Download cell membrane - McEachern High School

CELL SIZE AND
CELL MEMBRANE
SB1.A. EXPLAIN THE ROLE OF CELL ORGANELLES FOR BOTH
PROKARYOTIC AND EUKARYOTIC CELLS, INCLUDING THE
CELL MEMBRANE, IN MAINTAINING HOMEOSTASIS AND CELL
REPRODUCTION.
TODAY 2/8
• Pick up journal and handout- complete the
handout and put your answers on your notebook
paper in your journal
• TURN IN CELL COMPARISON LAB (from Wednesday)
AND CELLS ALIVE (from Friday)
• Prepare for organelle quiz
WHY DO WE NEED A
“BOUNCER” FOR OUR CELLS?
HOW DO WE KNOW WHAT
MEMBRANES ARE MADE OF?
WHY ARE CELLS SO SMALL?
• If cell is too big, takes
too long for necessary
chemicals to get
around the cell.
• Insects and elephants
have cells that are the
same size, the
elephant just has
more of them and the
ones they have are
more specialized.
WHY IS THE CELL MEMBRANE SAID
TO BE SELECTIVELY PERMEABLE?
• Controls what goes in
and out.
• What goes in and out is
controlled by proteins
embedded in the cell
membrane.
WHAT IS THE CELL MEMBRANE
COMPOSED OF?
1. Phospholipid Bilayer
• Phospholipid• “Phospho”• phosphate heads
• hydrophilic (polar);
• form outer boundary of cell
membrane
• “Lipid”• two lipid tails
• Hydrophobic (nonpolar)
• form inner layer of cell membrane
• Bilayer- two layers of
phospholipid molecules
WHAT IS THE CELL MEMBRANE
COMPOSED OF?
2. Proteins
•
•
•
Channel proteinsallow larger
molecules in/out
Carrier proteinsallow larger
molecules in/out but
change shape to do
so.
Glycoproteins- allow
cells to recognize
each other
WHAT IS THE CELL MEMBRANE
COMPOSED OF?
3. Cholesterolstabilizes the cell
membrane so not too
“loose.”
WHY IS THE CELL MEMBRANE
DESCRIBED AS A FLUID MOSAIC?
• Fluid Mosaic Model
• “Fluid”Phospholipids &
proteins can drift
sideways in the
membrane.
• “mosaic”membrane is studded
with many different
kinds of proteins.
Fluid Mosaic Animation
QUIZ 1
1. Which part of the cell membrane repels
water?
a. proteins b. phospholipids c. enzyme
2. Hydrophilic means?
a. water loving b. water hating
c. contains water
3. Which part of the cell membrane has pores?
a. proteins b. phospholipids c. enzyme
layer
4. What part of the cell membrane acts as
recognition markers?
a. proteins b. phospholipids c. enzymes