Transcript CH 2 -CH 2 -CH 2 -CH 2 -CH 2

Macromolecules
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Organic Compounds
• Compounds that contain CARBON
are called organic.
• Macromolecules are large organic
molecules.
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Carbon (C)
• Carbon has 4 electrons in outer
shell.
• Carbon can form covalent bonds
with as many as 4 other atoms
(elements).
• Usually with C, H, O or N.
• Example:
CH4(methane)
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Macromolecules
• Large organic molecules.
• Also called POLYMERS.
• Made up of smaller “building blocks”
called MONOMERS.
• Examples:
1. Carbohydrates
2. Lipids
3. Proteins
4. Nucleic acids (DNA and RNA)
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Question:
How Are
Macromolecules
Formed?
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Answer: Dehydration Synthesis
• Also called “condensation reaction”
• Forms polymers by combining
monomers by “removing water”.
HO
H
HO
H
H2O
HO
H
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Dehydration Synthesis
• Combining simple molecules to form a
more complex one with the removal of
water
– ex. monosaccharide + monosaccharide ---->
disaccharide + water
– (C6H12O6 + C6H12O6 ----> C12H22O11 +
H2O
• Polysaccharides are formed from
repeated dehydration syntheses of
water
– They are the stored extra sugars known as
starch
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Question:
How are
Macromolecules
separated or
digested?
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Answer: Hydrolysis
• Separates monomers by “adding
water”
HO
H
H2O
HO
H
HO
H
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Carbohydrates
used as a source of energy; short term
and long term energy also some animals
and organisms use carbs for structural
purposes.
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Carbohydrates
• Small sugar molecules to large
sugar molecules.
• Examples:
A. monosaccharide
B. disaccharide
C. polysaccharide
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Carbohydrates
Monosaccharide: one sugar unit
Examples:
glucose
glucose (C6H12O6)
deoxyribose
ribose
Fructose
Galactose
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Carbohydrates
Disaccharide: two sugar unit
Examples: (C12H22O11)
– Sucrose (glucose+fructose)
– Lactose (glucose+galactose)
– Maltose (glucose+glucose)
glucose
glucose
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Carbohydrates
Polysaccharide: many sugar units
Examples: starch (bread, potatoes)
glycogen (beef muscle)
cellulose (lettuce, corn)
glucose
glucose
glucose
glucose
cellulose
glucose
glucose
glucose
glucose
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Lipids
some store energy, some lipids form
important parts of biological membranes
& waterproof coverings.
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Lipids
• General term for compounds which are
not soluble in water.
• Lipids are soluble in hydrophobic
solvents.
• Remember: “stores the most energy”
• Examples: 1. Fats
2. Phospholipids
3. Oils
4. Waxes
5. Steroid hormones
6. Triglycerides
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Lipids
Six functions of lipids:
1. Long term energy storage
2. Protection against heat loss
(insulation)
3. Protection against physical shock
4. Protection against water loss
5. Chemical messengers (hormones)
6. Major component of membranes
(phospholipids)
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Lipids
Triglycerides:
composed of 1 glycerol and 3
fatty acids.
H
O
H-C----O C-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH3
O
H-C----O C-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH3
O
fatty acids
H-C----O C-CH -CH -CH -CH
2
2
2
H
glycerol
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Fatty Acids
There are two kinds of fatty acids you may see
these on food labels:
1. Saturated fatty acids: no double bonds
(bad)
O
saturated C-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH2-CH3
2. Unsaturated fatty acids: double bonds
(good)
O
unsaturated C-CH2-CH2-CH2-CH
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Proteins
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Proteins (Polypeptides)
• Amino acids (20 different kinds of aa)
bonded together by peptide bonds
(polypeptides).
