Biology 1610 Chapter 5

Simple diffusion is defined as the movement of?

molecules from areas of higher concentration to areas of lower concentration.

Explain the fluid? phospholipid bilayer

Hydrogen bonding of water keeps the membrane in its bilayer configuration; however, phospholipids and unanchored proteins in the membrane are loosely assoiated and can diffuse laterally.

How are phospholipids arranged?

In a bilayer. Tail to tail in middle, heads oriented towards fluids inside and outside cells.

How does bulk material enter the cel lin vesicles?

In endocytosis, the cell membrane surrounds materail and pinches off to form a vesicle. In recepotor mediated endocytosis, specific molecules bind to receptors on the cell membrane.

What 4 major component groupsd do cellular membranes consist of?

In eukaryotic cells, membranes have four components: a phospholipid bilayer, transmembrane proteins(integral membrane proteins), an interior protein network, and cell-surface markers. The interior protein network is composed of cytoskeletoal filaments and peripheral membrane proteins, which are associated with the membrane but are not an integral part. Membranes contain glycoproteins and glycolipids on the surface that act as cell identity markers.

How does materail leave the cel lby exocytosis?

In exocytosis, material in a vesicle is discharged when the vesicle fuses with the membrane

Diffusion?

net movement of a substance from a region where it has a higher concentration to a region where it has a lower concentration.

What does bulk transport do?

It moves large quantities of substances that cannot pass through the cell membrane

When studying with a friend for a test, what key points about osmosis would you make sure you tell them? Check all that apply.

Osmosis refers to the movement of water along a concentration gradient.

Integral Proteins?

Penetrate the lipid layer trans-membrane vs partial

Which processes are most similar, differing only in the size of materials that they move?

Pinocytosis and phagocytosis

A chemical force?

The ions concentration gradient

If a cell is in an isotonic enviorment, then?

osmosis still occurs, but there is no net gain or loss of cell volume.

Is the Na+/K+ transporter an electrogenic pump?

Yes it removes 3 Na+ for each 2 K + taken in, net loss of 1 +. (primary membrane potential pump in animals)

Is facilitated diffusion passive?

Yes, because the solute moves down its concentration gradient and the transport requires no energy.

Which of the following does not contribute to the selective permeability of a biological membrane?

a.specificity of the carrier protein in the membrane b.selectivelity of channel proteins in the membrane c. hydrophobic barrier of the phospholipid bilayer d.hydrogen bond formation between water and phosphate groups. (D)

What are membrane proteins and their functions?

-A membrane is a collage of different proteins, often grouped together, embedded in the fluid matrix of the lipid bilayer -Differing protein content enable different membranes to have different functions -Even regions of membranes can differ in their function

Clatherins?

-Anchor certain proteins to specific sites, especially on the exterior plasma membrane in receptormediated endocytosis -Proteins line coated pits and facilitate binding to specific molecules -EX.Localization of low-density lipoprotein receptor within coated pits

Bilayers?

-Are fluid -Protein embedded in the membrane can diffuse laterally within the membrane (they cannot flip flop)

Within the transmembrane proteins, you have what three compositions that make up it?

-Carriers -Channels -Receptors

How do multicellular animals coordinate their cells?

-Cells communicate and interact by direct contact -Intercellular junctions facilitate this coordination

Hydrophilic?

Loves water

Facilitated diffusion is used to transport?

sugars and amino acids.

What chemical property characterizes the interiro of the phospholipid bilayer?

It is hydrophobic

The epidermis (top layer of skin) does not have a blood supply. Nutrients reach the epidermis?

By diffusing through the tissue fluid from blood vessels in the dermis.

Hypertonic?

Solution has a higher solute concentration than the cell

Cell junctions?

How cells stick together.

The idea that the cell a living unit is greater than the sum of its parts?

-Cells rely on the integration of structures and organelles in order to function -For example, a macrophages ability to destroy bacteria involves the whole cell, coordinating compeonents such as the cytoskeleton, lysosomes, and plasma membrane -Cells are an example of an emergent property

Two types of proteins used in facilitated diffusion are?

-Channel proteins-hydrophilic channel when open -Carrier protein-bind specifically to molecules they assist

Gap Junctions?

-Channels between cells enabling direct communication through cytoplasm. -Chemical or electrical signal passes directly from one cell to an adjacent pone -Communicating juncitons- provide cytoplasmic channels between adjacent cells (similar to plasmodemsmatat in platns)

Tight junctions?

