chapter 6.4 the structure and function of macromolecules “you are what you eat!”
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CHAPTER 6.4The Structure and Function of
Macromolecules
“You are what you eat!”
6.4: The Building Blocks of LifeThe elements of life:Organisms are made up of cells. Cells contain molecules made up of the following elements:
CHNOPSCarbon (C)Hydrogen (H)Nitrogen (N)Oxygen (O)Phosphorus (P)Sulfur (S)
These elements come from the foods we eat.
Matter Cannot be Created nor Destroyed!
It gets recycled!!!!
How does CHONPS get into our cells?
Carbon:
All life on Earth is made of carbon-containing molecules.
Carbon can form 4 covalent bonds with other atoms.
Examples: Glucose (C6H1206) & Carbon Dioxide (CO2)
The chemistry of all living things is based on the key element: CARBON
Organic Chemistry:Because of the many important and
unique properties of carbon-based molecules, there is a special branch of chemistry devoted just to the study of these molecules.
Organic chemistry is the study of compounds containing carbon.
The carbon compounds we are studying are called Macromolecules.
There are 4 major categories of macromolecules:1. Carbohydrates
CHO2. Lipids
CHO3. Proteins
CHONPS4. Nucleic Acids
CHNOP
http://www.brainpop.com/health/bodysystems/bodychemistry/
What does it mean to be a MACROmolecule?
You must be a Large molecule You have a complex structure
“little” moleculeMacromolecule
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?
• A monomer is a sub-unit of a polymer.
Three of the classes of life’s organic molecules are polymers (made up of monomers)• Carbohydrates, Proteins, Nucleic acids
A. Making and Breaking Polymers
How do monomers bind to form polymers?• condensation reactions called
dehydration synthesis (removal of water)
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.
Hydrolysis
II. Classes of Organic Molecules:
• Carbohydrates• Lipids• Proteins• Nucleic Acids
1. 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• Complex sugars = building material in
plants What is the Carbohydrate Monomer?
• Monosaccharide (“mono” = one; “saccharide” = sugar)
1. Structure of Monosaccharides Contain only C, H, O Hydroxyl group is attached to each carbon One carbon contains a carbonyl group
• Classified according to the size of their carbon chains and location of Carbonyl group
In aqueous solutions many monosaccharides form rings:
2. Structure of Disaccharides
Consist of two monosaccharides Are joined by a glycosidic linkage What reaction forms the glycosidic linkage?
• Dehydration synthesis
3. Polysaccharides
Structure: Polymers of a few hundred or a few thousand monosaccharides.
Functions: energy storage molecules or for structural support:
Starch is a plant storage form of energy, easily hydrolyzed to glucose units
Cellulose is a fiber-like structural material made of glucose monomers used in plant cell walls
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 that’s difficult to break!
Glycogen is the animal short-term storage form of energy
Glucose monomers
Chitin is a polysaccharide used as a structural material in arthropod exoskeleton and fungal cell walls.
2. LIPIDS What are Lipids?• Fats, phospholipids, steroids, waxes, pigments• Hydrophobic (“hydro”=water; “phobic” = fearing)• Consist mostly of hydrocarbons• Do NOT consist of monomers and polymers
Functions of Lipids in living things:• Energy storage • membrane structure• Protects against desiccation (drying
out) • Insulates against cold.• Absorbing shock
1. Structure of Lipids Consist of a single glycerol and usually 1-3
fatty acid hydrocarbon chains 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
A. Phospholipids Structure: Glycerol + 2 fatty acids +
phosphate group. Function: Main structural component of
membranes, where they arrange in bilayers.
Phospholipids in Water
B. Triglycerides
Structure - Have one glycerol and three fatty acid chains
Function - necessary for certain bodily functions (fat stores), but high levels of them can lead to heart disease.
This is a triglyceride:
C. Waxes
Function:• Lipids that serve as coatings for
plant parts and as animal coverings.
