Water
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The Nature of Water - H2O
►Exists
in three forms (gas, liquid and
solid)
►Makes up approx 90% of organisms
►Versatile Solvent
►Important in the cell’s chemistry
►Gains and releases heat slowly
►High surface tension
►A “polar” molecule:
 2 small hydrogen atoms
 1 large oxygen atom
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2-3: Carbon Compounds
• Compounds that contain CARBON are called
organic.
• Carbon has 4 electrons in outer shell.
• Carbon can form covalent bonds with as
many as 4 other atoms (elements).
• Usually with C, H, O or N.
• Example: CH4(methane)
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naturally occurring elements are
essential for life. Carbon, hydrogen, oxygen
and nitrogen (C, H, O, N) make up 96% of
living matter.
► The remaining 4% is composed of seven
elements (Ca, P, K, S, Na, Cl, Mg). Some
elements, like iron (Fe) and iodine (I) may
be required in very minute quantities and
are called trace elements.
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Biological
Macromolecules
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Macromolecules
► Large organic molecules.
► Also called POLYMERS.
► Made up of smaller “building
blocks” called
MONOMERS.
► The monomers in a polymer may be identical or
they may be different. Some of the molecules
that serve as monomers also have other functions
on their own.
► Examples:
1. Carbohydrates
2. Lipids
3. Proteins
4. Nucleic acids (DNA and RNA)
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Carbon – the backbone of organic
macromolecules!
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Carbon – the backbone of organic
macromolecules!
Double bond
Single bond
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Polymerization
► The
process of stringing together monomers to
make polymers is called polymerization (or
dehydration synthesis).
► Monomers are connected by a reaction in which
two molecules are covalently bonded to each
other through the loss of a water molecule.
► Each monomer contributes part of the water
molecule that is lost: one molecule provides the –
OH, while the other provides the hydrogen (–H).
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Hydrolysis
► Polymers
are disassembled to monomers by
hydrolysis (from the Greek word hydro
meaning “water” and lysis meaning “to
split”.)
► In hydrolysis, polymers are split by water in
a process that is essentially the reverse of
dehydration synthesis.
► Bonds between monomers are broken by
the addition of water molecules, a hydrogen
from water attaching to one monomer and
an –OH attaching to the adjacent monomer.
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Animation
► Animation
Hydrolysis
of Dehydration Synthesis and
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Carbohydrates
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The Nature of Carbohydrates
► Recognized
by the formula: (CH2O)n
► 1:2:1
► Grouped
into mono-, di-, and
polysaccharides
► Important as:
 A “quick energy” nutrient - glucose
 Serve as a storage of energy - glycogen
(animals) and starch (plants)
 Structural significance – chitin of Arthropods
and fungus and cellulose of plants
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product of photosynthesis
Milk + sugar beets
fruit
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Common Disaccharides
► Sucrose
(glucose + fructose)
►Found
in plant like sugar cane, sugar beets
►“table sugar”
► Maltose
(glucose + glucose)
►Found
► Lactose
in germinating grain
(glucose + galactose)
►Found
in the milk of mammals
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Polysaccharides
• Cellulose – Structural component of plants
(cell walls: lettuce, corn, some protists)
• Starch – storage of energy in plants
(bread, potatoes, rice)
•Glycogen – storage of energy in animals
(beef muscle)
• Chitin – structural component of arthropods
(roaches, crickets)
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Lipids
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The Nature of Lipids
► Lipids
are one class of biological
macromolecules that does not include
polymers.
► The lipids are grouped together because
they are not soluble in water.
► Lipids are a highly varied group in form and
function.
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► Highest
source of energy – that’s why our
extra energy is stored as fat in fat tissue
► Also important as:
 structural components of cells (membranes)
 Chemical messengers - hormones (steroids)
 protective waxes (earwax, outer covering of
insects)
 Protection against heat loss (insulation)
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Examples of Lipids
► General
term for compounds which are not soluble
in water.
► Lipids are soluble in hydrophobic solvents.
► Remember: “stores the most energy”
► Examples:
►1. Fats
►2. Phospholipids
►3. Oils
►4. Waxes
►5. Steroid hormones
►6. Triglycerides
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Fats
►(long-term
energy storage )
►Cushions organs
►insulation
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► Two
types of molecules used to make a fat:
► Glycerol (three carbon molecule)
► Fatty acids (long hydrocarbon chain, usually 16-18
carbons atoms in length) that is hydrophobic
(does not dissolve in water).
