Ch. 5 The Molecules of Life
5.1 Carbon is the main
ingredient of organic
molecules
I. Carbon Skeletons and Functional
Groups
A. Carbon is very common in living things
1. Carbon can form up to 4 bonds with
other atoms due to 4 electrons in the
outer shell
2. Carbon may bond with other carbon
atoms
Carbon
Carbon Skeletons and Functional
Groups
B. Carbon backbones
Carbon Skeletons and Functional
Groups
C. Classification
1.Organic molecules- most molecules
that are comprised of Carbon in various
shapes (living)
2. Inorganic molecules- most noncarbon molecules (H2O, O2, and NH3)
(non-living)
Carbon Skeletons and Functional
Groups
D. Hydrocarbons- organic molecules
composed of only Carbon and
Hydrogen
1. Fuels such as methane CH4 as
natural gas
Carbon Skeletons and Functional
Groups
E. Functional Groups- group of atoms
within a molecule that interacts in a
predictable way; attached to a
hydrocarbon skeleton
1.Hydroxyl group- polar hydrophilic –
attract water around; also know as
alcohols (like ethanol)
Carbon Skeletons and Functional
Groups
• 2. Carbonyl group- polar hydrophilic;
bonds with two other molecules or
atoms. Oxygen end polar negative
charge.
Carbon Skeletons and Functional
Groups
a. If one or more of the bonds is
connected to a hydrogen – it is called
an aldehyde –polar hydrophilic
(vanilla bean, lemon grass)
Carbon Skeletons and Functional
Groups
b. If both bonds with carbon are other
than hydrogen – it is called a ketone polar hydrophilic (acetone, camphormoth balls)
Carbon Skeletons and Functional
Groups
3. Carboxyl group- polar, hydrophilic
weak acid, (fatty acid chains, vinegar,
niacin)
Carbon Skeletons and Functional
Groups
4. Amino group- polar hydrophilic, weak
base responsible for amino acid
formation (proteins)
Functional Groups
II. Monomers and Polymers
A. Monomers- small molecular units
B. Polymers- large chains of monomers
in various shapes
C. Life’s major Polymers: carbohydrates,
lipids, proteins, and nucleic acids
III. Building and Breaking
Polymers
A. Dehydration Synthesis- to lengthen a
polymer chain
1. A hydrogen atom and a hydroxyl group
from two monomers react
2. A new bond is formed and water is
released.
Dehydration Synthesis
Building and Breaking Polymers
B. Hydrolysis- to shorten a polymer
chain
1.A water molecule is added to a bond
between two monomers
2. The bond is broken an a H is added to
one monomer and a hydroxyl group to
another monomer
Hydrolysis
5.2 Carbohydrates provide fuel
and building material
I. Carbohydrates
I. Carbohydrates- organic compound
made of a sugar molecule
A. Sugars contain C,H,O in a 1 carbon : 2
hydrogen : 1 oxygen ratio
1. Multiple of CH2O
2. Most are ring structures
II. Monosaccharides
II. Monosaccharides- one sugar unit
molecule (end in –ose)
A.Glucose- both in straight chain and ring
1. Main fuel source for energy and to
build other organic molecules
2. Molecules not used may be
connected into larger molecules and
stored for later use
Glucose
Glucose - monosaccharide
Isomers
• Different compounds having the same
molecular formula are called isomers
• C4H8 hydrocarbons
Stereoisomers
• any of a group of isomers in which
atoms are linked in the same order but
differ in their spatial arrangement
• 1,2-dichlorocyclopentane
Stereoisomers of Glucose
Stereoisomers of Fructose
Isomers of C2H4O
III. Disaccharide
III. Disaccharide- a double sugar formed
from a dehydration reaction
A. Formation of Sucrose
1. Found in plant sap and table sugar –
can be broken down easily for energy
use
Glucose + Fructose  Sucrose + water
C6H12O6 + C6H12O6  C12H22O11 + H2O
Dehydration synthesis of sucrose
Disaccharide
Maltose (glucose + glucose)
Maltose
IV. Polysaccharides
IV. Polysaccharides- long polymer
chains made up of simple sugars
A. Starch- polysaccharide found in plants
made totally of glucose monomers
1. Found in potatoes, rice, and corn
Polysaccharides
B. Glycogen- polysaccharide found in
animals made totally of glucose
monomers that are highly branched
1. Stored as granules in muscle and
liver – broken down when body needs
energy
Polysaccharides
C. Cellulose- made up of glucose
monomers that arrange in cable-like
fibers in plants
1. Chains are linked by hydrogen bonds to form
tough cell walls in plants like
broccoli stems
2. Human unable to digest – functions as fiber
to help keep digestive system healthy
Polysaccharides
3. Cow and termites can break down
cellulose due to organism in side them
to get energy from it.
