Download The structure and Function of Macromolecules

THE STRUCTURE AND
FUNCTION OF
MACROMOLECULES
MACROMOLECULES DEFINED…
• Large
• Organic (made of carbon compounds)
• 4 Classes
• Essential for life
• Most are polymers (long chains of
covalently-bonded building blocks
called, “monomers”)
• Form by dehydration (removing H2O)
• Break apart by hydrolysis (adding H2O)
OVERVIEW:
1. Carbohydrates
• Roles: fuel, building materials
• Sugars
2. Lipids
• Roles: energy storage, cell
membranes
• Fats
OVERVIEW:
3. Proteins
• Speed up chemical reactions,
structural support, storage,
transport, cellular communication,
movement, defense
• Enzymes
4. Nucleic Acids
• Store and transmit hereditary
information
• DNA (deoxyribonucleic acid)
CARBOHYDRATES
CARBOHYDRATES
• Monomers: MONOSACCHARIDES
• Multiples of the unit CH2O
• Key features:
• Carbonyl group (>C=O)
• Hydroxyl groups (-OH)
• Aldose (aldehyde: =O on end) or Ketose (ketone: =O in middle)
• names end in “-ose”
• Most form rings in aqueous solutions
CARBOHYDRATES
• Monosaccharides - Major nutrients for cells and raw material for
small organic molecules
• Disaccharides – joined by glycosidic linkage (sucrose = glucose +
fructose)
• Polysaccharides – macromolecules, 100’s to 1,000’s, ex. = starch
(energy storage in plants) and glycogen (energy storage in
animals), cellulose (plant cell walls), chitin (arthropod exoskeletons)
LIPIDS
LIPIDS
• Do not consist of polymers
• Little or no affinity for water
• Three kinds • 1. Fats: Energy Storage
• Consist of glycerol (alcohol with 3 C’s) and fatty acids (long
hydrocarbon chain with a carboxyl group on one end)
O=C-OH
• Triacylglycerol = 3 FA molecules joined to a glycerol by an ester
linkage
• Saturated – no double bonds, pack tightly, solid @ room temp.,
animal fat; Unsaturated = at least 1 double bond, pack less
tightly, liquid @ room temp, plant fats
LIPIDS
• Three kinds (continued) • 2. Phospholipids: Cell Membranes
• Only 2 FA’s attached to a glycerol (hydrophilic head &
hydrophobic tail)
• Bilayers shield hydrophobic regions from water
• 3. Steroids
• 4 fused rings (with varying functional groups)
• Ex. = cholesterol – a component of animal cell membranes,
precursor for other steroids (such as hormones)
PROTEINS
PROTEINS
• Many different functions (named earlier)
• Enzymes are very important
• Catalysts – speed up chemical reactions without being consumed
• Structures are diverse
• 20 different Amino Acids = building blocks
• Each has an amino group (N), a carboxyl group (O & OH), and an
“R” group
• Can be Nonpolar (hydrophobic), Polar (hydrophilic), or Charged
(acidic/basic)
• Many amino acids = polypeptide; 1 or more polypeptides folded into
a unique shape = protein
• Peptide bonds join amino acids together
PROTEINS
• 4 Levels of Protein structure:
• 1. Primary – sequence of amino acids; like order of letters
in a word
• 2. Secondary – coils/folds in protein structure; alpha helix,
beta pleated sheet; results from interactions of the
polypeptide backbone (H and O)
• 3. Tertiary – overall shape resulting from interactions
between R groups (side chains); hydrophobic
interactions, disulfide bridges (sulfhydryl groups –SH bond)
• 4. Quaternary – 2 or more polypeptide chains
aggregated into one functional macromolecule;
example: hemoglobin (has 4 subunits)
PROTEINS
• Changes in Conformation: when shape is changed, ability
to function changes; Example: sickle cell disease (abnormal
hemoglobin  deformed blood cells blood clots)
• Denaturation – unraveling of protein due to pH, salt,
temperature, etc.
• Chaperonins – proteins that assist with folding other proteins
NUCLEIC ACIDS
NUCLEIC ACIDS
• http://thatsafacttv.com/
• Instructions for building proteins is found in genes, which consist of DNA
• DNA: deoxyribonucleic acid
• Genetic information inherited from parents
• Bound in structures called, “chromosomes”
• Sugar, phosphate, base  “nucleotide” building blocks
• Ribose/deoxyribose = sugar
• Pyrimidine (5C ring) (C,T) / purine (6C ring) (A,G) = base
• Complimentary bases: Cytosine-Guanine; Thymine-Adenine
• Found in nucleus of cells
• Double helix
• Strand direction is 5’ to 3’, antiparallel strands (like a highway)
NUCLEIC ACIDS
• RNA: ribonucleic acid
• mRNA = a copy of the DNA code that interacts with proteinsynthesizing machinery (“ribosomes”) to make a polypeptide
• Single stand
• Uracil instead of Thymine