 Organic Chemistry is the chemistry of carbon
compound
 Biochemistry is the branch of organic chemistry which
attempts to explain the chemistry in living organisms
 Four main types of organic molecule
 Carbohydrates
 Lipids
 Proteins
 Nucleic acids
 Assessment statements:
 3.1.1 states that the most frequently occurring chemical
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elements in living things are carbon, hydrogen, oxygen and
nitrogen
3.1.2 state that a variety of other elements are needed by living
organisms, including sulfur, calcium, phosphorus, iron, and
sodium
3.1.3 state one role for each of the elements mentioned in 3.1.2
3.1.4 draw and label water molecules to show their polarity
and hydrogen bond formation
3.1.5 outline the thermal, cohesive, and solvent properties of
water
3.1.6 explain the relationship between the properties of water
and its uses in living organisms as a coolant, medium for
metabolic reactions and transport medium
 Four most common elements found in living things
 Carbon, hydrogen, oxygen and nitrogen
 These elements are used in the molecular structures of
all carbohydrates, proteins, lipids and nucleic acids
Element
Example role in
plants
Example role in
animals
Example role in
prokaryotic
Sulfur
In some amino
acids
In some amino
acids
In some amino
acids
Calcium
Co-factor in some
enzymes
Co-factor in some
enzymes and
component of
bones
Co-factor in some
enzymes
Phosphorus
Phosphate group
in ATP
Phosphate group
in ATP
Phosphate group
in ATP
Iron
In cytochromes
In cytochromes
and in
heamoglobin
In cytochromes
Sodium
In membrane
function
In membrane
function and
sending nerve
impulses
In membrane
function
 Water is the solvent of life
 Virtually all cells have water within (cytoplasm) and
water in the surrounding environment (intercellular
fluid, pond water, etc)
 Water is an incredibly abundant substances on Earth
and has very interesting properties
 Many of these properties depend on the structure of
water molecules
H
H
 The hydrogen and oxygen atoms in a
single water molecule are held
together by a type of bond called a
polar covalent bond
 Polar covalent bond results from an
unequal sharing of electrons
 Results in a slight negative charge at
the oxygen end and a slight positive
charge at the end of the two hydrogen
 Because the two ends of each water
molecule have opposite charges, water
molecules interact with each other
 Thermal Properties
 High specific heat
 This means that water can absorb or give off a great deal of
heat without changing temperature greatly
 High heat of vaporization
 This means that water absorbs a great deal of heat when it
evaporates
 Cohesive Properties
 Water molecules are highly cohesive
 Is when molecules of the same type are attracted to each
other
 The attraction is due to the polar covalent bonding
 When water cools below the freezing point, molecular
motion has slowed to the point where these polar attractions
become locked into place and an ice crystal forms
 This cohesion between liquid water molecules explains
a variety of events, including
 Why water forms into droplets when spilled
 Why water has a surface tension that allows some
organisms to ‘walk on water’
 How water is able to move as a column in the vascular
tissues of plants
 Why water has a high heat capacity and high heat of
vaporization
 Solvent Properties
 Water is an excellent solvent of other polar molecules
 ‘like dissolves like’
 Most molecules typically found inside and outside of most
cells are also polar molecules
 Most types of lipids are relatively non-polar
Aqueous solution
Location
Common reactions
Cytoplasm
Fluid inside cells but
outside organelles
Glycolysis/protein
synthesis reactions
Nucleoplasm
Fluid inside nuclear
membrane
DNA
replication/transcription
Stroma
Fluid inside chloroplast
membrane
Light-dependent reactions
of photosynthesis
Blood plasma
Fluid in arteries, veins
and capillaries
Loading and unloading of
respiratory gases/clotting
 Examples of eater as a solvent in plants and animals
 Properties of eater makes it an excellent medium for
transport
 Vascular tissue in plants carries water and a variety of
dissolved substances
 Xylem carries water and dissolved minerals up from the root
system to the leaves of a plant
 Phloem then transports dissolved sugars from the leaves to
the stems, roots, and flowers of a plant
 Blood is the most common transport medium in
animals and is largely made up of water
 Transport medium for red blood cells, white blood cells,
platelets, and a wide variety of dissolved molecules
 The liquid portion of blood is blood plasma
 Some of the more common solutes in blood plasma are
 Glucose (blood sugar)
 Amino acids
 Fibrinogen (protein involved in blood clotting)
 Hydrogencarbonate ions (as a means of transporting CO2)