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The Molecules of Life: Structure and Function
Objective To understand the structure and function of biomac-romolecules and to be able to identify them based on their characteristics.
Essential Question: What are the molecules of life, what are their general structures, and functions?
Molecules of Life “Biomacromolecules”
Carbohydrates Lipids Proteins Nucleic Acids
These make up cells and can be used by cells for energy
Polymers vs. Monomers
Poly = many; Mer = part In biology, a polymer is a
large molecule consisting of many smaller sub-units (often repeated) bonded together.
Mono = one A monomer is a sub-unit
(single unit) of a polymer.
Making a Polymer Dehydration Synthesis reactions Monomers bond to one another through the removal of water. Why?
Stores energy Conserves space
Breaking a Polymer
Hydrolysis Reactions hydro = water lysis = to break or lyse
Polymers are broken down into monomers with the use of water.
Why? Access energy To build new polymers
Carbohydrates Molecular formula (C H2 O)n
Store energy in chemical structure Glucose
most common monosaccharide produced by photosynthetic autotrophs
Each “carbon” is surrounded by a “hydrate” (water)
Carbohydrates are classified according to the size of their carbon chains, varies from 3 to 7 carbons
Triose = 3 carbons Pentose = 5 carbons Hexose = 6 carbons
In aqueous solutions, many monosaccharides form rings:
Disaccharides “Double sugar” consisting of 2 monosaccharides joined
by a glycosidic linkage. What reaction forms the glycosidic linkage?
Example Disaccharides
Lactose = glucose + galactose Sucrose = glucose + fructose
Polysaccharides Polymers of a few hundred or a few thousand
monosaccharides Function as energy storage molecules or for structural support
Example Carbohydrates Starch = a plant storage from of energy, easily hydrolyzed
to glucose units. Polysaccharide. Cellulose = a fiber-like structural material; tough and
insoluble. Used in plant cell walls. Polysaccharide. Glycogen = a highly branched chain in animals to store
energy in muscles and the liver. Polysaccharide. Chitin = used as a structural material in arthropod
exoskeleton and fungal cell walls. Polysaccharide. Lactose = found in milk and dairy products. Disaccharide. Glucose = simplest sugar; used by mitochondria in all
cells for energy. Feeds brain. Monosaccharide.
Lipids Large molecules Diverse in structure Nonpolar, so insoluble in
water Store energy in chemical
structure Groups: Fats, oils,
phospholipids, sterols, waxes
Structure of Fatty Acids Long chains of mostly carbon and hydrogen atoms
with an acid (-COOH) group at one end Resemble long flexible tails
Saturated vs. Unsaturated Fats Unsaturated fats :
liquid at room temp one or more -C=C- (double bonds) between carbons
causing “kinks” in the tails most plant fats
Saturated fats: solid at room temp only single C-C bonds in fatty acid tails Carbons fully surrounded (“saturated”) with H’s most animal fats
Structure of Triglycerides 1 glycerol + 3 fatty acids Fatty acids and glycerol bound together by ester bonds. Found in food (oils and fats); long term energy storage
Structure of Phospholipids 1 glycerol + 2 fatty acids + phosphate group. Connected by “phosphodiester” bond Main structural component of cell membranes, where they arrange in
bilayers.
Waxes Lipids that serve as coatings for plant parts and as animal
coverings. Prevents dessication due to insolubility in water.
Steroids Four carbon rings with no fatty acid tails Component of animal cell membranes (cholesterol) Modified to form sex hormones (estrogen, testosterone)
Functions of Lipids Energy storage Membrane structure Protecting against desiccation (drying out) Insulating against cold Absorbing shock Regulating cell activities by hormone actions
Which lipids
provide these
functions?
Proteins 3-dimensional “globular” shape Consist of many peptide bonds between 20 possible
amino acid monomers, made by dehydration synthesis Polypeptide = “many” “peptide bond”s; A chain of
amino acids
Structure of Amino Acids Amino acids = monomers Consist of an asymmetric
carbon bonded to: Hydrogen Amine group Carboxyl (acid) group Variable R group specific
to each amino acid
Properties of Amino Acids Grouped by polarity Variable R groups (“side chains”) confer different
properties to each amino acid
Example Proteins Enzymes
Accelerate specific chemical reactions Structure
keratin - found in hair and nails collagen - found in connective tissue
Muscle Contraction actin and myosin fibers that interact in muscle
tissue
Immune System Function Antibodies recognize and flag foreign substances.
Carriers Membrane transport proteins move substances
across cell membranes Blood proteins (hemoglobin) carry oxygen
throughout the body Signaling and Communication
Hormones such as insulin (regulate blood sugar levels) and adrenaline (increase heart rate to adjust to needs) used to help body respond
Example Proteins
Carbohydrate Functions: Examples include: How?
Lipid Functions: Examples include: How?
Protein Functions: Examples include: How?
Recap: Discuss with your group…
http://www.youtube.com/watch?v=Oz2x_yxPXww&feature=related&safety_mode=true&persist_safety_mode=1&safe=active
http://www.youtube.com/watch?v=lijQ3a8yUYQ&safety_mode=true&persist_safety_mode=1&safe=active
How to make a Protein in 4 easy steps!
1. Primary Structure2. Secondary Structure3. Tertiary Structure4. Quaternary Structure
Primary Structure Sequence of amino acids in a protein, bonded by peptide bonds This creates the “polypeptide”
Let’s Model the Primary Structure: Salivary Amylase Observe the properties
of the 20 Amino Acids. What do the different colors
represent? How do you think they
would interact?
MSDKRCTYPCAENQ
Make this Primary Sequence:
Place amino acids about 1 inch apart (2 finger widths) and fold pieces
White = polar/hydrophilic Yellow = nonpolar/hydrophobic Blue = basic (+ charged) Red = acidic (- charged) Green = “sulfur R-group” (bonds only Cysteines)
Secondary Structure Repeated folding of backbone of polypeptide How? H bonds form between atoms in backbone 2 types: helix, pleated sheets
Let’s model Secondary Structure Look at your string of amino acids.
What do the different colors represent? Note the order of colors. Take the “backbone” and create some -helices
and some -pleated sheets.
Tertiary Structure Behavior of R groups
determines folding of polypeptide
How? Interactions between R groups
http://www.youtube.com/watch?NR=1&v=ysPt1lIllcs&safety_mode=true&persist_safety_mode=1&safe=active
Let’s model Tertiary Structure Note the colors on your polypeptide.
White = polar/hydrophilic Yellow = nonpolar/hydrophobic Blue = basic (+ charged) Red = acidic (- charged) Green = “sulfur R-group” (bonds only Cysteines)
Quaternary Structure 2 or more polypeptides
bonded together How? Attraction
between backbones and R groups of neighboring globs
Let’s model Quaternary Structure Find a neighbor, and attach R groups that
might be attracted to each other. What types would?
Factors That May Impact Protein Folding Depends on physical conditions of environment
pH, temperature, salinity, etc. Change in environment may lead to denaturation of protein Denatured protein is biologically inactive Can renature if primary structure is not lost What happens when protein folding goes wrong?
http://www.youtube.com/watch?NR=1&v=H2Ouxl_GNjA&safety_mode=true&persist_safety_mode=1&safe=active http://www.youtube.com/watch?v=RNIwwLdDLnI&feature=related&safety_mode=true&persist_safety_mode=1&safe=active
Your Tasks Protein Activity Wrap Up
Stamps for journal activity (models) Draw your last diagram!
Homework due Thursday The Structure and Function of Macromolecules Reading (linked to website) and WS