I)Early Observations
A) At turn of the century, researchers noted lipid-soluble molecules entered cells more rapidly that water-soluble molecules, suggesting______are component of plasma membrane.
B)Later chemical analysis revealed the membrane contained ______
C)______(1925) found amount of phospholipid extracted from a red blood cell was just enough to form one bilayer; suggested nonpolar tails directed inward, polar heads outward.
D)To account for permeability of membrane to non-lipid substances, Danielli and Davson proposed ______(later proved wrong) with phospholipid ______between layers of protein.
E) 5. With the electron microscope available, ______proposed proteins were embedded in outer membrane and all membranes in cells had similar compositions—______
II)In 1972, ______introduced the currently accepted ______of membrane structure.
A)Plasma membrane is phospholipid bilayer in which______molecules are partially or wholly embedded.
B)Embedded proteins are ______throughout membrane in irregular pattern; varies among membranes.
C) Electron micrographs of freeze-fractured membrane supports ______
III)Plasma Membrane Structure and Function
A)Fluid-mosaic Model
1)Membrane structure has two components, ______.
2)Lipids are arranged into a ______
(a)Most plasma membrane lipids are ______, which spontaneously arrange themselves into a bilayer.
(b). ______and directed inward; ______and are directed outward to face extracellular and intracellular fluids.
(c)______have a structure similar to phospholipids except the hydrophilic head is a variety of sugar; they are protective and assist in various functions.
(d)______is a lipid found in animal plasma membranes; reduces the permeability of membrane.
(e)______have an attached carbohydrate chain of sugar that projects externally.
(f)The plasma membrane is asymmetrical; glycolipids and proteins occur only on outside and ______attach to proteins only on the inside surface.
IV)Fluidity of the Plasma Membrane
A)At body temperature, the phospholipid bilayer has consistency of ______
1). The greater the concentration of unsaturated fatty acid residues, the more fluid the bilayer.
2). In each monolayer, the hydrocarbon tails______, and entire phospholipid molecules can move sideways at a rate of about 2 µm—the length of a prokaryotic cell—per second.
3)Phospholipid molecules rarely ______one layer to the other.
4)Fluidity of the phospholipid bilayer allows cells to be pliable.
5)Some proteins are held in place by cytoskeletal filaments; most ______in fluid bilayer.
V)The Membrane Is a Mosaic
A)Plasma membrane and organelle membranes have unique proteins; RBC plasma membrane contains 50+ types of proteins.
B)Membrane proteins determine most of the membrane’s______.
C)______allow a particular molecule to cross membrane freely (e.g., Cl- channels).
D)______selectively interact with a specific molecule so it can cross the plasma membrane (e.g., Na+ - K+ pump, sodium potassium pump).
E)______are shaped so a specific molecule (e.g., hormone or other molecule) can bind to it.
F)______catalyze specific metabolic reactions.
VI)Cell-Cell Recognition
A)Carbohydrate chains of glycolipids and glycoproteins ______cell; diversity of the chains is enormous.
1)Chains vary by number of ______(from 15 to several hundred).
2)Chains vary in branching.
3)______of sugars in chains varies.
4)Glycolipids and glycoproteins vary from ______from individual to individual of same species, and even from cell to cell in same individual.
5)In development, different type cells in embryo develop their own carbohydrate chains; these chains allow tissues and cells of the embryo to sort themselves out.
6)Immune system rejection of ______tissues is due to recognition of unique glycolipids and glycoproteins; blood types are due to unique glycoproteins on the membranes of red blood cells (RBC).
VII)Types of Membranes and Transport
A)The plasma membrane is ______; only certain molecules can pass through freely.
1)A permeable membrane allows all molecules to pass through; an impermeable membrane allows no molecules to pass through; a ______allows some moleculesto pass through.
(a)Small ______lipid molecules (______) pass through the membrane freely.
(b)Small polar molecules (______) easily pass following their concentration gradient.
(c)______cannot freely cross a plasma membrane.
(d)Ions and charged molecules have difficulty crossing the ______phase of the bilayer.
2)Both passive and active mechanisms move molecules across membrane.
(a)______moves molecules across membrane without expenditure of energyby cell; includes______and ______
(b)______uses energy (ATP) to move molecules across a plasma membrane; includes ______, and ______.
VIII)Diffusion and Osmosis
A)In ______, molecules move from higher to lower concentration (i.e., down their concentration gradient).
1)A ______contains a ______, usually a solid, and a ______, usually a liquid.
2)In the case of a dye diffusing in water, dye is a solute and water is the solvent.
