Chapter 3C - active transport

Question 1

Active transport…

Answer 1

is the movement of molecules across a semipermeable membrane requiring an energy imput.

• it involves the use of ATP and membrane proteins (typically protein pumps and carrier proteins)

Question 2

ATP =

Answer 2

Adenosine triphosphate

Adenosine diphosphate + phosphate group + energy

Question 3

Types of active transport

Answer 3

• protein mediated transport
• bulk transport

Question 4

3 steps of active transport:

Answer 4

1. Binding - target molecule binds to the specific protein pump
2. Conformational change - one P from ATP

Question 5

3 steps of active transport:

Answer 5

1. Binding - target molecule binds to the specific protein pump
2. Conformational change - one P from ATP causes a conformational change in the protein pump
3. Release - target molecule is pushed through the protein and released to the other side of the membrane

Question 6

Bulk transport…

Answer 6

is a type of active transport that moves large molecules or groups of molecules (amino acids, proteins, signaling molecules or pathogens) into or out of a cell using vesicles.

There are 2 types:
- ENdocytosis - molecules ENtering the cell
- EXocytosis - molecules EXiting the cell

Question 7

Exocytosis…

Answer 7

Is a process that releases contents from a cell.

• proteins are made by ribosomes located on the surface of the Endoplasmic Reticulum, sorted, packaged and modified at the Golgi apparatus and then transported in vesicles to the membrane for exocytosis

Question 8

3 exocytosis steps:

Answer 8

1. Vesicular transport - a vesicle containing secretory produce is transported into the membrane
2. Fusion - membranes of the vesicle and cell fuse
3. Release - secretory products are released from the vesicle and out of the cell.

Question 9

Endocytosis…

Answer 9

Involves transporting groups of molecules into a cell.

• Many molecules that the cell requires to survive are too big to enter via protein channels
• Once inside the cell these substances are broken down, used for metabolic processes or become structural elements of the cell
• Can also be a defence mechanism – if a cell engulfs a invader or toxin, a lysosome can fuse with the vesicle and digest it

Question 10

3 endocytosis steps:

Answer 10

1. Fold - plasma membrane folds inwards to form a cavity that fills with extracellular fluid and the target molecule.
2. Trap - plasma membrane continues to fold back on itself until the 2 ends of the membrane meet and fuse together
3. Bud - vesicle (endosome) pinches off from the membrane. It can then be transported to the appropriate cellular location

Question 11

Types of endocytosis

Answer 11

• Phagocytosis (cell eating) - endocytosis of solid material or food particles. )*>
• Pinocytosis (cell drinking) – process of engulfing molecules dissolved in extracellular fluid. <*)