Carbohydrates, Lipids and Proteins
(Biological Building blocks)
IB Biology – Assessment Statements 3.2.1 to 3.2.7
Chemistry of Life

Organic chemistry is the study of carbon compounds

Carbon atoms are versatile building blocks
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bonding properties
4 stable covalent bonds

Organic compounds contain carbon (C) and
occur naturally only in the bodies of living
organisms.

They almost always contain hydrogen (H),
usually contain oxygen (O) and nitrogen (N),
Sometimes contain phosphate (P), sulfur (S), iron
(Fe), copper (Cu), sodium (Na), chlorine (Cl) or
potassium (K) in small amounts.

Assessment Statement 3.2.1

Inorganic compounds do not usually contain
carbon. This term is used when referring to any
compound that is not organic.
http://www.slideshare.net/gurustip/org
anic-or-inorganic-presentation
Assessment Statement 3.2.1

Carbon molecules can form long chains or rings.
Allowing for multiple branches for bonding.
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The size and arrangement of organic
compounds are unlimited.

Organic compounds are divided into 4 groups:
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Carbohydrates
Lipids
Proteins
Nucleic acids.
Assessment Statement 3.2.1
Complex molecules can be assembled like
building blocks.
Hydrocarbons can grow…
Isomers

Molecules with same molecular formula but
different structures (shapes)


different chemical properties
different biological functions
6 carbons
6 carbons
6 carbons
Identify amino acids
Form affects function

Structural differences create important
functional significance

amino acid alanine
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medicines

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L-alanine used in proteins
but not D-alanine
L-version active
but not D-version
sometimes with
tragic results…
stereoisomers
Form affects function

Thalidomide



prescribed to pregnant women in 50s & 60s
reduced morning sickness, but…
stereoisomer caused severe birth defects
Viva la difference!

Basic structure of male & female hormones is
identical



identical carbon skeleton
attachment of different functional groups
interact with different targets in the body

different effects
Macromolecules

Smaller organic molecules join together to
form larger molecules

4 major classes of
macromolecules:
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carbohydrates
lipids
proteins
nucleic acids
Our Organic Friends!
Assessment Statement 3.2.2
Assessment
Statement
3.2.3


Made of C, H and O, where the ratio of C to H to
O is 1:2:1.
There are monosaccharides, disaccharides and
polysaccharides.
Monosaccharides are
the simple sugars. Their
molecular formula is
C6H12O6.
They are single unit sugars.
Glucose, fructose and galactose.

Identify Glucose
Assessment Statement 3.2.2
Identify Ribose
Assessment Statement 3.2.2
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Most important source of energy – total
energy gain is 4 Calories/gram Assessment Statement 3.2.6
Carbohydrates are built from sugar molecules
(ending in “ose”).
Some famous sugars include:
 Glucose (found in human blood -#1 brain food),
 Fructose (plant sugar),
 deoxyribose (the sugar portion of DNA),
 Cellulose (a polysaccharide that makes up plant
walls- commonly known as ruffage or fiber).
Assessment Statement 3.2.3

Disaccharides are double sugars and are made by
combining 2 simple sugars together into a two unit sugar.

Examples are sucrose, maltose and lactose.
Polysaccharides are long chains of repeating sugar units.
Multiunit sugar – more than two sugars combined.


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Examples are starch, glycogen and cellulose.
Glycogen is stored in animal cells and is
often refered to as animal starch.
Glycogen is made up of 16 to 24 glucose
molecules. The liver converts glycogen
into glucose units for energy.
Assessment Statement 3.2.3
List one function each for:
Glucose, lactose, glycogen in animals:

Glucose = monosaccharide, major energy
source for fuelling cellular respiration.

Lactose = disaccharide, energy source found in
mammalian milk

Glycogen = polysaccharide; energy storage in
liver.
Assessment Statement 3.2.4
List one function each for:
Fructose, sucrose and cellulose in plants:

Fructose = monosaccharide: energy
component in flower nectar

Sucrose = disaccharide: energy molecule
transported via phloem

Cellulose = polysaccharide: major structural
component of plant cell walls.
Assessment Statement 3.2.4
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Commonly known as “fat” – total energy gain 9
Calories/gram. Assessment Statement 3.2.6
Foods – fish, olive oil, red meat, nuts.
Are a key component in cells, especially in the
cell membrane.
They are made of C, H and O.
Yield twice as much energy as carbohydrates.
Lipids are made up of fatty acids and glycerol.
2 types of lipids: saturated and unsaturated.
Assessment Statement 3.2.6

Structure: Lipids are made up of two portions a
glycerol head and fatty acid tails.
glycerol
fatty acids

Lipids can also go through condensation and
hydrolsis, just like carbohydrates and proteins.
3 functions of lipids:
1. Energy Storage: lipids provide concentrated
long-term energy storage which can release
fuel for cellular respiration as needed.

