HISTORY OF CHEMISTRYWhere does gold come from?

The Elements: Forged in Stars

MILLER AND UREY’S EXPERIMENT

• 1953 - Stanley Miller and Harold Urey performed a set of experiments that simulated the environment of early Earth

• Their results showed that certain amino acids and other organic molecules could form spontaneously under those conditions.

Mixture of gases simulatingatmospheres of early Earth

Spark simulating lightning storms

Condensation chamber

Cold water cools chamber, causing droplets to formWater

vapor

Liquid containing amino acids and other organic compounds

MILLER AND UREY’SEXPERIMENT

• Why did Miller & Urey use a mixture of nitrogen, hydrogen, methane and ammonia in their apparatus?

• Mixture of gases resembles Earths early atmosphere

• Why was it necessary to perform their experiment in a sterilized, closed system?

• To prevent oxygen from entering, because Earths atmosphere had no oxygen, and to prevent contamination by modern bacteria/fungi

MILLER AND UREY’S EXPERIMENT• Why did they boil water to

produce water vapor?

• Water vapor was present in a early atmosphere

• Does the Miller-Urey experiment show what actually happened on early Earth?

• No, it is only a model showing how simple compounds could have combined to form the organic compounds needed for life

STRUCTURE AND FUNCTION OFMACROMOLECULESChapter 5

TYPES OF MACROMOLECULESOrganic compounds in living cells are:

macromolecules/polymers - made from thousands/hundreds of thousands of smaller molecules

¢ Carbohydrates• Starch,sugars

¢ Lipids(fats)• Waxes,oils

¢ Proteins• Enzymes,somehormones,hemoglobin

¢ NucleicAcids• Deoxyribonucleicacid(DNA)• Ribonucleicacid(RNA)

FORMATION OF MACROMOLECULES

¢ Made by joining together smaller subunits to make a long repeating chain

¢ Monomers à Subunits that serve as building blocks of a polymer (links)� “Mono” = one

¢ Polymers à Large molecule made up of monomers linked together (chain) � “Poly” = many

monomer + monomer + monomer + monomer + monomer + monomer à polymer

MOST MACROMOLECULES ARE POLYMERSBUILT FROM MONOMERS

• The chemical mechanisms that cells use to make and break polymers are similar for all classes of macromolecules.

• Condensation reaction or dehydration reaction = Monomers connected by covalent bonds that form through the loss of a water molecule.

• The covalent bonds connecting monomers in a polymer are disassembled by hydrolysis, a reaction that is effectively the reverse of dehydration.

HYD

ROLY

SIS

DEH

YDRA

TIO

N

DEHYDRATION SYNTHESIS

• One monomer gives a hydroxyl group(-OH) • Other monomer provides a hydrogen (-H).• Uses energy• Aided by enzymes.• Body cells use dehydration reaction to assemble

monomers into polymers that carry out functions specific to particular cell type.

HYDROLYSIS

¢ Bonds are broken by the addition of water molecules.

¢ Literally: Water Breaks¢ Hydrogen atom attaches to one monomer¢ Hydroxyl group attaches to the adjacent

monomer.¢ Hydrolysis reactions are involved in digestion of

food

CARBOHYDRATES ¢ Carbohydrates –

macromolecule that consists of carbon, hydrogen, and oxygen (C, H, O)

¢ FUNCTION: main source of energy� The breakdown of sugars,

such as glucose, supplies quick energy for cell activities

� Plants: use carbs for structural purposes

TYPE OF CARBOHYDRATE: MONOSACCHARIDES - SIMPLE SUGARS

¢Monosaccharides –single sugar molecules

¢ Glucose – sugar found in your blood C6H12O6

¢ Fructose - in fruits ¢ Sucrose – ordinary table

sugar = glucose + fructose¢ molecular formulas that are

some multiple of the unit CH2O

MO

NO

SACC

HAR

IDES

TYPE OF CARBOHYDRATE:POLYSACCHARIDES – COMPLEX CARBOHYDRATES

¢ Polysaccharides – a large macromolecule formed from monosaccharides

¢ Glycogen– animals store excess sugar� When the level of glucose in your

blood runs low, glycogen is broken down into glucose, which is then released into the blood.

¢ Starch- plants store excess sugar¢ Cellulose – plant structure¢ Chitin – fungi and arthropods

+REVIEW:WHAT IS THE MONOMER OF CARBOHYDRATECALLED?

WHAT IS THE POLYMER OF CARBOHYDRATECALLED?

WHAT IS THE FUNCTION OF CARBOHYDRATES?

LIPIDS – OILS, WAXES, FATLipids – macromolecule that consists of C, H,O

� Not soluble in water� Fatty Acid - the lipid building block monomer� Lipid - polymer

FUNCTIONS:¢ Energy source/storage¢ Making cell membranes ¢ Steroids – structure, communication, immune

system

TRIGLYCERIDES

• Saturated fatty acid = saturated with hydrogens at every possible position. No carbon-carbon double bonds

• Most animal fats are saturated.• Saturated fats are solid at room temperature.

