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