2.
Cell membrane: the main component of cell
membraes are phospholipids
3.
Thermal insulators: reduce the loss of heat from
an organism (e.g. an under the skin layer of
lipids).
Assessment Statement 3.2.6

When an unsaturated fat has only one
unsaturated bond, it is known as
monounsaturated. When a fat has more than
one unsaturated bond it is known as
polyunsaturated.
Assessment Statement 3.2.6

Phospholipids and triglycerides and waxes are three
important groups of lipids.

Phospholipids are the building blocks of the fluid
mosaic model of the cell membrane. They have a
phosphate/glycerol head that is polar and
hydrophillic and two fatty acid tails that are
hydrophobic.

Triglycerides – are another type of lipid found in the
body. These special lipid molecules are built from
one glycerol and three fatty acids with the help of
an enzyme.
Saturated Fats


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Lipids that are solid or semi-solid at room
temperature are said to be saturated (loaded
up with covalent bonds to H atoms).
E.g. Butter, shortening and marbling in meat.
Saturated fats are very stable at room
temperature.
Unsaturated Fats
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Lipids that are liquid at room temperature are
said to be unsaturated (containing double
bonds, or less H atoms).
E.g. Oil is an example of an unsaturated fat.
Unsaturated fats are easier to break down in the
body than saturated fats. Hense the push for
people to use vegetable or canola oil rather
than butter while cooking.
Lipid Groups
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Waxes – are the third group of lipids. They are formed
from long chains of fatty acids joining long-chain alcohol
or carbon rings. Waxes are insoluble in water, and are
used for water proofing plant leaves or animal feathers
and fur.
Fats & Diet – stable fats in the body (saturated fats) tend
to stay put once ingested leading to plaque in the
arteries and ultimately to health complications (e.g.
stroke, cancer, high blood pressure, type two diabetes).
Cholesterol – not all fat is bad. Cholesterol is required by
the cell membrane and is also important for the
production of hormones (specifically sex hormones –
estrogen and testosterone). There are two different types
of cholesterol in the blood HDL and LDL. HDL is the
“good” cholesterol and LDL is the “bad” cholesterol.

Proteins are made of C, H, O and N. They are the
most abundant organic compound found in living
cells.

The most important macromolecule in the body.
Their importance can not be underestimated!
They form:
 The structural parts nails, hair, cell membrane and
cartilage
 Pigments (skin, eyes and chlorophyll),
 Hormones
 Contractile material of muscle tissues
 Antibodies
 Enzymes.
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The building blocks of proteins are amino acids.
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The amino acids are bonded together by
peptide bonds to form proteins.
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The smallest protein consists of 50 amino acids
bonded together and the largest consists of
over 100, 000.
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Proteins Rule Everything in the Body!
Total energy gain is 4 Calories/gram.
(however, energy gain is not their main
function).
Your body requries 22 essential amino acids,
but can only produce 8!
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We must rely on digestion to gain the other amino
acids we need.
22 different amino acid groups give rise to an
infinite amount of proteins.
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Proteins are large molecules constructed of
many amino acids.
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Again, condensation and hydrolysis apply to this
macronutrient.

The bond that is formed from an acid group
(COOH) and the amino group (NH2) is called a
peptide bond. Because of this special bond,
proteins are frequently called polypeptides
(many peptide bonds).
Assessment Statement 3.2.5
Assessment Statement 3.2.2

Shapes – primary (linear), secondary (coiled),
tertiary (bent-coiled) and quarternary (compact
with a specific structure).

You can unfold a protein (de-nature) by
exposing the protein to heat, radiation or a
change in pH. (i.e. frying an egg, baking a
cake, UV exposure, x-rays).
Assessment Statement 7.5.1
Primary protein structure:
 Sequence and number of amino acids
 Each position occupied by one of 20 amino
acids
 Linked by peptide bonds
Assessment Statement 7.5.1
Assessment Statement 7.5.1
Secondary protein structure:
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Weak hydrogen bonds between amino and carboxyl groups.
Form at regular intervals, creating a regular structure (not from
the interactions between variable R groups)
Alpha helix = coiling into a helix
Beta pleating = a folded sheet as polypeptide folds back onto
itself.
Not all of a polypeptide forms secondary structure in most
proteins.
Assessment Statement 7.5.1
Tertiary protein structure:
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Interactions between variable R-groups forming
Hydrophobic interactions between non-polar amino acids
Hydrogen bonds between polar amino acids
Ionic bonds between ionic amino acids
Covalent bonds between sulfur containing amino acids
Producing the three dimensional folded structure of most
proteins.
Assessment Statement 7.5.1
Quarternary protein structure:
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Aggregations of polypeptides form interactions between more
than 1 polypeptide
Polypeptides + non-proteinaceous molecules, such as:
Metals, e.g. iron in hemoglobin
Vitamins as enzyme co-factors
Nucleic acids as in ribosomes
Carbohydrates in glycoproteins
Lipids in lipoproteins.
http://www.youtube.com/watch?v=lijQ3a8yUYQ
Outline the difference between fibrous and
globular proteins, with reference to two
examples of each type of protein.
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Fibrous:
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Long fibers or sheets formed by parallel polypeptide
chains
Dominated mostly by secondary structure
Mostly water insoluble
Great strength and/or strechiness from affects of
regular H-bonds
Collagen in connective tissue
Actin and myosin in muscle tissue
Assessment Statement 7.5.2
Outline the difference between fibrous and
globular proteins, with reference to two
examples of each type of protein.
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Globular:
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Folded into complex 3D irregular spherical shape
Dominated mostly by tertiary structure
Mostly water soluble
Functions determined by 3D shape
Enzymes such as amylase
Hormones such as insulin
Transport such as hemoglobin
Protective, such as immunoglobulins
Assessment Statement 7.5.2
Explain the significance of polar and nonpolar amino acids

