Download Macromolecules

Chapter 5
The Structure and Function
of Large Biological
Molecules
Focus on:
• Elements in each large
biological molecule.
• How these molecules are linked
and unlinked.
• Examples and functions of each
type of molecule.
Macromolecules
• Large molecules formed by
joining many subunits together.
• Also known as “polymers”.
Monomer
• A building block of a polymer.
Condensation Synthesis or
Dehydration Synthesis
• The chemical reaction that joins
monomers into polymers.
• Covalent bonds are formed by
the removal of a water molecule
between the monomers.
Hydrolysis
• Reverse of condensation
synthesis.
• Hydro- water
• Lysis - to split
• Breaks polymers into
monomers by adding water.
Four Main Types of
Macromolecules or
Large Biological Molecules
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Carbohydrates
Lipids
Protein
Nucleic acids
For each Macromolecule
know the following:
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Elements it contains
Monomer units and structures
Examples
Uses or roles
Carbohydrates
• Used for fuel, building
materials, and receptors.
• Made of C,H,O
• General formula is CH2O
• C:O ratio is 1:1
Types Of Carbohydrates
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Monosaccharides
Disaccharides
Oligosaccharides
Polysaccharides
Monosaccharides
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Mono - single
Saccharide - sugar
Simple sugars.
3 to 7 carbons.
Can be in linear or ring forms.
Monosaccharides
• Can be “Aldoses” or “Ketoses”
depending on the location of the
carbonyl group.
Examples
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Glucose
Galactose
Ribose
Fructose
- OSE
• Word ending common for many
carbohydrates.
Disaccharides
• Di - two
• Sugar formed by joining two
monosaccharides through a
“glycosidic linkage”.
Examples
• Maltose = glucose + glucose
• Lactose = glucose + galactose
• Sucrose = glucose + fructose
Oligosaccharides
• Oligo – a few
• 2 - 10 joined simple sugars.
• Used in cell membranes.
Polysaccharides
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Poly - many
Many joined simple sugars.
Used for storage or structure.
Examples:
• Starch
• Cellulose
• Glycogen
a glucose and b glucose
Starch
• Made of 1-4 linkages of
a glucose.
• Linkage makes the molecule
form a helix.
• Fuel storage in plants.
a glucose
Cellulose
• Made of 1-4 linkages of
b glucose.
• Linkage makes the molecule
form a straight line.
• Used for structure in plant cell
walls.
b glucose
Comment
• Most organisms can digest
starch (1- 4 a linkage), but very
few can digest cellulose
(1- 4 b linkage).
• Another example of the link
between structure and function.
Glycogen
• “Animal starch”
• Similar to starch, but has more
1-6 linkages or branches.
• Found in the liver and muscle
cells.
Starch
Glycogen
Practice Essay
• This will be our first attempt to
writing an AP Biology essay.
Lipids
• Diverse hydrophobic
molecules
• Made of C,H,O
• No general formula
• C:O ratio is very high in C
• Not strictly speaking a
macromolecule like the others
Fats and Oils
• Fats - solid at
room temperature.
• Oils - liquid at
room temperature.
Fats and Oils
• Made of two kinds of smaller
molecules.
• Fatty Acids
• Glycerol
Fatty Acids
• A long carbon chain (12-18 C)
with a -COOH (acid) on one
end and a -CH3 (fat) at the
other.
Acid
Fat
Neutral Fats or
Triacylglycerols
• Three fatty acids joined to one
glycerol.
• Joined by an “ester linkage”
between the -COOH of the fatty
acid and the -OH of the alcohol.
Saturated Fats
Unsaturated Fats
• Saturated - no double bonds.
• Unsaturated - one or more C=C
bonds. Can accept more
Hydrogens.
• Double bonds cause “kinks” in
the molecule’s shape.
Question
• Why do fats usually contain
saturated fatty acids and oils
usually contain unsaturated
fatty acids?
• The double bond pushes the
molecules apart, lowering the
density, which lowers the
melting point.
Fats
• Differ in which fatty acids are
used.
• Used for energy storage,
cushions for organs, insulation.
Question ?
• Which has more energy,
a kg of fat or a kg of starch?
• Fat - there are more C-H bonds
which provide more energy per
mass.
