Biology A Notes - Lesson 12

Which describes how the sodium-potassium pump works? (Select all that apply.)

It transports the two types of ions in different directions. ATP provides the energy to operate the motion of the pump.

What happens when a specific substance binds to a carrier protein?

The carrier protein changes shape and moves the substance through the cell membrane.

Study the image. https://cdstools.flipswitch.com/asset/media/490837 Describe the process unfolding.

A carrier protein is helping a substance enter the cell by diffusion.

What is active transport's source of energy?

ATP

_____ provides energy for active transport.

ATP

Why does active transport require energy?

Active transport moves substances against their concentration gradient.

Identify the type of transport illustrated in each diagram.

A—facilitated diffusion using carrier proteins B—simple diffusion C—facilitated diffusion using channel proteins

Identify the similarity between diffusion and facilitated diffusion.

Both processes result in a net movement of substances down a concentration gradient that exists across the cell membrane.

Explain how carrier proteins facilitate in diffusion.

Carrier proteins provide a mechanism that usually requires some sort of movement or shape change on the part of the protein.

Which describes the sodium-potassium pump and its relation to concentration gradients that exist across the cell membrane? (Select all that apply.)

It creates a potassium concentration gradient. It creates a sodium concentration gradient.

Explain how channel proteins facilitate in diffusion.

Channel proteins act as passageways from one side of the cell membrane to the other. The channel is usually very narrow and takes on a specific shape, which results in only substances of a certain size and shape being able to travel through it.

Identify the difference between diffusion and facilitated diffusion.

Diffusion involves the unassisted movement of substances from areas of higher concentration to areas of lower concentration. Facilitated diffusion is diffusion that requires the assistance of specialized protein molecules found embedded in the cell membrane.

Carrier proteins are involved with only the sodium-potassium pump.

False

Channel proteins are not specific and can transport many different types of substances.

False

Study the image modeling the sodium-potassium pump. https://cdstools.flipswitch.com/asset/media/499067 Identify the error in the image.

The ATP used to power the pump should be located in the cytoplasm, not outside the cell.

Describe what happens in the type of transport.

The pump keeps less sodium and more potassium inside the cell than outside the cell. The following process is illustrated in the diagram: 1. Sodium ions (Na+) inside the cell bind to the sodium-potassium carrier protein. 2. ATP provides the energy needed to change the shape of the carrier protein. 3. The protein changes shape, exposing the Na+ ions to the outside of the cell and releasing them. 4. Potassium ions (K+) outside the cell bind to the protein. 5. The protein returns to its original shape, transports the K+ ions across the membrane, and releases them into the cell.

Facilitated diffusion does not require the cell to use energy because moving molecules from areas of higher concentration to areas of lower concentration is powered by diffusion.

True

Study the characteristics. - relies on proteins to act as pumps - requires an input of energy from the cell - moves substances against their concentration gradient Which process does it describe?

active transport

Read the following scenario. The movement of a large decaying food particle into the cell would provide a source of nutrition but might also be potentially hazardous to the cell if allowed into the cytoplasm. Which transport method would provide the most effective solution to this problem?

endocytosis

Distinguish between endocytosis and exocytosis.

endocytosis—moves large substances into the cell exocytosis—moves large substances outside of the cell

Which is an example of active transport? (Select all that apply.)

exocytosis endocytosis the sodium-potassium pump

Identify the difference between facilitated diffusion and active transport.

facilitated diffusion—moves substances from areas of higher concentration to areas of lower concentration without the use of energy active transport—moves substances from areas of lower concentration to areas of higher concentration with the use of energy

Which type of transport does not require energy but uses carrier proteins to help move substances across the cell membrane?

facilitated transport

Why might a cell use endocytosis rather than a carrier protein to take in substances from the outside environment?

if the substance is too large to be transported by a carrier protein or if the substance is not intended to be located directly in the cell's cytoplasm.

Which are substances that are moved into cells by facilitated diffusion?

ions such as K+

The energy used for active transport comes from the __________.

molecule ATP

What type of active transport does the diagram illustrate?

the sodium-potassium pump

Which is an example of an active transport protein? (Select all that apply.)

the sodium-potassium pump a carrier protein that uses ATP