Unit 1 Proteomics - Protein Structure

Question 1

What is the proteome and why is it larger than the genome of an organism

Answer 1

Proteome is the entire set of proteins expressed by a genome and it is larger due to PTM and alternative splicing

Question 2

What is alternative splicing

Answer 2

When introns are spliced out and removed from mRNA, leaving only the exons to be expressed in the protein molecule

Question 3

What is post translational modification and where can it be carried out

Answer 3

When other chemical constituents are added to the proteins after they have been made in translation
Carried out in : Golgi apparatus , rough ER , final functional site of protein.

Question 4

What are the chemical constituents added to proteins during ptm

Answer 4

Fat
Sugar ( glycoproteins )
Phosphate
Elements ( magnesium and iron )

Question 5

Explain gene expression

Answer 5

Set of proteins produced by a cell varies depending on cell function, shape, type, what tissue it came from and what it received from its environment and development stage.
Cells and tissues respond to changes in their environment and the proteome must mirror this.
Not all genes are expressed as proteins in a cell

Question 6

What are proteins and what is their primary structure

Answer 6

Proteins are polymers of amino acid monomers and their primary structure is the sequence of amino acids which determines the final structure of the protein .

Question 7

How are amino acids bound and how is this achieved

Answer 7

Bound by peptide bonds to form a polypeptide chain. This is achieved by a condensation reaction involving the removal of h2o.

Question 8

What is the basic structure of an amino acid and how can they be differentiated from one another

Answer 8

Basic structure consists of ;
Central carbon atom
Amino group
Carbonyl group

Amino acids differentiated from one another by their variable R group ; basic, polar, acidic and hydrophobic

Question 9

Basic R groups

Answer 9

Positively charged

NH3 or NH2 side groups

Question 10

Acidic R groups

Answer 10

Negatively charged

COO side group

Question 11

Hydrophobic (non polar) R groups

Answer 11

Repelled by water

Contain mostly carbon and hydrogen

Question 12

Polar R groups

Answer 12

Able to form hydrogen bonds

OH or SH side groups

Question 13

What is the secondary structure of a protein

Answer 13

Involves folding due to hydrogen bonding on the backbone of the polypeptide chain resulting in the formation of ; Alpha helices
Beta sheets
Turns

Question 14

What are alpha helices

Answer 14

Spirals with R groups sticking out
Stabilised by hydrogen bonds
➰➰➰➰➰

Question 15

What are beta sheets

Answer 15

Formed when polypeptide chains arrange themselves in ROWS.
Can be parallel 🔀
Anti parallel 🔁
Stabilised by hydrogen bonds

Question 16

What are turns

Answer 16

When polypeptide chain changes overall direction without forming helix or a sheet. ↩️
Stabilised by hydrogen bonds

Question 17

What’s the tertiary structure of a protein ? Give examples

Answer 17

Final 3D structure of protein, involves interactions between the R groups including ; disulphides bridges , van der waals, ionic bonds and hydrophobic interactions.
May also include non protein croup called a prosthetic group for example haemoglobin contains iron rich haem. Chlorophyll and magnesium.

Question 18

What is the quaternary structure of a protein

Answer 18

When two or more polypeptide chains are joined together to form a complex molecule of several domains.