Functional groupsFunctional groups

• Play pivotal role in chemical & physical properties of Play pivotal role in chemical & physical properties of organic molecules.organic molecules.

• Compounds that are made up solely of carbon and Compounds that are made up solely of carbon and hydrogen are not very reactive.hydrogen are not very reactive.

• Functional groupsFunctional groups:: One or more H atoms of the carbon skeleton may beOne or more H atoms of the carbon skeleton may be

replaced byreplaced by a a functionalfunctional group. group.

Groups of atoms that have unique chemical andGroups of atoms that have unique chemical and

physical properties.physical properties. Usually a part of molecule that isUsually a part of molecule that is chemically activechemically active..

Similar activity from one molecule to another. Similar activity from one molecule to another.

Together with size and shape, determine unique bonding Together with size and shape, determine unique bonding

and chemical activity of organic molecules.and chemical activity of organic molecules.

Structural PolysaccharidesStructural Polysaccharides::

Used as structural components of cells and tissues.Used as structural components of cells and tissues.

1. 1. CelluloseCellulose: Glucose polymer. : Glucose polymer.

The major component of plant cell walls. The major component of plant cell walls.

CANNOTCANNOT be digested by animal enzymes. be digested by animal enzymes.

Only microbes have enzymes to hydrolyze. Only microbes have enzymes to hydrolyze.

2. 2. ChitinChitin: Polymer of an amino sugar (with NH: Polymer of an amino sugar (with NH22 group) group)

Forms exoskeleton of arthropods (insects) Forms exoskeleton of arthropods (insects) Found in cell walls of some fungiFound in cell walls of some fungi

Cellulose: Polysaccharide Found in Plant and Algae Cell Walls

ProteinsProteins: :

• Large three-dimensional macromolecules Large three-dimensional macromolecules responsible for most cellular functions responsible for most cellular functions

Polypeptide chainsPolypeptide chains: : Polymers of amino acids linked byPolymers of amino acids linked by peptide bondspeptide bonds in a SPECIFIC linear sequencein a SPECIFIC linear sequence

ProteinProtein: : Macromolecule composed of Macromolecule composed of one or more one or more polypeptide chains folded into SPECIFIC 3-D polypeptide chains folded into SPECIFIC 3-D conformationsconformations

PolypeptidePolypeptide: :

Polymer of amino acids connected in Polymer of amino acids connected in a specific sequencea specific sequence

Amino acid Structure:Amino acid Structure:

Central carbon with: Central carbon with: H atom H atom

Carboxyl group Carboxyl group

Amino group Amino group

Variable R-groupVariable R-group

Amino Acid Structure: Amino Acid Structure:

H H

| |

(Amino Group)(Amino Group) NHNH22---C------C---COOH (Carboxyl group)COOH (Carboxyl group) | |

R R

(Varies for each amino acid)(Varies for each amino acid)

Amino Acids Have Both -NHAmino Acids Have Both -NH22 and -COOH Groups and -COOH Groups

Proteins have important and varied functions: Proteins have important and varied functions:

1.1. EnzymesEnzymes: : Catalysis of cellular reactions Catalysis of cellular reactions

2. 2. Structural ProteinsStructural Proteins: : Maintain cell shape Maintain cell shape

3. 3. TransportTransport: : Transport in cells/bodies (e.g. hemoglobin). Transport in cells/bodies (e.g. hemoglobin).

Channels and carriers across cell membrane. Channels and carriers across cell membrane.

4. 4. CommunicationCommunication: : Chemical messengers, hormones, and Chemical messengers, hormones, and

receptors. receptors.

5. 5. DefensiveDefensive: : Antibodies and other molecules that bind to Antibodies and other molecules that bind to

foreign molecules and help destroy them. foreign molecules and help destroy them.

6. 6. ContractileContractile: Muscular movement. : Muscular movement.

7. 7. StorageStorage: Store amino acids for later use (e.g. egg white). : Store amino acids for later use (e.g. egg white).

