BiochemistryMacromolecules and Enzymes

Unit 02

Organic Compounds

● Compounds that contain CARBON are called organic.

What is Carbon?● Carbon has 4 electrons in outer shell.

● Carbon can form covalent bonds with as many as 4 other atoms (elements).

● Usually with C, H, O or N.

● Example: CH4(methane)

Macromolecules

● Macromolecules are large organic molecules.

Macromolecules, con’t. ● Large organic molecules.

● Also called POLYMERS.

● Made up of smaller “building blocks” called MONOMERS.

● Examples:

1. Carbohydrates

2. Lipids

3. Proteins

4. Nucleic acids (DNA and RNA)

How are macromolecules

formed?

Answer: Dehydration Synthesis● Also called

“condensation reaction”

● Forms polymers by combining monomers by “removing water”

How are macromolecules

separated or digested?

Answer: Hydrolysis● Separates

monomers by “adding water”

Carbohydrates

Carbohydrates● Carbohydrates include small sugar

molecules to large sugar molecules.

● Examples:

A. monosaccharide

B. disaccharide

C. polysaccharide

Carbohydrates: MonosaccharidesMonosaccharide:

one sugar unit1C: 2H: 1H ratio

Examples:Glucose (C6H12O6)

Deoxyribose

Ribose

Fructose

Galactose

Carbohydrates: DisaccharidesDisaccharide: ● two sugar unit

Examples:

● Sucrose (glucose+fructose)

● Lactose (glucose+galactose)

● Maltose (glucose+glucose)

Carbohydrates: PolysaccharidesPolysaccharide: - many sugar units

Examples:- starch (bread, potatoes)

● glycogen (stored in liver)

● cellulose (lettuce, corn)

Function of CarbohydratesCarbohydrates● Quick source of energy

● Energy storage

● Structure (cellulose)

Carbohydrates: Energy SourceEnergy Source● Main source of energy for most organisms

● Cells utilize glucose for energy● Breaking of C-C bonds releases a lot of

energy ● Sugars have 5 C-C bonds per glucose

molecule

Carbohydrates: Energy SourceEnergy Source● Plants produce glucose through photosynthesis

● Animals obtain glucose from plants ● Human digestive system breaks down carbohydrates to

simple sugars● Small intestine absorbs simple sugars and blood transports

them to cells● Cells use glucose to form ATP (Cellular Respiration)

Carbohydrates: Energy StorageEnergy Storage● Animals

● Extra glucose is stored as glycogen

● Liver and muscle cells

● Plants● Stored as starch

Carbohydrates: StructureStructural Unit

● Cellulose is made up of glucose molecules

● Makes up cell walls of plants

● Uses

● Support plants

● Important in animal diets by helping digestive tract work smoothly

● Fun Fact

● Animals lack the enzyme to digest cellulose

● Some animals have a symbiotic relationship with a microorganism that can digest cellulose

Lipids

Lipids● Lipids

● Compounds which are not soluble in water.● “Stores the most energy”

● Examples:

● Fats/Oils

● Phospholipids

● Steroids

Lipids: Fats/OilsStructure of Fat/Oil

● Composed of 1 glyceroland 3 fatty acids.

Fatty acids are insoluble.

Lipids: Fats/OilsSaturated Fats

● All single bonds

● Solids

● Animal Fat

Unsaturated Fats

● 1+ double bond(s)

● Liquids

● Fish and Plant Oils

Lipid: Phospholipid● Phosphate Head:

● Polar

● Hydrophilic (attracted to

water)

● Two Fatty Acid Tails:

● Nonpolar

● Hydrophobic (avoids water)

● Two Layers

● Outsides: Polar Heads

● Inside: Nonpolar Tails

Cell Membrane Structure●Lipid Bilayer: a

double layer of

phospholipids that

make up the cell

membrane

Other lipids● Lipids

● Fatty acids

● Fats and waxes

● Steroids

● Cholesterol

● Testosterone

● Phospholipids

Lipids: FunctionsFunctions of lipids

● Long term energy storage

● Protection against heat loss (insulation)

● Protection against water loss

● Cutin (waxy coating on leaf) prevents water loss

● Chemical messengers (hormones)

● Major component of membranes (phospholipids)

Nucleic Acids

Nucleic AcidsNucleic acids are composed of long chains of nucleotideslinked by dehydration synthesis.

