Carbon&Molecules of Life

Organic CompoundsOrganic Compounds

Hydrogen and other elements covalently bonded to carbon

CarbohydratesLipidsProteinsNucleic Acids

p.34a

sodium (Na)

chlorine (Cl)

magnesium (Mg)

iron (Fe)

calcium (Ca)

phosphorous (P)

potassium (K)

sulfur (S)

carbon (C)

oxygen (O)

hydrogen (H)

nitrogen (N)

Organic CompoundsOrganic Compounds

structural formulafor methane

ball-and-stick model space-filling model

p.34b

Organic CompoundsOrganic Compounds

Carbon’s Bonding Carbon’s Bonding Behavior Behavior

Outer shell of carbon has 4 electrons; can hold 8

Each carbon atom can form covalent bonds with up to four atoms

Bonding ArrangementsBonding Arrangements

Carbon atoms can form chains or rings

Other atoms project from the carbon backbone

or

p.34e

Simplified structural formula for a six-carbon ring

icon for a six-carbon ring

Organic CompoundsOrganic Compounds

Fig. 3-2, p.35

Organic CompoundsOrganic Compounds

IsomersIsomersStructural isomers – differ in the

arrangement of their atomsGeometric isomers – differ in the

arrangement of atoms around a double bond

Enantiomers – Chiral Molecules – ◦Molecules are mirror images of each

other◦Cells can tell the two apart◦Usually one is biologically active while

the other is not

PolymersPolymersLarge molecules made by linking

many individual building blocks together in long chains

The building block subunits are called monomers

Subunits are linked by a reaction called dehydration synthesis

Can be cleaved by a reaction called hydrolysis

Functional GroupsFunctional GroupsAtoms or clusters of atoms that

are covalently bonded to carbon backbone

Give organic compounds their different properties

Examples of Functional Examples of Functional GroupsGroupsHydroxyl group - OH

Amino group - NH3+

Carboxyl group - COOH

Phosphate group - PO3-

Sulfhydryl group - SH

Common Common Functional Functional Groups in Groups in Biological Biological MoleculesMolecules

Fig. 3-4, p.36

Functional Groups in Functional Groups in HormonesHormones

Estrogen and testosterone are hormones responsible for observable differences in traits between male and female wood ducks

Differences in position of functional groups attached to ring structure (pg 63)

An Estrogen Testosterone

Fig. 3-5b, p.36

Dehydration Synthesis Dehydration Synthesis ReactionsReactionsForm polymers from subunits

Enzymes remove -OH from one molecule, H from another, form bond between two molecules

Discarded atoms can join to form water

Also called condensation reactions

Dehydration Synthesis

Fig. 3-6a, p.38

HydrolysisHydrolysis

A type of cleavage reactionBreaks polymers into smaller

unitsEnzymes split molecules into two

or more partsAn -OH group and an H atom

derived from water are attached at exposed sites

Hydrolysis

Fig. 3-6b, p.38

CarbohydratesCarbohydrates Monosaccharides(simple sugars)

Oligosaccharides(short-chain carbohydrates)

Polysaccharides(complex carbohydrates)

Monosaccharides Monosaccharides

Simplest carbohydrates

Most are sweet tasting, water soluble

Most have 5- or 6-carbon backbone

Glucose (6 C) Fructose (6 C)

Ribose (5 C) Deoxyribose (5 C)

Two MonosaccharidesTwo Monosaccharides

glucose fructoseFig. 3-7, p.38

DisaccharidesDisaccharides

Type of oligosaccharide

Two monosaccharides covalently bonded

Formed by condensation reaction

+ H2O

glucose fructose

sucrose

Fig. 3-7b, p.38

PolysaccharidesPolysaccharides

Straight or branched chains of many sugar monomers

Most common are composed entirely of glucose◦Cellulose

◦Starch (such as amylose)

◦Glycogen

Cellulose & StarchCellulose & StarchDiffer in bonding patterns

between monomers

Cellulose - tough, indigestible, structural material in plants

Starch - easily digested, storage form in plants

Cellulose and StarchCellulose and Starch

Fig. 3-8, p.38

GlycogenGlycogen

Sugar storage form in animals

Large stores in muscle and liver cells

When blood sugar decreases, liver cells degrade glycogen, release glucose

Fig. 3-9, p.38

ChitinChitinPolysaccharide

Nitrogen-containing groups attached to glucose monomers

Structural material for hard parts of invertebrates, cell walls of many fungi

ChitinChitin

Chitin occurs in protective body coverings of many animals, including ticks

Fig. 3-10a, p.39

Fig. 3-10b, p.39

LipidsLipidsMost include fatty acids

◦Fats◦Phospholipids◦Waxes

Sterols and their derivatives have no fatty acids

Tend to be insoluble in water

FatsFats

Fatty acid(s)

attached to

glycerol

Triglycerides

are most

common

Fig. 3-12, p.40

Fatty AcidsFatty Acids

Carboxyl group (-COOH) at one end

Carbon backbone (up to 36 C atoms)

