1.2 Protein Sythesis/ Secretory Pathway

Question 1

How a membrane is made
In step 1 What does that smooth ER synthesize

Answer 1

Lipids, and inserts them into its membrane

Question 2

How a membrane is made
In step 2 where do all proteins begin synthesis

Answer 2

In the ribosomes, in the cytosol

Question 3

How a membrane is made
In step 2 what types of proteins are completed in the cytosol

Answer 3

Cytosolic proteins

Question 4

How a membrane is made
In step 3 what carries a signal sequence
And what does the signal sequence do

Answer 4

A transmembrane protein carries a signal sequence to stop translation

Question 5

How a membrane is made
In step 4 where are unfinished proteins moved to

Answer 5

The ER in the ribosome

Question 6

How a membrane is made
What is the final step

Answer 6

The ribosome docks with the ER to form the rough ER

Question 7

Explain fully how a membrane is made

Answer 7

1. The smooth ER synthesizes lipids and inserts them into its membrane
2. All proteins begin synthesis in the ribosomes in the cytosol
   Cytosolic proteins are completed in the cytosol
3. Transmembrane proteins carry a signal sequence (amino acid) to stop translation
4. The unfinished protein is moved to the ER in the ribsome
5. The ribsome docks with the ER to form the rough ER

Question 8

Moving proteins between membranes
Step 1 Once proteins are in the ER what transports them to where

Answer 8

They are transported in vesicles which bud off of the ER and fuse with the Golgi apparatus

Question 9

Moving proteins between membranes
Step 2 Describe how molecules move through the Golgi apparatus

Answer 9

In vesicles that bud off of one disc and fuse to the next in the stack

Question 10

Moving proteins between membranes
Step 3 What occurs in the Golgi apparatus

Answer 10

Post translational modification

Question 11

Moving proteins between membranes
Step 3 What may be added to the proteins in post translational modification

Answer 11

Carbohydrates

Question 12

Moving proteins between membranes
Step 4 once proteins are complete where are they taken by vesicles

Answer 12

To the plasma membrane and the lysosomes

Question 13

Moving proteins between membranes
How do vesicles move

Answer 13

Along Microtubules to other membranes and fuse with them within the cell

Question 14

Explain fully the process of moving proteins between membranes

Answer 14

Once the proteins are in the ER they are transported by vesicles that bud off of the ER and fuse with the Golgi apparatus
Molecules move through the Golgi in vesicles that bud off of one disc and fuse to the next one in the stack
Proteins undergo post translational modification here
Carbohydrates may be added to
the protein
Once proteins are complete, vesicles take them to the plasma membrane and lysosomes
Vesicles move along microtubules to other membranes and fuse with them within the cell

Question 15

The secretory pathway
What are many secreted proteins synthesized as

Answer 15

Inactive precursors

Question 16

The secretory pathway
What do inactive precursors require to produce active proteins

Answer 16

Proteolytic cleavage

Question 17

The secretory pathway
Give two examples of secreted proteins

Answer 17

Peptide hormones and digestive enzymes

Question 18

The secretory pathway
Vesicles containing secreted proteins fuse with the cell membrane for ….. to occur

Answer 18

Exocytosis

Question 19

Explain fully the secretory pathway element

Answer 19

Many secreted proteins are synthesized as inactive precursors so require proteolytic cleavage in order to produce active proteins
Peptide grooms and digestive enzymes are examples of secreted proteins
Vesicles containing secreted proteins fuse with the cell membrane before exocytosis occurs

Question 20

Explain this entire pathway

Answer 20

How a membrane is made
1. The smooth ER synthesizes the lipids and inserts them into its membrane
2. All proteins begin synthesis in the ribosomes in the cytosol
Cytolosolic proteins are completed in the cytosol
3. Transmembrane proteins carry a signal sequence (amino acid) to stop translation
4. The unfinished protein is moved to the ER in the ribosome
5. The ribsome docks with the ER to form the rough ER

Moving proteins between membranes
1. Once the proteins are in the ER they are transported by vesicles that bud off of the ER and fuse with the Golgi apparatus
2. Molecules move through the Golgi in vesicles that bud off of one disc in the stack and fuse to the next
3. Proteins undergo post translational modification in the Golgi and carbohydrates may be added
4. Once the proteins are complete, vesicles take them to the plasma membrane and the lysosomes
Vesicles move along micro tubules to other membranes and fuse with them within the cell

The Secretory pathway
Many secreted proteins are synthesized as inactive precursors so require proteolytic cleavage in order to produce active proteins.
Two examples of secreted proteins are digestive enzymes and peptide hormones
Vesicles containing secreted proteins fuse with the cell membrane before exocytosis occurs