Protein Synthesis

Question 1

What is a key function of a cell?

Answer 1

• Synthesising proteins is a key function for both internal use and for secretion.
• Ribosomes, endoplasmic reticulum and the Golgi apparatus are all closely linked and have to coordinate

Question 2

Endoplasmic Reticulum

Answer 2

• Network of membranes enclosing flattened sacs called cisternae. Connected to outer membrane of nucleus
• Smooth E.R is responsible for lipid and carbohydrate synthesis
• Rough ER has ribosomes bound to the surface and is responsible for the synthesis and transport of proteins

Question 3

Ribosomes

Answer 3

• Can be free floating or attached to rough ER.
• Constructed of RNA molecules made in the nucleolus
• the site of protein synthesis

Question 4

Golgi Apparatus

Answer 4

• similar to smooth ER
• Compact structure formed of cisternae w/o ribosomes.
• Role is modifying proteins and ‘packaging’ them into vesicles
• Secretory vesicles to leave cell and lysosome to stay in cell

Question 5

Protein production

Answer 5

1) Proteins are synthesised on rough ER
2) Passed into cisternae and are packaged into transport vesicles
3) Vesicles containing new proteins go to Golgi apparatus via transport function of cytoskeleton
4) Vesicles fuse w/ Golgi apparatus and proteins enter. Proteins are structurally modified before leaving Golgi
5) Secretory vesicles carry proteins to release. Vesicles fuse with cell surface membrane and release them