Polysaccharide- Cellulose
Polysaccharides
Properties of carbohydrates
IV. Properties of carbohydrates
• A. Hydrophilic – attract to water due to
many hydroxyl groups
• B. Monosaccharides and Disaccharides
dissolve readily in water
• C. Cellulose and some starches do not
dissolve easily but are hydrophilic
5.3 Lipids include fats &
steroids
I. Characteristics of Lipids
A. Hydrophobic- water avoiding or
fearing molecules
B. Functions of lipids
1. Serves as a boundary that surrounds
and contains aqueous contents of cells
2. Others serve as chemical signals or
store energy as fats
II. Fats
II. Fats – consists of a 3 carbon backbone
called glycerol (C3H8O3) attached to
three fatty acids, that contain long
hydrocarbon chains
A.Saturated fats- where all three fatty
acid chains contain the maximum
number of hydrogen atoms
Glycerol
• A trihydroxy sugar alcohol that is an
intermediate in carbohydrate and lipid
metabolism.
• It is used as a solvent, emollient,
pharmaceutical agent, and sweetening
agent
• Food, medicines, cosmetics,
Glycerol
Fats
1. All the carbon atoms form single bonds
a. Butyric acid- C4H8O2
(antihistamine properties)
2. Found in lard and butter – they are
solid at room temperature
Butyric acid - C4H8O2
Fats
B. Unsaturated fats- contains less than
the maximum number of hydrogen
atoms in one or more fatty acid chain
1. Some of the carbon atoms are double
bonded
2. Fats in fruits and vegetables and fish
usually, corn, olive, other vegetable oils
Fats
3. Oleic acid- C18H34O2
a. Part of Lorenzo’s oil for clinical trial to
treat childhood cerebral
adrenoleukodystrophy (ALD), a
degenerative myelin disorder
b. Used commercially in the preparation
of oleates and lotions,
Oleic Acid – C18H34O2
Fats
4. Linoleic Acid - C18H32O2
a. Essential fatty acid in mammalian
nutrition
b. Biosynthesis of prostaglandins
(hormone) and cell membranes
Linoleic Acid – C18H32O2
Saturated fats
C. Saturated fats in high
amounts may lead to plaque
(lipid material) development in
arteries
1. Can lead to decrease blood
flow or complete blockage of
blood to the heart or brain.