• Unsaturated fatty acid = one or more carbon-carbon double bonds formed by the removal of hydrogen atoms from the carbon skeleton

• Plant and fish fats are liquid at room temperature• The kinks caused by the double bonds prevent the

molecules from packing tightly enough to solidify at room temperature.

FUNCTIONS OF FATS

¢ Long term energy storage¢ A gram of fat stores more than twice as much energy

as a gram of a polysaccharide such as starch.¢ Humans and other mammals store fats as long-term

energy reserves in adipose cells that swell and shrink as fat is deposited or withdrawn from storage.

¢ Insulation¢ Adipose tissue also functions to cushion vital

organs, such as the kidneys.

PHOSPHOLIPIDS

¢ Phospholipids are major components of cell membranes

¢ Phospholipids have two fatty acids attached to glycerol and a phosphate group at the third position.

¢ The fatty acid tails are hydrophobic, but the phosphate group and its attachments form a hydrophilic head.

PHOSPHOLIPIDS

STEROIDS¢ Steroids include cholesterol and certain hormones.

¢ Steroids are lipids with a carbon skeleton consisting of four fused rings.

¢ Cholesterol, an important steroid, is a component in animal cell membranes

¢ Cholesterol is also the precursor from which all other steroids are synthesized.

¢ Many of these other steroids are hormones, including the vertebrate sex hormones

+

REVIEW:WHAT IS THE MONOMER OF LIPID CALLED?

WHAT IS THE POLYMER OF LIPID CALLED?

WHAT IS THE FUNCTION OF A LIPID?

PROTEIN (ALSO CALLED POLYPEPTIDE)

¢ FUNCTIONS:¢ regulate cell processes/cell

signaling¢ form cell structures¢ Structural support/movement¢ Storage¢ transport substances into or out

of cells ¢ fight disease¢ ENZYMES

Proteins – macromolecule consists of C, H, O, N §Amino acid – protein building block (monomer)

- Two aminoacids=dipeptide- Many aminoacids=polypeptide(polymer)

PROTEIN FUNCTIONS

¢ Structural Proteins� Keratin (hair and

horns)� Collagen (connective

tissues)� Silk in spider webs

¢ Storage Proteins� Casein in milk� Ovalbumin in egg

whites� Zein in corn seeds

¢ Transport Proteins� In cell membranes� Hemoglobin

¢ Defense Proteins� Antibodies

¢ Enzymes� Regulate rate of

reactions

PROTEIN STRUCTURE

¢ Proteins are the most structurally complex molecules known.� Each type of protein has a

complex three-dimensional shape or conformation.

¢ All protein polymers are constructed from the same set of 20 amino acid monomers.� Polymers of proteins are called

polypeptides.� A protein consists of one or more

polypeptides folded and coiled into a specific conformation.

AMINO ACIDS ARE THE MONOMERS OF PROTEINS¢ Amino acids are organic

molecules with both carboxyl and amino groups

¢ Alpha carbon in center� Four components are attached

to the alpha carbon: a hydrogen atom, a carboxyl group, an amino group, and a variable R group (or side chain).

� physical and chemical properties of the R group determine the unique characteristics of a particular amino acid

POLYPEPTIDE FORMATION¢ Amino acids are joined

with a dehydration reaction � removes a hydroxyl

group from the carboxyl end of one amino acid

� Removes hydrogen from the amino group of another

� Peptide bond

AMINO ACIDS: FORMATION OF PROTEIN

• Peptide bonds (covalent) hold amino acids together

+

REVIEW:WHAT IS THE MONOMER OF A PROTEIN CALLED?

WHAT IS THE POLYMER OF A PROTEIN CALLED?

WHAT IS THE FUNCTION OF A PROTEIN?

PROTEIN CONFORMATION DETERMINESPROTEIN FUNCTION¢ A proteins shape is reinforced by a variety of bonds

between parts of the chain� These depend on the sequence of amino acids.

¢ Proteins can be globular or fibrous in shape.

LEVELS

OF

PRO

TEINS

TRUCTU

RE

PR

IMA

RY

STR

UC

TUR

E

unique sequence of amino acids

SE

CO

ND

AR

YS

TRU

CTU

RE

coils and folds along polypeptide chain caused by hydrogen bonds

TE

RTIA

RY

STR

UC

TUR

E

determined by interactions among various R group

QU

ATE

RN

AR

Y STRU

CTU

RE

interaction of two or more polypeptide chains.

PROTEIN SHAPE MAY BE INFLUENCED BYENVIRONMENTAL FACTORS¢ Alterations in pH, salt concentration, temperature, or

other factors can unravel or denature a protein.¢ Disrupt the hydrogen bonds, ionic bonds, and disulfide bridges

that maintain the protein’s shape.

¢ Also caused by heat� disrupts the weak interactions that stabilize conformation.