Transcript 1.2 The Chemicals of Life With the exception of water, virtually all chemicals of life are CARBON-BASED. Compounds that contain carbon (other than CO2 and.

1.2 The Chemicals of Life
With the exception of water,
virtually all chemicals of life are
CARBON-BASED.
Compounds that contain
carbon (other than CO2 and a
few other exceptions) are called
organic compounds.
Cells use these compounds
for:
COMMUNICATION
CARBON
• Carbon is a small, light element
• Carbon has 4 single valence electrons and
can form up to 4 stable covalent bonds.
• Molecules containing only carbon and
hydrogen are known as HYDROCARBONS
Large hydrocarbons tend to be non-polar due to
the symmetrical arrangement of their bonds.
BONDING CAPACITY
• Other elements
such as
hydrogen,
oxygen, sulfur
and
phosphorus
may also attach
to the carbon
backbone.
Element
Bonding
Capacity
Hydrogen
1
Oxygen
2
Sulfur
2
Nitrogen
3
Carbon
4
Phosphorus
5
Examples
FUNCTIONAL GROUPS
• Many organic molecules contain rings or
chains of carbon with additional hydrogen,
oxygen, sufer and phosphorus atoms
attached.
» These additional atoms are called
FUNCTIONAL GROUPS
FUNCTIONAL GROUPS
• FUNCTIONAL GROUPS give the organic
molecule specific chemical properties.
Chemical reactions between organic molecules usually
involve the molecules functional group.
FUNCTIONAL GROUPS
Functional Group
Chemical
Formula
Structural
Formula
Found In
Hydroxyl
-OH
Carboxyl
-COOH
acids
Amino
-HN2
bases
Sulfhydryl
-SH
Phosphate
-PO4
alcohols
--S--H
rubber
ATP
CAN YOU IDENTIFY THE
FUNCTIONAL GROUPS?
Phosphate group
Hydroxyl
group
Phosphate group
Amino group
Hydroxyl
group
Sulfhydryl group
Amino group
Carboxyl group
FUNCTIONAL GROUPS
• The hydroxyl group (-OH) and carboxyl
group (-COOH) are POLAR
» this is why SUGARS and ALCOHOLS are highly
soluble in water (because they contain the polar
hydroxyl group)
Ethanol molecule
Glucose molecule
BIOLOGICAL
MACROMOLECULES
• A very large organic molecule is called a
macromolecule.
• There are four major groups of biologically
important macromolecules:
»
»
»
»
1. Carbohydrates
2. Lipids
3. Proteins
4. Nucleic Acids
BIOLOGICAL
MACROMOLECULES
• All macromolecules are made up of
smaller subunits…
Macromolecule
Subunit
Polymer?
Complex
carbohydrate
Simple sugar
(glucose)
Yes
Lipid (triglycerol)
Glycerol backbone +
fatty acid
No
Protein
Amino Acids
Yes
Nucleic Acid (DNA &
RNA)
Nucleotides
Yes
POLYMER = a large molecule composed of long chains of
smaller subunits.
CARBOHYDRATES
• Carbohydrates are molecules that contain
CARBON, HYDROGEN, and OXYGEN in a
1:2:1 ratio, and are primarily used by living
organisms as a source of energy.
CARBOHYDRATES =
ENERGY!!
Organisms also use carbohydrates as building materials, and
as cell surface markers for cell-to-cell identification and
communication.
CARBOHYDRATES
• Plants produce carbohydrates by the process
of photosynthesis!
»(to use as ENERGY!)
CARBOHYDRATES
• Carbohydrates may be classified into 3 main
groups:
» monosaccharides – simple sugars
» oligosaccharides – sugars containing 2 or 3
simple sugars attached by covalent bonds called
glycosidic linkages
» polysaccharides – polymers composed of
several hundred to several thousand monosaccharide
subunits
MONOSACCHARIDES
• Monosaccharides are composed of a single
chain of carbon atoms to which hydroxyl
groups are attached.
Monosaccharides
also contain a
carbonyl group (COH or –CO).
MONOSACCHARIDES
• monosaccharides can be distinguished by
the number of carbon atoms they possess
3-carbon
sugar =
“triose”
5-carbon
sugar =
“pentose”
6-carbon
sugar =
“hexose”
MONOSACCHARIDES
• monosaccharides can also be distinguished
by the spatial arrangement of their atoms
» Molecules with the same chemical formula but with a
different arrangement of atoms are called ISOMERS
Glucose, galactose
and fructose all have
the chemical formula
C6H12O6 but have
atoms that are
arranged differently.
MONOSACCHARIDES
• Monosaccharides with 5 or more carbons are
linear in the dry state, but when dissolved in
water form a ring structure.
Glucose (C6H12O6) is a simple sugar with a 6-carbon ring structure.
OLIGOSACCHARIDES
- Two or three simple sugars held together by
glycosidic linkages
A glycosidic linkage
occurs between a
HYDROGEN from one
sugar and a
HYDROXYL from the
other sugar.
Via a condensation
reaction, the two
sugars are joined and a
water molecule is
produced.
1-4 glycosidic linkage
OLIGOSACCHARIDES
• Important disaccharides include: MALTOSE,
SUCROSE & LACTOSE
Lactose is the sugar
found in milk!
Maltose is found in grains and
used in the production of beer.
Sucrose is table sugar!
Sucrose is also used by
plants to transport glucose
from one place to another.
POLYSACCHARIDES
• Also known as “complex carbohydrates”
• are monosaccharide polymers – composed
of several hundred to several thousand
monosaccharide subunits held together by
glycosidic linkages!
Some
polysaccharides
are straight
chains, whereas
others are
branched!
POLYSACCHARIDES
• Polysaccharides serve 2 important
functions in living cells!
» 1. ENERGY STORAGE!
» 2. STRUCTURAL SUPPORT!
Examples of storage
polysaccharides:
Examples of structural
polysaccharides:
- STARCH
- CELLULOSE
- GLYCOGEN
- CHITIN
POLYSACCHARIDES
Starch is an
energy
storage
molecule in
plants.
Glycogen is
used for
energy
storage in
human
muscles.
Cellulose
gives
structural
integrity to the
plant cell wall.
Chitin gives
structural
integrity to the
hard
exoskeletons
of insects.
POLYSACCHARIDES
• Plants store the sun’s energy as glucose –
when they produce more glucose than is
immediately required, they store glucose as
STARCH – a polymer of glucose
Humans and animals possess digestive
enzymes which are able to break the
glycosidic linkages between glucose
molecules in starch – thus using glucose
for energy via cellular respiration.
Starch is the main energy storage molecule in plants. It is a
mixture of amylose and amylopectin.
POLYSACCHARIDES
Humans DO NOT possess digestive
enzymes that enable them to break
down cellulose.
THIS IS WHY HUMANS CAN’T EAT
GRASS! (…but cows can?!?!?!)
Some animals, such as cows, sheep and
rabbits possess digestive enzymes which
enable them to break down cellulose and
convert it to glucose for energy.
When eating fruit and vegetables, humans break down the starch
for energy needs, and the cellulose passes through the digestive
tract with out being digested. Also known as FIBRE, this helps to
scrape our inner intestinal walls and promotes healthy and
regular elimination of wastes!
LIPIDS
• LIPIDS = molecules made up of CARBON,
HYDROGEN and OXYGEN
Due to the smaller proportion of
polar O-H bonds and higher
proportion of the non polar C-H
bonds – fats are NON POLAR!
• LIPIDS have a much higher proportion of
HYDROGEN atoms than oxygen or carbon.
LIPIDS
•
LIPIDS
»
Store MORE chemical energy than
carbohydrates!!!
» Are used in the body for storing energy, building
membranes and other cell parts and are also
chemical signalling molecules.
» Lipids are soluble in NONPOLAR solvents
(like oil)
» Lipids are insoluble in water and aqueous
solutions.
LIPIDS
• The 4 families of lipids include…
WAXES
LIPIDS – OILS & FATS
•
Oils and fats are composed of lipid molecules called
triglycerides. (this is also how plants store fat)
Triglycerides are made up of 4
subunits:

A GLYCEROL backbone
 3 FATTY ACID chains
LIPIDS – OILS & FATS
• A GLYCEROL molecule
» Is a 3 carbon molecule with a hydroxyl group
attached to each carbon
LIPIDS – OILS & FATS
A FATTY ACID
molecule
 Is a long chain of
carbon and hydrogen
atoms with a carboxyl
group at one end.
Hydrocarbon chains usually have 16-18 C atoms
LIPIDS – OILS & FATS
• To form a TRYGLYCERIDE, a fatty acid is
attached to each of the 3 hydroxyl groups
of glycerol.
This is a CONDENSATION
REACTION
3 Water molecules (H2O) are
produced as a bi-product of
this reaction.
The resulting bond is called an
ESTER LINKAGE – and the
process is known as
esterification.
LIPIDS – OILS & FATS
FATTY ACIDS can differ in
 length
 single vs. double bonds
between the carbons
Fatty acids that only have single
bonds will be straight.
Fatty acids that possess double
bonds will be bent.
LIPIDS – OILS & FATS
• Based on the presence of single or double
bonds, we can classify FATTY ACIDS into
two main categories.
SATURATED
TRIGLYCERIDES
UNSATURATED
TRIGLYCERIDES
LIPIDS – OILS & FATS
• Saturated triglycerides contain fatty acids with
ONLY single bonds between carbon atoms.
• Unsaturated triglycerides contain fatty acids with
double bonds between two carbon atoms.
• Polyunsaturated triglycerides contain fatty acids
with more than one double bond.
LIPIDS – OILS & FATS
• Sources of fat in our diet…
Cooking Oils –
polyunsaturated fats
Animal meats – saturated fats
Margarine – saturated fat
LIPIDS – PHOSPHOLIPIDS
• Phospholipids play a key role in the structure
of CELL MEMBRANES!!!
Cell membranes are
made up of a
PHOSPHOLIPID
BILAYER
ie – a double layer of
phospholipids.
LIPIDS – PHOSPHOLIPIDS
• Phospholipids are similar to triglycerides except that
an additional functional group replaces one of the
fatty acids.
Phospholipids are composed of:
- a glycerol molecule
- two fatty acids
- a highly polar phosphate
group
In a phospholipid, one of the fatty
acids is replaced by a PHOSPHATE
GROUP.
LIPIDS – PHOSPHOLIPIDS
The POLAR head is HYDROPHILIC –
ie: “water loving”
The NONPOLAR tail is
HYDROPHOPBIC – ie: “water
fearing”
When placed in
water,
phospholipids will
arrange
themselves with
polar heads facing
outward and
nonpolar tails
facing inward
(away from the
water).
LIPIDS – PHOSPHOLIPIDS
One function of the cell membrane is to
separate two water compartments:
- the extracellular fluid
- the cell’s cytoplasm
The cells DOUBLE LAYER of
phospholipids allows the hydrophilic heads
to mix with water in both compartments
and tails to mix with one another in the
center of the bilayer.
Water and other polar and ionic materials CANNOT pass through the bilayer because
of the highly non polar center. The cell membrane will contain hydrophilic pores that
form channels though which charged materials can pass.
QUESTION!!
• What do Jell-O, antibodies, feathers,
blood clots, egg whites and finger-nails
have in common?!?!?!?!?
PROTEIN
•
They’re ALL made up of
PROTEIN!!!!!!!!!
Proteins are the most diverse molecules in living organisms and among the most
important!
PROTEIN
• The genetic information in DNA codes specifically
for the production of proteins and nothing else.
• Proteins are structural building blocks
• Proteins are involved in almost everything that the
cell does!
• Cells contain thousands of proteins, each
performing a specific task
PROTEIN
• Examples of protein in the body:
» ENZYMES = biological catalysts
» IMMUNOGOBULINS = protect animals against foreign
microbes and cancer cells
» CARRIER PROTEINS = help transport materials through
cell membranes
» HEMOGLOBIN = allows red blood cells to carry oxygen
» KERATIN = structural protein found in hair and nails
» FIBRIN = the protein that helps blood clot
» COLLAGEN = the protein component of bones, skin,
ligaments and tendons
PROTEIN
• Different proteins have various functions…
but all proteins have the same basic
structure.
• Proteins are polymers of amino acids
 PROTEINS ARE MADE UP OF AMINO
ACIDS!!!!!!!!!!
PROTEIN STRUCTURE
• AMINO ACIDS are small molecules that
contain
– A central carbon atom that has attached:
»
»
»
»
NH2
An Amino Group
COOH
A Carboxyl Group
H
a Hydrogen Atom
a side chain (which is different in each different
R
amino acid)
There are 20 different R groups possible and
therefore there are 20 different amino
acids!!!!
PROTEIN STRUCTURE
• AMINO ACIDS
CENTRAL CARBON
ATOM
AMINO GROUP
CARBOXYL GROUP
HYDROGEN ATOM
R-GROUP or Side
Chain
PROTEINS
• Overall there are 20 different AMINO
ACIDS
• Different proteins are made up of different
combinations of the 20 amino acids.
PROTEINS
• Of the 20 amino acids, we say that there
are 8 essential amino acids.
They are called essential amino acids because the body cannot
produce them naturally, and therefore, we must get them from
FOOD SOURCES!!!!!!
PROTEINS
• Proteins consist of one or more amino acid
polymers that have twisted and coiled into a
specific shape = CONFORMATION
An amino acid polymer is often
referred to as a
POLYPEPTIDE and the
bond between amino acids in a
polypeptide are referred to as
PEPTIDE BONDS.
The 3D shape of the protein
determines its function.
PROTEINS
• Peptide bonds are formed by a
condensation reaction between the amino
group of one amino acid and the carboxyl
group of an adjacent amino acid.
PROTEINS
• READ pages 44-46 in the textbook which
speaks further on protein structure.
PROTEINS
• Proteins can loose their shape if they are
subjected to high temperatures (above
40oC) OR if they are exposed to acidic, basic
or salty environments.
» When a protein looses it’s shape because of
environmental factors, we call this
DENATURATION
A denatured protein cannot carry out it’s biological functions!
PROTEINS
• Denaturing a protein can be both dangerous
OR useful…
Denaturing KERATIN in
curly hair is a way of
straightening the hair.
Raw meant is difficult to chew. Cooking
meat denatures the protein, making it
easier to chew.
NUCLEIC ACIDS
Organisms store
information about the
structure of their proteins
in macromolecules called
NUCLEIC ACIDS.
Nucleic acids are used by all
organisms to store hereditary
information that determines
structural and functional
characteristics.
NUCLEIC ACIDS
• There are TWO types of nucleic acids in
living organisms:
»DNA
(deoxyribonucleic acid) – the
instructions for creating an organism are stored in digital
code along coiled chains of DNA
» RNA (ribonucleic acid) – reads the information in
DNA and transports it to the protein-building apparatus of
the cell
DNA and RNA is found in the
nucleus of cells!!!!
NUCLEIC ACIDS
Nucleic Acids are made up of sub-units called
NUCLEOTIDES. Nucleic acids are nucleotide polymers.
Each nucleotide is made up
of:
 A 5 carbon sugar
 a phosphate group
 a nitrogenous base
In a NUCLEIC ACID CHAIN, the phosphate group of one nucleotide is linked to the
sugar of another nucleotide.
NUCLEIC ACIDS
• DNA contains the sugar DEOXYRIBOSE
whereas RNA contains the sugar RIBOSE.
The only difference
between these two sugars
is the lack of oxygen at
carbon 2 in deoxyribose –
this accounts for its name.
NUCLEIC ACIDS
• There are 4 types of nitrogenous bases in
DNA:
» Adenine (A)
» Guanine (G)
» Thymine (T)
» Cytosine (C)
NUCLEIC ACIDS
Purines have a doubleringed structure.
Pyrimidines have a
single-ringed structure.
NUCLEIC ACIDS
• DNA is made up of TWO strands of nucleic
acids
The TWO strands of
nucleic acids are wound
around each other like a
winding staircase – called a
DOUBLE HELIX
The double helix structure
causes the nitrogenous
bases to be facing each
other
The nitrogenous bases form
hydrogen bonds between
each other.
NUCLEIC ACIDS
• In DNA, the bases ALWAYS pair as follows:
» A pairs with T (2 H bonds)
» G pairs with C (3 H bonds)
NUCLEIC ACIDS
NUCLEIC ACIDS
Each strand of DNA has a free phosphate group and one end
(5’) and a free sugar at the other end (3’).
The free phosphate (5’) end of one
strand will line up with the free sugar (3’)
end of the other strand.
Thus, it is said that the two strands run
ANTIPARRALEL – they run in
opposite directions relative to one
another.
Every nucleotide pair is composed of a
purine (double ring) facing a pyrimidine
(single ring).
NUCLEIC ACIDS
• Unlike DNA, RNA is made up of only ONE
strand of nucleotides.
• All the bases in RNA are the same, except
that thymine (T) is replaced by a base called
Urasil (U).
NUCLEIC ACIDS
• RNA is single stranded
– Contains the base Urasil (U)
instead of (T)