Active transport

Question 1

Describe active transport

Answer 1

This transport requires energy to be able to transport across the cell membranes. It involves moving molecules against a concentration gradient.

Question 2

What is ATP?

Answer 2

ATP stands for Adenosine Triphosphate and it is a nucleotide.

Question 3

describe this:
energy
<———-
ATP ADP + P
———–>
energy

Answer 3

When ATP is converted to ADP which is Adenosine diphosphate it releases energy and an inorganic phosphate molecule.

This energy is then available for cell processes such as muscle contraction.

Question 4

What are the 3 special types of active transport?

Answer 4

1. Endocytosis
2. Exocytosis
3. Phagocytosis/pinocytosis

Question 5

Large …… and other particles, such as bacteria, are transported in ……….. ……..
They require …….. that is supplied by ATP

Answer 5

1. molecules
2. membrane-bound vesicles
3. energy

Question 6

Describe Endocytosis.

Answer 6

Endocytosis transfers INTO THE CELL.
It is important as most molecules needed for the cell to survive cannot normally pass through the plasma membrane.

Question 7

Describe Phagocytosis and Pinocytosis.

Answer 7

They are types of Endocytosis.

In Phagocytosis, the cells plasma membrane surrounds a molecule, such as a food particles, in the extracellular environment and buds off to form a vacuole that contains the molecule. The molecule is then digested by enzymes.

Pinocytosis is the same as Phagocytosis, EXCEPT the cells plasma membrane surrounds droplets of fluid containing dissolved solutes.

Question 8

Describe Exocytosis.

Answer 8

Exocytosis transfers OUT OF THE CELL.
Material is exported out of the cell via secretory vesicles. It is important in removing waste materials from the cell and in secreting cellular products.

Question 9

Sodium-potassium pumps.
What happens here?

Answer 9

Here, substances move from a LOWER to a HIGHER concentration. Energy is gained through respiration in the form of ATP

Question 10

Step one of Sodium-potassium pumps

Answer 10

The sodium-potassium pump binds three sodium ions and a molecule of ATP

Question 11

Step two of Sodium-potassium pumps

Answer 11

The splitting of ATP provides energy to change the shape of the channel. The sodium ions are driven through the channel.

Question 12

Step three of Sodium-potassium pumps

Answer 12

The sodium ion are released on the outside of the membrane and the new shape of the channel allows two potassium ions to bind.

Question 13

Step four (last step) of Sodium-potassium pumps

Answer 13

Release of the phosphate allows the channel to revert to its original form, releasing the potassium ions on the inside of the membrane.