Download L5 Cell Membranes Jan 2017

L5 Quiz: Cell Parts pg 1
89
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1. What is the energy producer of the cell?
1. Mitochondria, chloroplast
2. What packages and processes proteins?
1. Golgi apparatus
3. What does the smooth endoplasmic reticulum do?
1. Produce lipids
L5 Quiz: Cell Parts pg 2
90
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1. What does the nucleus do?
1. Stores DNA, information bank of cell, brain of cell
2. What does the nucleolus do?
1. Produces ribosomes/rRNA
3. What are the structures that support the cell called?
1. Cytoskeleton, microtubules
L5 The Cell Membrane and the “Fluid
Mosaic” Model
¨ 
Function
1.  Transport of materials in
and out of cell
2.  Recognition
3.  Communication
4.  Homeostasis
¨ 
Cells are surrounded by a
thin membrane of lipid and
protein, (about 10 nm thick.)
L5 The Cell Membrane and the “Fluid
Mosaic” Model
¨ 
¨ 
¨ 
scientists today agree upon
The Fluid Mosaic Model of
membrane structure.
The cell membrane is a
remarkable structure that has
properties of a solid and a
liquid.
It forms a "fluid sea" in which
proteins and other molecules
like other lipids or
carbohydrates are suspended
(like icebergs) or anchored at
various points on its surface.
L5 The Cell Membrane and the “Fluid
Mosaic” Model
The “fluid” part is
composed of side by side
phospholipids arranged
in a bilayer.
¨  The solid part (the
“mosaic”) is the variety of
proteins etc. embedded in
the bilayer.
¨ 
L5 The Cell Membrane and the “Fluid
Mosaic” Model
each phospholipid has a
hydrophobic tail and a
hydrophylic head.
¨  the membrane has
consistency of light machine
oil.
¨  the membrane is
SELECTIVELY PERMEABLE
(will let some substances in
but not others of the same
size).
¨ 
L5 Proteins in the Membrane
¨ 
Integral Proteins
¤  Large
proteins that are embedded in the cell
membrane
¤  Function
n  Channel
proteins (transport)
n  Receptors (communication)
n  Enzymes (chemical reactions)
n  Structural support
L5 Proteins in the Membrane
¨ 
Peripheral Proteins
¤  Proteins
that exist on the outside of the membrane
¤  Function: not needed
L5 The Cell Membrane and the “Fluid
Mosaic” Model
¨ 
Plant Cells also have a Cell
Wall surrounding their cell
membrane made up of
cellulose fibers.
L5 Assignment
¨ 
IB Biol 11
¤  Read
pgs 25-27 in Biology Course Companion
(Oxford)
¤  List the six main functions of Membrane Proteins
¨ 
Bi 11
¤  Watch
episode 2 of Hidden life of Cell for cell
membrane