3)Membrane ______properties allow only a few types of molecules to cross by diffusion.
(a)______molecules (e.g., alcohols) diffuse; lipids are membrane’s main structural components.
(b)______readily diffuse through lipid bilayer. Movement of oxygen from air sacs (______) to blood in lung capillaries depends on concentration of oxygen in alveoli.
4)______is the diffusion of water across a differentially permeable membrane.
(a)______is hydrostatic pressure, on side of membrane with higher solute concentration, produced by water diffusing to that side of membrane; ______example:
(i)A ______membrane separates two solutions.
(ii)Beaker has more water (lower percentage of solute) and thistle tube has less water.
(iii)The membrane does not permit passage of the ______
(iv)Membrane permits passage of water with net movement of water from beaker to inside of tube.
(v)Osmotic pressure allows liquid increase on side of membrane with great percent of solute.
(b)______is pressure that develops in a system due to osmosis.
(c)Osmosis is constant process in life: for example, water is absorbed in ______retained by ______, and taken up by ______
5)______is strength of a solution in relationship to osmosis; determines movement of water into or out of cells.
(a)______is where the relative solute concentration of two solutions are ______
(b)______is where a relative solute concentration of one solution is ______than another solution.
(c)______is where relative solute concentration of one solution is ______than another solution.
(d)Swelling of plant cell in hypotonic solution creates ______; how plants maintain erect position.
(e)Solutions that cause cells to shrink are hypertonic solutions; red blood cells placed in salt solution above 0.9% shrink and wrinkle, a condition called ______
IX)Transport by Carrier Proteins
A)Plasma membrane impedes passage of most substances but many molecules enter or leave at rapid rates.
1)______are membrane proteins that combine with and transport only one type of molecule; are believed to undergo a change in shape to move molecule across in active and facilitated transport.
2)______is passive transport of specific solutes down their concentration gradient, facilitated by a carrier protein; glucose and amino acids move although not lipid-soluble.
(a)______is transport of specific solutes across plasma membranes Iodine is concentrated in cells of thyroid gland, glucose is completely absorbed into lining of digestive tract, and sodium is mostly reabsorbed by kidney tubule lining.
(b)Active transport requires ATP and have high number of mitochondria near membranes.
(c)Proteins involved in active transport are often called "pumps"; ______is an important carrier system in nerve and muscle cells.
(d)______crosses a plasma membrane because sodium ions are pumped across and the chloride ion is attracted to the sodium ion and simply diffuses across.
3)Membrane-Assisted Transport
(a)In ______, a vesicle often formed by ______fuses with the plasma membrane as secretion occurs; method by which insulin leaves insulin-secreting cells.
(b)During ______cells take in substances by vesicle formation as plasma membrane pinches off.
(c)In ______, cells engulf large particles forming an ______
(i)Phagocytosis is commonly performed by ______cells (e.g., amoebas and macrophages).
(ii)When the endocytic vesicle fuses with a ______digestion occurs.
(d)______occurs when vesicles form around a ______or very small particles.
(e)______occurs when specific macromolecules bind to plasma membrane receptors.
(i)This allows cells to receive ______and then sort them within the cell.
(ii)A ______that binds to receptor is called a ______binding of ______to receptors causes receptors to gather at one location.
X)Plasma Membrane
A)The plasma membrane is outer living boundary of a cell.
B)Many cells have an ______component formed outside of membrane; plant, fungi, algae, and bacteria form ______; animal cells have an extracellular ______
XI)Junctions Between Cells
A)______points of contact that physically link neighboring cells or provide ______; animal cells have three types: adhesion junctions, tight junctions, and gap junctions.
1). In adhesion junctions (______) internal cytoplasmic plaques, firmly attached to cytoskeleton within each cell are joined by intercellular filaments; hold cells together where tissues ______(e.g. in heart, stomach, bladder).
2)In ______, plasma membrane proteins attach to each other, producing ______fastenings; hold cells together so tightly that tissues (e.g., epithelial lining of stomach, ______) are barriers.
3)A gap junction allows cells to communicate.
(a)They are formed by the joining of two identical plasma membrane channels; channel of each cell is lined by six plasma proteins.
(b)They provide strength to the cells involved and allow the movement of small molecules and ions from the cytoplasm of one cell to the cytoplasm of the other cell.
(c)______– channels through ______used to connect the cytoplasm of neighboring cells, molecules, ions pass through
(d)Gap junctions are important to function of heart muscle and smooth muscle because they ______of ______required for cells to contract.