5.4 Active Transport

What does the diffusion reduce the concentration gradient to?

Equilibrium (no concentration gradient)

However, what depends on the presence of a concentration gradient?

many biological processes

What has to happen to particles in order to maintain this concentration gradient?

particles have to be moved up the concentration gradient faster than the rate of diffusion

What is the process that causes these particles to be able to move against the concentration gradient?

active transport

Active transport definition?

the movement of molecules or ions into or out of a cell from an area of lower concentration to an area of higher concentration (against the concentration gradient)

What two things does the process of moving particles against a concentration gradient (active transport) require?

energy (ATP) and carrier proteins

Is active transport a passive or active process?

active - requires metabolic energy (ATP)

What do the carrier proteins that span the cell membrane act as?

'pumps'

The process of active transport into a cell 1: What does the molecule or ion to be transported bind to on the outside of the cell?

binds to receptors in the channel of the carrier protein on the outside of the cell

The process of active transport into a cell 2: What binds to the carrier protein on the inside of the cell?

ATP binds to the carrier protein on the inside of the cell

The process of active transport into a cell 2.1: What is the ATP hydrolysed into after binding to the carrier protein on the inside of the cell?

ATP hydrolysed into ADP and phosphate

The process of active transport into a cell 3: What does the binding of the phosphate molecule to the carrier protein cause?

the carrier protein to change shape

The process of active transport into a cell 3.1: What does the changing of the shape of the carrier protein cause to open up?

changes shape to open up the carrier protein which opens up the inside of the cell

The process of active transport into a cell 4: what is the molecule or ion released into?

the inside of the cell

The process of active transport into a cell 5: what is the phosphate molecule released from?

the carrier protein

The process of active transport into a cell 5.1: What does the phosphate molecule recombine with?

phosphate molecule recombines with ADP

The process of active transport into a cell 5.2: what does the phosphate molecule recombining with ADP reform?

forms ATP

The process of active transport into a cell 6: what returns to its original shape?

the carrier protein

What does it mean by the process of active transport being selective?

specific substances are transported by specific carrier proteins

What is the process of active transport into cells the exact same process as?

active transport out of cells

Active transport diagram?

…

What is bulk transport a form of?

active transport

Examples of large molecules that are too large to move through a channel or carrier proteins to cross the membrane (3)?

enzymes, hormones and whole cells like bacteria

How are these large molecules that are too large to move through channel or carrier proteins moved into and out of cells?

by bulk transport

Endocytosis?

the bulk transport of materials into cells

Exocytosis?

bulk transport out of cells

The two types of endocytosis?

phagocytosis and pinocytosis

What is phagocytosis for?

solids

What is pinocytosis for?

liquids

What is the process of endocytosis the same for?

both phagocytosis and pinocytosis

The process of Endocytosis 1: What does the cell membrane do when it comes into contact with the material to be transported?

it invaginates

Invaginates?

bends inwards

The process of Endocytosis 2: when does the membrane enfold the material until?

The process of Endocytosis 3: what happens to this newly formed vesicle?

it pinches off the cell membrane to move further into the cytoplasm and form a vesicle that is inside the cell

The process of Endocytosis 4: why does the vesicle pinch off the cell membrane to travel further into the cytoplasm?

to transport the materials the vesicles contains for further processing within the cell

Example of Endocytosis: what are vesicles containing bacteria moved towards within the cell (once they are in there due to endocytosis)?

lysosomes

Example of Endocytosis: what happens to the bacteria in these vesicles at lysosomes?

the bacteria are digested by enzymes

The process of exocytosis 1: what do vesicles move towards and fuse with?

the cell surface membrane - from within the cell

The process of exocytosis: what are the contents of this vesicle then released to?

contents are released outside of the cell

Diagram of exocytosis and endocytosis?

…

What does both endocytosis and exocytosis use as its energy source?

ATP

What are the vesicles usually formed by in exocytosis?

the golgi apparatus within the cell

Processes energy in the form of ATP is required for: what is ATP needed for the movement of along the cytoskeleton?

required for the movement of vesicles along the cytoskeleton

Processes energy in the form of ATP is required for: what is ATP needed to change the shape of?

needed to change the shape of cells - in order for them to engulf materials

Processes energy in the form of ATP is required for: what is ATP needed for the fusion of?

cell membranes - as vesicles form or as they meet the cell surface membrane