U1-KA2 Proteins

Question 1

Proteome

Answer 1

Entire set of proteins expressed by a genome - larger than a genome

Question 2

Why is the proteome larger than the genome?

Answer 2

Due to alternative RNA splicing

Question 3

Endoplasmic Reticulum

Answer 3

Forms a network of tubules continuous with the nuclear membrane.
Lipids and proteins are synthesised in the ER.

Question 4

Intracellular Membranes

Answer 4

Membranes within the cell are called intracellular membranes.
Eukaryotic organisms have a variety of intracellular membranes- increasing the total area of the membrane.

Question 5

Difference between the Rough ER and Smooth ER

Answer 5

RER - Has ribosomes on its cytosolic face (facing into cell away from the nucleus)
SER - Lacks ribosomes

Question 6

Cytosol

Answer 6

The cytoplasm of a cell has two parts.
The cytosol is the liquid component of the cytoplasm.
The second part is the ribosomes and the membrane bound organelles which are suspended in the cytosol.

Question 7

Golgi Apparatus

Answer 7

Series of flattened membrane discs where proteins undergo post-translational modifications.

Question 8

Vesicles

Answer 8

Vesicles transport materials between membrane compartments

Question 9

Lysosomes

Answer 9

Membrane bound organelles containing a variety of hydrolyses.
Proteins, lipids, nucleic acids and carbohydrates are digested.

Question 10

Integral and Peripheral Proteins

Answer 10

Integral - permanently attached
Peripheral - temporarily attached

Question 11

Lipids

Answer 11

Lipids (oils/phospholipids/steroid hormones) are synthesised in the SER and inserted into its membrane.

Question 12

Synthesis of Proteins Location

Answer 12

Cytosolic Ribosomes

Question 13

Synthesis of Proteins Process

Answer 13

• The synthesis of transmembrane proteins begins in the cytosolic ribosomes
• Transmembrane proteins carry a signal sequence. The signal sequence halts translation and directs the ribosomes synthesising the protein to dock with the ER, forming the RER.
• Translation continues after docking, and the protein is inserted back into the ER membrane.
• The ribosome is released back into the cytosol once translation is completed.
• Once the proteins are in the ER membrane, they are transported by vesicles that bud off the ER and fuse with the Golgi Apparatus.

Question 14

Secretory proteins are translated in …

Answer 14

Ribosomes on the RER and enter it’s lumen

Question 15

The Secretory Pathway

Answer 15

Secreted proteins are translated in ribosomes on the RER and enter its lumen.
The proteins move through the Golgi apparatus and are then packaged into secretory vesicles.
These vesicles move to and fuse with the plasma membrane, releasing the proteins out of the cell.

Question 16

Proteolytic Cleavage

Answer 16

A protein with a carbohydrate added by post-translational modification.

Question 17

Post-Translational Modification

Answer 17

Addition of different chemical groups to, or modification of, a protein to allow a particular function.