The Complex Proteome

Question 1

What is the proteome?

Answer 1

The full number of proteins expressed by our DNA

Question 2

How many protein encoding genes do we have? How does protein regulation affect this number?

Answer 2

20000-25000

Protein regulaiton can contribute to over 1 million proteins due to post translational modifications

Question 3

mRNA is transcribed in the ____, prepared and exported to the _____, and translated by ____ or ______ _________ into _____________

Answer 3

Nucleus, cytosol, free or ER bound, polypeptides

Question 4

What are the 4 steps of a cell detecting a signal in order?

Answer 4

Stimulus, Sensor, Effector, Response

Question 5

What is the stimulus after consuming glucose?

Answer 5

An increase in blood sugar levels

Question 6

What is the sensor when glucose is consumed?

Answer 6

Regulation from Beta islet cells in the pancreas

Question 7

What is the effector after glucose is consumed?

Answer 7

Insulin secreted by pancreas cells decreases blood glucose

Question 8

How does insulin result in a decrease in blood glucose

Answer 8

Body cells take up glucose, liver and muscle cells store glucose as glycogen

Question 9

What is the response when glucose is consumed?

Answer 9

Glucose absorption decreases blood glucose

Question 10

Where does most glucose absorption happen?

Answer 10

Some in the mouth, most due to microvilli in the small intestines

Question 11

Glucose metabolism leads to an ____ in ______ gene transcription and translation

Answer 11

Increase, insulin

Question 12

Where is insulin produced in the cell?

Answer 12

The rough endoplasmic reticulum (because it is secreted)

Question 13

What 2 amino acid chains make up insulin?

Answer 13

An alpha chain and a beta chain

Question 14

What does the insulin gene code for?

Answer 14

A 110 amino acid precursor of the mature insulin protein called preproinsulin

Question 15

What is the function of the n-terminal sequence of preproinsulin?

Answer 15

Interacts with SRPs for transfer into the ER lumen

Question 16

The cleavage of the _____ __________ of preproinsulin yields ___________

Answer 16

signal sequence, proinsulin

Question 17

How is proinsulin modified by post-translation modification?

Answer 17

-Folding in the ER using chaperones
-Cleavage in the GA forming the mature insulin dimer (A and B chains) and releasing a C chain
-Formation of 3 disulfide bonds

Question 18

What is phosphorylation?

Answer 18

Reversible modification involving covalent attachment of phosphate to serine, threonine, or tyrosine by kinase enzymes

Question 19

Where does insulin go when released?

Answer 19

Bind to receptors called kinases on target tissues, allowing glucose to be taken into the cytosol

Question 20

What are receptors?

Answer 20

Receptors recieve and interpret information from signalling molecules

Question 21

Receptor kinases exist in ______ forms and when insulin binds, they ________

Answer 21

mononeric, dimerize

Question 22

What happens when receptor kinases dimerize?

Answer 22

-phosphorylation of specific amino acids, and the
-binding and activation of cytoplasmic proteins
-Activation of glucose transporter proteins at the cell membrane

Question 23

_______ cells absorb glucose more efficiently than ____ cells

Answer 23

skeletal muscle, liver

Question 24

What is alternative splicing of pre-mRNA?

Answer 24

Allows pre-mRNA to be spliced at different junctions to create many different mRNA molecules with different exon combinations

Question 25

What is different about insulin receptors in skeletal muscle cells?

Answer 25

Exon 2 is removed during processing, translating a higher affinity version so the cells can have greater glucose uptake