Biology I
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Organic Compounds
Compounds that
contain CARBON
are called organic
compounds.
 Organic chemistry
is the study of
carbon compounds
Although a cell is
mostly water, the
rest of the cell
consists mostly of
carbon-based
molecules
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Giant Molecules = Polymers
Large molecules are
called polymers
Polymers are built
from smaller
molecules (building
blocks) called
monomers
 Biologists call them macromolecules
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 Large organic molecules.
 Also called POLYMERS.
 Made up of smaller “building blocks”
called MONOMERS.
Examples:
1. Carbohydrates
2. Lipids
3. Proteins
4. Nucleic acids (DNA and RNA)
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Most Macromolecules are Polymers
Polymers are made by stringing
together many smaller molecules called
monomers
Nucleic Acid
Monomer
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Macromolecules in Organisms
• There are four categories of large
molecules in cells:
Carbohydrates
Lipids
Proteins
Nucleic Acids
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 Carbohydrates are compounds
composed of C,H,& O atoms in the
ratio of 1:2:1
 The monomers are sugar molecules
They include:
Small sugar molecules in soft drinks
Long starch molecules in pasta and
potatoes
Consist of 3 major types of
sugars:
Monosaccharides
 Disaccharides
 Polysaccharides
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Monosaccharides:
Called simple sugars
Include glucose,
fructose, & galactose
Have the same
chemical, but
different structural
formulas
C6H12O6
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Monosaccharides
Glucose is found in
sports drinks
Fructose is
found in fruits
Honey contains
both glucose &
fructose
Galactose is
called “milk sugar”
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Isomers
• Glucose &
fructose are
isomers because
they’re
structures are
different, but
their chemical
formulas are the
same
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Cellular Fuel
Monosaccharides are
the main fuel that cells
use for cellular work
ATP
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Disaccharides
A disaccharide is a
double sugar
They’re made by
joining two
monosaccharides
Common disaccharides
include:
►Sucrose (table sugar)
►Lactose (Milk Sugar)
►Maltose (Grain sugar)
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Disaccharides
Sucrose is
composed of
glucose + fructose
 Maltose is
composed of 2
glucose molecules
 Lactose is made
of galactose +
glucose
GLUCOSE
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Polysaccharides
Complex
carbohydrates
Composed of many
sugar monomers
linked together
Polymers of
monosaccharide
chains
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Examples of Polysaccharides
Glucose Monomer
Starch
Glycogen
Cellulose
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Starch
Starch is an
example of a
polysaccharide in
plants
Plant cells store starch
for energy
Potatoes and grains are
major sources of starch in
the human diet
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Glycogen
Glycogen is an
example of a
polysaccharide in
animals
Animals store
excess sugar in
the form of
glycogen
Glycogen is similar in
structure to starch
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Cellulose
►Cellulose is the most abundant
organic compound on Earth
►It
forms cable-like fibrils in the tough walls
that enclose plants
►It
is a major component of wood
►It
is also known as dietary fiber
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Cellulose
SUGARS
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Large molecules composed of mostly carbon &
hydrogen atoms
Lipids are hydrophobic –”water fearing”
They’re not soluble in water
Includes
fats,
waxes, steroids,
& oils
FAT MOLECULE
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Function of Lipids
• Fats store energy, help to insulate
the body, cushion and protect
organs.
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Types of Fatty Acids
Unsaturated fatty acids~ have less than
the maximum number of hydrogens bonded
to the carbons (a double bond between
carbons). Usually liquids at room temp.
Saturated fatty acids~ have the maximum
number of hydrogens bonded to the carbons (all
single bonds between carbons). Usually solids at
room temp.
