5.1-5 Biological membranes

Question 1

What are all cells and organelles surrounded by?

Answer 1

• a partially permeable membrane made of lots of phospholipids with protein molecules between the phospholipid molecules

Question 2

What is the main function of the membrane?

Answer 2

• controlling the movement of substances in and out of the cell/ organelle

Question 3

What does the membrane contain that helps with the release of other substances?

Answer 3

• receptors for other molecules such as hormones
• enables adjacent cells to stick together

Question 4

What is the name of the model and why is it called this?

Answer 4

• fluid mosaic model
• fluidity of the membrane
• mosaic arrangement of the protein give the structure

Question 5

What does the movement of molecules through a cell membrane depend on?

Answer 5

• the properties of the molecule
• requirements of the cell

Question 6

What are the different types of movement?

Answer 6

• diffusion
• facilitated diffusion
• osmosis
• active transport
• exocytosis

Question 7

What is diffusion?

Answer 7

• the passive movement of small, non-polar lipid soluble molecules such as carbon dioxide and oxygen from an area of high concentration to an area of low concentration
• the molecules move directly through the phospholipid bilayer

Question 8

What is facilitated diffusion?

Answer 8

• requires a channel protein in the cell membrane to transport polar molecules, charged and water soluble molecules across a membrane

Question 9

What is diffusion (solute)?

Answer 9

• the diffusion of water molecules from an area of low solute concentration to an area of high solute concentration through a partially permeable membrane

Question 10

What is diffusion (water potential)?

Answer 10

• the diffusion of water molecules from from an area of high water potential to an area of low water potential through a partially permeable membrane

Question 11

What is active transport?

Answer 11

• can transport all types of molecules through carrier proteins from an area of low concentration to an area of high concentration
• this process requires energy in the form of ATP as it is going against the concentration gradient

Question 12

What is exocytosis?

Answer 12

• transport large particles and bulk transport
• vesicles containing large particles fused with the cell surface membrane

Question 13

What is endocytosis?

Answer 13

• the particles are enclosed in vesicles made from the cell surface membrane and transported into the cell

Question 14

The rate of gas exchange by diffusion becomes more rapid as …

Answer 14

• surface area of the surface increases
• diffusion difference decreases
• diffusion gradient becomes more steep