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Anatomy & Physiology
Ch. 2 BIOCHEMISTRY
What is biochemistry?
Biochemistry is the study of the
chemical composition and reactions of
living matter.
 Organic compounds contain carbon and
are covalently bonded, such as starch.
 Inorganic compounds (not organic)
include chemicals such as water, salts,
acids, and bases.

Water

Water is the most
abundant and
important inorganic
compound in
organisms. 60-80 %
of cellular volume.
 Water has many
properties essential
to an organisms
survival.
Properties of Water

High heat capacity- absorbs or releases a
large amount of heat before changing its
temperature. Important for temp. regulation.
 High heat of vaporization- large amount of
energy is needed for water to evaporate.
Provides cooling effect when we sweat.
 Polarity- water is a polar molecule which
makes it an excellent solvent. Many
important nutrients, gases, and other
compounds are in solution.
Properties of water, cont.
Reactivity- water is an important in
many chemical reactions. (Hydrolysis
and dehydration synthesis)
 Cushioning- fluid surrounding body
organs and tissues provides protection
from physical trauma and reduces
friction.

What is a salt?
Salts are ionic compounds that
dissociate into ions in solution.
 Salts found in the body include NaCl,
KCl,and calcium carbonate. Calcium
phosphates make up bones and teeth.
 K+ and Na+ ions are important for nerve
transmission and muscle contraction.

Electrolytes
Acids, bases, and salts are electrolytes
because they ionize and dissociate in
water.
 These solutions can then conduct an
electric current.

Acids
Acids and bases are covalently bonded
molecules that dissociate in solution.
Acids release H+ ions in solution. They
are sour and corrosive. pH<7

– Acids in the body include HCl (gastric
juice), uric acid, amino acids, lactic acid,
carbonic acid, Vitamin C,fatty acids,
vaginal fluid
Bases
Bases are proton acceptors, some are
hydroxides (OH-)
 Bases are slippery and bitter, pH > 7.
 Bases in the body include blood,
semen, ammonia, and bicarbonate ion.

pH



The relative concentrations
of hydrogen [H+] and
hydroxyl [OH-] ions in body
fluids is measured in pH
units.
The pH scale runs from 0 to
14. pH of 7 is neutral, below
7 is considered to be acidic,
and above 7 is basic.
Each unit of pH represents a
10x change. For example, a
pH of 2 is ten times more
acidic than a pH of 3.
Neutralization

Neutralization reactions occur when
acids and bases are mixed to form
water and salt.
Ex) HCl + NaOH -> H2O + NaCl
Buffers
Buffers are weak acids or bases that
prevent extreme changes in pH.
 One buffer system helps maintain pH
homeostasis of the blood: carbonic
acid/bicarbonate ion

Carbohydrates



Carbohydrates contain
carbon, hydrogen, and
oxygen in a ratio of
1:2:1.
Carbohydrates include
sugars and starches,
and are important for
energy. A few
carbohydrates are used
for structural purposes.
Larger molecules are
less soluble in water.
Carbs, cont.
Monosaccharides (simple sugars) are
single-chain or single ring structures
containing 3-7 carbon atoms. Ex)
glucose, fructose, and galactose
 Disaccharides are made up of two
sugar units. Ex) lactose and maltose
 Polysaccarhides- chains of
monosaccharides forming a polymer.
Ex) starch, cellulose, glycogen

Lipids

Contain carbon,
hydrogen,and
oxygen. Structure
often includes fatty
acids and glycerol.
 Phosphorus is found
in some more
complex lipids.
 Insoluble in water,
but dissolve in other
lipids and organic
solvents.
Neutral fats

Formed by fatty acids and glycerol in a 3:1
ratio. Also called triglycerides.
Concentrated source of energy.
 Fats when solid, and oils when liquid.
 Saturated fats have only single bonds. Meat
fat and butter fat are examples.
 Unsaturated fats contain double bonds.
Olive oil and peanut oil are examples.
Usually considered to be healthier.
Phospholipids



