Lecture 7

Question 1

List the components of the Endomembrane system and describe the structure and function of each component

Answer 1

ER (internal membrane of flattened sacs, transport of synthesised proteins in vesicles to the Golgi apparatus)
Nuclear envelope - (surrounds the nucleus with a double membrane with multiple pores, pores regulate the passage of macromolecules like proteins and RNA, but permit free passage of water)
Golgi apparatus (membrane-bound sacs, to process and bundle macromolecules like proteins and lipids as they are synthesised within the cell)
Lysosomes (organelles that contain digestive enzymes. They digest excess or worn out organelles, food particles, and engulfed viruses or bacteria)
Plasma membrane (allows movement of ions in and out of the cell, also helps with protection of the cell and permeability
Vacuoles (membrane-bound structures are basically just enclosed compartments that are filled with both inorganic and organic molecules, along with water to support the organelle.)

Question 2

Describe the route taken by a secreted protein, from synthesis to export and compare this to how non-secreted proteins are produced

Answer 2

Proteins destined to be secreted move through the secretory pathway in the following order: rough ER → ER-to-Golgi transport vesicles → Golgi cisternae → secretory or transport vesicles → cell surface (exocytosis)
Small transport vesicles bud off from the ER and fuse to form the cis-Golgi reticulum.

Question 3

Explain the roles of the ‘signal peptide’ and ‘signal recognition particle’ in targeting a protein to its final destination

Answer 3

Signal peptide - Signal peptides function to prompt a cell to translocate the protein, usually to the cellular membrane
Signal recognition particle - s a ribonucleoprotein particle essential for the targeting of signal peptide-bearing proteins to the prokaryotic plasma membrane or the eukaryotic endoplasmic reticulum membrane for secretion or membrane insertion.

Question 4

Describe the process of glycosylation

Answer 4

is the process by which a carbohydrate is covalently attached to a target macromolecule, typically proteins and lipids

Question 5

Explain the principle of phagocytosis and autophagy

Answer 5

Phagocytosis - ingest or engulf other cells or particles

Autophagy - acts as a maintenance apparatus which keeps the cell functioning properly by recycling “waste”