CHAPTER 5 The Structure and Function of Macromolecules

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CHAPTER 5The Structure and Function of
Macromolecules

• You are what you eat!

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What does it mean to be a MACROmolecule?

• You must be a Large molecule
• You have a complex structure

Macromolecule
little molecule
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I. 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 of a polymer.

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• Three of the classes of lifes organic molecules
  are polymers
• Carbohydrates, Proteins, Nucleic acids

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A. Making and Breaking Polymers

• How do monomers bind to form polymers?
• condensation reactions called dehydration
  synthesis (removal of water)

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How can polymers break down when monomers are
needed?

• Hydrolysis reaction
• Hydro water lysis break
• Water is added and the lysis of the polymer
  occurs.

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Hydrolysis
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II. Classes of Organic Molecules

• Carbohydrates
• Lipids
• Proteins
• Nucleic Acids

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A. CARBOHYDRATES
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• 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)

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1. Structure of Monosaccharides

• Contain only C, H, O
• Hydroxyl group is attached to each carbon
• One carbon contains a carbonyl group

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• Classified according to the size of their carbon
  chains and location of Carbonyl group

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• In aqueous solutions many monosaccharides form
  rings

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2. Structure of Disaccharides

• Consist of two monosaccharides
• Are joined by a glycosidic linkage
• What reaction forms the glycosidic linkage?
• Dehydration synthesis

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3. Polysaccharides

• Structure Polymers of a few hundred or a few
  thousand monosaccharides.
• Functions energy storage molecules or for
  structural support

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• Starch is a plant storage form of energy, easily
  broken down into glucose units

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• Cellulose is a fiber-like structural material
  made of glucose monomers used in plant cell walls

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Why is Cellulose so strong?

• Glucose monomers are flipped to expose equal
  Hydroxyl groups on either side of the chain
• When Cellulose chains are lined up next to each
  other, they Hydrogen Bond making a strong
  material thats difficult to break!

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• Glycogen is the animal short-term storage form of
  energy
• Glucose monomers

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• Chitin is a polysaccharide used as a structural
  material in arthropod exoskeleton and fungal cell
  walls.

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B. LIPIDS

• What are Lipids?
• Fats, phospholipids, steroids, waxes, pigments
• Hydrophobic (hydrowater phobic fearing)
• Consist mostly of hydrocarbons
• Do NOT consist of polymers

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• 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.

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1. Structure of Fats (Triglycerides)

• Consist of a single glycerol and usually three
  fatty acids
• Glycerol an alcohol with three carbons
• Fatty Acid - Long Hydrocarbon chains with a
  Carboxyl group at one end.

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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

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Saturated fatty acid
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Saturated fatty acid
Unsaturated fatty acid
Why are Unsaturated Fats better for you than
Saturated Fats?
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3. Phospholipids

• Structure Glycerol 2 fatty acids phosphate
  group.
• Function Main structural component of
  membranes, where they arrange in bilayers.

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Phospholipids in Water
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4. Waxes

• Function
• Lipids that serve as coatings for plant parts and
  as animal coverings.

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5. Steroids

• Structure Four carbon rings with no fatty acid
  tails
• Functions
• Component of animal cell membranes (Ex
  Cholesterol)
• Modified to form sex hormones

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PROTEINS
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C. Proteins

• What are Proteins?
• Chains of amino acid monomers connected by
  peptide bonds
• Have a 3 dimensional globular shape

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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.

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Amino Acids

• Monomers of polypeptides
• Molecules with carboxyl and amino groups
• Differ in their properties due to differing side
  chains, called R groups

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20 different amino acids exist
The sequence of amino acids and the interactions
of the different amino acids determine a proteins
shape
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• Peptide bonds connect amino acids to form
  polypeptide chains
• One or more polypeptide chains make up a protein

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Proteins are very complex! Their specific
structure determines their function.
HEMOGLOBIN Transport of gases and iron in blood
ACTIN Filament involved in muscle contraction
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Four Levels of Protein Structure

• Primary structure
• Is the unique sequence of amino acids in a
  polypeptide

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• Secondary structure
• Is the folding or coiling of the polypeptide into
  a repeating configuration resulting from hydrogen
  bonding of amino with carboxyl groups
• Includes the a helix and the ß pleated sheet

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• Tertiary structure
• Is the overall three-dimensional shape of a
  polypeptide
• Results from interactions between amino acids and
  R groups

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• Quaternary structure
• Is the overall protein structure that results
  from the aggregation of two or more polypeptide
  subunits

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• Chaperonins
• Are protein molecules that assist in the proper
  folding of other proteins

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Sickle Cell Disease A simple change in Primary
Structure
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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.

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Environmental Factors That Determine Protein
Conformation

• Change in environment may lead to denaturation of
  protein (pH, temperature, salinity, etc.)
• Denatured protein is biologically inactive
• Can renature if primary structure is not lost

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NUCLEIC ACIDS
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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

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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

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1. 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
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2. Building the Polymer

• Phosphate group of one nucleotide forms strong
  covalent bond with the 3 carbon of the sugar of
  the other nucleotide.

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• DNA
• Double helix
• 2 polynucleotide chains wound into the double
  helix
• Base pairing between chains with H bonds
• A - T
• C - G

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Summary of the Organic Molecules