Unit 1: Proteomics & Protein Structure 1

Question 1

What is a Proteome

Answer 1

A proteome is the entire set of proteins expressed by a genome.

Question 2

What are the two reasons for proteomes being bigger than genomes?

Answer 2

RNA Splicing and Post-Translational Modification

Question 3

What is RNA Splicing?

Answer 3

When introns are spliced (removed) from mRNA, leaving only the exons expressed in the protein molecule.

Question 4

What is an intron?

Answer 4

A non-coding sequence of mRNA

Question 5

What is Post-translational Modification?

Answer 5

Either the addition of a chemical group to a protein or covalent cleavage of the polypeptide.

Question 6

When does post-translational modification take place?

Answer 6

After translation of the protein

Question 7

Where does post-translational modification take place?

Answer 7

In the RER, golgi apparatus and target site of protein

Question 8

List the five chemical groups that can be added to a protein in post translational modification

Answer 8

Addition of; Phosphate, acyl, alkyl, glucose and oxygen

Question 9

Addition of a phosphate to a protein is known as what?

Answer 9

Phosphorylation

Question 10

Addition of an acyl group to a protein is known as what?

Answer 10

Acylation

Question 11

Addition of an alkyl group to a protein is known as what?

Answer 11

Alkylation

Question 12

Addition of a sugar group such as glucose to a protein is known as what?

Answer 12

Glycoylation

Question 13

Addition of oxygen to a protein is known as what?

Answer 13

Oxidation

Question 14

Covalent cleavage of the polypeptide is essentially what?

Answer 14

A part of the peptide being removed from the molecule, resulting in it become active. Trypsinogen to trypsin

Question 15

An example of autocatalytic cleavage is

Answer 15

zymogen pepsinogen to pepsin.

Question 16

What is the purpose of post translation modification?

Answer 16

To modify the protein for it’s specific function

Question 17

What are the three different groups relating to the position of the protein in the cell?

Answer 17

1. Intracellular 2. Membrane bound 3. Extracellular

Question 18

Intracellular proteins such as lysosomes are…

Answer 18

found and formed in the cell

Question 19

A membrane protein called an intrinsic protein…

Answer 19

spans the membrane, acting as a carrier

Question 20

A membrane protein called an extrinsic protein…

Answer 20

is embedded on one side of the membrane like an enzyme

Question 21

An extracellular protein such as insulin is…

Answer 21

excreted outside the hormone.

Question 22

Membranes are made up of

Answer 22

phospholipid molecules

Question 23

Phospholipid molecules in a membrane form a

Answer 23

phospholipid bilayer

Question 24

What term is used to describe the head of this molecule?

Answer 24

Hydrophillic (water loving)

Question 25

What term is used to describe the tail of this molecule?

Answer 25

Hydrophobic - (Water repellant)

Question 26

A peripheral protein is found

Answer 26

on the surface and partially inside the membrane.

Question 27

An integral protein …

Answer 27

spans the whole width of the membrane.

Question 28

What is this type of protein?

Answer 28

A channel protein

Question 29

What type of protein is this?

Answer 29

A glycoprotein

Question 30

What type of protein is this?

Answer 30

An integral protein

Question 31

What type of protein is this?

Answer 31

An peripheral protein

Question 32

Not all genes in a particular cell are expressed as proteins because of

Answer 32

gene expression

Question 33

An example of regulation of gene expression is

Answer 33

Lac Operon

Question 34

The purpose of Lac Operon is to?

Answer 34

Conserve energy in the cell

Question 35

What are the four components of Lac Operon?

Answer 35

Promoter, Repressor, Operator, Gene

Question 36

In Lac Operon, when the lactose concentration increases what happens?

Answer 36

A lactose binds to the repressor changing the confirmation of the repressor so it is no longer bound to the operator.

Question 37

In Lac Operon, once the repressor is no longer bound to the operator what happens?

Answer 37

RNA polymerase comes along now able to make a protein due to the operator being ‘on’.

Question 38

In Lac Operon, RNA polymerase makes a protein that does what?

Answer 38

Breaks down the lactose

Question 39

In Lac Operon, once the lactose is broken down what happens next?

Answer 39

The lactose bound to the repressor unbinds and is broken down. The repressor changes back to the original conformation and binds to the operator turning it off.

Question 40

Extrinsic proteins use what process to release proteins from the cell ?

Answer 40

Exocytosis

Question 41

Four methods of genome anaylsis are:

Answer 41

• Sanger sequencing
• Gel Electrophoresis
• Cycle Sequencing
• Microarray

Question 42

Analysis of proteome involves:

Answer 42

• Isolation of proteins expressed by a cell at a certain time
• The functional interaction between the proteins active in the cell

Question 43

Three techniques used to identify expressed proteins are:

Answer 43

• 2D electrophoresis
• Western Blotting
• Mass Spectrometry

Question 44

2D electrohoresis works by

Answer 44

seperating proteins from cell samples according to their charge

Question 45

Western blotting works by

Answer 45

exposing proteins to specific antibody coupled to a radioisotope which binds to the protein

Question 46

Mass Spectrometry works by

Answer 46

seperating out proteins to identify speicfic fragments.

Question 47

The isoelectric point is the

Answer 47

pH at which the protein has no net charge and doesn’t migrate.

Question 48

Binding of a substrate to an enzymes causes a

Answer 48

conformational change which may result in an altered function.