Macromolecules• Organic compounds– Contain both hydrogen and carbon

• Large molecules composed of smaller subunits– Carbohydrates– Proteins– Lipids– Nucleic Acids

Carbohydrates (Sugars)• Bio-molecule consisting of

carbon, oxygen, and hydrogen.

• General molecular formula (CnH₂nOn) (C₆H₁₂O₆)

• Roles– Energy storage - plants – Structural support in cells

and tissues • Hydrophilic • Pentose/Hexose ring

structure

Monosaccharides• Simplest type of

carbohydrate• Used as primary energy

source for cellular metabolism (making ATP)

• 1 sugar unit – Glucose – grape sugar,

blood sugar– Fructose – honey, fruit

juices

Monosaccharides• Most Common– 3 carbon (linear) – triose– 5 carbon – pentose ring– 6 carbon – hexose ring

• Why?– Folding into a ring

occurs through a reaction between carbonyl group and hydroxy l group

• Link together to form disaccharides

Glucose• Linear and ring structures• Hexose ring– Two possible arrangements

• α - glucose• Β – glucose

– Isomers – same molecular formula, different structural formula

• Carbon atoms have assigned numbers– Used when discussing structures of sugars

Linkages are designated α or β from the position of the –OH group on the 1 carbon

Disaccharides• Consist of two monosaccharides – Maltose – used to make beer – Sucrose – simple sugar found

in plant sap– Lactose – milk

• Used as energy sources and building blocks for larger molecules

• Joined together by a dehydration synthesis reaction

• Glycosidic bond – links monosaccharides together

• Common carbon linkages – 1 4 1 2– 1 3 1 6

Polysaccharides• Complex carbohydrate/polymer– Chain of hundreds to thousands of monosaccharides

(monomers) with many subunits– Unbranched – side chains – Branched – single chain

Polysaccharides• Assembled by dehydration reaction– Glycosidic linkage– Polymerization – linkage of identical or various monomers to

form long chains• Linear unbranched – hydrogen bonds form between molecules

• Polar • Hydrophilic• Non-soluble in water

Examples Amylose – soluble component of

starch α- glucose chains

Glycogen – energy storage in animals α- glucose chains

Cellulose – main component of plant cell walls β- glucose chains

Chitin – hard exoskeleton of insect and crustaceans

Lipids• Non-polar • Made up of mostly

carbon and hydrogen • Not polymers• Do not dissolve in water• Roles – Formation of cell

membranes – Energy source – Hormones – Vitamins

• 5 main categories – Fatty acids – Fats – Phospholipids – Steroids – Waxes

Fatty Acids• Derivative of most lipids

(structural backbone)• Consists of– Single hydrocarbon

chain (14 to 22)– Carboxyl functional

group at one end (-COOH)

– Gives the fatty acid its acidic properties

• As chain length increases, insolubility in water increases

Fatty Acids• Saturated – Max number of hydrogen

atoms attached to carbons– Single bonds throughout the

carbon chain– Solid at room temp

• Unsaturated– Formation of double bonds

in carbon chain– Monounsaturated – one

double bond– Polyunsaturated – many

double bonds– Causes a bent formation in

molecule – Liquid at room temp

Cis and Trans Fats• Presence of a double

bond (unsaturated)• Cis – Naturally occuring– Good for health– Forms kinks in carbon

chain• Trans– Artificially produced– Found in processed

foods– Raise bad cholesterol

(LDL) – Forms straight chains

Fats • Consists of

– 1 to 3 fatty acid chains– Glycerol

• Dehydration synthesis– Hydroxyl group of

glycerol and carboxyl group of fatty acid

• Can have identical/different fatty acid chains

• Hydrophobic• Ester linkage forms

between FA chain and glycerol

Triglycerides • Most well known fat• Contains 3 fatty acid chains• Stored energy (food) in fat cells • Liver produces triglycerides • Yield more than twice as much energy as carbohydrates• Normal blood level – less than 150 mg/dL

Phospholipids• Consists of– 2 fatty acid chains

(hydrophobic) – Glycerol – Phosphate group • contains a polar

unit (hydrophilic)

