Transcript Macromolecules

Chapter 5:
The Structure and Function of
Macromolecules
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.
4 Main Types Of Macromolecules
 Carbohydrates
 Lipids
 Protein
 Nucleic acids
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
 Monosaccharides
 Disaccharides
 Oligosaccharides
 Polysaccharides
Monosaccharides
 Mono - single
 Saccharide - sugar
 Simple sugars.
 3 to 7 carbons.
 Can be in linear or ring forms.
 Can be “Aldoses” or “Ketoses” depending on
the location of the carbonyl group.
Examples
 Glucose
 Galactose
 Ribose
 Fructose
- OSE
 Word ending common for many
carbohydrates.
Disaccharides
 Sugar formed by joining two
monosaccharides through a “glycosidic
linkage”.
Examples
 Maltose = glucose + glucose
 Lactose = glucose + galactose
 Sucrose = glucose + fructose
Oligosaccharides
 2 - 10 joined simple sugars.
 Used in cell membranes.
Polysaccharides
 Many joined simple sugars.
 Used for storage or structure.
 Examples:
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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 (14 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
Lipids
 Diverse hydrophobic molecules.
 Made of C,H,O
 No general formula.
 C:O ratio is very high in C.
Fats and Oils
 Fats - solid at room temperature.
 Oils - liquid at room temperature.
Fats and Oils
 Made of two kinds of smaller molecules.
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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:
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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
Movie
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:
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Nonpolar - 9 AA
Polar - 6 AA
Electrically Charged
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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 the
R groups.
 Two main secondary structures:
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a helix
pleated sheets
Tertiary
 Bonding between the R groups.
 Examples:
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hydrophobic
ionic bonding
Disulfide bridges
interactions
(covalent bond)
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:
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pH shifts
high salt concentrations
heat
Nucleic Acids
 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:
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nitrogenous base
pentose sugar
phosphate
Nitrogenous Bases
 Rings of C and N
 The N atoms tend to take up H+ (base).
 Two types:
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Pyrimidines (single ring)
Purines (double rings)
Pentose Sugar
 5-C sugar
 Ribose - RNA
 Deoxyribose – DNA
 RNA and DNA differ in a –OH group on the
3rd carbon.
Nucleosides and Nucleotides
 Nucleoside = base + sugar
 Nucleotide = base + sugar + Pi
DNA
 Deoxyribonucleic Acid.
 Makes up genes.
 Genetic information source
for most life.
RNA
 Ribonucleic Acid.
 Structure and protein synthesis.
 Genetic information for a few viruses only.
Summary
 For each macromolecule, know the following:
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Elements and monomers
Structures
Functions