chapter 3 the structure and function of macromolecules “you are what you eat!”
TRANSCRIPT
CHAPTER 3The Structure and Function of
Macromolecules
“You are what you eat!”
What does it mean to be a MACROmolecule?
You must be a large molecule with a complex structure
“little” moleculeMacromolecule
Most macromolecules are polymers, built from monomers
What is a polymer?• Poly = many; mer = part. • A long molecule made of monomers
bonded together What is a monomer?
• Mono = one; mer = part• A monomer is a sub-unit (building block)
of a polymer.
Three of the classes of life’s organic molecules are polymers• Carbohydrates, Proteins, Nucleic acids
Making Polymers How do monomers bind together to form
polymers?• condensation or dehydration
synthesis reactions occur (removal of water)
Breaking Polymers How can polymers break down when
monomers are needed? Hydrolysis reaction
• Hydro = water; lysis = break• “Water” is added to “break” the
molecule apart
Hydrolysis
Classes of Organic Molecules:
• Carbohydrates• Lipids• Proteins• Nucleic Acids
CARBOHYDRATES
What are Carbohydrates?• Sugars and their polymers• Carbo = carbon, hydrate = water;
carbohydrates have the molecular formula (CH2O)n
Functions of Carbohydrates in living things:• Major fuel/energy source• Can be used as raw materials for other
Macromolecules• Structural/building material in plants
What is the Carbohydrate Monomer?• Monosaccharide (“mono” = one;
“saccharide” = sugar)
Structure of Monosaccharides Contain only C, H, O Hydroxyl group is attached to each carbon One carbon contains a carbonyl group
In aqueous solutions many monosaccharides form rings:
Structure of Disaccharides
Consist of two monosaccharides Are joined by a glycosidic linkage What reaction forms the glycosidic linkage?
• Dehydration synthesis
Polysaccharides Structure: Polymers of a few hundred or a
few thousand monosaccharides.
Functions: • energy storage molecules in animals • structural support in plants
Starch is a plant storage form of energy, easily broken down into glucose units
Glycogen is the animal short-term storage form of energy
Made up of many glucose monomers linked together
Cellulose is a fiber-like structural material made of glucose monomers used in plant cell walls
Why is Cellulose so strong?Why can we not break down
cellulose?
Cellulose polymers are bonded together with different arrangements and bonds
Chitin is a polysaccharide used as a structural material in arthropod exoskeleton and fungal cell walls.
PROTEINS
Proteins
What are Proteins?• Chains of amino acid monomers connected
by peptide bonds• Have a 3 dimensional globular shape
Examples of Protein Functions Immune System
• Binding of antibodies (proteins) to foreign substances
Transport• Membrane transport proteins that move substances
across cell membranes• Hemoglobin carries oxygen, iron, and other
substances through the body. Muscle Contraction
• actin and myosin fibers that interact in muscle tissue.
Signaling• Hormones such as insulin regulate sugar levels in
blood.
Amino Acids
Monomers of polypeptides• Molecules with carboxyl and amino
groups• Differ in their properties due to differing
side chains, called R groups
20 different amino acids
exist
The sequence of amino acids and the interactions of the different amino acids determine a proteins shape
Peptide bonds connect amino acids to form polypeptide chains
One or more polypeptide chains make up a protein
Proteins are very complex! Their specific structure determines their
function.
HEMOGLOBIN: Transport of gases and iron in blood ACTIN: Filament involved in
muscle contraction
Sickle Cell Disease: A simple change in Primary Structure
Enzymes Are a type of protein that acts as a catalyst,
speeding up chemical reactions up to 10 billion times faster than they would spontaneously occur.
Environmental Factors That May Affect Protein Structures
Change in environment may lead to denaturation of protein (pH, temperature, salinity, etc.)• Denature = change in structure
Denatured protein is biologically inactive Can renature IF primary structure is not lost
B. LIPIDS What are Lipids?• Fats, phospholipids, steroids, waxes, pigments• Hydrophobic (“hydro”=water; “phobic” = fearing)• Consist mostly of hydrocarbons• Do NOT consist of polymers
Functions of Lipids in living things:• Energy storage • membrane structure• Protecting against desiccation
(drying out). • Insulating against cold.• Absorbing shocks. • Regulating cell activities by
hormone actions.
Structure of Fats (Triglycerides) Consist of a single glycerol and three fatty
acids Glycerol – an alcohol with three carbons Fatty Acid - Long Hydrocarbon chains with a
Carboxyl group at one end.
Saturated and Unsaturated Fats
Unsaturated fats :• one or more double bonds
between carbons in the fatty acids allows for “kinks” in the tails
• liquid at room temp• most plant fats
Saturated fats:• No double bonds in fatty
acid tails• solid at room temp• most animal fats
(a) Saturated fat and fatty acid
Stearic acid
(b) Unsaturated fat and fatty acidcis double bondcauses bending
Oleic acid
Saturated fatty acid
Saturated fatty acid
Unsaturated fatty acid
Why are Unsaturated Fats better for you than Saturated Fats?
3. Phospholipids Structure: Glycerol + 2 fatty acids +
phosphate group. Function: Main structural component of
membranes, where they arrange in bilayers.
Phospholipids in Water
4. Waxes
Function:• Lipids that serve as coatings for
plant parts and as animal coverings.
5. Steroids Structure: Four carbon rings with no fatty acid
tails Functions:
• Component of animal cell membranes (Ex: Cholesterol)
• Modified to form sex hormones
NUCLEIC ACIDS
D. Nucleic Acids : The stuff of Genes
Nucleic acids store and transmit hereditary information
Genes• Are the units of inheritance• Program the amino acid sequence of
polypeptides• Are made of nucleic acids
Two Kinds of Nucleic Acids DNA (Deoxyribonucleic acid)
• double stranded• can self replicate• makes up genes which code for
proteins is passed from one generation to another
RNA (Ribonucleic acid)
• single stranded • functions in actual synthesis of
proteins coded for by DNA• is made from the DNA template
molecule
Nucleotide Monomer Structure
Both DNA and RNA are composed of nucleotide monomers.
Nucleotide = 5 carbon sugar, phosphate, and nitrogenous base
Deoxyribose in DNA Ribose in RNA
2. Building the Polymer Phosphate group of one nucleotide forms
strong covalent bond with the #3 carbon of the sugar of the other nucleotide.
DNA:
• Double helix
• 2 polynucleotide chains wound into the double helix
• Base pairing between chains with H bonds
• A - T
• C - G
Summary of the Organic Molecules: