Transcript Chapter 5 Molecules of Life

Chapter 3
Biochemistry

Water
Water – makes up 70% of a cell’s weight
– Most intracellular rxns occur in the aqueous
environment

Properties:
– Inorganic Molecule – nonliving and does not
contain C
– H2O
– Polar compound – one that has a more
positive charge on one side, and a more
negative charge on the other
– Makes a great solvent; dissolves ions and
other polar molecules easily
Water
– Hydrogen Bonds – weak attraction between a
molecule with a negative charge (ex oxygen)
and a hydrogen atom
– Cohesion – tendency of the molecules of a
substance to stick together
– Adhesion – attractive force between unlike
substances
– Capillary action – ability to spread through
narrow pores or tubes against gravity
 Is water more or less dense at 4°C (ice)?
Salts

Salts – formed when an acid reacts
with a base
– Na+ ions help nerves carry messages
Carbon Compounds

Organic Compounds – contain C and
living
– Exceptions: graphite, diamonds, CO2
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Carbon exhibits bonding power of 4
– Most often bonds with hydrogen, oxygen,
nitrogen, or to itself and forms chains
Carbon Compounds
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Polymer – complex molecules consisting
of repeated monomers
– Macromolecules – large polymers

Monomer - A single, repeated molecule
unit
– Ex: a sugar molecule in starch
Carbon Compounds
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Condensation Reaction (dehydration
synthesis) – process of bonding two
monomers together by the removal of a
H2O

Hydrolysis – process of breaking apart a
complex molecule by the addition of a
water
Carbon Compounds

I. Carbohydrates – the most abundant of
all biological molecules
– Made up of C, H, and O
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Monosaccharide (simple sugars) – one
monomer of sugar
– Cannot be hydrolyzed into a smaller unit,
C6H12O6
– Ex: Glucose, Fructose, Galactose
Carbon Compounds
Isomers – Compounds that have the same
exact molecular formula but differ in
structure and function
 Disaccharide – two monosaccharides
joined together by a condensation
reaction forming a double sugar,
C12H22O11

– Ex: Sucrose, Maltose, Lactose
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Polysaccharides – complex carbohydrates
made up of many joined monosaccharides
– Ex: Cellulose, Starch, Glycogen
Carbon Compounds
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II. Lipids (fats) – Fatty hydrocarbon
compounds also composed of C,H,O
– Ex: Fats, oils, wax
4 Kinds of Lipids
 1. Triglycerides – neutral fats having 3
fatty acid tails attached to a glycerol
molecule

– Ex: Butter, Lard, Vegetable Oils
Carbon Compounds

2. Phospholipids – a lipid composed of
glycerol, 2 fatty acid tails, and a head
containing a phosphate group
 Hydrophilic – water loving carboxyl end
 Hydrophobic – water fearing hydrocarbon end
Carbon Compounds
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3. Waxes – long-chain fatty acids linked
to long chain alcohols
– Ex: Wax coating on cherries, wax in human
ears
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4. Sterols (steroids) – Complex lipids
comprised of 4 interlocking carbon rings
– Ex: hormones, cholesterol, nerve tissue, plant
poisons
Carbon Compounds

III. Proteins – organic compound
composed of amino acids, CHON
– Most diverse group of the large
biological molecules

Amino Acids – building blocks of
proteins, 20 kinds
Carbon Compounds
– Peptide bonds – bond that links two
amino acids together
 Ex: Dipeptide – 2 amino acids joined together
Polypeptide – 3 or more amino acids
– Enzymes – Class of proteins which speed
up specific metabolic reactions by
lowering the activation energy
Carbon Compounds

IV. Nucleic Acids – complex organic
molecules made up of monomers of
nucleotides
– Ex:
DNA – Deoxyribonucleic Acid
RNA – Ribonucleic Acid
Carbon Compounds

Nucleotides – Small organic
compound comprised of:
– 1. Phosphate group
– 2. 5-C sugar (pentose) – ribose or
deoxyribose
– 3. nitrogen base –
Adenine
Guanine
Cytosine
Thymine