-Connect the plasma membranes of adjacent cells in a sheet no leakage -Provide a varrier to prevent leakage and have differential functions on apical and basal cell faces -Membranes of neighboring cells are pressed together, prevents leakage of extracellualr fluid. -Make a band of connection around the top of cells in layer -Allow coordinated movement of cells and fomration of epithelial sheets of cells (all organs are bound by epitheial cells. -Adherens junctions bind to epitheilial cells to each other to form sheets.

Cotransport?

-Coupled transport by a membrane protein. Occurs when active trasnport of a solute indirectly drives transport of other solutes. -Inward transport of sucrose, against its gradient, is coupled to the flow of H+ ions inward, along its concentration gradient. (electrochemcial H+ gradient is stronger than the sucrose gradient)

Spectrins?

-Determine shape of cell -Form supporting scaffold beneath membrane, anchored to both membrane and cytoskeleton -EX-red blood cell

Sodium potassium (Na+--K+) pump? (refer to page 101)

-Direct use of ATP for active transport -uses an antiporter to move 3 Na+ out of the cell and 2 K+ into the cell. (against their concentration gradient) -ATP energy is used to change the conformation of the carrier protein -Affinity of the carrier protein for either Na+ or K+ changes depending on what is currently bound -So the ions can be carried across the membrane by conformational changes in the carrier protein.

Cell-surface markers contain which two compositions?

-Glycoproteins -Glycolipid

When 2 solutions have different osmotic concentrations they may be?

-Hypertonic -Hypotonic

Transmembrane proteins?

-Integral membrane proteins that are exposed to both sides of the membrane -Types of membrane proteins make membranes different from each other.

Diffusion?

-Is the movement of molecules from a high concentration to low concentration. -It will continue until the concentration is the same in all regions

Why do all cells have a membrane and what's its purpose?

-It acts as a selective barrier to keep things in or out -They also allow for sequestration, concentration, and diffusion specialization. -Membranes are fluid and allow components to move around

Desmosomes?

-Mechanically attaches cytoskeletons of neighboring cells. -Attach cells tighly together into sheets , interact with actin cytoskelton -Ancoring strenght-like rivets, stengthening connections. Fasten cells together into strong sheets

Endocytosis?

-Movement of substances into the cell -Requires energy -Intake by vesicle formation -Cell takes in Receptor-mediated endocytosis

Exocytosis?

-Movement of substances out of cell -Requires energy (endomembrane delivery system) -Discharge of materials out of the cell -Used in plants to export cell wall material -Used in animals to secrete hormones, neurotransmitters, digestive enzymes. -Transport vesicles migrate to the plasma membrane, fuse with it, and realease their contents -Secretory cells

Peripheral proteins?

Are only at the surface attached to lipid heads or to other proteins.

Electrogenic pumps?

Are transport proteins that generate voltage across membranes

Active transport?

-Moves solutes against their gradients. Uses energy -Requires use of cellular energy ATP is directly or indirectly to fuel active transport -Moves substances from a low to high concentration -Always used carrier proteins (highly selective for a particular solute) -EX-sodium potassium pump -Allows cells to maintain concentration gradients that differ from their surroundings.

Channels?

-Passively transport molecules across membranes -Create a selective tunnel that acts as a passage through membrane -EX.Sodium and potassium channels in nerve, heart, and muscle cells

Interior protein network?

-Peripheral proteins (intracellular proteins that interact with the membrane on the inside of the cell)

4 types of intercullular junctions are?

-Plasmodesmata -Tight junctions -Desmosomes -Gap Junctions

Glycoprotein?

-Self -recognition -Create a protein/carbohydrate chain shape characteristic of individual -EX.Major histocompatibility complex protein recognition by immune system

The interior protein network contains two different compositions which are?

-Spectrins -Clathrins

Carriers?

-They actively or passively transport molecules across membrane -Move specific molecules through the membrane in a series of conformational changes -EX.Glycophorin carrier for sugar transport sodium potassium pump

Phospholipids?

-They associated with water spontaneously from a selective barrier to solutes -All membranes consists of phospholipid bilayers -They are amphipathic

glycolipid?

-Tissue recognition -Create a lipid/carbohydrate chain shape characteristic of tissue -EX. A,B,O blood group markers

Receptors?

-Transmit information into cell -Signal molecule bind to cell surface portion of the receptor protein. This alters the portion of the receptor protein within the cell, inducing activity -EX.Specific receptors bind peptide hormones and neurotransmitters

6 major functions of membrane proteins are?

