1. Plasma Membrane Part 1

Question 1

What are the functions of the plasma/cell membrane? What are the benefits of membrane-bound organelles in Eukaryotes?

Answer 1

• Acts as a boundary to control what enters and exits the cell
• Separates the internal and external environments
• Different parts of the cell can have varied conditions to allow specialisation

Question 2

Describe phospholipid heads:

Answer 2

• Are hydrophilic (hydro=water) and polar

- Love water

Question 3

Describe fatty acid tails:

Answer 3

• Are hydrophobic and non-polar

- Hate/fear water

Question 4

Explain the Fluid Mosaic Model:

Answer 4

• Fluid= Because the phospholipids are moving

- Mosaic= Proteins sit in the phospholipids like tiles in a mosaic

Question 5

What is the function of sterols, what are their different types and where are they located

Answer 5

• Change the fluidity of the membrane so that it is able to remain stable.
• Phytosterol in plants and animals and only Chlorestoral in animals
• Located in the hydrophobic region of the membrane

Question 6

What are the 2 types of membrane proteins?

Answer 6

Can be integral (permanent parts of the membrane) or peripheral (temporary)

Question 7

List the 6 functions of membrane proteins:

Answer 7

1. Transport substances across the membrane
2. Secure the cytoskeleton to the membrane
3. Are enzymes
4. Are receptors
5. Responsible for cell-to-cell adhesion
6. Act as identity marks

Question 8

Describe the internal environment of multi-cellular organisms:

Answer 8

Contain interstitial/tissue (extracellular) fluid between cells (fluid bathes the cells, as well as blood plasma.

Question 9

Describe the internal environment of unicellular organisms:

Answer 9

Contain only the internal environment of the cell itself.

Question 10

What is a solute?

Answer 10

A substance dissolved in a liquid.

Question 11

What is a solvent?

Answer 11

A liquid

Question 12

What is a solution?

Answer 12

A solute and a solvent

Question 13

What is a concentration gradient?

Answer 13

Describes the difference between relative amounts of solute and solvent in two solutions.

Question 14

What does polar refer to? Give an example:

Answer 14

When one end of a molecule has a different charge to the other.
Eg. Water

Question 15

What does non-polar refer to? Give an example:

Answer 15

When one end of a molecule has the same charge as the other.

Eg. Oil

Question 16

What are vesicles?

Answer 16

Small storage compartments of membrane which transport solids or liquids across membranes

Question 17

What is exocytosis and does it require energy?

Answer 17

• Exiting the cell

- Requires energy

Question 18

What is endocytosis and does it require energy?

Answer 18

• Entering the cell

- Requires energy

Question 19

What is the difference between eukaryotes and prokaryotes?

Answer 19

• Eukaryotes are complex cells which contain membrane-bound organelles, DNA present as chromosomes, and can be either unicellular or multicellular
• Prokaryotes are primitive cells which lack membrane-bound organelles, nuclei, and can only be unicellular.

Question 20

What are ribosomes? What cells are they present int?

Answer 20

They are made of proteins and ribosomal RNA (rRNA) and assemble to translate mRNA (messenger RNA) into protein.
-Present in prokaryotic, animal, and plant cells

Question 21

What is the rough endoplasmic reticulum and why is it called this? What cells are they present in?

Answer 21

Its surface is used to create protein to export. Is called ‘rough’ because of the presence of ribosomes.
-Present in animal and plant cells

Question 22

What is the function of the Golgi Apparatus? What cells are they present in?

Answer 22

Packages and modifies proteins for transport to other organelles or to secrete from the cell.
-Present in animal and plant cells

Question 23

Name the 2 types of endocytosis:

Answer 23

• Phagocytosis

- Pinocytosis

Question 24

What is phagocytosis?

Answer 24

The bulk transport of solids into a cell

Question 25

What is pinocytosis?

Answer 25

The bulk transport of liquids into a cell

Question 26

Describe the process of producing and transporting protein:

Answer 26

1. DNA is transcribed into mRNA in the nucleus 2. mRNA leaves nucleus and ribosomes assemble to translate the message into protein 3. Protein is either made in the cytosol or moved into the rough endoplasmic reticulum 4. Protein moves via vesicles to the Golgi Apparatus 5. Golgi sorts protein into correct vesicles to move either out of the cell or into other organelles