General Biology: Cell Membrane Transport Mechanism Flashcards
Function of Plasma Membrane: Channels & Pumps
Transport of Molecules
Function of Plasma Membrane: Engulfing particles
Phagocytosis and Pinocytois
Function of Plasma Membrane: Due to the presence of carbohydrates
Cell-cell communication
Function of Plasma Membrane: Cell membrane bound receptors, enzymes, and proteins.
Cell signaling
Function of Plasma Membrane: Protects the cellular _________
organelles
Function of Plasma Membrane:
Segregates one part of the cell from another.
Compartmentalization
Function of Plasma Membrane: Myelin sheat of neurons, microvilli in intestine.
Membrane modifications for specialized functions
This refers to why small, nonpolar molecules get in ions and polar molecules don’t get in.
Selective Permeability
Cell Membrane. Described as ____________. The structure of it is FLEXIBLE and fluid rather than a rigid solid barrier.
fluid mosaic
Fluid Mosaic Model. Similar with a mosaic art, it is also made up of different molecules namely ——(4)——- that made up one functional structure, the cell membrane
phospholipids, proteins, carbohydrates and cholesterol
Phospholipid.
Hydrophobic? Hydrophilic?
(a) Tail
(b) Head
(a) Hydrophobic
(b) Hydrophilic
Membrane Proteins.
- Penetrate the hydrophobic inside of lipid bilayer.
- most are transmembrane proteins
Integral Proteins
Membrane Proteins.
Appendages loosely bound to either surface
Peripheral Proteins
Membrane Proteins.
A receptor that binds to chemical messengers such as hormones sent by other cells
Receptor Protein
Membrane Protein.
Breaks down a chemical messenger and terminates its effect on the target cell
Enzyme
Membrane Protein.
Constantly open and allows solutes to pass into and out of the cell
channel protein
Membrane Protein.
Closes and Opens to allow solutes through only at certain times
Gated Channel Protein
Membrane Protein.
À glycoprotein acting as a —— distinguishing the body’s own cells from foreign cells
Cell-identity marker
Membrane Protein.
Binds one cell to another
Cell-adhesion
molecule (CAM)
Membrane Proteins.
Provides Hydrophilic Channel
Transport Proteins
Transport Protein.
(a) Uniport
(b) Symport
(c) Antiport
(a) Transports 1 substance and 1 direction
(b) Transports 2 substances 1 direction
(c) Transports 2 substances in 2 directions
Cell Membrane. It is made up of different molecules namely (4) ________________ that made up one functional structure.
Phospholipids, Proteins, Carbohydrates, and Cholesterol
Membrane Protein.
They are embedded in the cell membrane to help transport too large molecules
such as glucose and amino acids to go through ion channels across the membrane.
Transport/Carrrier Protein
What are the 2 parts of a phospholipid?
Hydrophilic Head & Hydrophobic Tail
Animal Membranes. __________ reduces membrane fluidity at moderate temps by reducing phospholipid movement.
Cholesterol
Animal Membranes. At LOW TEMPS it hinders _____________ by disrupting the regular packing of phospholipids.
solidification
What are the 2 types of membrane proteins?
Integral Proteins & Peripheral Proteins
A glucose molecule (C6H12O6) is ___________ large, and amino
acids are even bigger than that, so they need support to pass into and out of the cell.
24 atoms
____________ are a very narrow tube-shaped protein that help establish a tiny pore in the cell membrane.
Ion Channels
Each ion channel open and close specifically for certain ions like (4) ________________
Na+, K+, Cl–, Ca+2
Glycoproteins. Glyco means carbohydrates so these are _______________.
proteins with carbohydrates attached to them
____________ are always on the outside surface and are different from receptor sites.
- Allows white blood cells to recognize your cells vs foreign ones.
Recognition Sites
Glycoprotein.
(a) Cell recognition and _________
* Impart -ve charge to cell - repels other particles.
(b) Helps in inter-cellular ______________.
(c) act as ___________
(d) Cell identity markers (glycoproteins & __________), antibody processing.
a. communication
b. attachment/adhesion
c. receptors
d. glycolipids
Osmosis True or False.
High Concentration moves with the flow going to solvent lower concentrations
True
Recognition Sites/Cell Identity Markers.
Recognizes specific ________ and alters cell’s function in some way.
ligand
It is diffusion of substance across membrane with no energy investment.
Passive Transport
Diffusion. In the absence of other forces, a substance will diffuse from ___________ to ______________.
from where it is more concentrated to where it is less
(it will move down the concentration gradient)
Diffusion. No work required: spontaneous because particles have _____ and are in constant motion.
Kinetic Energy
Factors Affecting Diffusion Rate.
The greater the difference in concentration, the
faster the molecules will go down this hence more rapid
diffusion. The closer the distribution of the material gets to equilibrium, the slower the molecules will move and rate of diffusion decreases.
Concentration Gradient
Factors Affecting Diffusion Rate.
Higher ________ increase the energy and therefore the
movement of the molecules, increasing the rate of diffusion. Lower __________
decrease the energy of the molecules, thus decreasing the rate of diffusion.
Temperature
Movement of solvent (water) across a semi permeable membrane from high to
low solvent concentration where ONLY solvent moves
Osmosis
Factors Affecting Diffusion Rate.
Heavier molecules move more slowly; therefore, they
diffuse more slowly. The reverse is true for lighter molecules.
Mass of Particles
Factors Affecting Diffusion Rate.
Diffusion is significantly influenced by viscosity and density.
- The denser or viscous the medium is, the harder it is for the given particle to diffuse through it. The diffusion rate would be lower.
*If the medium is less dense or less viscous, then the particles will be able to move more quickly and will diffuse faster.
Solvent Properties
Channel or CARRIER PROTEINS that allow hydrophilic substances to cross membranes moving down their concentration gradients
Facilitated Diffusion
ability of a surrounding solution to cause a cell to gain or lose water
Tonicity
Open/close mechanism works in response to stimuli (electrical, specific ligand).
Gated Ion Channels
True or False.
Tonicity depends on the concentration of solutes that cannot cross membrane relative to the concentration of all solutes in cell
True
Hypertonic, Hypotonic, & Isotonic.
- Higher solute OUTSIDE
- Higher water INSIDE
- Water moves OUT
- Cell SHRINKS
Hypertonic (Plasmolyzed)
Hypertonic, Hypotonic, & Isotonic.
- Equal solute
- Equal water
- No net movement
- Normal
Isotonic (Flaccid)
Hypertonic, Hypotonic, & Isotonic.
- Higher solute INSIDE
- Higher water OUTSIDE
- Water moves IN
- Cell SWELLS
Hypotonic (Turgid)
Cell uses transport protein
* Moves substances AGAINST concentration gradient (LOWER to HIGHER)
* Similar to facilitated diffusion except this requires ENERGY
* cell to maintain concentration gradients
Active Transport
