Transcript Ch 2 - Biochemistry

Ch 2 - Biochemistry
INORGANIC COMPOUNDS
lack carbon (with the exception of carbon dioxide) and tend to
be simple, small molecules
water, salts, most acids and bases
Water
Important Properties:
High heat capacity - prevents sudden change in body temp that could result from
sun exposure, winter winds, vigorous exercise, etc
Polarity/solvent properties - “universal solvent” allows chemicals to react in
solution like blood plasma; also important in lubrication, saliva, serous fluids and
synovial fluids
Chemical Reactivity - hydrolysis reactions, water molecules added to bonds of
foods or large molecules
Cushioning - protective function, i.e. cerebrospinal fluid and amniotic fluid
Salts
Most plentiful salts in body contain Ca and P, found in bones
and teeth
All salts in the body are electrolytes - dissociate into ions and
conduct an electrical charge in solution
Na and K ions are essential for nerve impulses
Fe forms part of the hemoglobin molecules
Ionic (electrolyte) balance is essential to homeostasis
Acids and Bases
Acids - sour taste, release H+ ions, proton donors;
hydrochloric acid, acetic acid, carbonic acid
Bases - bitter taste, release OH-, proton acceptors; sodium
hydroxide, bicarbonate
Neutralization Rxn: Acid + Base --> Water + Salt
pH scale, 0-14, 1 pH unit change = 10X change in [H+]
Weak acids and bases are important buffers in body fluids
ORGANIC COMPOUNDS
Carbon-containing compounds, large covalently bonded
molecules
Carbohydrates, Lipids, Proteins, and Nucleic Acids
Carbohydrates
contain carbon, hydrogen, and oxygen; end in -ose
usually in ratio of 1:2:1 (glucose is C6H12O6; ribose is C5H10O5)
Glucose (blood sugar) is called the universal cellular fuel. 1 g carb= 4 Calories
monosaccharide - one unit (simple sugars), single chain or single ring; glucose,
fructose, galactose, ribose, deoxyribose
disaccharide - double sugars; sucrose (glucose-fructose), lactose (glucosegalactose), maltose (glucose-glucose)
polysaccharide - many sugars; long branching chains, used for storage (not
sweet); starch (plants), glycogen (animals)
Carbohydrates
Dehydration synthesis and hydrolysis
Lipids
most abundant lipids in body: fats, phospholipids, steroids
carbon, hydrogen, and oxygen molecules (mostly C and H)
building blocks: fatty acids and glycerol
most are insoluble in water
1 g fat = 9 calories
large amount of energy, insulation, protection
saturated-animal fats, butter, lard, grease (solid at room temp)
unsaturated-most plant oils, olive oil, fish oils (liquid at room temp)
Lipids
Triglycerides (fats) - insulation and energy storage
Phospholipids - main component in cell membranes
Steroids - (cholesterol, Vit D, estrogen, cortisone) many
functions - stimulate growth, develop repro organs, sexual
function, anti-inflammatory, essential in brain function
Waxes
Proteins
building block = amino acids (C, H, O, N); amine group, acid group, and
variable R-group (makes a.a. chemically unique)
peptide = short chain of amino acids; polypeptide = long chain of a.a.
Humans must have 20 different a.a., but can produce only 10, others must
come from food
Structure is VERY important for function - pH and temperature can affect
shape
Food sources: legumes, eggs, milk, fish, poultry, meat
1 g protein = 4 Calories
Protein Functions
Over 50% of organic matter in body is protein
structural or fibrous proteins (bones, ligaments, cartilage,
tendons,skin) - collagen, keratin
Globular or functional proteins:
defense against infection - antibodies
hormones - insulin, prolactin, nerve growth factor
transport - hemoglobin
histones - “spool” around which DNA winds
ENZYMES - speed up chemical reactions in body, help break
down molecules
Amino Acid Sequence
One wrong a.a.
sequence in the
hemoglobin
protein=mis-shapen
RBC and severely
limits function
Enzymes
most end in -ase
substrate = molecule the enzyme acts on
active site = location where enzyme fits with substrate
Nucleic Acids
made of nucleotides (pentose (5-C) sugar,
phosphate group, nitrogen base); in all cells
bases: adenine (A), guanine (G), cytosine (C),
thymine (T), and uracil (U)
deoxyribonucleic acid (DNA) - double helix;
genetic material; replicates itself; provides
instruction for building every protein in body AT, G-C
ribonucleic acid (RNA) - single strand; makes
proteins in the cell A-U, G-C
Adenosine Triphosphate (ATP)
form of energy used by all cells
modified nucleotide: adenosine base, ribose
sugar, three phosphate groups
when glucose is oxidized, energy is captured
by ATP and stored
high-energy phosphate bonds are
hydrolyzed to release energy to do work