Protein functionProtein function is dependent upon its 3-D shape. is dependent upon its 3-D shape.

Protein Protein FunctionFunction is dependent upon Protein Structure is dependent upon Protein Structure (Conformation) (Conformation)

CONFORMATIONCONFORMATION: : The 3-D shape of a protein is determined by its The 3-D shape of a protein is determined by its amino amino acid sequence. acid sequence.

Four Levels of Protein StructureFour Levels of Protein Structure

1. 1. Primary structurePrimary structure: : Linear amino acid sequenceLinear amino acid sequence, , determined by determined by gene for that protein.gene for that protein.

2. 2. Secondary structureSecondary structure: : Regular coiling/folding of Regular coiling/folding of polypeptide. polypeptide.

Alpha helix or beta sheet. Alpha helix or beta sheet.

Caused by H-bonds between amino acids.Caused by H-bonds between amino acids.

3. 3. Tertiary structureTertiary structure:: Overall 3-D shape of a polypeptide chain. Overall 3-D shape of a polypeptide chain.

4. 4. Quaternary structureQuaternary structure: : Only in proteins with 2 or more Only in proteins with 2 or more polypeptides. Overall 3-D shape of all chains. polypeptides. Overall 3-D shape of all chains.

Example: Hemoglobin (2 alpha and 2 beta polypeptides)Example: Hemoglobin (2 alpha and 2 beta polypeptides)

Primary Structure of Protein: Amino Acid Sequence is Determined by Gene

Secondary Structure of Protein: Regular Folding Patterns (Alpha Helix or Pleated Sheet)

Protein Shape is determined by bonding between elementsProtein Shape is determined by bonding between elements

of different amino acids.of different amino acids.

There are 4 types of bonds that occur in proteins:There are 4 types of bonds that occur in proteins:

1.1. Ionic bondIonic bond

2.2. Disulphide bondDisulphide bond

3.3. HydrogenHydrogen

4.4. Hydrophobic interactionsHydrophobic interactions

Due to the functional groups attached to amino acidsDue to the functional groups attached to amino acids

Tertiary Structure: Overall 3-D Shape of Protein

Tertiary Structure of Lysozyme

Quaternary Structure: Overall 3-D Shape of Protein with 2 or More Subunits

What determines a protein’s shape? What determines a protein’s shape?

A. A. Primary structurePrimary structure: : Exact location of each amino Exact location of each amino

acid along the chain determines the protein’s acid along the chain determines the protein’s

folding pattern.folding pattern.

ExampleExample: : Sickle Cell Hemoglobin proteinSickle Cell Hemoglobin protein

Mutation changes amino acid #6 on the alpha chain.Mutation changes amino acid #6 on the alpha chain.

Defective hemoglobin causes red blood cells to assumeDefective hemoglobin causes red blood cells to assume

sickle shape, which damages tissue and capillaries. sickle shape, which damages tissue and capillaries.

Sickle cell anemia gene is carried in 10% of African Sickle cell anemia gene is carried in 10% of African

Americans.Americans.

What determines a protein’s shape? What determines a protein’s shape?

B. B. Chemical & Physical Environment:Chemical & Physical Environment:

Presence of other compounds, pH, temperature, salts.Presence of other compounds, pH, temperature, salts.

– Denaturation:Denaturation: Process which alters native conformation and Process which alters native conformation and

therefore biological activity of a protein. Several factors can therefore biological activity of a protein. Several factors can

denature proteins:denature proteins:

1.1. pH and saltspH and salts:: Disrupt hydrogen, ionic bondsDisrupt hydrogen, ionic bonds..

2.2. TemperatureTemperature:: Can disrupt weak interactionsCan disrupt weak interactions..

Example:Example: Function of an enzyme depends on pH, Function of an enzyme depends on pH,

temperature, and salt concentrationtemperature, and salt concentration. .

