Transcript Small Business Success on the Web

The Chemicals of Life 1.2
Why study Carbon?
• All living things are made of cells
• Cells
– ~72% H2O
– ~3% salts (Na, Cl, K…)
– ~25% carbon compounds
–
–
–
–
carbohydrates
lipids
proteins
nucleic acids
Chemistry of Life
• Organic chemistry is the study of carbon
compounds (in living things)
• C atoms are versatile building blocks
– bonding properties
– 4 stable covalent bonds
Hydrocarbons
• Simplest C molecules = hydrocarbons
– combinations of C & H
• Simplest HC molecule = methane
– 1 carbon bound to 4 H atoms
– non-polar
– not soluble in H2O
– hydrophobic
– stable
– very little attraction between molecules
– a gas at room temperature
Hydrocarbons can grow
• adding C-C bonds
methane
ethane
– straight line
• ethane
• hexane
– branching
hexane
• isohexane
– ring
• cyclohexane
isohexane
cyclohexane
Diversity of organic molecules
Isomers
• Molecules with same molecular formula
but different structures
– different chemical properties
Structural isomers
• Molecules differ in structural arrangement
of atoms
Geometric isomers
• Molecules differ in arrangement around
C=C double bond
– same covalent partnerships
Enantiomer (stereo) isomers
• Molecules which are mirror images of
each other
– C bonded to 4 different atoms or groups
• assymetric
– left-handed & right-handed versions
• “L” versions are
biologically active
Form affects function
• Structural differences create important
functional significance
– amino acid alanine
• L-alanine used in proteins
• but not D-alanine
– medicines
• L-version active
• but not D-version
– sometimes with
tragic results…
Form affects function
• Thalidomide
– prescribed to pregnant women in 50’s & 60’s
– reduced morning sickness, but…
– stereoisomer caused severe birth defects
Diversity of molecules
• Substitute other atoms or groups
around the C
– ethane vs. ethanol
• H replaced by an hydroxyl group (–OH)
• nonpolar vs. polar
• gas vs. liquid
ethane
ethanol
Functional groups
• Components of organic molecules that are
involved in chemical reactions
– give organic molecules distinctive properties
– ex: male & female hormones…
Viva la difference!
• Basic structure of male & female
hormones is identical
– identical C skeleton
– attachment of different functional groups
– interact with different targets in the body
Types of functional groups
• 6 functional groups most important to
chemistry of life: (p.25)
– hydroxyl
– carbonyl
– carboxyl
amino
u sulfhydryl
u phosphate
u
• Affect reactivity
– hydrophilic
– increase solubility in water
Hydroxyl
• –OH (do not confuse this with (OH)-!!)
– organic compounds with OH = alcohols
– names typically end in -ol
• ethanol
Carbonyl
• C=O
– O double bonded to C
• if C=O at end molecule = aldelhyde
• if C=O in middle of molecule = ketone
Carboxyl
• –COOH
– C double bonded to O & single bonded to OH
group
• compounds with COOH = acids (e.g., acetic acid)
– fatty acids
– amino acids
Amino
• -NH2
– N attached to 2 H
• compounds with NH2 = amines
– amino acids
• NH2 acts as base
– ammonia picks up H+ from solution
Sulfhydryl
• –SH
– S bonded to H
• compounds with SH = thiols
• SH groups stabilize the structure of proteins
Phosphate
• –PO4
– P bound to 4 O
• connects to C through an O
• PO4 are anions with 2 negative charges
• function of PO4 is to transfer energy between
organic molecules (ATP)
Why study Functional Groups?
• These are the building blocks for
biological molecules
…and that comes next!
p.27 Q 1
Macromolecules
• Smaller organic molecules join together
to form larger molecules
– macromolecules
• 4 major classes of macromolecules:
– carbohydrates
– lipids
– proteins
– nucleic acids
Polymers
• Long molecules built by linking chain of
repeating smaller units
– polymers
– monomers = repeated small units
– covalent bonds
How to build a polymer
• Condensation reaction
– Aka dehydration synthesis
– joins monomers by “taking” H2O out
• 1 monomer provides OH
• the other monomer provides H
• together these
form H2O
– requires energy
& enzymes
How to break down a polymer
• Hydrolysis
– use H2O to break apart monomers
• reverse of condensation reaction
• H2O is split into H and OH
• H & OH group attach where the covalent bond
used to be
• This process releases energy
– ex: digestion is
hydrolysis
Carbohydrates
Carbohydrates
• Carbohydrates are composed of C, H, O
carbo - hydr - ate
CH2O (empirical formula)
(CH2O)x  C6H12O6
• Function:
– energy
– raw materials
energy storage
u structural materials
u
• Monomer: simple sugars (e.g., glucose)
• ex: sugars & starches
Sugars
• All monosaccharides can be distinguished
by the carbonyl group they possess
(aldehyde or ketone) along with the # of C in
the backbone
– 6C = hexose (glucose)
– 5C = pentose (fructose, ribose)
– 3C = triose (glyceraldehyde)
What functional groups?
carbonyl
aldehyde
ketone
hydroxyl
Sugar structure
• 5C & 6C sugars form rings in aqueous solutions
– in cells!
Carbons are numbered
Sugar Structure cont’d
• When glucose becomes aqueous, there is a 50%
chance that the –OH group at C1 will end up
below the plane of the ring. If so, it is called αglucose.
• If the –OH group at C1 ends up above the plane
of the ring, then it becomes β-glucose.
Numbered carbons
C 6'
5' C
O
4' C
C1'
C3'
C2'
Simple & complex sugars
• Monosaccharides
– simple 1 monomer sugars
– glucose
• Disaccharides
– 2 monomers
– sucrose
• Polysaccharides
– large polymers
– starch
Complex Sugars
• All sugars are made up of monosaccharides
held together by glycosidic linkages.
• Glycosidic linkages are the covalent bonds that
hold 2 monosaccharides together and are
formed by condensation reactions in which the H
atom of the hydroxyl group comes from one
sugar and the –OH group comes from the
hydroxyl group of the other.
Building sugars
• Dehydration synthesis
monosaccharides
|
glucose
|
glucose
disaccharide
|
maltose
glycosidic linkage
Building sugars
• Dehydration synthesis
monosaccharides
|
glucose
|
fructose
structural isomers
disaccharide
|
sucrose
glycosidic linkage
Polysaccharides
• Polymers of sugars
– costs little energy to build
– easily reversible = release energy
• Function:
– energy storage
• starch (plants)
• glycogen (animals)
– building materials = structural support
• cellulose (plants)
• chitin (arthropods & fungi)
• Humans and other organisms use plants’ stockpile of
energy as a food source for themselves.
Branched vs linear
polysaccharides
Polysaccharide diversity
• Molecular structure determines function
– isomers of glucose
– How does structure influence function…
Digesting starch vs. cellulose
Cow
can digest cellulose well; no need
to eat supplemental sugars.
Have symbiotic bacteria that
produce enzymes.
Gorilla
can’t digest cellulose well; must
supplement with sugar source,
like fruit
Cellulose
• Most abundant organic
compound
on Earth (polymer of βglucose)
• Used by plants to create
the cell wall
• Humans are not able to
break the glycosidic
linkages in cellulose and
therefore we cannot
digest it.
• Practice p.34 Q 2-8, 10