Amino acids fit into three groups:
1.
2.
3.
Polar
Ionic
Non-polar
Assessment Statement 7.5.3
Ionic and Polar amino acids
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Have hydrophillic R groups
Attracting the protein to water
Forming H bonds and ionic bonds between
different amino acid R groups
Contributing to tertiary structure
Assessment Statement 7.5.3
Non-polar amino acids
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Have hydrophobic R groups
Repelling the protein from water
Forming hydrophobic bonds between different
amino acid R groups
Contributing to tertiary structure
Contributing to protein attraction to fatty acids
in the phospholipid bilayer
Assessment Statement 7.5.3
Polar and Non-polar Amino Acids:

The distribution of polar and non-polar amino
acids in a protein determine where in a
membrane or cell a protein will be located and
the function it will perform.
Assessment Statement 7.5.3
State four functions of proteins, giving a
named example of each.
Protein
Function
Haemoglobin
A protein containing iron that transports O2 from the
lungs to all parts of the body in vertebrates.
Actin and Myosin
Insulin
Immunoglobulins
Amylase
Proteins that interact to bring about muscle
movement (contractions) in animals
A hormone secreted by the pancreas that aids in
maintaining blood glucose level in vertebrates
Group of proteins that act as antibodies to fight
bacteria and viruses.
Digestive enzymes that catalyses the hydrolysis of
starch.
Assessment Statement 7.5.4
Metabolism

All the chemical reactions that occur in your
body. Approximately 200, 000 chemical
reactions occur daily within one single cell.

Catabolic and anabolic reactions are two types
of reactions that occur inside the cells.
Catabollic reactions occur when large
chemicals are broken down into smaller
components.
Anabollic reactions, complex chemicals are
built from smaller components.
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The chemical compounds of life are made by
dehydration synthesis and broken down by
hydrolysis. Condensation occurs when
molecules bond together by removing a water
(H2O) molecule. Enzymes are involved in this
type of synthesis. Disaccharides,
polysaccharides, lipids and proteins can be
made this way. Hydrolysis is the breaking apart
of molecules by replacing it with a water
molecule at the place where it was removed in
dehydration synthesis.
Assessment Statement 3.2.5
Condensation

Polymers are long molecules built by linking
repeating building blocks in a chain by
removing water.

monomers
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building blocks
repeated small units
H2O
covalent bonds
HO
H
HO
H
Condensation!
Assessment Statement 3.2.5
HO
H
How to build a polymer

Condensation allows for synthesis!

joins monomers by “taking” H2O out
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1 monomer provides OH–
other monomer provides H+
together these form H2O
requires energy & enzymes
HO
H2O
H
HO
H
enzyme
Condensation reaction
Assessment Statement 3.2.5
HO
H
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Condensation builds larger molecules by
releasing water
It is an ANABOLIC REACTION
Used to build carbohydrates, lipids, and
proteins!
Requires an ezyme to act as a catalyst and
speed the reaction along.
Condensation of amino acids to form proteins.
 http://www2.nl.edu/jste/proteins.htm
 http://www.biotopics.co.uk/as/aminocon.html
Assessment Statement 3.2.5
Assessment Statement 3.2.5
Assessment Statement 3.2.5
How to break down a polymer

Hydrolysis – aka. digestion

use H2O to breakdown polymers

reverse of condensation

Cleaves off one monomer at a time

H2O is split into H+ and OH–


H+ & OH– attach to ends
H2 O
requires enzymes
HO
Hydrolysis
Assessment Statement 3.2.5
HO
H
enzyme
H
HO
H




Breaks bonds in larger molecules to produce
smaller pieces.
It is a CATABOLIC REACTION
Used to break apart carbohydrates, lipids and
proteins.
Requires the use of an enzyme to act as a
catalyst and spead the reaction along.
Assessment Statement 3.2.5
Assessment Statement 3.2.5
http://www.wisc-online.com/objects/ViewObject.aspx?ID=AP13104
Assessment Statement 3.2.5
Assessment Statement 3.2.5
Assessment Statement 3.2.5
Assessment Statement 3.2.5
LIPIDS – saturated vs. unsaturated
Let’s See How you are doing with a mini-quiz!
Get out a piece of paper and try the next few
questions! We will return to these questions to
discuss your answers at the end.
Ready? Set? Here we go! 
Quiz time!
Question 2:
Question 3 and 4
Question 5