Chapter 3 – Biological Molecules • 3.1 Why is Carbon So Important in Biological Molecules? • 3.2 How Are Organic Molecules Synthesized? • 3.3 What Are Carbohydrates? • 3.4 What Are Lipids? • 3.5 What Are Proteins? • 3.6 What Are Nucleic Acids?
Dec 20, 2015
Chapter 3 – Biological Molecules
• 3.1 Why is Carbon So Important in Biological Molecules?
• 3.2 How Are Organic Molecules Synthesized?
• 3.3 What Are Carbohydrates?
• 3.4 What Are Lipids?
• 3.5 What Are Proteins?
• 3.6 What Are Nucleic Acids?
3.1 Why Is Carbon So Important in Biological Molecules?
• Organic molecules have a carbon skeleton with hydrogen
• Inorganic molecules do not have carbon (except CO2)
• Organic molecules have functional groups that determine their reactivity
3.2 How Are Organic Molecules Synthesized?
• Monomers (“one part”) are subunits (like Legos)
• Polymers (“many parts”) are made up of monomers, often long chains of monomers
OHH
OHO OH HO OHOH HO
Dehydration synthesis(dry out the molecule)
Molecules are broken apart by removing water
OHH
OOHHO HO OH HO OH
Hydrolysis (“cut water”)
Molecules are joined together by adding water
3.3 What Are Carbohydrates?
• Carbohydrates are made of carbon, hydrogen & oxygen in approximately 1:2:1 ratio
• Energy sources
• Most are soluble in water
• Monosaccharides are “one sugar”• Disaccharides are “two sugars”• Polysaccarides are “many sugars”
galactose
HO OHHOCH2
CH2OH
HO
HO
fructose
OH
H
H
H
H
H
H
CH2OH
H
OH
O
H HO
O
Carbohydrates usually have the approximate chemical formula of (CH2O)n
ribosein RNA
deoxyribosein DNA
H
HOCH2
H
OHOH
H H
H
HOCH2
H
OH
H H
H
OHOH OO
Glucose most common monosaccharideC6H12O6
glucose
2356 4 1
5
6
4
3 2
1
H
H
CH2OH
HO
OH
OH
O
H H
OH H
H
O OOOO
H H H
H
O
CCCCCCH
H
H
H H
H
H
OC
C
C
C
O
H
HH
H H
H
H
H O
O
C
C H
H
H
=
=
H
O O
OHH
O
glucose fructose sucrose
HO
OHOCH2
OH
HO
CH2OH
H H
OH
H OH
H
H
O HO
OCH2OH
H H
OH
H OH
H
HH
H
H
HOCH2 OHH
HOCH2H
H
H
HOCH2OH
O
OH
Dehydrationsynthesis
O
Common disaccharides• sucrose• lactose – milk sugar• maltose – malt sugar
3.3 What Are Carbohydrates?• Main types of polysaccharides:
– Starch is an energy-storage polysaccharide made of glucose subunits (plants)
– Glycogen like starch but for animals
– Cellulose structure and function. Cell walls in plants. Most things can’t digest it. (Roughage or fiber)
– Chitin: structure - exoskeletons of insects, crabs and spiders. Also cell walls of some fungi.
H
CH2OH
O
HO
H
OH H
OH
CH2OHO
HO
H
OH H
OH
CH2
O
HO
H
OH H
OH
CH2OH
OH
H
OH H
OH
CH2OH
OH
H
OH H
OH
O
CH2OH
OH
O
H
OH H
OH
H H H H
H H HH
O
H HH
masses ofstarch globules
100 micrometers
O
bundle ofcellulosemolecules
1 micrometer 1 micrometer
wood is mostly cellulose plant cell with cell wall close-up of cell wall
cellulose fiberindividual cellulosemolecules
CH2OH
O
OH H
HH
O
HH OH
H
CH2OH CH2OH
CH2OH
O
O
O
O
O
O
OH
OH OH
OH
OHH
H
H
HH H
H
H
HH H
H
H
H H
OH
CH2OH
H
CH3
H N H
H
H N H
OO
H
O
N H
O
O
O
H
OH OH HH H OH
H
H
H H
HO
N H
CH3
H
OH H
OH H
HO
H
CH2OH
CH2OH
O CO C
O C O C
CH3
CH3
CH2OH
Chitin
3.4 What Are Lipids?• Contain almost all carbon and hydrogen
• Hydrophobic and insoluble in water
• Energy storage, waterproof covering, cell membranes and hormones
• 3 Main Types:– Oils, fats and waxes– Phospholipids– “Fused-ring” steroids
CO
HO
CO
HO
C OHHH
C OHH
C OHHH
glycerol fatty acids
CHCO
HOCH
+
etc.
etc.
etc.