Modified triglyceride
with phosphorus
containing group.
Has hydrophobic tail
(nonpolar) and
hydrophilic (polar) head.
Amphipathic molecule.
Chief component of cell
membranes, also found
in nervous tissue
Steroids

Flat molecules
made up of four
interlocking
hydrocarbon rings.
 Fat soluble and
contain little oxygen.
 Examples:
cholesterol, sex
hormones, bile salts,
and important for
cell membranes
Fat-Soluble vitamins




Some vitamins are not water-soluble. These
nonpolar vitamins can accumulate in fat tissues if
consumed in excess.
Vitamin A- found in orange fruits and vegetables, part
of the photoreceptor pigment involved in vision
Vitamin E- found in green leafy vegetables, important
in wound healing, has antioxidant properties
Vitamin K- made available by the action of intestinal
bacteria, prevalent in many foods, necessary for
blood clotting
Prostaglandins
Diverse group of lipids formed from a
20-carbon fatty acid found in cell
membranes.
 play a role in blood clotting,
inflammatory response, and labor
contractions

Lipoproteins

Protein-based substances that transport
fatty acids and cholesterol in the
bloodstream; major varieties are highdensity lipoproteins (HDLs) and lowdensity lipoproteins (LDLs)
Proteins
Contain carbon, hydrogen, oxygen, and
nitrogen. Many contain phosphorus and
sulfur.
 Composed of chains of 20 amino acid
types, joined by peptide bonds
 Basic structural material of the body,
making up 10-30% of cell mass.
 Includes enzymes, hemoglobin, and
contractile proteins of muscles

Amino Acids

Amino acids are
the building blocks of
protein.
Protein structure




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Proteins have a complex structure on four
levels:
Primary-sequence of amino acids
Secondary- chain bends or twists (B-pleated
sheet or alpha-helix)
Tertiary- secondary structure folds to
produce a compact, globular structure
Quaternary- two or more polypeptide chains
group to form a complex protein such as
hemoglobin
Fibrous vs. Globular proteins
Overall structure of a protein determines
its biological function.
 Fibrous proteins (structural proteins) are
extended and thread-like. Water
insoluble, have secondary structure
Ex) collagen, keratin, elastin
 Globular proteins (functional proteins)
are spherical and compact. Water
soluble with tertiary structure.
Ex) enzymes and antibodies

Types of Globular proteins



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Antibodies-proteins important in the
immune response
Hormones-chemical messengers
carried in the blood that stimulate target
cells.
Transport proteins-carry materials in
the blood (hemoglobin) and across cell
membranes
Catalysts (Enzymes)-act as biological
catalysts, to regulate and accelerate
the rate of biochemical reactions
without being used up in the process.
Enzymes


When enzymes and
other proteins are
exposed to conditions
outside the optimum
temperature and pH
range, their three
dimensional shape
changes
(denaturation).
Since enzymes are
shape-specific, any
changes prevent them
from carrying out their
function.
Nucleic Acids (DNA and RNA)

Nucleic acids are composed of C,H,O, N, and
P. The structural unit of nucleic acids are
nucleotides.
 A nucleotide consists of a nitrogen containing
base, a five carbon sugar, and a phosphate
group.
DNA

DNA contains
deoxyribose, is
double stranded,
and contains the
bases adenine,
thymine, adenine,
and guanine. Base
pairing: A—T and
G—C
 DNA stores genetic
information
RNA

RNA is single
stranded, contains
ribose, the base
uracil instead of
thymine
 RNA helps carry out
its instructions.
Adenosine triphosphate (ATP)
• Although glucose is the
most important cellular
fuel, its energy cannot be
used directly by cells.
• Glucose catabolism is
coupled with ATP
synthesis, with energy
being stored in the bonds
of ATP.
• ATP is the universal
energy compound of body
cells.
How ATP Drives Cellular Work
• ATP has 3 phosphates
attached (P)
• Removal of a P releases
energy from the bond,
leaving ADP
• Removal of another P
releases less energy,
leaving AMP
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