Nucleic acidsNucleic acids

Store and transmit hereditary information for all living Store and transmit hereditary information for all living thingsthings

There are two types of nucleic acids in living things: There are two types of nucleic acids in living things: A. A. Deoxyribonucleic Acid Deoxyribonucleic Acid (DNA)(DNA)

Contains genetic information of all living organisms. Contains genetic information of all living organisms.

Has segments called Has segments called genesgenes which provide information towhich provide information to

make each and every protein in a cell make each and every protein in a cell

Double-stranded molecule whichDouble-stranded molecule which replicates replicates each time a cell each time a cell

divides.divides.

B. B. Ribonucleic Acid Ribonucleic Acid (RNA)(RNA) Three main types called Three main types called mRNA, tRNA, rRNA mRNA, tRNA, rRNA

RNA molecules areRNA molecules are copiedcopied from DNA and used to make from DNA and used to make

gene products (proteins). gene products (proteins).

Usually exists in single-stranded form.Usually exists in single-stranded form.

DNA and RNADNA and RNA

are polymers of are polymers of nucleotidesnucleotides that determine the that determine the primary structure of proteins primary structure of proteins

NucleotideNucleotide:: Subunits of DNA or RNA. Subunits of DNA or RNA.

Nucleotides have three components: Nucleotides have three components:

1. Pentose sugar1. Pentose sugar ( (riboseribose or or deoxydeoxyriboseribose))

2. Phosphate group to link nucleotides (-PO2. Phosphate group to link nucleotides (-PO44) )

3.3. Nitrogenous baseNitrogenous base (A,G,C,T or (A,G,C,T or UU) )

Purines:Purines: Have 2 rings. Have 2 rings.

Adenine (A) and guanine (G) Adenine (A) and guanine (G)

PyrimidinesPyrimidines: Have one ring. : Have one ring.

Cytosine (C), thymine (T) in DNA or Cytosine (C), thymine (T) in DNA or uracil (U) in uracil (U) in

RNA.RNA.

James Watson and Francis Crick Determined the 3-James Watson and Francis Crick Determined the 3-D Shape of DNA in 1953 D Shape of DNA in 1953

Double helixDouble helix:: The DNA molecule is a double helix. The DNA molecule is a double helix.

AntiparallelAntiparallel: : The two DNA strands run in opposite The two DNA strands run in opposite directions. directions.

Strand 1: 5’ to 3’ direction (------------>) Strand 1: 5’ to 3’ direction (------------>)

Strand 2: 3’ to 5’ direction (<------------)Strand 2: 3’ to 5’ direction (<------------)

Complementary Base Pairing:Complementary Base Pairing: A & T (U) and G & C. A & T (U) and G & C. A on one strand hydrogen bonds to T (or U in RNA). A on one strand hydrogen bonds to T (or U in RNA).

G on one strand hydrogen bonds to C. G on one strand hydrogen bonds to C.

ReplicationReplication: : The double-stranded DNA molecule can The double-stranded DNA molecule can easily replicate based on easily replicate based on A=T and G=C pairing. A=T and G=C pairing.

--- ---

SEQUENCE of nucleotides in a DNA molecule dictate SEQUENCE of nucleotides in a DNA molecule dictate the amino acid SEQUENCE of polypeptidesthe amino acid SEQUENCE of polypeptides

DNA: Double Helix of Two Complementary Strands Held Together by H-Bonds

A GeneA Gene

• A specific segment of a DNA molecule with information for A specific segment of a DNA molecule with information for

cell to make one polypeptide.cell to make one polypeptide.

DNA DNA ((transcribedtranscribed into single stranded RNA “copy”) into single stranded RNA “copy”)

mRNAmRNA (single stranded “copy” of the gene) (single stranded “copy” of the gene)

PolypeptidePolypeptide (mRNA message (mRNA message translatedtranslated into polypeptide) into polypeptide)

Genetic Information Flow: DNA to RNA to Protein

LipidsLipids: :

Fats, phospholipids, and steroids Fats, phospholipids, and steroids

Diverse groups of compounds.Diverse groups of compounds.

