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