Download Lecture, The Molecules of Life

The Molecules of Life:
Structure and Function
Objective
To understand the structure and function of biomacromolecules 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
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“Biomacromolecules”
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Carbohydrates
Lipids
Proteins
Nucleic Acids
These make up cells and can be used by
cells for energy
Polymers vs. Monomers
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Poly = many; Mer = part
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In biology, a polymer is a
large molecule consisting of
many smaller sub-units
(often repeated) bonded
together.
Mono = one
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A monomer is a sub-unit
(single unit) of a polymer.
Making a Polymer
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Dehydration Synthesis reactions
Monomers bond to one another through the
removal of water.
Why?
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Stores energy
Conserves space
Breaking a Polymer
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Hydrolysis Reactions
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hydro = water
lysis = to break or lyse
Polymers are broken down into monomers with
the use of water.
Why?
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Access energy
To build new polymers
Carbohydrates
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Molecular formula (C H2 O)n
Store energy in chemical structure
Glucose
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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
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“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
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Polymers of a few hundred or a few thousand
monosaccharides
Function as energy storage molecules or for structural
support
Example Carbohydrates
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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
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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
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Long chains of mostly carbon and hydrogen atoms
with an acid (-COOH) group at one end
Resemble long flexible tails
Saturated vs. Unsaturated Fats
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Unsaturated fats :
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liquid at room temp
one or more -C=C- (double bonds) between carbons
causing “kinks” in the tails
most plant fats
Saturated fats:
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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
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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
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1 glycerol + 2 fatty acids + phosphate group.
Connected by “phosphodiester” bond
Main structural component of cell membranes, where they
arrange in bilayers.
Waxes
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Lipids that serve as coatings for plant parts and as animal
coverings. Prevents dessication due to insolubility in water.
Steroids
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Four carbon rings with no fatty acid tails
Component of animal cell membranes (cholesterol)
Modified to form sex hormones (estrogen, testosterone)
Functions of Lipids
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Energy storage
Membrane structure
Protecting against desiccation (drying out)
Insulating against cold
Absorbing shock
Regulating cell activities by hormone actions
Proteins
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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
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Amino acids = monomers
Consist of an asymmetric
carbon bonded to:
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Hydrogen
Amine group
Carboxyl (acid) group
Variable R group specific to
each amino acid
Properties of Amino Acids
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Grouped by polarity
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Variable R groups (“side chains”) confer different
properties to each amino acid
Example Proteins
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Enzymes
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Accelerate specific chemical reactions
Structure
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keratin - found in hair and nails
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collagen - found in connective tissue
Muscle Contraction
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actin and myosin fibers that interact in muscle
tissue
Example Proteins
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Immune System Function
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Antibodies recognize and flag foreign substances.
Carriers
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Membrane transport proteins move substances
across cell membranes
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Blood proteins (hemoglobin) carry oxygen
throughout the body
Signaling and Communication
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Hormones such as insulin (regulate blood sugar
levels) and adrenaline (increase heart rate to adjust
to needs) used to help body respond
Recap: Discuss with
your group…
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Carbohydrate Functions:
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Lipid Functions:
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Examples include:
How?
Examples include:
How?
Protein Functions:
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Examples include:
How?
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http://www.youtube.com/watch?v=Oz2x_yx
PXww&feature=related&safety_mode=true
&persist_safety_mode=1&safe=active
http://www.youtube.com/watch?v=lijQ3a8y
UYQ&safety_mode=true&persist_safety_m
ode=1&safe=active
How to make a Protein
in 4 easy steps!
1.
2.
3.
4.
Primary Structure
Secondary Structure
Tertiary Structure
Quaternary Structure
Primary Structure
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Sequence of amino acids in a protein, bonded by peptide bonds
This creates the “polypeptide”
Let’s Model the Primary Structure:
Salivary Amylase
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Observe the properties
of the 20 Amino Acids.
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What do the different colors
represent?
How do you think they
would interact?
Make this Primary Sequence:
MSDKRCTYPCAENQ
Place amino acids about 1 inch apart (2 finger widths)
and fold pieces
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White = polar/hydrophilic
Yellow = nonpolar/hydrophobic
Blue = basic (+ charged)
Red = acidic (- charged)
Green = “sulfur R-group” (bonds only Cysteines)
Secondary Structure
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Repeated folding of backbone of polypeptide
How? H bonds form between atoms in backbone
2 types: a-helix, b-pleated sheets
Let’s model Secondary Structure
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Look at your string of amino acids.
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What do the different colors represent?
Note the order of colors.
Take the “backbone” and create some a-helices
and some b-pleated sheets.
Tertiary Structure
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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&per
sist_safety_mode=1&safe=active
Let’s model Tertiary Structure
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Note the colors on your polypeptide.
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White = polar/hydrophilic
Yellow = nonpolar/hydrophobic
Blue = basic (+ charged)
Red = acidic (- charged)
Green = “sulfur R-group” (bonds only Cysteines)
Quaternary Structure
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2 or more polypeptides
bonded together
How? Attraction
between backbones and
R groups of neighboring
globs
Let’s model Quaternary
Structure
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Find a neighbor, and attach R groups that
might be attracted to each other. What types
would?
Factors That May Impact Protein Folding
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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?
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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
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Protein Activity Wrap Up
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Stamps for journal activity (models)
Draw your last diagram!
Homework due Thursday
The Structure and Function of Macromolecules
Reading (linked to website) and WS