Chapter 7B 2 Flashcards
What is the overall function for the cell membrane?
Maintain Homeostasis
Interaction of a cell with its surroundings
Cells take in nutrients (H2O), salts, minerals) dispose of waste and release cell products such as hormones and neurotransmitters.
What is selectively permeable?
some substances can pass across them and others cannot.
The specific structure of the cell membrane depends upon what?
the function of that particular cell. EX: Red Blood Cells vs White Blood cells.
Overall description of the cell membrane
fluid mosaic level.
What are membrane lipids?
Phospholipids
What is the structure of phospholipids?
Phosphate Polar Head and Fatty Acid tails
Phosphate Polar heads are…
hydrophilic (Love water)
Fatty acid tails are…
hydrophobic
Polar heads are found in
inside and outside surfaces
Fatty acids are within.
membrane
The arrangement of phospholipids determines permeability of substances.
Polar vs Non Polar
An additional lipid in the cell membrane
Steroids
Function of Cholesterol
provide stability
Where are peripheral proteins?
on either the interior or exterior surfaces of the membrane.
What is the function of peripheral proteins?
involved in the biding mechanisms of molecules to the lipid bilayer and assist their activity
Ex: Enzymes for metabolic activity, interaction with biotocins
Integral proteins are…
embedded in the bilayer and are exposed to at least one or both surfaces of the membrane.
Function of Integral proteins…
- control the passage of materials (such as channel protein, gated protein, aquapoins, pump proteins, and carrier proteins)
- Act as chemical markers in order to be recognized
- Act as receptors
Example of Chemical markers
Glycoproteins: integral proteins having specialized carbohydrate chains
Example of Receptors
- Hormones
- Neurotransmitters
Integral proteins may allow…
adjoining cells to directly communicate or anchor together.
What is Passive Transport
the movement of materials or substances across the cell membrane without requiring ATP
What is Diffusion
the process by which particles tend to move from an area where they are more concentrated to an area of lower concentration.
What is the concentration gradient?
the difference between concentration of substances
What are examples of diffusion?
Perfume, food coloring in water
Diffusion is driven entirely by…
the kinetic energy of the particles
Final result of diffusion is
the equilibrium (state of balance)
Equilibrium is when
the concentration of solutes is equal on both sides of the cell membrane
Random movement of particles continues even
after equilibrium is reached
Factors that influence whether certain types of substance can pass
-Size
-Solubility of the molecules with the phopholipid
EX: Nonpolar O2+CO2 can pass while polar H2O cannot.
What is the solubility principle?
Like dissolves Like
What is Osmosis
diffusion of water through a selectively permeable membrane
What are specialized membrane protens
Auraporins
What is Isotonic?
the concentration of solute particles outside the cell is the same as the concentration inside the cell. Osmosis occurs equally into and out of the cell
EX: IV bag with 0.9% equal saline solution
What is Hypotonic?
the concentration of solute particles outside the cell is lower or less then the inside of the cell.
EX: -IV bag with less than 0.9% saline
- Red blood cells in pure H20
- Saltwater fish in fresh water
HypOtonic may lead to…
cytolysis (dissruption of cells)
What is Hypertonic?
concentration of solute particles outside the cell is greater than the concentration inside the cell.
EX: -freshwater fish in saltwater
- Drinking ocean water - Gargling salt water.
Hypertonic may lead to
Plasmolysis
Freshwater organisms may have a
contractile vacuole to pump out excess water
Saltwater fish often possess
pumps to extract salts out of the cell
Plants possess
a central vacuole to store water but also a cell wall to prevent bursting.
What is facilitated diffusion?
process of moving substances across the membrane, but requires assistance from membrane proteins.
Aquaporins are an example of
channel proteins that assist water
Carrier proteins are
membrane proteins to move substances across
Facilitaed diffusion is still passive transport since
cell ATP is not needed
Example of Facilitated Diffusion
Transport of glucose.
Diffusion may also occur through
Ion channels
Ion channels are
specialized proteins that move ions across the membrane
Since ions are charged they are..
not soluble in phospholipids and need assitance to pass
Ion channels provide passageways for
specific ions to pass
Active transport is
transport that requires energy
Cell Membrane Pumps
- are
- function
- EX
- specialized membrane proteins that use energy from ATP to pump small molecules and ions across the membrane.
- expends ATP
- sodium potassium, Pump: nerve impulses within neurons.
Bulk Transport is used to…
transport large quantities of molecules into or out of the cell.
What is endocytosis
process of moving large quantities of material into the cell.
Endocytosis requires
the formation of a vesicle (Membrane-bound organelle)
Two types of Endocytosis
Pinocytosis: (cell drinking) large quantities of fluid.
Phagocytosis: (cell eating) solid materials (certain White blood cells)
What is Exocytosis is
the process that moving large quantities of material out of the cell.
Exocytosis occurs with
Golgi Aperatus
Endocytosis occurs with
Cell membrane
Released cell products are often called
Secretion
Example of Exocytosis
The release of neurotransmitters by neurons and the release of hormones by glands.