CHCO
CO
CO
C OHH
C OH
OHH
triglyceride
CH
etc.
etc.
etc.O
HH
OHH
OHH
3 watermolecules
C
+
CH2 CH2 CH2 CH2 CH2 CH2 CH2
CH2
CH2
CH2
CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2
CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2
CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2 CH2
CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2CH2
CH2 CH2 CH2 CH2 CH2 CH2 CH2
CH2
CH2
CH2carboxyl groups
FatsandOils
Fat Wax
Fats are efficient storage (9.3 Calories compared to 4.1 for sugars)
Waxes remain firm in outdoor temperatures
(Waxes are not a food source)
Beef fat (saturated)
Most saturated fat comes from animals, and should be eaten inlimited amounts
oleic acid
Linseed oil (unsaturated)
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Hydrogenation
Copyright 2005 Wadsworth Group, a division of Thomson LearningCopyright 2005 Wadsworth Group, a division of Thomson Learning
Cis- and Trans- Fatty Acids Compared
3.4 What Are Lipids?
• Phospholipids are similar to triglycerides
• Phospholipids Have Water-Soluble “Heads” and Water-Insoluble “Tails”
• These are crucial to the structure and function of the cellular membrane (and other plasma membranes)
polar head fatty acid tailsglycerolbackbone
CH3 O
OO
CH2 -CH2-CH2-CH2
(hydrophobic)(hydrophilic)
C-N-CH2-CH2-O-P-O-CH2 O
HC-O-C-
C-O-C-
CH3
H3
H2 CH2 -CH2-CH2-CH2-CH2 -CH2-CH2-CH2-CH2 -CH2-CH2-CH2-CH2 -CH2-CH2-CH3
-CH2 -CH2-CH2-CH2
CH2CH2
CH2CH2
CH2CH2
CH2CH3
CH2=-
- --
- - - -
3.4 What Are Lipids?• Steroids Consist of Four Carbon Rings
Fused Together
• One type of steroid is cholesterol
• Also used in – Animal cell membranes
– To synthesize other steroids including male and female sex hormones
– Hormones to regulate salt levels
– Bile to assist in fat digestion
HC
HC
HO
CH3
OH
HO
OH
O
cholesterol testosterone
estradiol
CH3
CH3
CH3
CH3
CH2
CH2
CH2
CH3
CH3
CH3
3.5 What Are Proteins?• Chains of amino acids
aminogroup
hydrogen
variablegroup
carboxylicacid group
O
CC
O
R
H
H
HH
N
Hair
Horn
Silk
C
O
C
H
CH2
C
H
H2N
C
O OH
OH
CH2
glutamic acid (glu)
C
O
C
H
H2N
CH2
C
H
OH
CH2
CH2
NH
C NH
NH2
arginine (arg)
C
O
C
H
H2N
CH2
C
H
OH C
O
C
H
H2N
CH2
C
H
OH
hydrophilic
CH
CH3hydrophobic
leucine (leu)phenylalanine (phe)
C
O
CH2N C
H
OH
cysteine (cys)
formsdisulfidebridges
CH2
SH
CH3
ss
s-s
ss
s-ss-s
ss
keratin
(Curly Hair!)
waterpeptide
peptidebond
amino acid
aminogroup
aminogroup
carboxylgroup
amino acid
carboxylgroup
• Amino Acids Are Joined to Form Chains by Dehydration Synthesis
3.5 What Are Proteins?• A Protein Can Have Up to Four Levels
of Structure– Primary is the sequence of amino acids– Secondary is any helix or pleated sheets– Tertiary is folding due to hydrophobic and
hydrophilic parts of the molecule plus disulfide bridges
– Quaternary is individual polypeptides linked together
• Denatured means to disrupt the secondary or tertiary structure
gly
leuleu
val
val
lys
lys
lys
lys
gly
gly
his
his
ala
ala
lys
lys
val
lys
pro
val
lyspro
Pleated sheet
hydrogenbond
polypeptide
R R R R R
RRRR
R R R
RRRR
CC
C C
CC
CC
CC
CC
CC
CC
C
CCC
CCCC
CCCCCC
CCCC
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
O
N N N N N N N
NN
NN
N
N
NN
N
R
R
H H H H
P O
O
OCH
H
OH
H HH
H
OH
HO
Deoxyribose nucleotide
phosphatebase
sugar
C
N CH
NC
C
N
HC
N
NH2
phosphate base
Nucleotide chain
sugar
3.6 What Are Nucleic Acids?
• Nucleic acids are longs chains of nucleotides
• DNA and RNA, the Molecules of Heredity, Are Nucleic Acids
• Other Nucleotides Act as Intracellular Messengers, Energy Carriers, or Coenzymes
P O
O
OH
P O
O
OH
P O
O
OH
HO
Vitamin
C
N CH
NC
C
N
HC
N
CH2
H
O
H
OH OH
HH
P O
O
O
HO
CH2
H
O
H
OH OH
HH
P OHO
O
C
N CH
NC
C
N
HC
N
C
N CH
NC
C
N
HC
N
NH2 NH2
NH2
CH2
H
O
H
O OH
HH
O P
O
OH
Cyclic adenosine monophosphate (cyclic AMP)(intracellular communication)
Adenosine triphosphate (ATP)(energy carrier)
Coenzyme (active in cellular
metabolism)