-Transport across membranes -Enzymatic activity -Signal transduction -Cell-cell recognition -Intercellular joining -Attachment to the cytoskeleton and extracellular matric (ECM)

Since membrane lipids are not the same they vary in what? Membrnes differ in?

-Type of fatty acid tails -Type of polar heads -Amount of cholesterol

Plasmodesmata?

-communicating junctions in plants -Similar to gap junctions

phospholipid bilayer?

-flexible matrix, barrier to permeability -phosopholipid molecule -Provides permeability barrier, matrix for proteins -excludes water-soluble molecules from nonpolar interior of bilayer and cell -EX. Bilayer of cell is impermeable to large water-soluble molecules, such as glucose

Facilitated Diffusion?

-is diffusion with help, across a barrier with help -(molecules that cannot cross membrane easily may move through it with the help of specialized proteins called facilitated diffusion )

Passive transport?

-is the movement of molecules across the membrane in which: 1-no energy required 2-molecules move down their concentration gradient

bulk transport?

-movement of big bulky items across cell membrane; vesicles; into cell = endocytosis; out of cell = exocytosis -Requries energy

Membrane raft?

-regions of membrane with specific functions -higher concentration of specefic proteins -higher concentration of cholestrol

Receptor-mediated endocytosis?

-specific molecules are taken in after they bind to a receptor -Intake of specific solutes using recepotors

What are the membrane proteins 6 functions?

1-Transporters 2-Enzymes 3-Cell-surface receptors 4-Cell-surface identity markers 5-Cell-to-cell adhesion proteins 6-Attachments to the cytoskelton

What are the 4 components of cellular membranes?

1-phospholipid bilayer 2-Transmembrane proteins 3-Interior protein network 4-Cell surface markers

Seven ATP molecules can theoretically cause how many Na+ and K+ to move across the membrane?

21 Na+ out and 14 K+ in

During one cycle, the sodium-potassium pump binds and moves?

3 Na+ and 2 K+.

Hypotonic?

Solution has a lower solute concentration than the cell

THe transmembrane domain of an integral membrane protein?

A.is composed of hydrophobic amino acids b.Often forms an cx-helical structure c.can cross the membrane multiple times

How does active transport use energy to move materials against a concentration gradient.

Active transport uses specialized protein carriers that couple a source of energy to transport. They are classified based on the number of molecules and direction of transport. Uniporters transport a specific molecule in one direction; symporters transport two molecules in the same direction; and antiporters transport two molecules in opposite directions.

Aquaporins?

Are channel proteins that facilitate osmosis by providing a hydrophilic path through the membrane that water can cross through

Freeze Fracture experiments are?

Are evidence that membranes are bilayers and that they differ in protein content on the inside and outside layers.

An experiment involves 4 beakers of fluid containing bags with different solutions. Beaker 1 contains a 0.2M solution with a 0.2M solution bag. Beaker 2 has a 0.2M solution with a 1M solution bag. Beaker 3 holds a 0.2M solution with a 0.4M solution bag. Beaker 4 contains a 0.2M solution with a 0.6M solution bag. Predict which beaker will have a bag with the largest change in mass at the end of 30 minutes.?

Beaker 2

What do the processes of active transport and facilitated diffusion have in common?

Both use transport proteins to move material across the membranes

What is the source of energy used to power the sodium-potassium pump?

Breakdown of ATP

WHat is the cellular membrane organized substructure consist of?

CHolesterol and sphingolipid can associate to form microdomains. The two leaflets of the plasma membranes are also not identical.

What are two properties of transmembrane protein?

Can span both layers of a membrane, can form channels to allow small molecules to cross membranes

A cell using protein-mediated facilitated diffusion is treated with a toxin that prevents conformation change in the membrane protein. What is the most likely outcome?

Carrier protein dysfunction will increase the gradient.

Pinocytosis?

Cell takes in only fluid with dissolved solutes. Fluid droplets are englufed by the membrane, which forms vesicles around them.

Phagocytosis?

Cell takes in particular matter. Particle is englufed by the membrane, which folds around it and forms a vesicles.

Enzymes?

Cells carry out many chemical reactions on the interior surface of the plasma membrane, using enzymes attached to the membrane

Cell-to-cell adhesion proteins?

Cells use specific proteins to glue themselves to one another. Some act by forming temporary interactions and others form a more permanent bond

How does coupled transport uses ATP directly?