◦Saturated - Single bonds between carbons

◦Unsaturated - One or more double bonds

Three Fatty AcidsThree Fatty Acids

Fig. 3-11, p.40

PhospholipidsPhospholipids

Main components of cell

membranes

WaxesWaxes

Long-chain fatty acids linked

to long chain alcohols or

carbon rings

Firm consistency, repel water

Important in water-proofing

WaxesWaxes

Bees construct honeycombs from their own waxy secretions

Fig. 3-14, p.41

Sterols and DerivativesSterols and Derivatives

No fatty acidsRigid backbone of

four fused-together carbon rings

Cholesterol - most common type in animals

Fig. 3-14, p.41

Amino Acid StructureAmino Acid Structure

aminogroup

carboxylgroup

R group

Properties of Amino AcidsProperties of Amino Acids

Determined by the “R group”

Amino acids may be:

◦Non-polar

◦Uncharged, polar

◦Positively charged, polar

◦Negatively charged, polar

Protein SynthesisProtein Synthesis

Protein is a chain of amino acids linked by peptide bonds

Peptide bond◦Type of covalent bond

◦Links amino group of one amino acid with carboxyl group of next

◦Forms through condensation reaction

Fig. 3-15b, p.42

Fig. 3-15c, p.42

Fig. 3-15d, p.42

Fig. 3-15e, p.42

Primary StructurePrimary Structure

Sequence of amino acids

Unique for each protein

Two linked amino acids = dipeptide

Three or more = polypeptide

Backbone of polypeptide has N atoms:

-N-C-C-N-C-C-N-C-C-N-

one peptide group

Protein Shapes Protein Shapes

Fibrous proteins

◦Polypeptide chains arranged as

strands or sheets

Globular proteins

◦Polypeptide chains folded into

compact, rounded shapes

Primary StructurePrimary Structure & Protein Shape & Protein Shape

Primary structure influences shape in two main ways:◦Allows hydrogen bonds to form

between different amino acids along length of chain

◦Puts R groups in positions that allow them to interact

Secondary StructureSecondary StructureHydrogen bonds form between

different parts of polypeptide chain

These bonds give rise to coiled or extended pattern

Helix or pleated sheet

Examples of Secondary Examples of Secondary StructureStructure

Tertiary StructureTertiary Structure

Folding as a result of interactions between R groups

heme group

coiled and twisted polypeptide chain of one globin molecule

Quaternary StructureQuaternary Structure

Some proteins

are made up

of more than

one

polypeptide

chain

Hemoglobin

heme alpha globin alpha globin

beta globin beta globin

Fig. 3-17, p.44

Polypeptides with Attached Polypeptides with Attached Organic CompoundsOrganic Compounds

Lipoproteins

◦Proteins combined with cholesterol,

triglycerides, phospholipids

Glycoproteins

◦Proteins combined with

oligosaccharides

DenaturationDenaturation

Disruption of three-dimensional shape

Breakage of weak bondsCauses of denaturation:

◦pH

◦Temperature

Destroying protein shape disrupts function

Nucleotide StructureNucleotide Structure

Sugar

◦Ribose or deoxyribose

At least one phosphate group

Base

◦Nitrogen-containing

◦Single or double ring structure

Nucleotide FunctionsNucleotide Functions

Energy carriersCoenzymes

Chemical messengers

Building blocks for

nucleic acids

ATP - A NucleotideATP - A Nucleotide

three phosphate groups

sugar

base

Nucleic AcidsNucleic Acids

Composed of nucleotidesSingle- or double-strandedSugar-phosphate backbone

AdenineCytosine

Bonding Between Bases in Bonding Between Bases in Nucleic AcidsNucleic Acids

THYMINE(T)

base with asingle-ringstructure

CYTOSINE(C)

base with asingle-ringstructure

Fig. 3-20, p.46

DNADNA

Double-stranded Consists of four

types of nucleotides

A bound to TC bound to G

RNARNA

Usually single strandsFour types of nucleotidesUnlike DNA, contains the base uracil

in place of thymineThree types are key players in

protein synthesis