Biochemistry Notes:Macromolecules

Organic vs. Inorganic Molecules

Organic Molecules◦ALWAYS contain carbon and have C to

H bonds and are found in living organisms

◦Also typically contain H, O, N, P, S◦Examples: nucleic acids, fats, sugars,

proteins, enzymes, and many fuelsInorganic Molecules

◦Sometimes contain carbon, but not C-H bonds

◦Examples: NaCl (salt), CO2, diamonds (pure carbon)

Properties of CarbonCarbon has 4 valence electrons (on outermost level)

Carbon will form 4 covalent bonds with many elements (HONPS) and with other carbon atoms

Can form single, double, or triple bonds

Properties of CarbonIt can form chains of unlimited

length, branched molecules, or rings

MacromoleculesMacro - Large (Molecules)

Macromolecules are formed when monomers are linked

together to form longer chains called polymers.

Four major types of Macromolecules

Macromolecule(Polymer) Monomer

Carbohydrates (Polysaccharide)

Monosaccharide

Proteins Amino Acids

Lipids diff.types – triglyceride, phospholipid and steroid, cholesterol

Fatty acids & glycerol make up a triglyceride (most common lipid)

Nucleic Acids Nucleotides

Dehydration Reaction (aka Condensation Reactions)

Monomers can be linked together by a process called dehydration synthesis ◦ (dehydrate – take out a

water molecule. synthesis- to make)

In dehydration synthesis, ◦1)a covalent bond

forms between the two monomers

◦2)a water molecule is also formed from the removal of –OH and –H from 2 different carbon atoms

Hydrolysis ReactionsPolymers can be

broken apart by hydrolysis reactions.

In hydrolysis, the addition of a water molecule breaks the covalent bond between monomers, separating the monomers, adding an –OH group to one and a –H group to another.

Carbohydrate StructureCarbohydrates are always

composed of carbon, hydrogen and oxygen molecules in a 1:2:1 ratio (ex: glucose = C6H12O6)

MonosaccharidesMonosaccharides typically have five

or six carbon atoms and function on their own ◦Glucose : found in plants- main source of

cellular energy (absorbed directly into the bloodstream)

◦ fructose: found in fruit- source of energy (absorbed directly into the bloodstream)

◦Both are C6H12O6 in different arrangements

DisaccharidesDisaccharides – 2

monosaccharides joined ◦Sucrose (table sugar)= comes from

beets, sugar cane- used for energy ◦Lactose= found in milk- used to give

energy to young nursing organisms or those who drink milk

◦Both sucrose and lactose have a chemical formula of C12H22O11

Carbohydrate StructurePolysaccharides- many

monosaccharides put together (ex: Starch, Glycogen, and Cellulose)

Polysaccharides play various roles from energy storage in Starch for plants and Glycogen for animals- to structural support in Cellulose for plants.

Dehydration in Carbohydrates

-OH of one monomer and the –H of another monomer are released (forming H20) and a disaccharide forms

What would hydrolysis look like?

Hydrolysis ReactionDisaccharide (Maltose) has water

(H20) added to it.-OH from water is added to one monomer and the –H of water is added to the other monomer to break the disaccharide.

Carbohydrate FunctionCarbohydrates are the main source of

energyPolysaccharides play various roles from

energy storage (starch: plants and glycogen: animals) to structure (cellulose in plants).

Food for thought: Why eat pasta dinner the night before the big game and a glucose packet during a marathon?

Lipids

Lipids are a very diverse group of molecules that are all hydrophobic and nonpolar ( do not interact with water= repel water).

Made mostly of C and H

Many lipids have fatty acids that can be saturated or unsaturated

Saturated: absence of double bonded carbon atoms which results in the lipid being solid at room temperature (like butter)Unsaturated: presence of double bonded carbon atoms which results in the lipid being liquid at room temperature (like oil)

Saturated and Unsaturated Fats

Lipid Functions

protection of all cells (phospholipids of the cell membrane)

chemical signaling (steroids and hormones).◦Cholesterol (most common type of steroid)-Provides

rigidity to cell membrane and precursors to steroid compounds

Lipids are used for long term energy storage (body fat) and water proofing and insulation of organs/body – Triglycerides (cutin, suberin, waxes)

Types of lipidsName of lipid and basic components

Basic Structure

Triglyceride: 1 glycerol and 3 fatty acid tails

Phospholipid: 1 hydrophilic/polar phosphate head and 2 hydrophobic fatty acids tails

Steroid (cholesterol): 3 hexagons and 1 pentagon all connected (4 rings) and a functional group (tail)

What kind of Fatty Acids are contained in the following lipids?

A

B

C

Saturated Fatty Acids

Saturated Fatty Acids

Unsaturated Fatty Acids

Saturated Fatty Acids

Dehydration in a Triglyceride

-OH of the fatty acid and the –H of glycerol are released (forming H20) and a triglyceride forms

•What would hydrolysis look like?

Dehydration/Condensation Continued…

Hydrolysis in Triglycerides

Protein StructureProteins are made by linking

amino acids (monomers) together using peptide bonds to make a polypeptide chain (polymer)

Dipeptides are 2 amino acids joined together

All proteins are made from the same 20 amino acids (all amino acids have –NH2 and –COOH), each with different chemical properties.

Peptide bonds form as a result of a dehydration reaction between the –NH2 of one amino acid and the –COOH of another amino acid (releasing H2O).

Protein Structure

Dehydration in Proteins

-OH of one amino acid and the –H of another amino acid are released (forming H20) and a peptide bond forms

What would hydrolysis look like?

Protein Function

Regulate cell processes, form bone and muscle, move substances in or out of cells, and are part of the immune system

Proteins can act as enzymes – biological catalysts for very specific chemical reactions inside cells/organisms.

EnzymesActivation energy: energy required to

start a chemical reactionEnzymes are catalysts which lower the

activation energy, thus speeding up reactions that would otherwise not occur

You have a huge amount of enzymes in your body!◦Ex: lactase in your digestive systems breaks

down lactose in dairy◦Anytime you see an “ase” word, think

ENZYME!

Activation Energy

Lock and KeyEach enzyme is used for a specific

reaction because the enzyme has a specific active site

Substrate is the molecule on which enzymes act

A lock (enzyme) and a key (substrate) = Enzyme-Substrate Complex

While attached to the substrate, the enzyme causes a weakening of certain chemical bonds in the substrate molecule, resulting in a breakdown (hydrolysis) of the substrate into two smaller products.

Example: If the substrate was a disaccharide then the products may be 2 monosaccharides

Enzymes

The enzyme is unaltered during the reaction and is free to catalyze the breakdown of another substrate molecule.

Nucleic AcidsDNA –

deoxyribonucleic acid◦ “D” is for

deoxyribose

RNA – ribonucleic acid◦ “R” is for ribose

Nucleotide StructureMonomer of a nucleic acid =

Nucleotides ◦A nucleotide is made of:

1) a 5-carbon sugar2) a phosphate3) a nitrogen base

Guanine Cytosine Adenine Thymine (only in DNA) Uracil (only in RNA)

Nucleic Acid StructureDNA = Double

Helix (2 strands)◦5-C sugar

(deoxyribose) and phosphate alternate the sides of the “ladder”

◦Nitrogen bases connect by hydrogen bonds between the “ladder” like the rungs

RNA = one strand

Nucleic Acid FunctionNucleic acid function:

store/transmit genetic information of organisms

Dehydration in a Nucleic Acids

-OH of one nucleotide and the –H of another nucleotide are released (forming H20) and a nucleic acid forms

What would hydrolysis look like?

-OH

-H

H20