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Fats in Organisms
• Most animal fats have a high proportion of
saturated fatty acids & exist as solids at room
temperature (butter, margarine, shortening)
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Fats in Organisms
• Most plant oils tend to be low in
saturated fatty acids & exist as
liquids at room temperature (oils)
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Types of Fatty Acids
Single
Bonds in
Carbon
chain
Double bond in carbon chain
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Triglyceride
Monomer of lipids
Composed of
Glycerol & 3
fatty acid chains
Glycerol forms
the “backbone”
of the fat
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Triglyceride
Glycerol
Fatty Acid Chains
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Steroids
The carbon skeleton
of steroids is bent to
form 4 fused rings
Cholesterol is the
“base steroid” from
which your body Testosterone
produces other
steroids
Cholesterol
Estrogen
Estrogen & testosterone are also steroids
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Synthetic Anabolic Steroids
They are variants
of testosterone
Some athletes use
them to build up their
muscles quickly
They can pose
serious health risks
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Are macromolecules that contain the
element N as well as C, H, & O.
Proteins are polymers made of
monomers called amino acids
 All proteins are made of 20 different
amino acids linked in different orders
 Proteins are used to build cells, act as
hormones & enzymes, and do much of the work
in a cell
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Four Types of Proteins
Storage
Structural
Contractile
Transport
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20 Amino Acid Monomers
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Structure of Amino Acids
Amino acids have
a central carbon
with 4 things
bonded to it:
Carboxyl
group
Amino
group
R group
Amino group -NH3
Carboxyl group -COOH
Hydrogen
Side group
-H
-R
Side
groups
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Linking Amino Acids
Carboxyl
Amino
Cells link amino
acids together to
make proteins
Peptide bonds
form to hold the
amino acids
together
Side
Group
Peptide Bond
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Proteins as Enzymes
Many proteins act as biological
catalysts or enzymes & end in ase
Thousands of different enzymes exist
in the body
Enzymes control the rate of chemical
reactions by weakening bonds, thus
lowering the amount of activation energy
needed for the reaction
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Enzymes
Enzymes are globular
proteins.
Their folded conformation
creates an area known as the
active site.
The nature and arrangement
of amino acids in the active site
make it specific for only one
type of substrate.
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Enzyme + Substrate = Product
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How the Enzyme Works
Enzymes are reusable!!!
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Primary Protein Structure
The primary
structure is
the specific
sequence of
amino acids in
a protein
Amino Acid
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Protein Structures
Secondary protein structures
occur when protein chains coil or
fold
When protein chains called
polypeptides join together, the tertiary
structure forms
In the watery environment of a cell,
proteins become globular in their
quaternary structure
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Protein Structures
Amino acid
(a) Primary structure
Alpha helix
(b) Secondary
structure
(c) Tertiary
structure
(d) Quaternary structure
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Changing Amino Acid Sequence
Substitution of one amino acid for
another in hemoglobin causes sickle-cell
disease
1
2
(b) Sickled red blood cell
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7
4
5
Normal hemoglobin
(a) Normal red blood cell
1
3
2
3
6
7
4
5
Sickle-cell hemoglobin
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Macromolecules that contain
H, O, N, C,& P.
Store hereditary information
Contain information for making all
the body’s proteins
Two types exist - DNA & RNA
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Nucleic Acids
Nitrogenous base
(A,G,C, or T)
Nucleic
acids are
polymers of Phosphate
group
nucleotides
Thymine (T)
Sugar
(deoxyribose)
Phosphate
Base
Sugar
Nucleotide
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Bases
• Each DNA
nucleotide has
one of the
following bases:
Thymine (T)
Cytosine (C)
–Adenine (A)
–Guanine (G)
–Thymine (T)
–Cytosine (C)
Adenine (A)
Guanine (G)
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Nucleotide Monomers
Backbone
Form long
chains called
DNA
Nucleotide
Nucleotides are
joined by sugars &
phosphates on the
side
Bases
DNA strand
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DNA
Two strands of
DNA join together
to form a double
helix
Base
Has the sugar
pair
deoxyribose
Bases are:
A, T, C, & G
Double helix
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RNA – Ribonucleic Acid
Has the sugar
ribose
Single stranded
It has the base
uracil (U)
instead of
thymine (T)
A,U,C & G
Nitrogenous base
(A,G,C, or U)
Uracil
Phosphate
group
Sugar (ribose)
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Nucleic Acids
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Macromolecules
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Macromolecules
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