Transcript AS Biology Core Principles

Lipids
Aims
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Elements of lipids
Structure of glycerol & fatty acids
Condensation reactions to form
triglycerides
Phospholipids
http://www.youtube.c
om/watch?v=vccnaNS
wUs4
What does this have to
do with lipids?
How does the hump
help the camel
survive?
What is the related
biochemical reaction?
Introduction to lipids
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Lipids contain the elements
carbon, hydrogen and oxygen.
They have numerous functions,
primarily energy stores in animals
and plants.
Lipids consist of two types of
molecules - glycerol & fatty acids.
Glycerol
A molecule of
glycerol is made up
of three carbon
atoms.
o Each of these has a
hydroxyl group
attached to it.
o Hydrogen atoms
occupy the
remaining
positions.
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Fatty Acids
Fatty Acids
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A single fatty acid molecule contains an
acid (COOH) group attached to a
hydrocarbon chain.
Hydrocarbon usually denoted by the letter
’R’.
Saturated = If every carbon atom in the
chain is joined by a single C-C bond.
Unsaturated = at least one C=C bond.
Polyunsaturated = many double bonds.
Most animal fats are saturated while most
plant fats are unsaturated.
Triglycerides
Triglycerides
A triglyceride molecule is made of a
glycerol molecule and three fatty acids.
o The molecules join together through the
process of condensation losing a molecule
of water each time a link is made.
o The link between the glycerol molecule &
each fatty acid is an ‘Ester Link’.
o The fatty acids in a lipid molecule can
differ in length and can be saturated or
unsaturated.
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Triglycerides
Condensation
Phospholipids
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In phospholipids one
of the fatty acids of
a triglyceride is
substituted by a
phosphate group.
Phospholipids
Formation of a phospholipid
Lipids & water
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Triglycerides and phospholipids
have hydrophobic and hydrophilic
groups.
o What does this mean?
o To what use is this feature put in
biology?
o What happens when you mix oil in
water? Describe and explain.
Cholesterol
Steroids e.g. testosterone
•Makes notes on cholesterol
and steroids
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Draw and compare them (find the
relevant challenge question on the
challenge board in S8)
More Info
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To make further notes on Lipids :
o www.mrothery.co.uk
o www.biologymad.com
o http://chemincontext.eppg.com/chap
ter11/cic_interface11.swf
o http://www.cassiopeiaproject.com/vi
deos.php