proper folding of proteins

Protein structure and function are sensitive to chemical and physical conditions Unfolds or denatures if pH and temperature are not optimal

change in structure = change in function

Function: store hereditary info II. Nucleic Acids Function: store hereditary info DNA RNA Double-stranded helix N-bases: A, G, C, Thymine Stores hereditary info Longer/larger Sugar: deoxyribose Single-stranded N-bases: A, G, C, Uracil Carry info from DNA to ribosomes tRNA, rRNA, mRNA, RNAi Sugar: ribose

Nucleotides: monomer of DNA/RNA Nucleotide = Sugar + Phosphate + Nitrogen Base

Nucleotide phosphate A – T Nitrogen G – C base 5-C sugar Purines Pyrimidines Adenine Guanine Cytosine Thymine (DNA) Uracil (RNA) Double ring Single ring 5-C sugar

Information flow in a cell: DNA  RNA  protein

II. Lipids Fats (triglyceride): store energy Glycerol + 3 Fatty Acids saturated, unsaturated, polyunsaturated Steroids: cholesterol and hormones Phospholipids: lipid bilayer of cell membrane hydrophilic head, hydrophobic tails Hydrophilic head Hydrophobic tail

Have some C=C, result in kinks Saturated Unsaturated Polyunsaturated “saturated” with H Have some C=C, result in kinks In animals In plants Solid at room temp. Liquid at room temp. Eg. butter, lard Eg. corn oil, olive oil

Cholesterol, a steroid

The structure of a phospholipid

Hydrophobic/hydrophilic interactions make a phospholipid bilayer

Wednesday’s Lecture Starts Here

Catalyst: substance that can change the rate of a reaction without being altered in the process Enzyme = biological catalyst Speeds up metabolic reactions by lowering the activation energy (energy needed to start reaction)

SUBSTRATE SPECIFICITY OF ENZYMES The reactant that an enzyme acts on is called the enzyme’s substrate The enzyme binds to its substrate, forming an enzyme-substrate complex The active site is the region on the enzyme where the substrate binds

INDUCED FIT: ENZYME FITS SNUGLY AROUND SUBSTRATE -- “CLASPING HANDSHAKE”

An enzyme’s activity can be affected by: temperature pH chemicals

COFACTORS Cofactors are nonprotein enzyme helpers such as minerals (eg. Zn, Fe, Cu) Coenzymes are organic cofactors (eg. vitamins) Enzyme Inhibitors Competitive inhibitor: binds to the active site of an enzyme, competes with substrate Noncompetitive inhibitor: binds to another part of an enzyme  enzyme changes shape  active site is nonfunctional

INHIBITION OF ENZYME ACTIVITY

REGULATION OF ENZYME ACTIVITY To regulate metabolic pathways, the cell switches on/off the genes that encode specific enzymes Allosteric regulation: protein’s function at one site is affected by binding of a regulatory molecule to a separate site (allosteric site) Activator – stabilizes active site Inhibitor – stabilizes inactive form Cooperativity – one substrate triggers shape change in other active sites  increase catalytic activity