Chapter 5 - Biology

Sodium-potassium Pump

A carrier protein in animal cells.

Hypertonic, plasmolysis

A hypertonic solution has a higher solute concentration than the cytosol of a cell. In a hypertonic solution a plant cell will lose water and shrink away from the cell wall, a process called plasmolysis.

Difference between hypotonic and hypertonic

A hypotonic solution has a lower solute concentration outside the cell than inside the cell. A hypertonic solution has a higher solute concentration outside the cell than inside the cell.

Compare endocytosis and exocytosis.

Are active transport mechanisms in which large substances enter or leave cells inside vesicles.

Carrier Protein

Assist movement of molecules across the cell membrane in a facilitated diffusion, transport molecules from an area of higher concentration to lower concentration - doesn't require energy

What happens to the movement of molecules at equilibrium?

At equilibrium, the movement of molecules continues, but because there is no concentration gradient, there is no net movement in any particular direction.

Explain how a cell that consumes glucose can speed up its intake of glucose from an environment.

The cell could use carrier proteins to transport glucose by facilitated diffusion

Equilibrium

The concentration of molecules will be the same throughout the space the molecules occupy (it's equal)

Exocytosis

The process by which a substance is released from the cell through a vesicle that transports the substance to the cell surface and then fuses with the membrane to let the substance out of the cell.

Endocytosis

The process by which cells ingest external fluid,macromolecules, and large particles.

. What types of stimuli can cause the gates on ion channels to open or close?

The stimuli are stretching of the cell membrane, electrical signals, and chemicals in the cytosol or external environment.

Distinguish between the processes of endocytosis and exocytosis.

They are active transport mechanisms in which large substances enter or leave cells inside vesicles. Endocytosis uses vesicles to bring external substances into the cell. Exocytosis uses vesicles to release substances from the cell.

Concentration gradient, diffusion

They both mean the movement of molecules from higher concentration to lower concentration

Concentration Gradient

The different in the concentration of molecules across a distance

Summarize the factors that determine the direction of net movement of water across a cell membrane.

The factors that determine the directions of net movement of the cell are the concentration of solutes inside and outside of the cell.

Explain how substances cross the cell membrane through facilitated diffusion.

The movement is assisted by carrier proteins. A molecule bind to a specific carrier protein for transport. As soon as it binds, the shape of the carrier protein changes. Once it's shielded, it can be transported through the cell membrane. The molecules is released on the other side of the cell membrane and the protein returns to it's original shape.

Explain how substances cross a cell membrane through facilitated diffusion

The movement is assisted by carrier proteins. A molecule bind to a specific carrier protein for transport. As soon as it binds, the shape of the carrier protein changes. Once it's shielded, it can be transported through the cell membrane. The molecules is released on the other side of the cell membrane and the protein to it's original shape.

Phagocytosis

The movement of large particles or whole cells

Determine how the phospholipid bilayer of a membrane forms a barrier to molecules

The phospholipid bilayer is selectively permeable and only allows certain things to enter through it. It forms a barrier around the cell.

Phagocyte

Allow lysosomes to fuse with the vesicles that contain the ingested bacteria and viruses.

Explain how a phagocyte destroys bacteria.

A phagocyte will engulf the bacteria, the lysosomes, which have powerful hydrolytic enzymes, fuse with the bacterial vesicle and the enzymes destroy the bacteria.

Identify how ATP is involved in maintaining the sodium and potassium gradients across a cell membrane

ATP gives energy that makes the sodium potassium pump work, which pumps Na+ out of the cell an K into the cell

Distinguish between passive transport and active transport.

Active transport moves molecules across the cell membrane from an area of lower concentration to an area of higher concentration. Unlike passive transport, active transport requires cells to expend energy.

Why is it important that ions being transported across a cell membrane be shielded from the interior of the lipid bilayer.

Because the interior of the lipid bilayer is polar and ions could, through electromagnetic forces, tear apart the membrane

How does the interaction between a carrier protein & the substance it transports resemble the interaction between an enzyme & its substrate?

Both involve the binding of a specific substance to a particular kind of protein and a change in shape of the protein as the process (transport or chemical reaction) proceeds. After the process is completed, the protein is unchanged.

Distinguish between diffusion and osmosis.

Both involve the movement of molecules from high concentration to low concentration. Diffusion doesn't need water, while osmosis does. Basically, osmosis is a special kind of diffusion

Distinguish between diffusion and osmosis

Both involve the movement of molecules from high concentration to low concentration. Diffusion doesn't need water, while osmosis does. Basically, osmosis is a special kind of diffusion.

How do carrier proteins transport substances across cell membranes?

Carrier proteins bind to a molecule of the substance on one side of the membrane, change shape, transport the molecule across the membrane, and release the molecule on the other side

Explain how ion channels assist the diffusion of ions across the cell membrane.

Certain ions important for cell function are not soluble in lipids. Ions cannot diffuse across the phospholipid bilayer without assistance. Ion channels provide passageways across the membrane through which ions can diffuse. Each channel is specific to an ion.

Passive Transport

Certain substances that can cross the cell membrane without any input of energy by the cell

Define the term contractile vacuole. What is a contractile vacuole's function?

Contractile vacuoles are organelles that remove water. They collect the excess water and contract to pump out the water. It is not passive transport because it uses energy.