• Amphipathic – Contains both

hydrophobic and hydrophilic regions

Phospholipids• Roles– Lipid bilayer of cell

membranes – Hydrophilic end faces

toward water– Hydrophobic end

faces inward• Unsaturated tail

makes membrane more permeable to water and small molecules

Steroids

• Consists of – Four fused carbon ring– Side group

• Sterols– Most abundant – Consists of • Single polar –OH group • Non – polar hydrocarbon chain

– Amphipathic molecule– Eg; Cholesterol , Phytosterols

Cholesterol• Formed in the liver • Structural component of

plasma membrane (nearly half)

• Amphipathic• Function– Maintains integrity of

membrane– Proper membrane

permeability/fluidity

Cholesterol • Can’t dissolve in

blood• Transported by

carriers • Types

– LDL – low density lipoprotein

– Promote cardiovascular disease

– HDL – high density lipoprotein

– Good cholesterol– removes cholesterol

from artery– Eliminated in liver

Sex Hormones• Control development of sexual traits and sex cells – Eg; testosterone, estrogen, progesterone

Waxes• Consist of – Long fatty acid chains– Alcohol molecule or Carbon

ring• Hydrophobic• Extremely non-polar• Soft Solids• Functions– Waterproof coating on

various plant and animal parts

– Cutin – plants conserve water and fights disease

– Beeswax – production of honeycomb

Proteins• Polymer with many subunits• Composed of Amino Acids

(monomers)• Folded into a 3-D structure

– Primary Secondary– Tertiary Quaternary

• Folding allows protein to function

• Structure specifies function of protein

• Formed by dehydration reaction

• Peptide bonds link amino acids together

Amino Acids• 20 different amino acids– 8 essential - supplied by

diet• Contain:– Central carbon– Amino group (-NH₂)– Carboxyl group (-COOH)– R group

• R groups give each amino acids specific characteristics– Polarity, acidity

Amino Acids

Peptide Bond• Covalent bond between

(NH₂) group of one amino acid and (COOH) group of another.

• Amino acids are only added to the C-terminal of a growing peptide

• Peptide– String of 1-49 amino acids– Contains no side branches

• Polypeptide– String of 50 or more amino

acids

Proteins• Structural – framework support

(hair, tendon, ligaments)• Defensive – infection fighters

(antibodies)• Signal – messenger (hormones)• Carrier – transport of materials

(hemoglobin)• Recognition and Receptor –

cellular markers (major histocompatability complex)

• Enzyme – catalyst (amylase)• Motile – movement (actin and

myosin)

Protein Structure

• Primary Structure 1⁰– Linear sequence of amino acids in polypeptide chain– Changing one amino acid with change overall structure

of protein

Protein Structure • Secondary Structure • Polypeptides fold or coil

into patterns• Result of hydrogen

bonding– β-pleated sheets

• Side-by-side alignment• (Eg; strength of silk)

– α-helix • Coil that is held together by

hydrogen bonds between every 4th amino acid

• (Eg; filamentous proteins, transmembrane proteins)

Protein Structure• Tertiary Structure 3⁰• 3-D shape of a polypeptide chain• Intermolecular reactions of

amino acid R groups determines shape

• Include• Ionic bonds• Hydrogen bonds• Hydrophobic interactions

– Non-polar side groups cluster when introduced to water

• Disulfide bridges– Bond formed from two cysteine

amino acids (-SH group)– Stabilizes proteins shape

Protein Structure • Quaternary Structure 4⁰– Composed of 2 or more

polypeptides– Functional proteins– Forms subunits – Same bonds and forces

as tertiary structure

Protein Prosthetic Groups• Non-protein components– Metal ions (Fe²⁺ Mg²⁺)

• Needed for protein to function• Hemoglobin– 4 polypetide chains each with a

heme groups – Each group has s single iron ion

(Fe²⁺) – Oxygen binds to heme groups via

(Fe²⁺)– How many molecules of O₂ can

hemoglobin carry at one time?

