2.1.7 - Active Transport

Question 1

What Is Active Transport (AT)?
(2 Points)

Answer 1

~ Movement of molecules and ions through a cell membrane from a region of lower concentration to a region of higher concentration.

~ Active process, as it requires energy in the form of ATP to move substances AGAINST their concentration gradient.

Question 2

What Type Of Transport Protein Does AT Use?

Answer 2

Carrier proteins.

Question 3

Describe The Role Of Carrier Proteins In AT
(3 Points)

Answer 3

~ Each carrier protein is specific to a particular type of molecule or ion.

~ Energy is required to allow the carrier protein to change shape, the energy provided is in the form of ATP.

~ A molecule attaches to the carrier protein, protein changes shape moving the molecule across the membrane, releasing it on the other side.

Question 4

Describe How Energy Comes From ATP
(4 Points)

Answer 4

~ ATP is produced during respiration.

~ Acting as an immediate source of energy in the cell.

~ ATP is hydrolysed in the cell, energy is then released.

~ This energy is then used to move the molecule against its concentration gradient.

Question 5

Describe Endocytosis
(4 Points)

Answer 5

~ Larger molecules cannot be taken into the cell via carrier proteins. E.g. Proteins, lipids and carbohydrates.

~ Instead a cell surrounds a substance with a section of its cell membrane.

~ The membrane then engulfs and pinches off to form a vesicle inside the cell containing the substance.

~ Active process, requires energy in the form of ATP.

Question 6

Describe Exocytosis
(4 Points)

Answer 6

~ Some substances produced by the cell need to be secreted. E.g. Hormones, enzymes and lipids.

~ Vesicles containing the substance pinch off to from sacs of the Golgi apparatus, then move towards the cell surface.

~ Vesicles then fuse with the cell surface membrane to be released outside of the cell.

~ Active process, requires energy in the form of ATP.