Download Notes Unit 2 Part 3 POWERPOINT

Biology Notes
Cells
Part 3
Pages 81-91
Standard
2.6 Explain the role of cell membranes as a
____
highly selective barrier (passive and active
transport)
Essential Question:
1. How do materials enter and leave cells?
I. Cell Communication &
Cell Membranes
Cells must communicate with each other in order
homeostasis
to keep an organism in ____________
Homeostasis = regulation of an organism’s
internal environment in order to maintain
________
balance
e.g.pH, body temperature, heart rate, etc.
• Cells send messages to other cells about what
need and what they need to get rid of in
they _____
order to keep this homeostasis
– messages can be sent between cells that are
chemical or _________
electrical
_________
Cell Membrane = the organelle that surrounds
support and protection as
cells to provide ________
well as to regulate what _______
enters and______
exits
the cell
a.k.a. – plasma membrane
• The cell membrane plays a vital role in cell
communication by regulating what messages
enter and ____
exit the cell
can ______
• The cell membrane also plays a vital role in
homeostasis by regulating what molecules can
enter and ____
exit the cell
______
e.g. in = H2O, food out = waste, CO2
• selective permeability = the ability of the cell
___________
membrane to allow some materials to
enter into a cell while keeping others out
______
II. Cell Membrane Structure
Protein-lipid bilayer = a strong double layer of
lipids containing embedded ________
proteins make
_____
up the majority of the cell membrane structure
fluid mosaic model
• Also called the _____
Why would the cell membrane be made out of
lipids???
- It needs to be waterproof
• The lipids are called ______________
phospholipids because
phosphate molecule attached
each one has a __________
soluble whereas the
• The lipid heads are not ________
soluble
tails are ________
lipid heads = hydrophilic &
polar
lipid tails = hydrophobic &
non-polar
• The embedded ________
proteins carry out most of the
functions of the plasma membrane
enzymes and
- some proteins serve as _________
destroy any material that could ______
harm the cells
strengthen the cell
- cholesterol serves to ____________
membrane
– other proteins have ______________
carbohydrates
attached that serve as a “beacon” for
inside the cell
materials needed ______
DIAGRAM:
III. Cell Membrane Action
In order to maintain ____________,
homeostasis the
concentration of most substances in and out of
the cell must be _________
balanced
• Concentration = in a ________,
solution the amount of
solute in a given volume of _______
solvent
______
volume
(mass / _______)
e.g. What is the concentration of salt if there are
12 grams of salt in 3 liters of water? 4g/L
• Concentration gradient = the difference in
_____________
concentration across a space
• If the concentration of substances are not
equal in and out of cells, then the cell
______
actions to balance the
membrane may take _______
concentrations
– there may be exceptions to this rule
e.g. food always in / CO always out
2
A. Diffusion = the net movement of particles
high concentration to an area
from an area of _____
low concentration until dynamic equilibrium
of ____
is reached
down their
• Substances are said to be moving ______
gradients
concentration _________
• Dynamic equilibrium = when the
concentration of particles are ______
equal both
cell
inside and outside of the ____
energy
• Diffusion requires no _______
DIAGRAM:
• Diffusion will only occur with small molecules
CO2 ____,
H2O _____
NH3 and ___.
O2 Other larger
like _____,
glucose (C6H12O6) cannot use
molecules, like ________________,
diffusion to enter or exit a cell.
_________
B. Osmosis = the diffusion of ______
water from an
high concentration to an area of low
area of _____
concentration through a selectively
_____________
membrane
permeable ___________
energy because it is
– requires no _______
diffusion
_________
– occurs in solutions when the solute is too
______
large to pass through the membrane so the
water will move until the concentrations on
either side of the membrane are ______
equal
Why is this picture wrong?
• Isotonic solution = a solution in which the
concentration of ________
solution is the same on both
cell
sides of the _____
– there is no net movement of ______
water
DIAGRAM:
• Hypotonic solution = a solution in which the
solution is lower ________
concentration of ________
outside
the cell than ______
inside the cell
into the cell
– water will move ____
and the cell will appear
swollen
________
– osmotic pressure =
pressure created inside
the cell when water moves ___
in
DIAGRAM:
• Hypertonic solution = a solution in which the
solution is higher ________
outside
concentration of ________
inside the cell
the cell than ______
leave the cell a
– water will ______
and the cell will appear
wilted
_______
– plasmolysis = the drop of ________
osmotic
leaves
pressure inside a cell when water _______
the cell
DIAGRAM:
C. Facilitated Diffusion = movement of
cell membrane by means
materials across a ____
transport proteins
of _________
a.k.a. passive transport
larger molecules like ________
C6H12O6 to
• allows ______
cross
• does not require _______
energy
• molecules still move ______
down their concentration
gradient
DIAGRAM:
D. Active Transport = the movement of materials
cell membrane when it is ________
against
across a ____
their concentration gradient
energy to move materials from ____
low
• requires _______
to high concentration
DIAGRAM:
E. Endocytosis = a process of taking material
into the cell by means of _______
moving the entire
____
cell membrane
1. phagocytosis = a type of endocytosis in
membrane surrounds
which extension of the __________
a particle and packages it within a food
________
vacuole
e.g. How amoebas intake food.
2. pinocytosis = a process by which cells take
liquids from the surrounding environment
in _______
by forming ________
pockets along the cell
membrane
___________
F. Exocytosis = a process by which material is
_________
excreted from a cell by ______
fusion with the cell
membrane
e.g. lysosomes
IV. Everyday Cell Membrane
A. Food Preservation
salt to make food last longer
• Adding ____
hypertonic solution so that water
– creates a ___________
cell
moves out of the _____
spoiling by killing any
– prevents food from ________
bacteria
________
osmosis
– Works through _________
B. Kidneys
• The nephron filters the ______
blood as it moves
through the kidneys
N2 ____
NH3 and waste or
– substances like ___,
H2O are removed and sent for
excess ____
excretion
_________
e.g. urine in bladder
osmosis
• Substances are removed by _________,
facilitated diffusion and active _________
__________________
transport
C. Lungs
• The alveoli exchanges _____
CO2 for ___
O2 through
diffusion
simple _________