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What Does Fat Look Like?
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The Letter “E”
Glycerol
E
Fatty Acids
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Saturated vs. Unsaturated Fats
► Saturated
Fats
Solid at room temp.
White in color
Derived from animals
No double bonds
between carbons
 Fatty acids straight
 Examples are the hard
fats (lard)
 BAD (unhealthy)




► Unsaturated
Fats
Liquid at room temp.
Yellow in color
Derived from plants
Some double bonds
between carbons
 Fatty acids crooked
 Examples include corn,
canola, and olive oils
 BETTER (healthier)




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Polyunsaturated
Many carbon-carbon double bonds
• Liquid at room temperature
• Cooking oils: corn, sesame, peanut, canola,
olive
• BEST (healthiest) because they do not collect in
your blood vessels and cause plaque.
•
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Phospholipids
►
►
►
Phospholipids are a major component of
cell membranes.
The cell membrane regulates what enters
and leaves the cell and provides protection
and support.
Phospholipids are similar to fats but they
only have two fatty acid tails, instead of
three, attached to a glycerol molecule.
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►A
phospholipid has a hydrophilic head that wants
to interact with water and two fatty acid tails that
are hydrophobic and are repelled by water.
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Steroids
► Steroids
are lipids characterized by a carbon
skeleton consisting of four fused rings.
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► One
steroid, cholesterol, is a common
component of animal cell membranes and is
the precursor from which other steroids are
synthesized.
► Too much cholesterol in the blood may
contribute to heart disease.
► About 10% of people ages 12 to 19 have
blood cholesterol levels, which put them at
risk later in life for developing heart disease
– the leading cause of death in the United
States.
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► Hormones
are chemicals released in one
part of the body that travel through the
bloodstream and affect the activities of cells
in other parts of the body.
► They do this by binding to specific chemical
receptors on target cells. If a cell does not
have receptors, the hormone has no effect.
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Proteins
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The Nature of Proteins
►Elements:
N, C, H, O
►Made of units called amino acids (only
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►Twenty Amino acids combine in
different ways to make, perhaps,
100,000 different proteins!
►Amino acids link together by peptide
bonds
 Makes polypeptides
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Six functions of proteins:
1.
2.
3.
4.
5.
6.
Storage:
Transport:
Regulatory:
Movement:
Structural:
Enzymes:
albumin (egg white)
hemoglobin
hormones
muscles
membranes, hair, nails, bones
cellular reactions
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Proteins (Polypeptides)
►Four
levels of protein structure:
A. Primary Structure (1°)
B. Secondary Structure (2°)
C. Tertiary Structure (3°)
D. Quaternary Structure (4°)
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A. Primary Structure (1°)
►
Amino acids bonded
together by peptide
bonds.
Amino Acids (aa)
aa1
aa2
aa3
Peptide Bonds
aa4
aa5
aa6
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B. Secondary Structure
(2°)
► 3-dimensional
folding arrangement of a primary
structure into coils and pleats held together by
hydrogen bonds.
► Two examples:
Alpha Helix
Beta Pleated Sheet
Hydrogen Bonds
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C. Tertiary Structure (3°)
► Secondary
structures bent and folded into a more
complex 3-D arrangement.
► Bonds: H-bonds, ionic
► Called a “subunit”.
Alpha Helix
Beta Pleated Sheet
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D. Quaternary Structure (4°)
► Composed
of 2 or more “subunits”.
► Example: enzymes, hemoglobin
3° subunits
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Enzymes
►
►
►
►
►
►
Acts as catalysts
Speed up a
chemical reaction
Lower activation
energy
Needed to start a
reaction
Specific
Act on a substrate
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Enzyme Action
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Denaturation
Denaturation of proteins involves the disruption and possible
destruction of both the secondary and tertiary structures.
Usually caused by: acids, bases, heat, alcohol
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Nucleic Acids
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The Nature of Nucleic Acids
► Two
types: DNA and RNA
► Composed of units called nucleotides:
 Phosphate molecule
 5 carbon sugar
 organic base (a purine or pyrimidine)
► May
be double or single-stranded
► Single strands united by “base-pairing”
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Organic (Nitrogenous) Bases
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Importance of Nucleic Acids
► Insure
genetic continuity from one cell
generation to the next
► Directs the production of proteins at the
ribosome “construction site” in the
cytoplasm
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