D. Steroids Structure: Four carbon rings with no fatty acid
tails Functions:
• Component of animal cell membranes (Ex: Cholesterol)
• Modified to form sex hormones
PROTEINS
3. Proteins
What are Proteins?• Chains of amino acid monomers connected
by peptide bonds• Have a 3 dimensional globular shape
Examples of Protein Functions
Enzymes (see next slide for a visual)• Act as catalysts to speed up the rate of reactions
Immune System• Binding of antibodies (proteins) to foreign substances in
the body Transport
• Transport proteins move substances across cell membranes
• Hemoglobin carries oxygen, iron, and other substances through the body
Muscle Contraction• actin and myosin protein fibers interact in muscle tissue
Cell Signaling• Hormones such as insulin regulate sugar levels in blood
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.
Amino Acids
Are the monomers of polypeptides• Structure: amino groups, carboxyl
groups, and• Differing side chains, called R groups,
effects the properties of amino acids.
20 different amino acids
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
Four Levels of Protein Structure
Primary structure• Is the unique
sequence of amino acids in a polypeptide
Figure 5.20–
Amino acid subunits
+H3NAmino end
oCarboxyl end
oc
GlyProThrGlyThr
Gly
GluSeuLysCysProLeu
MetVal
Lys
ValLeu
AspAlaVal ArgGly
SerPro
Ala
Gly
lle
SerProPheHisGluHis
Ala
GluVal
ValPheThrAlaAsn
AspSer
GlyProArg
ArgTyrThr
lleAla
Ala
Leu
LeuSer
ProTyrSerTyrSerThr
Thr
Ala
ValVal
ThrAsnProLysGlu
ThrLys
SerTyrTrpLysAlaLeu
GluLle Asp
O C α helix
β pleated sheet
Amino acidsubunits NC
H
C
O
C NH
CO
H
R
C N
H
C
O H
C
R
NH
H
R C
O
R
C
H
N
H
C
OHN
CO
R
C
H
N
H
HC
R
C
O
C
O
C
N
HH
R
C
C
O
NH
H
C
R
C
O
N
H
R
C
HC
ONH
H
C
R
C
O
N
H
R
C
H C
ONH
H
C
R
C
O
N H
H C R
N H O
O C N
C
RC
HO
CH R
N H
O C
RC H
N H
O C
H C R
N H
CC
N
RH
O C
H C R
N H
O C
RC H
HC
RNH
CO
C
N
H
R
C
HC
O
NH
C
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 α helix and the β pleated sheet
H H
Figure 5.20
Tertiary structure• Is the overall three-dimensional shape
of a polypeptide• Results from interactions between
amino acids and R groups
CH2CH
OH
O
CHO
CH2
CH2 NH3+ C-O CH2
O
CH2SSCH2
CH
CH3
CH3
H3C
H3C
Hydrophobic interactions and van der Waalsinteractions
Polypeptidebackbone
Hydrogenbond
Ionic bond
CH2
Disulfide bridge
Quaternary structure• Is the overall protein structure that results
from the aggregation of two or more polypeptide subunits
Sickle Cell Disease: A simple change in Primary Structure
Factors That Affect Protein Shape
Proteins can denature (fall apart) if:• pH is too high or too low• Temperature is too high• Salinity is too high
Denatured proteins are biologically inactive
NUCLEIC ACIDS
4. 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 DNA
1. Monomers of Nucleic Acids
Both DNA and RNA are composed of nucleotide monomers.
Nucleotides are composed of: a 5 carbon sugar, a phosphate group, and a nitrogenous base
Phosphate
5 Carbon Sugar
Nitrogenous Base
2. Building the Polymer On your paper, label the phosphate groups
and 5 carbon sugars. List the 4 different kinds of nitrogenous bases, too.
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:
Saturated fatty acid
Unsaturated fatty acid
Why are Unsaturated Fats better for you than Saturated Fats?
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