31

Nucleic acids• Nucleotides include

Phosphate groupPentose sugar (5-carbon)Nitrogenous bases

Adenine (A)Cytosine (C)Guanine (G)Thymine (T) DNA onlyUracil (U) RNA only

Nucleic Acids● Two types

● Deoxyribonucleic acid● DNA● Sugar: Deoxyribose● Double helix

● Ribonucleic acid ● RNA● Sugar: Ribose● Single strand

33

DNA - double helix

P

P

P

O

O

O

1

23

4

5

5

3

3

5

P

P

PO

O

O

1

2 3

4

5

5

3

5

3

G C

T A

Function of Nucleic AcidsNucleic Acids● Stores and transmit information in the form of

a code

● Passes this information from one generation to the next

Proteins

ProteinsFour levels of protein structure:

A.Primary Structure

B.Secondary Structure

C.Tertiary Structure

D.Quaternary Structure

Proteins● Primary Structure● Amino acids

(20 different kinds)● Bound together by

peptide bonds● Straight chains

Proteins● Secondary Structure● 3-dimensional folding

arrangement of a primary structure held together by hydrogen bonds.● Alpha Helix: Coils

● Beta Pleated Sheets: Folds

Proteins● Tertiary Structure● Structures bent and

folded into a more complex 3-D arrangement of linked polypeptides

● Bonds: H-bonds, ionic, disulfide bridges (S-S)

● Call a “subunit”

Proteins● Quaternary Structure● Composed of 2 or more

“subunits”

● Globular in shape

● Form in aqueous environments

● Example: enzymes (hemoglobin)

Proteins: FunctionsShape of protein determines its functionFunctions of Proteins● Storage: albumin (egg white)

● Transport: hemoglobin

● Regulatory: hormones

● Movement: muscles

● Structural:membranes, hair, nails

● Enzymes: cellular reactions

Proteins: Fun Facts●Essential Amino Acids: 8 of the 20 AA must be

obtained from diet because humans cannot make

them

●Different organisms need different amino acids● Domestic cats must eat taurine, however humans

can produce it.

ENZYMES

◼Most enzymes are proteins

◼Act as a catalyst to speed up a chemical reaction

by helping molecules react with each other faster

WHAT IS AN ENZYME?

◼Reusable!

◼Specific for what they catalyze (speed up)

▪ End in “-ase”

▪ Named for the reaction they help. For example…

▪ Sucrase breaks down sucrose

▪ Proteases break down proteins

▪ Lipases break down lipids

▪ DNA polymerase builds DNA

ENZYMES ARE…

◼Lactase breaks down lactose, a common component of dairy products (like milk)

◼People lacking the enzyme lactase are considered “lactose intolerant”-they can’t digest large amounts of milk!!

CASE STUDY: LACTOSE INTOLERANCE

◼Re-used again for the same reaction with other

molecules

◼Very little enzyme is needed to help in many

reactions!

ENZYMES ARE NOT USED UP!

Product

s

Substrat

e

Active

Site

Enzym

e

◼Remember, enzymes are specific!

◼Lock and Key Model: Shape of

enzyme allows substrate to fit

▪ Specific enzyme for each

specific reaction

LOCK AND KEY MODEL

Chemical

ReactionEnzyme + Substrate → Enzyme +

Product

REACTANTS

◼Enzymes work by weakening bonds, which lowers

ACTIVATION ENERGY

▪ Activation Energy=energy needed for the chemical

reaction to occur (energy needed to activate!)

▪ By lowering the activation energy, the reaction can occur

faster!

SO…HOW DO ENZYMES WORK?

Reactions can occur without

the help…but not at the

speed our bodies need!

◼Temperature

▪ High temperatures can cause enzymes to denature (unfold and lose shape), while low temperatures slow molecules down

◼pH

▪ Changes in pH changes protein shape (most human proteins sit at a pH of 6-8)

◼Denaturing=extreme temperature and pH can change enzyme shape, rendering it useless!

WHAT EFFECTS ENZYME ACTIVITY?

◼Every reaction in your body is helped by an

enzyme. They are necessary for all biological

reactions!

◼Video

WHY ARE ENZYMES IMPORTANT?