Coupled transport occurs when the energy realeased by a diffusing molecule is used to transport a different molecule against its concentration gradient in the same direction. Countertransport is similar to coupled transport, but the two molecules move in opposite directions.

How are active transport and coupled transport related?

Coupled transport uses the concentration gradient established by active transport

Solutes?

Dissolved substances

Membranes used to form vesicles coming into and leaving the cell have the potential to change the size of a cell, yet under normal circumstances the cell's membrane doesn't change it's volume very much. What two processes involving the membrane would need to be balanced over time?

Endocytosis and exocytosis

The hormone insulin is a protein produced in the pancreas and then secreted into the blood stream after a meal to increase glucose uptake by tissues. What cellular process is used to secrete insulin from the pancreas?

Exocyosis

Which of the folllowing is not a mechanism for bringing material into a cell?

Exocytosis.

When taking oral medications, several lipid cell membrane barriers will have to be passed before the polar drug can reach circulation. What is the most likely method of transport mechanism the drug would use to cross the membrane?

Facilitated diffusion

Glucose is taken up by red blood cells by binding to a specific pocket in a membrane protein which then allows it to cross the membrane and move down its concentration gradient. What would be the best definition of this process?

Facilitated diffusion using a transporter

Cells are placed in a solution of glucose. The rate at which glucose enters the cells increases as the concentration of the glucose solution is increased. Eventually the rate of glucose movement stops increasing. How is glucose moving into cells?

Facilitated diffusion via a carrier protein

If a pump moves 3 positive ions out and 2 positive ions in against their concentration gradients, the membrane potential in the cell will become more positive.?

False

What are two properties of a phospholipid bilayer?

Forms a semipermeable barrier, can allow diffusion of gases

A cellular protein is involved in the cotransport of glucose and sodium ions into the cell. If sodium is blocked from moving through this transporter, what would be the most likely outcome?

Glucose would be unable to move without the movement of sodium into the cell, down its concentration gradient.

Cell surface markers?

Glycoprotein and glycolipids (can be integral, transmembrane or peripheral)

The production of phagolysosomes depends directly on which organelle?

Golgi Apparatus

hydrophobic?

Hates water

What is one property of interior protein network?

Helps determine the overall shape of a cell

A bacterial cell that can alter the composition of saturated and unsaturated fatty acids in its membrane lipids is adapted to a cold environment. If this cell is shifted to a warmer enviornment, it will react by?

Increasing the degree of saturated fatty acids in its membrane

What can move laterally through the membrane?

Individual phospholipids and unanchored proteins

How do proteins allow membrane diffusion to be selective?

Ions and large hydrophilic molecules cannot cross the phosphlipid bilayer. Diffusion can still occur with the help of proteins, thus we call this facilitated diffusion. These proteins can be either channels, or carriers. Channels allow the diffusion of ions based on concentration and charge across the membrane. They are specific for different ions, but form an aqueous pore in the membrane. Carrier proteins bind to the molecules as they transport, much like an enzyme. The rate of transport by a carrier is limited by the number of carriers in the membrane.

Trans-membrane?

Is a type of membrane protein spanning the entirety of the biological membrane to which it is permanently attached. Proteins span from one side of a membrane through to the other side of the membrane.

What is osmosis?

Is the movement of water across membranes. The direction of movement due to osmosis depends on the solute concentration on either side of the membrane. Solutions can be isotonic, hypotonic, or hypertonic.Cells in an isotonic solution are in osmotic balance; cells in a hypotonic solution will gain water; and cells in a hypertonic solution will lose water. Aquaporins are water channels that facilitate the diffusion of water.

How is the H+ ion gradient used to do work?

It is a form of energy transfer (transfers chemcial E in ATP to potential E in H+ gradient formation.) The E pot in the gradient, can now be used to do work (in case, to move sucrose against its gradient)

What are membranes made of of?

Lipids and proteins

Glycolipids?

Located on the outer phospholipid layer of the membrane.

The fluid mosaic model of the membrane describes the membrane as?

Made of proteins and lipids that can freely move.

How can membrane fluidity change?

Membrane fluidity depends on the fatty acid composition of the membrane. Unsaturated fats tend to make the membrane more fluid because of the kinks of double bonds in the fatty acid tails. Temperature also affects fluidity. Some bacteria have enzymes that alter the fatty acids of the membrane to compensate for temperature changes.

Cell-surface receptors?