Protein Denaturation• When a protein loses its 3-D structure• Often irreversible • Extreme temperatures• pH• Chemcials

Enzymes• 3-D biological catalyst• Protein • Used in reactions– Speeds up a chemical

reaction – Is not consumed – Does not change

products of the reaction– Lowers activation energy

of reaction• Energy required to start a

chemical reaction

• Eg. Catalase breaks down the build up of hydrogen peroxide in the body

Reactants →Products

Enzyme Cycle

Factors That Affect Enzyme Activity• Enzyme and substrate concentration– Increasing enzyme concentration increases rate of

reaction– Increasing substrate increases rate of reaction to a point

called saturation level

Factors That Affect Enzyme Activity

• Temperature– Increasing temperature increases rate of reaction

(collision between enzyme and substrate)– 40⁰C or higher - enzyme begins to denature

Factors That Affect Enzyme Activity• pH– Optimal enzyme pH is 7 (most)• Increasing or decreasing pH from optimal

value decreases rate of reaction

Enzyme Function• http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_enzymes_work.html

• http://www.youtube.com/watch?v=hoBhOdQV7vw&list=PLBAC6D002DBAE5224

• Binds substrate (reactant or reactants) at the active site (pocket in enzyme)– Forms an enzyme-substrate complex– Enzyme changes shape to better bind substrate• Induced-fit model

Cofactors and Coenzymes• Enzymes require them

to function properly– Cofactor• Non-protein group that

binds to an enzyme• Often metals (Fe²⁺ Cu²⁺)

– Coenzyme• Organic • Derived from water-

soluble vitamins• Shuttle molecules from

enzyme to another• Eg. NAD⁺

Enzyme Inhibition• Bind to an enzyme lowering the rate at which an

enzyme catalyzes a reaction • Occur at different locations on enzyme– Competitive– Non-competitive– Allosteric

Competitive Inhibition• Competes with

normal substrate to bind at the active site of enzyme

• Penicillin (bacterial cell walls)

• Protease Inhibitors (HIV)

Non-competitive Inhibition

• Sometimes irreversible • Binds to enzyme at a

location other than the active site

• Changes shape of enzyme (substrate cannot bind)

• Cyanide

Allosteric Inhibition/Activation • Regulates enzyme activity

via feedback• Helps maintain

homeostasis in cell • Increases or decreases

enzymatic activity depending on concentration of product (turn enzyme “on” or “off”)

• Use allosteric regulators– Inhibits or activates enzyme– Bind to enzyme at an

allosteric site – Can be competitive and

non-competitive

Nucleic Acids• Polynucleotide chains

serve as assembly instructions for all proteins in living organisms

• DNA – deoxyribonucleic acid– Stores hereditary

information• RNA – Ribonucleic acid

– Hereditary molecule of some viruses

– Involved in protein synthesis

• Composed of nucleotides • Linked by a

phosphodiester bond

Nucleotides• Consists of– Nitrogenous base

• Uracil (U), thymine (T), cytosine (C), adenine (A), guanine (G)

– Sugar– Phosphate groups

• Functions– Data storage– Energy currency (ATP)– Cellular communication (cAMP,

ATP)– Co-enzyme catalysis

Nitrogenous Bases• 2 types– Pyrimidines• Uracil (U), Thymine (T), Cytosine (C)

– Purines • Adenine (A), Guanine (G)

Phosphodiester Bond• Links nucleotides

together– Phosphate bridge forms

between the 5’ carbon of one sugar and the 3’ carbon of the next sugar.

– Forms the backbone of a nucleic acid chain

– Nitrogenous bases project from the backbone

DNA• Consists of – Deoxyribose sugar– Phosphate group– A, T, C, G

• Double stranded molecule (Double Helix)– Two strands of DNA run antiparallel to each

other (opposite direction)– 5’ to 3’ – 5’ is the end with the phosphate group– 3’ is where deoxyribose sugar is located

• Nitrogenous bases– Held together by hydrogen bonds– A pairs with T ( forms double bond)– C pairs with G (forms a triple bond) – A to T and C to G is known as

complementary base pairing

RNA• Consists of– Ribose sugar– Phosphate group – A, U, C, G

• Single stranded molecule• Converts information stored in DNA into proteins