5.4 Active Transport

Question 1

Define active transport

Answer 1

The movement of molecules from an area of low concentration to an area of high concentration against the concentration gradient . This process is done via carrier proteins and the use of energy in the form of ATP.

Question 2

How does it basically work with carrier proteins

Answer 2

Carrier proteins spam the width of the membrane

1) the molecule to be transported binds to the inside of the carrier protein
2) once bound ATP will bind to the carrier protein and is hydrolysed to form ADP and a phosphate
3) the phosphate now binds to the protein and this causes the protein to CHANGE SHAPE
4) now the meocluke can exit into the cell, it has been actively transported
5) once done the phosphate molecule is released from the carrier protein and can now recombine with ADP to produce ATP again, but only in a respiration reaction
6) the detachment of the phosphate means the protein returns back to its original shape so process can restart

Question 3

How is facilitated diffusion and active transport somewhat selective

Answer 3

1) facilitated diffusion have protein channels specific to molecules
2) similarly s Carrie protein will only Transport a specific molecule too

Question 4

What is bulk transport and what is it for

Answer 4

Another form of active transport but this time to transport large molecules such as ENZYMES, HORMONES AND WHOLE CELLS LIKE BACTERIA which are too large to fit through channelmportiejd

Question 5

What is it split into (bulk )

Here what is exocytosis

Answer 5

Endocytosis- bulk transport of molecules INTO CELLS

• phagocytosis
• pinocytosis

Exocytosis = movement of molecules OUTSIDE THE CELL
- done by vesicles formed by Golgi apparatus to package proteins or whatever move towards and fuse with the cell surface membrane, as they are all made from phospholipids , and then contents released

Question 6

Phagocytosis and pniocytosid of endocytosis of bulk transport of active transport

How does it work ?

Answer 6

Phagocytosis : movement for solids and Lino for liquids but method is same =

1) cell surface membrane first invaginate when coming into contact with molecule to be transported (bend inwards)
2) the membrane enfolds the material until it fuses , forming a VESICLE
3) The vesicles then pinches off snd moves into the cytoplasm for further professions ( like going to lysosomes to be digested )

Question 7

How is ATP USED IN BULK TRANSPORT ?

Answer 7

ATP is needed to move idles across the cells via the cytoskeleton ,

• also to change the shapes of cells to engulf the molecule
• used to fuse cell membranes to vesicles or when escaping too