Membranes are exquisitely sensitive to chemical messages, which are detected by receptor proteins on the surface.

In the fluid mosaic model how are proteins embedded in a fluid lipid bilayer?

Membranes are sheets of phospholipid bilayers with assoicated proteins. Hydrophobic regions of a membrane are oriented inward and hydrophilic regions oriented outward. In the fluid mosaic model, proteins float on or in the lipid bilayer.

Transporters?

Membranes are very selective, allowing only certain solutes to enter or leave the cell, either through channels or carriers composed of proteins

Cell-surface identity markers?

Membranes carry cell-surface markers that identify them to other cells. Most cell-surface proteins and protein complexes such as glycoproteins that are characteristic of that cell type.

A defect in which organelle might have the biggest effect on the Na-K pump?

Mitochondria

The fluid mosaic model?

Mosaic of proteins floats in or on the fluid lipid bilayer like boats on a pond. ( mosaic means membranes are made of patches that differ from each other (due to different protein content and also different phospholipid structure) Explains various observations regarding the structure of functional cell membranes. The model, which was devised by SJ Singer and GL Nicolson in 1972, describes the cell membrane as a two-dimensional liquid in which phospholipid and protein molecules diffuse easily.

A cell can use the process of facilitated diffusion to?

Move ions or large polar molecules from a region of high concentration to a region of low concentration.

Uniporters?

Move one molecule at a time in one direction

Antiporters?

Move two molecules in opposite directions

Symporters?

Move two molecules in the same direction

What is one property of cell surface marker?

Often carbohydrate attached to lipid or protein

Equal amounts of methylene blue (319.85 g/mol) and potassium permanganate (158.034 g/mol) dyes were added to identical agar plates and allowed to diffuse. After 24 hours, the halo was measured to see how far the dyes had moved. Based on this information, which dye do you think will diffuse faster through the agar, and why?

Potassium permanganate had a lower molecular weight so it was able to diffuse more rapidly spreading farther through the agar in the same time.

The Epstein-Barr Virus (EBV), which causes mononucleosis, binds to receptors on B-cells, and tricks them into taking them inside. Determine how EBV gets into the host cell.

Receptor-mediator endocytosis

Exocytosis is a process by which cells

Release substances from the cell via vesicles.

Coupled transport

Secondary active transport is a form of active transport across a biological membrane in which a transporter protein couples the movement of an ion (typically Na+ or H+) down its electrochemical gradient to the uphill movement of another molecule or ion against a concentration/electrochemical gradient.

How can transport occur by simple diffusion?

Simple diffusion is the passive movement of a substance along a chemcial or electrical gradient. Biological membranes pose a barrier to hydrophilic polar molecuels, while they allow hydrophobic substances to diffuse freely.

Amphipathic?

Some regions that are hydrophilic and hydrophobic

H + ion electrogenic pump?

Stores energy by generateing voltage across memranes. Moves positive charge in form of protons (H+). Important for ATP synthesis in respiration and for contransport.

What are the structural features of membrane proteins that are related to the function?

Surface proteins are attached to the surface by nonpolar regions that associate with polar regions of phospholipids. Transmembrane proteins may cross the bilayer a number of times, and each membrane spanning region is called a transmembrane domain. Such a sdomain is compposed of hydrophobic amino acids usually arranged in cx helices. In certain proteins beta-pleated sheets in the nonpolar region form a pipe like passageway having a polar environment. An example is the porin class of proteins.

Attachments to the cytoskelton?

Surface proteins that interact with other cells are often anchored to the cytoskeleton by linking proteins.

The movement of water across a membrane is dependent on?

THe solute concentration

A red blood cell has a salt concentration of 0.85% is placed in a 4% salt solution, which of the following will most likely happen?

The cells would lose water and shrink.

What would happen if red blood cells in an isotonic NaCl solution were diluted with pure water by a factor of five?

The cells would swell and lyse (burst).

What determines chemcial potential?

The concentration gradient

What variables influence whether a nonpolar molecule can move across a membrane by passive diffusion.

The difference in concentration of the molecule across the membrane.

electrochemical gradient

The diffusion gradient of an ion, representing a type of potential energy that accounts for both the concentration difference of the ion across a membrane and its tendency to move relative to the membrane potential.

Osmosis?

The diffusion of water ( net diffusion of water across a membrane towards a higher solute concentration)

An electrical force?

The effect of the membrane potential on the ions movement

How do membranes form spontaneously?

