lipids l2 biology. as biology. foundation. cell membranes and transport 2 do now: key words to look...
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LIPIDSL2 BIOLOGY
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AS Biology. Foundation. Cell membranes and Transport
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Do Now: Key words to look up Phospholipids
Hydrophilic Hydrophobic Cholesterol Proteins (in
cell membrane)
Selectively permeable
Phospholipid bilayer
Fluid mosaic model
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What are Lipids?
Lipids include substances like fats, oils and waxes
Typical formula C51H98O6
What can you tell me about lipids from looking at this formula?
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Lipid Structure
one glycerol three fatty acids(also called a triglyceride)
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GLYCEROL
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FATTY ACIDS
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LIPID=Glycerol +3 fatty acids
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Two Types of Fatty Acids
SATURATED– The fatty acids are completely full of
hydrogen atoms (no double bonds!)
UNSATURATED– There are one or more double bonds
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Cont…
SATURATED FATS – Usually solid, fully hydrogenated –
animal sources
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Cont…
UNSATURATED FAT– Usually a liquid; not fully
hydrogenated - plant sources
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SATURATED OR UNSATURATED?
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Trans Fats: Bad in your diet!
Trans fats–Unsaturated, but the double bond between carbons is turned so they are now SOLID at room temperature
–Considered “bad” fats (we create them artificially from liquid oils)
–Margarine, creams in snacks foods
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3 functions of Lipids
Major component of cell membranes.
Long term energy storage. Protection.
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1. What types of substances are lipids?
2. What are the four parts that make up a lipid?
3. What is the difference between a saturated fat, unsaturated fat, trans fat?
4. How are lipids like proteins?
5. How are lipids different from proteins?
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Cell Membranes: Question: Can We live totally fat Free ?
Every cell is enclosed by a double layer of lipids: that is the cell membrane
-Called a phospholipid bi-layer-What does this mean?
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Cell (plasma) Membrane Encloses the cell’s
contents Function:
Regulates which particles (nutrients, wastes) can enter and exit the cell.
Also is way cells “communicate”
Selectively permeable
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A Phospholipid BilayerPhospholipids can
form:
BILAYERS
-2 layers of phospholipids with hydrophilic heads (on outside) and hydrophobic (fatty acid) tails protected inside.
The PHOSPHOLIPIDBILAYER is the basicstructure of
membranes.
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Properties of Cell Membranes
Basic structure is Phospholipid
Bilayer.
Phospholipids have HYDROPHOBIC
(non-polar) tails and HYDROPHILIC
(polar) heads.
The fatty acid tails of phospholipids
can be SATURATED (straight) or
UNSATURATED (bent)
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Plasma Membrane Structure Building blocks are phospholipids…
– Lipid with a polar phosphate group attached to one end.
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Properties of Cell Membranes Phospholipids act as a barrier to
most water soluble substances
BUT, Phospholipids are only PART of the story…………
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Fluid mosaic model
Cell membranes also contain cholesterol and proteins within the phospholipid bilayer.
This ‘model’ for the structure of the membrane is called the: FLUID MOSAIC MODEL
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Why call it a Fluid Mosaic Model?
FLUID- because phospholipids and some proteins move around freely within the layer, like it’s a liquid.
MOSAIC- because of the pattern produced by scattered protein molecules in the membrane when viewed from above.
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Visualizing structure and function membrane animation
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Functions of Proteins/Cholesterol in Cell Membrane 1. Proteins act as channels for substances
to move in or out of cell.
2. Some act as membrane enzymes in
chemical reactions.
3. Proteins help to stabilize the membrane.
Cholesterol stabilizes and prevents ions
from entering.
4. glycoproteins act as markers for cell
communication or receptors that
hormones & other proteins can bind.
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Functions of components of cell membranes
Use the following headings to produce a table summarizing the functions of the different types of molecules found in the cell membrane. Use your notes to find the information.
Component Description Function
1. Phospholipids
2. Proteins
3. Cholesterol
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Quick Quiz:
1. What is the main component of the cell membrane?
2. a. What does the word “hydrophobic” mean? b. What does the word “hydrophilic” mean?
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3. Name 1 function for proteins in the cell membrane.
4. What is the function of cholesterol in the cell membrane?
5 a. What do we call a protein with a carbohydrate (sugar) attached?b. Name 1 function for these molecules in the membrane.