Phospholipids
D. Phospholipids- looks just like a lipid but
has one of the fatty acid chains
replaced with a Phosphate group (PO4)3 and then a R-group following the
phosphate
1. Phosphates are a polar, hydrophilic, &
acidic molecule
Phosphate
Phospholipids
2. Phospholipids are the key component
of cell membranes
3. Phospholipids have a polar,hydrophilic
head (phosphate region) and a
nonpolar, hydrophobic tail (two fatty
acid chains)
Phospholipid
Fats – simplified drawing
Unsaturated fats
Decanoic
acids
C18H34O2
Fat (unsaturated)
• Palmitic acid - C16H32O2
• Stearic acid - C18H36O2
• Oleic acid - C18H34O2
Steroids
III. Steroids- lipid molecule where the
carbon skeleton forms four fused rings
A.Lipid molecule where the carbon
skeleton forms four fused rings; differ in
functional groups and locations of
functional groups
Steroids
• B. Steroids are lipids due to their
hydrophobic nature; however are
different from fats structurally &
functionally
C. Sex hormones
1. Testosterone- male hormone
C19H28O2
2. Estrogen- female hormone C18H24O2
Steroids
Cholesterol
D. Cholesterol – essential material found
in cell membranes and starting point for
other Steroids (C27H46O)
1. LDL – low density cholesterol builds up
in arteries to cause cardiovascular
disease
2. HDL – high density cholesterol helps
remove LDL cholesterol that clogs
arteries
Cholesterol
5.4 Proteins perform most
functions in cells
I. The Functions of Proteins
A. Protein- a polymer made from a set of 20
kinds of monomers called amino acids
B. Functions
1. Makes up structures hair, fur, muscle and
long-term nutrient stores
2. Defend against foreign invader and serve
as chemical signals
3. Controls chemical reactions
II. Amino Acids
A. Amino acid- monomer that
consists of a carbon bonded to an
amino group, carboxyl hydrogen
and side chain (R)
1. Side group or R-group gives the
amino acid its specific property and
way interacts
2. Leucine is hydrophobic (CH3CH3)
3. Serine is hydrophilic (OH)
Amino Acid Structure
• 20 different types based on R group
Properties of Amino Acids
• Properties of Amino Acids vary based
on the R group
– Non-polar, hydrophobic (8)
– Polar,hydrophilic (7)
– Acidic (Aspartic and glutamic acid)
– Alkaline (Lysine, arginine, histidine)
Non-polar, hydrophobic
amino acids
Polar, hydrophilic amino acids
Acidic Amino Acids
Alkaline Amino Acids
Zwitter ion
• The amino acid has performed an acidbase reaction on itself.
• pH affects charge of the amino acid
III. Building a Protein
A. Polypeptide- chain of amino acids
created by dehydration reaction
between each amnion and carboxyl
group
B. Most polypeptide chains are at least
100 amino acids long
Peptide
bonds
Polypeptide
• N-terminus and c-terminus
IV. Protein Shape
A. Influenced by the interaction between bonds
between chains
B. The environment helps to determine shape
like a aqueous (water) environment
1. Hydrophilic amino acids like water so will
position on outside edge of protein
2. Hydrophobic amino acids repel water so
they will cluster in center of protein
Primary Structure
• The sequence of amino acids forming a
polypeptide chain.
Secondary Structure
• Coiling or
folding of its
polypeptide
chain
Tertiary Structure
• Attraction
between
alpha and
beta sheets
• Caused by
interactions
in R groups
Quarternary Structure
• Three
dimensional
structure of all
polypeptide
chains
5.5 Enzymes are proteins that
speed up specific reactions in
cells.
I. Enzymes (proteins) and
Activation Energy
A. Activation Energy- “start-up” energy
needed to start the chemical reaction for the
reactants
B. Catalysts- chemical compounds that speed
up chemical reactions in the cell
C. Enzymes allow chemical reaction to occur
without raising the cell’s temperature
D. Enzymes lower the activation energy in the
body to allow certain products to be made
Activation Energy
Activation Energy
II. How Enzymes Work
A. Substrate- the substance or substances
which the enzyme acts upon
B. Enzymes are substrate specific- fit like a lock
and key
C. Induced fit model explains how enzymes
work
1. Active site- location where substrate
binds to an enzyme
D. Enzymes remained unchanged by the
substrate in a chemical reaction
Enzymatic Reaction
E + S --> ES --> E + P
• E is the enzyme
• S is the substrate (reactant)
• ES is the enzyme-substrate complex
• P is the product
Induced-Fit Model
How Enzymes Work
E. Efficiency of enzyme is affected by
temperature and pH
1. Denature- enzymes lose their ability to
catalyze when T> 104 F in humans
2. Excessive in pH can also cause
denaturation
F. –ase is the standard suffix found on enzymes
like
G. Enzymes can hold molecules in closer
proximity – helps form larger molecules
Sucrase + Sucrose -->
glucose and fructose