• Six functions of proteins:
1. Storage:
albumin (egg white)
2. Transport:
hemoglobin
3. Regulatory:
hormones
4. Movement:
muscles
5. Structural:
membranes, hair, nails
6. Enzymes:
cellular reactions
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Major Protein Functions
•
•
•
Growth and repair
Energy
Buffer -- helps keep body pH constant
referred to as maintaining
homeostasis
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Proteins (Polypeptides)
Four levels of protein structure:
A.Primary Structure
B. Secondary Structure
C. Tertiary Structure
D.Quaternary Structure
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Primary Structure
Amino acids bonded together
by peptide bonds (straight
chains)
Amino Acids (aa)
aa1
aa2
aa3
aa4
aa5
aa6
Peptide Bonds
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Secondary Structure
• 3-dimensional folding arrangement of a
primary structure into coils and pleats
held together by hydrogen bonds.
• Two examples:
Alpha Helix
Beta Pleated Sheet
Hydrogen Bonds
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Tertiary Structure
• Secondary structures bent and folded
into a more complex 3-D arrangement
of linked polypeptides
• Bonds: H-bonds, ionic, disulfide
bridges (S-S)
• Call a “subunit”.
Alpha Helix
Beta Pleated Sheet
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Quaternary Structure
• Composed of 2 or more
“subunits”
• Globular in shape
• Form in Aqueous environments
• Example: enzymes (hemoglobin)
subunits
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Nucleic
Acids
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Nucleic acids
• Two types:
a. Deoxyribonucleic acid (DNAdouble helix)
b. Ribonucleic acid (RNA-single
strand)
• Nucleic acids are composed of long
chains of nucleotides linked by
dehydration synthesis.
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Nucleic acids
• Nucleotides include:
phosphate group
pentose sugar (5-carbon)
nitrogenous bases:
adenine (A)
thymine (T) DNA only
uracil (U) RNA only
cytosine (C)
guanine (G)
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DNA Nitrogenous bases
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DNA Nucleotide
Phosphate
Group
O
O=P-O
O
5
CH2
O
N
C1
C4
Nitrogenous base
(A, G, C, or T)
Sugar
(deoxyribose)
C3
C2
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RNA Nucleotide
• directs cellular protein synthesis
• found in ribosomes & nucleoli
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5
DNA
double
helix
O
3
3
O
P
5
O
C
G
1
P
5
3
2
4
4
2
3
1
P
T
5
A
P
3
O
O
P
5
O
3
5
P
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Enzymes and Enzyme Action
• Catalyst : inorganic or organic substance
which speeds up the rate of a chemical
reaction without entering the reaction itself
• enzymes: organic catalysts made of protein
• most enzyme names end in -ase
• enzymes lower the energy needed to start a
chemical reaction. (activation energy)
• begin to be destroyed above 45øC. (above this
temperature all proteins begin to be
destroyed)
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It is thought that, in order for an enzyme to affect the
rate of a reaction, the following events must take
place.
1. The enzyme must form a temporary association with
the substance or substances whose reaction rate it
affects. These substances are known as substrates.
2. The association between enzyme and substrate is
thought to form a close physical association between
the molecules and is called the enzyme-substrate
complex.
3. While the enzyme-substrate complex is formed,
enzyme action takes place.
4. Upon completion of the reaction, the enzyme and
product(s) separate. The enzyme molecule is now
available to form additional complexes.
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How do enzymes work?
• substrate: molecules upon which an enzyme
acts
• the enzyme is shaped so that it can only lock
up with a specific substrate molecule
enzyme
substrate -------------> product
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Factors Influencing Rate of Enzyme
Action
1. pH - the optimum (best) in most living things
is close to 7 (neutral)
• high or low pH levels usually slow enzyme
activity
• A few enzymes (such as gastric protease) work
best at a pH of about 2.0
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. 2-Temperature
- strongly influences enzyme
activity
optimum temperature for maximum enzyme
function is usually about 35-40 C.
reactions proceed slowly below optimal
temperatures above 45 C most enzymes are
denatured (change in their shape so the
enzyme active site no longer fits with the
substrate and the enzyme can't function)
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3-Concentration
Concentrations of Enzyme and Substrate
• ** When there is a fixed amount of enzyme
and an excess of substrate molecules -- the
rate of reaction will increase to a point and
then level off.
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