Active Transport and Co-Transport in Biology

These flashcards cover the key concepts and details regarding active transport and co-transport in biology, particularly in the context of glucose absorption in the human digestive system.

What is active transport?

The movement of substances from an area of low concentration to an area of higher concentration through a carrier protein, requiring energy in the form of ATP.

What are the three types of transport across membranes discussed?

Simple diffusion, facilitated diffusion, and active transport.

What type of transport occurs when molecules move down their concentration gradient without a protein?

Simple diffusion.

What is facilitated diffusion?

The movement of molecules down their concentration gradient through a protein.

In active transport, what does ATP get hydrolyzed into?

ADP (adenosine diphosphate) and inorganic phosphate (Pi).

What role do carrier proteins play in active transport?

They facilitate the movement of molecules against their concentration gradient.

What are sodium ions transported against?

Their concentration gradient.

What molecule is required for the shape change of the carrier protein in active transport?

Phosphate group (from ATP hydrolysis).

What is co-transport?

A type of active transport where two different molecules are transported together across a membrane.

Which two molecules are involved in co-transport in the ileum?

Glucose and sodium ions.

Why is co-transport of glucose necessary in the ileum?

Glucose concentrations are usually higher inside epithelial cells than in the lumen, making facilitated diffusion insufficient.

What is the primary role of microvilli in the epithelial cells?

To increase the surface area for absorption.

How does the flow of blood help maintain glucose concentration gradients?

It continuously carries away absorbed glucose, preventing buildup in the capillary.

What happens to glucose after it enters the epithelial cell?

It moves down its concentration gradient into the bloodstream by facilitated diffusion.

What is the purpose of using ATP in active transport?

To provide the energy needed to move molecules against their concentration gradient.

Is co-transport a form of active transport?

Yes, co-transport is a type of active transport.

What structure allows sodium ions to be actively transported into the blood from the epithelial cells?

A carrier protein.

What are the two main components of the process of active transport?

Carrier proteins and energy supplied by ATP.

What happens to the carrier protein after sodium ions are released on the other side?

It returns to its original shape after the phosphate group is released.

In what section of the digestive system does co-transport of glucose primarily occur?

In the ileum.

What type of gradient does co-transport rely on?

It relies on the sodium ion concentration gradient.

What is the result of sodium ions diffusing from the lumen into the epithelial cell?

It facilitates the simultaneous transport of glucose into the cell.

What happens to the concentration of sodium ions in the epithelial cell after they are transported into the blood?

The concentration of sodium ions decreases.

What role do carrier proteins play specifically in the absorption of glucose in the ileum?

They transport glucose along with sodium ions into the epithelial cells.

What is the process of moving glucose from the epithelial cell to the bloodstream called?

Facilitated diffusion.

What are complementary shapes in the context of carrier proteins?

The specific shapes of molecules that allow them to bind to their respective receptor sites on carrier proteins.

What is the importance of maintaining a concentration gradient for glucose absorption?

It allows glucose to move into the bloodstream efficiently after being absorbed.

What is the initial concentration of glucose in the lumen compared to the epithelial cells?

Lower in the lumen, resulting in the need for active transport.

What is an example of a molecule that can be co-transported with sodium?

Glucose or amino acids.

How is the shape of a carrier protein changed during active transport?

By the attachment of an inorganic phosphate group during ATP hydrolysis.

Why is ATP considered important for active transport?

It provides the necessary energy to transport substances against their concentration gradient.

What role does the sodium concentration in the lumen play in glucose transport?

It helps drive the facilitated diffusion of glucose into the epithelial cell.

What is facilitated diffusion characterized by?

Movement of molecules down their concentration gradient through a specific protein.

How do epithelial cells in the ileum increase their absorption capacity?

By having microvilli and numerous co-transport proteins on their membrane.

What can happen if the concentration of glucose is higher in the epithelial cell than in the blood?

Glucose will diffuse from the epithelial cell to the blood.

In the co-transport process, what happens when sodium ions and glucose both bind to the carrier protein?

They are jointly transported across the membrane to the other side.

What triggers the process of sodium being actively transported into the blood?

Hydrolysis of ATP by the carrier protein.

Why do cells prefer to use co-transport for glucose absorption?

It allows glucose to be absorbed even against its concentration gradient.

What defines a carrier protein?

A protein that transports specific substances across a membrane by changing shape.

What ensures continuous glucose absorption in the ileum?

Constant blood flow carrying glucose away.

What is the significance of the tertiary structure of a protein in transport?

It determines the protein's function and ability to bind to specific molecules.

Why must the carrier protein change shape during transport?

To allow the molecule to be released on the other side of the membrane.

What does the phosphate group do to the carrier protein during active transport?

It induces a conformational change allowing the transport of the molecule.

What ultimately happens to glucose after being absorbed in the ileum?

It enters the bloodstream for distribution to body cells.

What defines the difference between simple and facilitated diffusion?

Simple diffusion does not require proteins while facilitated diffusion does.