Topic 2.1.5 Biological Membranes

Question 1

What are the roles of the plasma membrane?

Answer 1

• separates cell contents from the outside environment
• Regulates the passage of substances into and out of cells
• Involved in cell recognition, cell signalling and cell adhesion (sticking together)

Question 2

What are some examples of substances that pass into and out of cells?

Answer 2

• Oxygen
• Water
• Glucose
• Hormones
• Carbon dioxide
• Secreted enzymes

Question 3

What are the roles of organelle membranes?

Answer 3

• Divide the cell into compartments with specialised functions (division of labour)
• isolates potentially harmful enzymes in lysosomes
• Provides surfaces for holding chlorophyll
• Provides surfaces for holding enzymes and coenzymes for making ATP (cristae in mitochondria) and attachment sites for ribosomes (rough ER)

Question 4

What is an example of division of labour?

Answer 4

nuclear envelope isolates DNA and enzymes for DNA replication

Question 5

What is the role of lysosomes?

Answer 5

Break things down

Question 6

What part of the chloroplast holds chlorophyll?

Answer 6

Thylakoids

Question 7

What is the basic structural component of cell membranes?

Answer 7

• phospholipid

- a molecule made from a phosphate ion (head) attached to two fatty acid chains (tails)