Lesson 5

Question 1

During protein synthesis, what happens in:
Nucleus?

Answer 1

• Contains DNA which is copied in transcription, forming mRNA
• mRNA molecules leave through nuclear pores and attach to ribosomes around cell

Question 2

RER?

Answer 2

• Some mRNA attach to ribosomes on RER and protein synthesis occurs, forming polypeptides
• Polypeptides moved through RER and packaged into vesicles
• Vesicles bud off RER and carried to Golgi body

Question 3

Golgi body?

Answer 3

• Vesicles fuse with membranes and releases contents into Golgi body
• Protein modified
• Modified proteins packaged into vesicles

Question 4

After leaving Golgi body?

Answer 4

• Secretory vesicles carry proteins to cell membrane and be secreted by exocytosis
• OR they may become lysosomes within the cells

Question 5

What is the cell membrane?

Answer 5

Phospholipid bilayer contains glycoproteins, glycolipids, cholesterol and transport proteins, controlling what enters and exits cell. It is 7-8nm wide

Question 6

Describe structure of cell membrane

Answer 6

• Phospholipids form bolsters which have hydrophilic heads pointing outwards and hydrophobic tails pointing inwards
• Globular proteins which can be extrinsic (partly embedded) or intrinsic (extending through whole membrane)
• Carbohydrates pointing outside the cell
• Cholesterol embedded in cell membrane