Transport-cell membrane
• Do Now:
• Brainstorm:
• What is homeostasis?
• Can you brainstorm one
• What is transport?
way that transport helps
to maintain homeostasis
in your body?
(explain)
Definitions…..
• TRANSPORT
• -absorption,
distribution,
circulation, cyclosis,
osmosis, diffusion
• HOMEOSTASIS
• -maintaining a stable
internal environment
What does venom have to do
with cell membranes?
• Brown Recluse
Spider Bite!
Western Diamondback
Rattlesnake bite!
Vocabulary
• Solution- mixture in which one or more
substances are UNIFORMLY distributed in
another. “homogenous solution”
• Solute- what gets dissolved.
• Solvent- what does the dissolving.
• Ex- salt water- salt is solute, water is
solvent. Ice tea- mix=solute,
water=solvent
Why is the cell membrane so
important???
Names!
• Cell membrane
• Plasma membrane
• Selectively permeable
membrane
• Semi permeable membrane
Honors Know diagram on pg 82!
• Variety of Proteins:
• I. Glycoproteins
a)
b)
c)
d)
e)
Receptor protein
Recognition proteins
Enzymatic proteins
Attachment proteins
Transport proteins
Functions of the Cell Membrane
•
•
•
•
•
Protects the cell
Regulates what goes in and out of cell
Helps to communicate with other cells
Creates attachments between cells
Dynamic!
Fluid Mosaic Model
dev. By Singer & Nicolson 1972
• Proteins move within layers of lipids w/I viscous
fluid
• Hydrogen bonds can form between water and
phospholipid heads inside and outside of cell
• The more double bonds there are in the tails the
more fluid the membrane
• Incr. in temp. causes membr. To be more fluid
(because mol. Move faster)
• Decr. Temp. (mol. Move slower -> less fluid)
Active & Passive
Transport
Illustrations
Chapter 5 Lab Biology
Chapter 5 Honors Biology
Passive Transport
•Requires NO energy!!
•Movement from a high
concentration to a low
concentration!
Passive Transport
• 1. diffusion
• 2. osmosis
• 3. facilitated diffusion
• 4. diffusion through ion
channels
Diffusion
Diffusion
• Molecules moving from a greater
concentration to a lower concentration
• Ex: perfume
• Simple diffusion: Oxygen, Carbon
Dioxide, water and lipid soluble molecules
Vocabulary
• Concentration gradient:
difference in concentrations (amount of
solute)
• Equilibrium: particles/molecules are
equal on both sides of membrane
More diffusion -> “equilibrium”!!
Osmosis
Osmosis
•Movement of WATER
from a high
concentration to a low
concentration across the
cell membrane
Iso – Hyper – Hypotonic Solutions
Vocabulary
• Isotonic: concentration inside and
outside of cell are the same  no
diffusion
• Hypertonic: when concentration of
solute outside of cell is greater, water
moves out of cell (shrink)
• Hypotonic: concentration of solute
inside of cell is greater, water moves
into cell (burst)
Plasmolysis
Plants!
• Plasmolysis = cell shrinks away
from cell wall due to water loss ex:
drought (low rain fall) causing plants to
wilt
• Turgor Pressure = cell wall
sustains shape, otherwise would
explode
Facilitated Diffusion
Facilitated Diffusion
• Carrier Protein –
-protein recognizes substance->changes
shape->delivers substance to inside of
the cell
• Facilitated Diffusion: water soluble
molecules (hydrophillic). Ex: ions,
amino acids (small proteins), and
sugars
Ion Channels
Ion channels
• -allows ions Ca2+ and Cl- to enter cell
• Some are open all the time
• Others are gated and will open when
– Cell membrane stretches
– Electrical signals
– Chemical signals
Active Transport
•REQUIRES ENERGY!
•Movement from a LOW
concentration to a
HIGH concentation!
Active Transport
• 1. Sodium Potassium Pump
• 2. Endocytosis
• 3. Exocytosis
Active Transport
Sodium Potassium Pump
• -pumps like to keep ions in balance
• 3 Na+ out for every 2 K+ in
• This creates a build up of Na+ outside cell
and K+ inside cell forming a net electrical
charge across the membrane
• Allows for nerve impulses
• Contraction of muscles
• 1/3 of all energy in animal cells goes to
running this pump even as we sleep!
Endocytosis
Endocytosis
• Take in external fluid, macromolecules
and other large particles.
• Forms “vesicle” some fuse with
lysosomes (digestion) others fuse with
membrane of other organelles.
• 2 Types: a) pinocytosis – cell drinking
fluid
•
b) phagocytosis – cell eats
Exocytosis
opposite of endocytosis!!