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Chapter 7: Cell Membrane (plasma membrane)
Review: the Characteristics of Life
Try to come up with as many characteristics you can. Living things… Reproduce. Have genetic material. Grow and develop. Use materials and energy. Respond to their environment. Maintain homeostasis. Change over time. Are made up of units called cells.
What is a cell? Smallest unit of living tissue collected
together surrounded by a barrier that separates it from the surroundings.
All living things are made up of cells.
Here is a neat animation of relative size of cells and other ‘objects’.
Cell Theory The cell theory states:
All living things are composed of cells. Cells are the basic units of structure and
function in living things. New cells are produced from existing
cells.
“Pro” versus “Eu” Cells fall into two broad categories,
depending on whether the contain a nucleus (controls cell’s activities). Prokaryotic
Does not contain Eukaryotic
Does Contain
Review If a cell of an organisms contains a
nucleus, the organism is a (an) A. plant B. eukaryote C. animal D. prokaryote
Review In many cells, the structure that controls
the cell’s activities is the A. cell membrane B. organelle C. Nucleolus D. Nucleus
Review the Biomolecules Four main biomolecules found in living
things: Proteins
Various functions throughout cells/organism. Lipids
Fats, steroids, oils. Doesn’t mix with water. Function: store energy.
Carbohydrates Function: main source of energy.
Nucleotides Function: store genetic information DNA or RNA
Cell Boundaries The cell MEMBRANE regulates what
enters and leaves the cell and also provides protection and support. All cells have membranes. Also phospholipid bilayer
Cell Membrane
Cell Membrane The cell membrane is made up of
two layers called the “lipid bilayer”. The heads of the lipids are on the
outsides. They are hydrophilic (hydro = water;
philic = loving). The tails of the lipids are on the
insides. They are hydrophobic (phobic =
fearing/hating) Studded throughout the
membrane are proteins with various functions.
Lipids
made of alcohol and carbon
Tails are fatty acid chains
Slight movement to allow water and substances to pass through membrane (simple diffusion no energy)
Cell Membrane as a “mosaic” Carbohydrate chain
(glyco)- act like chemical identification cards allowing individual cells to identify one another Glycoproteins Glycolipids
Proteins channels and pumps – help move material across the membrane Integral protein
(channel) Peripheral protein
Lipids bilayer- gives the membrane a flexible structure that forms a strong barrier
Polar vs. Non-polar
POLAR/NONPOLAR Polar means that the substance has positive or negative
poles. Non-polar does NOT have positive or negative poles. Polar things like other polar things. Water
is polar!!!!!!!!! Non-polar things like other non-polar
things. Oil is non-polar!!!!!! Selectively permeable- Some molecules can cross the
membrane without assistance, most cannot.
Review Cell membranes are constructed mainly
of A. lipid bilayers B. protein pumps C. carbohydrate gates D. free-moving proteins
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