AP Biology Chapter 5: Membrane Transport

What is exocytosis? Give an example.

The exporting of macromolecules, taking them outside of the cell Ex: Insulin being released from the pancreas cells

What side of the membrane is positive when using a sodium-potassium pump?

The exterior

What is endocytosis? List the process' three subcategories.

The importing of macromolecules, bringing them into the cell Three subcategories: phagocytosis, pinocytosis, receptor-mediated endocytosis

What is receptor-mediated endocytosis? Give an example.

When materials bunch outside the cell, and receptors mediate what can enter and exit the cell Ex: A lack of cell receptors causes a condition of high cholesterol

What is an isotonic substance?

When surrounding a cell, the substance causes no net movement of water in or out of the cell

What is a hypotonic substance?

When surrounding a cell, the substance causes the cell to gain water

What is a hypertonic substance?

When surrounding a cell, the substance causes the cell to lose water

What is osmosis?

When water diffuses through a selectively permeable membrane

Are transport proteins specific about what they move?

Yes, they are very specific; they won't even recognize the isomer of a molecule

How is co-transport used in the treatment of diarrhea?

You lose salt and glucose when suffering from diarrhea, and our bodies have a co-transporter that moves both glucose and salt at the same time...This co-transporter would replenish nutrients lost very efficiently, when both salt and glucose are taken in simultaneously

How does a sodium-potassium pump work?

1. NA+ binds to the sodium-potassium pump, because the pump starts out having a high attraction for NA+ 2. NA+ binding stimulates phosphorylation (the leaving behind of a phosphate) by ATP 3. Phosphorylation leads to a change in the protein shape, reducing its attraction for NA+, which is then released 4. The new shape is attracted to K+, which binds to the pump, and triggers the release of the phosphate 5. Loss of the phosphate group restores the protein's original shape 6. K+ is released, attraction for NA+ increases again, and the cycle begins again

What is membrane potential?

A difference of some kind between the interior and exterior of a cell

What are the two ways bulk transport can occur?

Endocytosis or exocytosis

How is H+ moved across the cell membrane?

-facilitated diffusion; transport proteins move it across the membrane -ion channels; protein tunnels allow ions to pass through them

What are the two main categories of membrane proteins, and what do each do?

-integral proteins: they pass all the way through the membrane and "bulge out" on either side -peripheral proteins: the don't pass all the way through the membrane, and "bulge out" from either the outside or the inside

What are two examples of facilitated diffusion?

-ions traveling through channel proteins -glucose traveling through carrier proteins

What are two examples of membrane carbohydrates being important in cell-to-cell recognition?

-organ rejection: the new organ transplanted gets rejected because it has a different carbohydrate chain than your own body's -blood transfusion: red blood cells don't have DNA, so blood transfusion is easier than organ transplants, because there's less recognition proteins present

How is H2O moved across the cell membrane?

-osmosis; specific to water, it allows it to diffuse through a selectively permeable cell membrane -aquaporins; protein tunnels allow water to quickly pass through them

What is the fluid mosaic model?

-the current accepted model of the cell membrane -states that the cell membrane is many small parts that are in motion, put together -states that proteins are dispersed throughout the membrane

What is concentration gradient?

A region along which the density of a chemical substance increases or decreases

What does enzymatic activity do?

Catalyzes chemical reactions inside the cell, and often triggers receptor proteins

What is the difference between channel proteins and carrier proteins?

Channel proteins are like "open doorways," and open up to allow materials to move through them, while carrier proteins are like "elevator doors," changing shape and opening and closing to allow materials to move through them

What are aquaporins?

Channels allowing for the extremely fast diffusion of multiple water molecules at a time, and their process is much faster than osmosis

What is co-transport?

Co-transport is when two materials move across the membrane simultaneously (both materials must be present for this process to work)

What are the two forces that drive the diffusion of ions across the membrane, what is the combination of these forces called?

Concentration differences and charged differences; when combined they are known as an electrochemical gradient

Give examples of materials involved in the following types of transport: facilitated diffusion with a carrier protein, facilitated diffusion with a channel protein, active transport with a carrier protein, simple diffusion

Facilitated diffusion with a carrier protein: Glucose Facilitated diffusion with a channel protein: Ions Active transport with a channel protein: Potassium/Sodium Simple diffusion: Water

What are the three types of passive transport?

Facilitated diffusion, simple diffusion, and osmosis

How is glucose moved across the cell membrane?

Facilitated diffusion; transport proteins move it across the membrane

What is the difference between glycolipids and glycoproteins?

Glycolipids are sugar units covalently bonded to lipids, and glycoproteins are sugar units covalently bonded to proteins

What does intercellular joining do?

Helps similar cells stick together and maintain shape (tissue formation)

What is the difference between high and low permeability?

High permeability allows molecules to slide through the membrane without transport proteins, while low permeability requires molecules to pass through using transport proteins

What does cell-to-cell recognition do?

Identifies the cell as a certain type, providing information for other cells

What is the role of ATP in active transport?

It's the energy source that allows the pump proteins to function

What is pinocytosis? Give an example.

Known as "cellular drinking," it's when fluid outside of the cell pushes its way inside Ex: Digestive system takes in broken down materials

What is phagocytosis? Give an example.

Known as "cellular eating," it's when the membrane engulfs outside materials and drags them into the cell Ex: White blood cells engulf invaders and break them down with lysosomes inside the cell

What type of transport proteins are involved in active transport?

Pumps

What do transport proteins do?

Move substances across the membrane, and act like a doorway

What does it mean when phospholipids are amphipathic?

Parts of the phospholipids are hydrophilic, and other parts are hydrophobic

Why does the red blood cell burst when placed in a hypotonic solution, but not the plant cell?

Plant cells have central vacuoles, which regulate pressure, so it is not possible for them to absorb too much water; however, red blood cells do not have this defense, so they could absorb too much water from a hypotonic solution, causing them to burst

What are the three types of active transport?

Pump proteins, endocytosis, and exocytosis

How is CO2 moved across the cell membrane?

Simple diffusion; because it is non-polar, it can easily slip through the lipid bilayer

How is O2 moved across the cell membrane?

Simple diffusion; because it is non-polar, it can easily slip through the lipid bilayer

What does it mean if a plant cell is turgid?

The cell is swollen or firm

What does it mean if a plant cell is flaccid?

The cell lacks stiffness or firmness

What is bulk transport?

The moving of materials that are too big or too charged to pass through the lipid bilayer, or be transported through transport proteins

What is meant by membrane fluidity?

The phospholipids and proteins shift and move around in the fluid membrane and the rest of the cell, and are able to move side to side or flip positions with one another

What is plasmolysis?

The pulling away of the cell membrane from the cell wall in a dehydrated plant

What is diffusion?

The spreading out of molecules from areas of high concentration into areas of low concentration

What is facilitated diffusion?

The use of a transport protein to move things across the membrane without the expending of energy (passive transport)

What is active transport?

Transportation across the membrane with the use of energy

What is passive transport?

Transportation across the membrane without the use of energy

What do receptor proteins, also known as signal transduction proteins, do?

Trigger changes in the cell interior when substances bind, and receive messages from the outside to alter the inside