The hydrophobic fatty acid tails on phospholipids are repelled by water.

How do the phospholipids spontaneously form bilayers?

The phosphate group of a phospholipid is polar and hydrophilic; the fatty acids are nonpolar and hydrophobic, and they orient away from the polar head of the phospholipids. The nonpolar interior of the lipid bilayer impedes/delay the passage of water and water-soluble substances.

A lysosome adds cell immunity and protection because it?

contains lysozyme and proteases which digest bacteria.

Ethylene glycol (62), glycerol (92), ethanol (46) and propanol (60) all cause red blood cells to burst. Based on the information provided, what can one hypothesize about solutes on hemolysis rate?

The smaller the compound, like ethanol, the faster the hemolysis rate due to increased ability to move through the membrane.

What is the purpose of pumping sodium and potassium across a membrane?

The sodium potassium pump is a well understood example of active transport. Sodium and potassium ions are pumped in opposite directions across the membrane building up a chemical and electrical gradient for each. These gradients can be used to drive other transport processes. In nerve cells the pump is used to generate gradients of both sodium and potassium ions. These gradients are used to propagate electrical signals that travel along nerves. Therefore the action of nervous tissue requires ATP to generate resting potentials. Poisons that disable the pump prevent proper functioning of the nervous system. View the animation below, then complete the quiz to test your knowledge of the concept.

How does the sodium-potassium pump run directly on ATP?

The sodium-potassium pump moves Na+ out of the cell and K+ into the cell against their conecentration gradients using ATP. In every cycle of the pump, three Na+ leave the cell and two K+ enter it. This pump appears to be almost universal in animal cells.

What are phospholipids composed of?

They are composed of two fatty acids and a phosphate group linked to a three-carbon glycerol molecule.

What evidence has the electron microscope provided?

Transmission electron microscopy (TEM) and scanning electron microscopy (SEM) have confirmed the structure predicted by the fluid mosaic model.

What are the key funcitons of proteins and protein complexes?

Transporters are integral membrane proteins that carry specific substances through the membrane. Enzymes often occur on the interior surface of the membrane. Cell-surface receptors respond to external chemical messages and change conditions inside the cell; cell identity markers on the surface allow recognition of the bodys cells as self. Cell-to cell adhesion proteins glue cells together; surface proteins that interact with other cells anchor to the cytoskelton.

Complement factor C3b coats a bacterium and binds to C3b receptors on phagocytes, making the bacterium more susceptible to being phagocytized.?

True

Due to the unequal transport of sodium and potassium ions by the Na-K pump, a membrane potential is generated.?

True

Electrochemical Gradient?

Two combined forces, that drive the diffusion of ions across membranes

The specific function of a membrane within a cell is determined by the?

Type and number of membrane proteins

Solvent?

Water

Isotonic?

When the cell and solution have the same osmotic concentration

After hand washing your clothes, your fingers appear wrinkled because they've taken in water. What is the most plausible explanation?

Your skin is hypertonic to the water

Red blood cells put in a hypotonic solution will?

be destroyed by hemolysis.

An animal cell encounters a new type of bacterium. The ordered process of phagocytosis likely to be used by the animal cell to engulf and consume the bacterium would be?

detection, ingestion, fusion with lysosome, phagolysosome, digestion.

Two processes involved in bulk transport?

endocytosis and exocytosis

Dephosphorylation of the pump in response to dopamine would most likely result in?

inhibited pump activity in cells.

Chemiosmosis?

is the process of using the potential energy in a gradient to do work.

Sea water is approximately 3% salt. Sea water is hypertonic to tissues of freshwater fish. Their tissue contain?

less than 3% salt

Red blood cells put in a hypertonic solution will?

shrivel and become crenated.

he sodium-potassium pump functions to move

sodium ions out of the cell and potassium ions into the cell.

Cell-cell recognition

the ability of a cell to distinguish one type of neighboring cell from another is crucial to the functioning of an organism carbohydrates are important for this.Cell recognition is one of the ways by which cells communicate with one another. It is possible through specific cellular adhesion molecules on the surface of the cell.

Cotransport captures its energy from?

the movement of one of the transported substances down its concentration gradient.

Osmosis is best defined as the movement of?

water molecules across a membrane from an area of high water concentration to an area of lower concentration.

In the process of diffusion, when sugar is mixed with water, equilibrium would be reached?

when the dissolved sugar molecules are evenly distributed throughout the solution.