Phospholipids
• Similar to fats, but have only
two fatty acids.
• The third -OH of glycerol is
joined to a phosphate
containing molecule.
Result
• Phospholipids have a
hydrophobic tail, but a
hydrophilic head.
• Self-assembles into micells or
bilayers, an important part of
cell membranes.
Steroids
• Lipids with four fused rings.
• Differ in the functional groups
attached to the rings.
• Examples:
• cholesterol
• sex hormones
Proteins
• The molecular tools of the cell.
• Made of C,H,O,N, and
sometimes S.
• No general formula.
Uses Of Proteins
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Structure
Enzymes
Antibodies
Transport
Movement
Receptors
Hormones
Proteins
• Polypeptide chains of Amino
Acids linked by “peptide bonds”.
Amino Acids
• All have a Carbon with four
attachments:
• -COOH (acid)
• -NH2 (amine)
• -H
• -R (some other side group)
R groups
• 20 different kinds:
• Nonpolar - 9 AA
• Polar - 6 AA
• Electrically Charged
• Acidic - 2 AA
• Basic - 3 AA
Amino Acids
Amino Acids
R groups
• Contain the S when present in a
protein.
• Cysteine or Cys
• Methionine or Met
• The properties of the R groups
determine the properties of the
protein.
Polypeptide Chains
• Formed by dehydration
synthesis between the carboxyl
group of one AA and the amino
group of the second AA.
• Produce an backbone of:
(N-C-C)X
Levels Of Protein Structure
• Organizing the polypeptide
into its 3-D functional shape.
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Primary
Secondary
Tertiary
Quaternary
Primary
• Sequence of amino
acids in the
polypeptide chain.
• Many different
sequences are
possible with
20 AAs.
Secondary
• 3-D structure formed by
hydrogen bonding between
parts of the peptide
backbone.
• Two main secondary
structures:
 a helix
 β pleated sheets
Tertiary
• Bonding between the R groups.
• Examples:
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hydrophobic interactions
ionic bonding
Disulfide bridges (covalent bond)
Can also include H bonds
Quaternary
• When two or more
polypeptides unite to form a
functional protein.
• Example: hemoglobin
Is Protein Structure
Important?
Denaturing Of A Protein
• Events that cause a protein to
lose structure (and function).
• Example:
• pH shifts
• high salt concentrations
• heat
Chaperone Proteins
• Large protein complexes that
help fold other proteins into
their correct shape.
• Often used when cells are
stressed to keep proteins intact
and functioning.
• First found in “heat stress”.
Comment
• Many other amino acids are
possible (change the R group).
• Whole new group of proteins
with new properties can be
made.
• Genetic engineering can use
bacteria to make these new
proteins.
Nucleic Acids
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Informational polymers
Made of C,H,O,N and P
No general formula
Examples: DNA and RNA
Nucleic Acids
• Polymers of nucleotides
• Nucleotides have three parts:
• nitrogenous base
• pentose sugar
• phosphate
Nitrogenous Bases
• Rings of C and N
• The N atoms tend to take up
H+ (act as a base).
• Two types:
• Pyrimidines (single ring)
• Purines (double rings)
Pentose Sugar
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5-C sugar
Ribose - RNA
Deoxyribose – DNA
RNA and DNA differ in a
–OH group on the 2nd carbon.
Nucleosides and
Nucleotides
• Nucleoside = base + sugar
• Nucleotide = has the trio of
base + sugar + Pi
DNA
• Deoxyribonucleic Acid.
• Makes up genes.
• Genetic information
for life.
RNA
• Ribonucleic Acid.
• Structure and protein
synthesis.
• Genetic information for a
few viruses only.
• Control mechanisms for
genes (major future topic).
Kiara Goodwine IA
Biology
AP
BiologyAP
!
Kiara - IA
Assignments
• Read Chapters 7 in Campbell
and/or Chapters 5 in Hillis
• Chapter 5 – today
• Lab – essay writing exercise
• Exam 1 – next week
• Have you enrolled for dual
credit? – Deadline is Friday
DNA and RNA
• More will be said about DNA
and RNA in future lessons.
Chapter Summary
• Role of hydrolysis and
dehydration synthesis
• For each macromolecule,
know the following:
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Elements and monomers
Structures
Functions
Examples