Transcript Ch 4/5 Power Point - Carbon/Macromolecules

• Chapter 4~
Carbon &
The Molecular
Diversity of Life
• Chapter 5~
The Structure &
Function of
Macromolecules
Organic chemistry
• Biological thought:
• Vitalism (life force outside physical
& chemical laws) – organic
compounds can only arise in living
organisms - Berzelius
• Mechanism (all natural phenomena
are governed by physical & chemical
laws) – organic compounds may be
produced in lab - Miller
• Carbon
– Ability to branch in 4 directions
allows large molecules possible
– Tetravalence, tetrahedron
– Shape determines function
Hydrocarbons
• Only carbon & hydrogen
(petroleum; lipid ‘tails’)
• Covalent bonding; nonpolar
• High energy storage
• Isomers (same molecular formula,
but different structure & properties)
– 1. Structural~differing covalent
bonding arrangement
– 2. Geometric~differing spatial
arrangement
– 3. Enantiomers~mirror images
pharmacological industry
(thalidomide)
Functional Groups, I
• Attachments that
• 1. Hydroxyl Group
– H bonded to O (-OH);
replace one or more of
alcohols; polar (oxygen);
the hydrogens bonded
solubility in water
to the carbon skeleton
of the hydrocarbon
• 2. Carbonyl Group
• Each has a unique
property from one
organic to another
– C double bond to O
– At end of C skeleton aldehyde - ex. proponal
– Within C skeleton – ketone –
ex. acetone
Functional Groups, II
• 3. Carboxyl Group
– O double bonded to C to hydroxyl
– carboxylic acids, organic acids
– covalent bond between
O and H is very polar leads to
dissociation,
H ion
• 4. Amino Group
– N to 2 H atoms (-NH2)
– Amines
– acts as a base
• 5. Sulfhydral Group
– sulfur bonded to H
– thiols
• 6. Phosphate Group
– phosphate ion covalently
attached by 1 of its O to
the C skeleton
– transfer energy
Polymers
• Macromolecules – may have
thousands of linked molecules
• Poly = many; mers = parts
• Covalent monomers link to form
polymers
• Condensation reaction (dehydration
reaction):
– One monomer provides a
hydroxyl group while the other
provides a hydrogen to form a
water molecule
– Forms polymers
• Hydrolysis: bonds between
monomers are broken by adding
water (digestion) – aided by
enzymes
Carbohydrates, I
• Monosaccharides
– CH2O (1:2:1) formula
– Multiple hydroxyl (-OH)
groups and 1 carbonyl (C=O)
group
– Location determines if
aldehyde (aldose) sugar or
ketone (ketose) sugar
– Cellular respiration breaks them
down
– Raw material for amino acids
and fatty acids
– Ex. Glucose, fructose
Carbohydrates, II
• Disaccharides
– Glycosidic linkage
(covalent bond) between 2
monosaccharides
– No longer have 1:2:1
multiples – water is pulled
out (condensation/
dehydration reaction)
– Sucrose (table sugar) most common
disaccharide
Carbohydrates, III
• Polysaccharides
Storage: Starch~ glucose monomers
Plants: plastids Animals: glycogen
• Polysaccharides
Structural:
Cellulose~ most abundant
organic compound;
Chitin~ exoskeletons; cell
walls of fungi; surgical thread
Lipids, I
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Fats, phospholipids, steroids
No polymers; glycerol and fatty acid
Glycerol – alcohol w/ 3C each w/ hydroxyl group
Fatty acid – long C chain w/ carboxyl group
Non-polar C-H bonds in fatty acid ‘tails’
Cause to be hydrophobic
Ester linkage: 3 fatty acids to 1 glycerol
(dehydration formation)
Triacyglycerol (triglyceride)
Saturated (solid) vs. unsaturated (liquid) fats;
single vs. double bonds
Lipids, II
• Phospholipids
– 2 fatty acids instead of
3 – replaced by a
phosphate group
– ‘Tails’ hydrophobic;
‘heads’ hydrophilic
– Micelle (phospholipid
droplet in water)
– Form a bilayer (double
layer) - cell
membranes
Lipids, III
• Steroids
– Lipids with 4 fused carbon
rings
– Ex: cholesterol:
• Cell membranes
• Precursor for other
steroids (sex hormones –
estrogen, testosterone)
• Too mcuh =
atherosclerosis –
narrowing of vessel walls
Proteins, I
• Importance - instrumental in nearly everything organisms do; 50% dry
weight of cells; most structurally sophisticated molecules known –
enzymes, insulin, antibodies
• Monomer: amino acids (there are 20)
– Contain a carboxyl (-COOH) group, amino group (NH2), H atom,
variable group (R – aka side chain – gives each its identity and
properties)
• Variable group characteristics:
polar (hydrophilic), nonpolar (hydrophobic), acid or base
• Three-dimensional shape – conformation – determines function
• Polypeptides (dehydration reaction)
– Joined by peptide bonds (covalent bond); carboxyl group to amino
group (polar)
Proteins, II
• Primary Structure
– Conformation: Linear structure
– Molecular Biology: each type
of protein has a unique primary
structure of amino acids
– Ex: lysozyme
– Amino acid substitution:
hemoglobin; sickle-cell anemia
Proteins, III
• Secondary Structure
– Conformation: coils &
folds (hydrogen bonds)
– Alpha Helix: coiling;
keratin
– Beta Pleated Sheet:
parallel; silk
Proteins, IV
• Tertiary Structure
– Conformation:
irregular contortions
from R group
bonding
• hydrophobic
• disulfide bridges
• hydrogen bond
• ionic bonds
Proteins, V
• Quaternary Structure
– Conformation: 2 or more
polypeptide chains
aggregated into 1
macromolecule
• collagen (connective
tissue)
• hemoglobin
– Heat, pH, other body
disturbances may denature
protein (becomes inactive)
– loses conformation
Nucleic Acids, I
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Deoxyribonucleic acid (DNA)
Ribonucleic acid (RNA)
DNA>RNA>protein
Polymers of nucleotides
(polynucleotide):
– nitrogenous base
– pentose – 5 carbon sugar
– phosphate group
• Nitrogenous bases:
– Pyrimidines – single ring ~cytosine,
thymine (DNA), uracil (RNA)
– Purines – double ring~adenine,
guanine
Nucleic Acids, II
• Pentoses:
– ribose (RNA)
– deoxyribose (DNA)
– nucleoside (base + sugar)
• Polynucleotide:
– phosphodiester linkages (covalent) –
btw phosphate + sugar
Nucleic Acids, III
• Inheritance based on DNA
replication
• Double helix (Watson & Crick
- 1953)
– H bonds~ between paired
bases
– van der Waals~ between
stacked bases
• A to T; C to G pairing
• Complementary