Composition of Lipids:Composition of Lipids:

C, H, and small amounts of O. C, H, and small amounts of O.

Functions of Lipids: Functions of Lipids:

Biological fuels Biological fuels

Energy storage Energy storage

Insulation Insulation

Structural components of cell membranes Structural components of cell membranes

HormonesHormones

LipidsLipids: :

Fats, phospholipids, and steroids Fats, phospholipids, and steroids

1. Simple Lipids1. Simple Lipids: Contain C, H, and O only. : Contain C, H, and O only.

A. A. FatsFats (Triglycerides). (Triglycerides).

GlycerolGlycerol : : Three carbon molecule with three hydroxylsThree carbon molecule with three hydroxyls. .

Fatty AcidsFatty Acids: : Carboxyl group and long hydrocarbon Carboxyl group and long hydrocarbon chains.chains.

Characteristics of fats: Characteristics of fats:

Most abundant lipids in living organismsMost abundant lipids in living organisms. .

HydrophobicHydrophobic (insoluble in water) because nonpolar (insoluble in water) because nonpolar. .

Economical form of energy storage (provide 2X theEconomical form of energy storage (provide 2X the

energy/weight than carbohydrates).energy/weight than carbohydrates).

Greasy or oily appearance.Greasy or oily appearance.

Fats (Triglycerides): Glycerol + 3 Fatty Acids

LipidsLipids: :

Fats, phospholipids, and steroids Fats, phospholipids, and steroids

Types of Fats Types of Fats

Saturated fatsSaturated fats: : Hydrocarbons saturated with H. Hydrocarbons saturated with H.

Lack -C=C- double bonds. Lack -C=C- double bonds.

Solid Solid at room temp (butter, animal fat, lard)at room temp (butter, animal fat, lard)

Unsaturated fatsUnsaturated fats: : Contain -C=C- double bonds. Contain -C=C- double bonds.

Usually Usually liquidliquid at room temp (corn, peanut, olive oils) at room temp (corn, peanut, olive oils)

Saturated Fats Contain Saturated Fatty Acids

Complex Lipids:Complex Lipids:

PhospholipidsPhospholipidsIn addition to C, H, and O, also contain other elements, such In addition to C, H, and O, also contain other elements, such

as phosphorus, nitrogen, and sulfur. as phosphorus, nitrogen, and sulfur.

A.A. PhospholipidsPhospholipids: : Are composed of: Are composed of: Glycerol Glycerol

2 fatty acid 2 fatty acid

Phosphate groupPhosphate group

AmphipathicAmphipathic Molecule Molecule

HydrophobicHydrophobic fatty acid “tails”. fatty acid “tails”.

HydrophilicHydrophilic phosphate “head”. phosphate “head”.

FunctionFunction:: Primary component of the plasma Primary component of the plasma membrane of cellsmembrane of cells

Phospholipids: Amphipathic Molecules

In Water Phospholipids Spontaneously Assemble into Organized Structures

SteroidsSteroids: :

Lipids with four fused carbon ringsLipids with four fused carbon rings

1.1. Includes cholesterol, bile salts, reproductive, and adrenal Includes cholesterol, bile salts, reproductive, and adrenal hormones. hormones.

CholesterolCholesterol: : The basic steroid found in animals The basic steroid found in animals

• Common component of animal cell membranes. Common component of animal cell membranes.

• Precursor to make Precursor to make sex hormones (estrogen, sex hormones (estrogen, testosterone)testosterone)

• Generally only Generally only soluble in other fatssoluble in other fats (not in water) (not in water)

• Too much increases chance of Too much increases chance of atherosclerosis.atherosclerosis.

WaxesWaxes: : One fatty acid linked to an alcohol. One fatty acid linked to an alcohol.

• Very hydrophobic. Very hydrophobic. • Found in cell walls of certain bacteria, plant and insect coats. Found in cell walls of certain bacteria, plant and insect coats.

Help prevent water loss. Help prevent water loss.