Contractile Vacuole

Organelles that remove water, collect the excess and then contract - pump water out of cell, not passive transport because it requires the cell to expend energy

Explain how an equilibrium is established as a result of diffusion.

Diffusion is the movement of molecules from an area of higher to lower concentration. Once this occurs, the concentration will eventually even out and equilibrium will be established because the concentrations will be the same throughout the space occupied by molecules.

Explain why diffusion eventually results into equilibrium

Diffusion is the movement of molecules from an area of higher to lower concentration. Once this occurs, the concentration will eventually even out and equilibrium will be established because the concentrations will be the same throughout the space occupied by molecules.

Use each of the following terms in the same sentence: carrier protein, concentration gradient, facilitated diffusion, and passive transport.

Facilitated diffusion is passive transport because it doesn't require energy, but it uses carrier proteins to travel across the concentration gradient

Plasmolysis

In a hypertonic environment - water leaves the cell and the cells shrink away from the cell walls (no turgor pressure), reason plants wilt when they don't have enough water

Difference between diffusion and facilitated diffusion

In both processes, molecules move down their concentration gradient. Infacilitated diffusion, carrier proteins speed the rate of diffusion

Determine how hypotonic, hypertonic, and turgor pressure are interrelated.

In hypotonic solutions water is diffused into the cell which causes turgor pressure to increase. In hypertonic solutions water is diffused out of the cell and turgor pressure is decreased, causing the cell the shrivel

Pinocytosis

Involves the transport of solutes or fluids.

Describe how ion channels assist in the diffusion of ions through a cell membrane.

Ion channels transport ions from areas of higher concentration to areas of lower concentration. Since ions are not soluble in lipids, they cannot diffuse across the phospholipid bilayer. Ion channels provide passageways for ions to diffuse across the cell membrane.

Describe what it means to say that two solutions are isotonic.

It means that the concentrations are equal and there is no net movement of water.

Why is the sodium-potassium transport called a "pump"?

It moves the ions against the concentration gradient like a pump would.

Explain how the sodium-potassium pump operates.

It moves three Na+ ions into the cell's external environment for every two K+ ions it moves into the cytosol.

Vesicle

Membrane bound organelle

Diffusion

Movement of the molecules from an area of higher concentration to an area of lower concentration

The sodium-potassium pump transports

Na+ out of the cell & K+ into the cell

Identify whether all molecules dissolve through cell membranes. Explain.

No, because some are too big or not soluble in lipids, so they have to use facilitated diffusion in order to pass into the cell.

Cytolysis

Occurs in a hypotonic environment when red blood cells have water diffused into them causing it to swell and burst - bursting is cytolysis

Substances that can pass through cell membranes by diffusion include

Oxygen

Difference between pinocytosis and phagocytosis

Pinocytosis moves solutes or fluids into cells phagocytosis moves particles or whole cells into cells.

Difference between plasmolysis and cytolysis

Plasmolysis is cell shrinking, while cytolysis is cell bursting.

Explain the relationship between plasmolysis and turgor pressure in plant cells.

Plasmolysis occurs when water is lost and the cells shrink away from the cell walls. The turgor pressure is gone because there isn't any pressure against the cell wall. This causes the cell to wilt.

Turgor Pressure

Pressure that water molecules exert against the cell wall

Osmosis

Process ny which water molecules diffuse across a cell membrane from an area of higher concentration to an are of lower concentration

Describe how a cell produces and releases proteins

RNA from the nucleolus tells the ribosomes on the rough er how to assemble, carried to Golgi, modified and enter vesicles, which lead them outside the cell or inside the cell

Osmosis, turgor pressure

Turgor pressure is the pressure in plants created by either an excess or lack of water. Osmosis diffuses the water & is the main way that plants can increase or decrease their turgor pressure.

Facilitated diffusion

Type of passive transport - used for molecules that cannot readily diffuse through cell membranes even when there is a concentration gradient across the membrane,

Ion Channel

Type of transport involving membrane proteins, transport ions from higher to lower concentrations

Active Transport

When a cell moves materials from an area of low to high concentration.

Hypertonic

When the concentration of solute molecules outside the cell is higher than the concentration of the cytosol, solution is hypertonic to the cytosol, water diffuses out of the cell until equilibrium is established

Hypotonic

When the concentration of solute molecules outside the cell is lower than the concentration in the cytosol, solution outside is hypotonic to cytosol, water diffuses into the cell until equilibrium is established

Isotonic

When the concentrations of solutes outside and inside the cell are equal, water diffuses into and out of the cell at equal rates - no net movement of water

Facilitated-diffusion carrier proteins and cell-membrane pumps both

are specific for the kinds of substances they transport

Na+ ions enter cells by

diffusion through Na+ ion channels

Pinocytosis involves the transport of

fluids into a cell

The contractile vacuole of a paramecium should be active when the paramecium is in

hypotonic environment

On which side of the membrane are K+ ions released from the pump?

inside

Facilitated diffusion is often used to transport

molecules that are not soluble in lipids

On which side of the membrane are Na+ ions released from the pump?

outside

The energy needed to power the sodium-potassium pump is provided by the

removal of a phosphate group from ATP

When a human red blood cell is placed in a hypotonic environment, it will

undergo cytolysis

Exocytosis is a

way for cells to release large molecules, such as proteins