Protein Structure and Function

Question 1

What is the genome?

Answer 1

It is like the blueprint for life, all necessary info to make an animal is present in it’s genome.
The genome has 3% genes and is separated by regulatory molecules.

Question 2

What is the transcriptome?

Answer 2

The transcriptome is the complement of genes that are transcribed.
All an organism’s cells will have the same genome but a different transcriptome.

Question 3

What is the proteome?

Answer 3

The proteome is the complement of proteins in the cell.

Question 4

What are the 4 levels of protein structure?

Answer 4

• Primary
• Secondary
• Tertiary
• Quaternary

Question 5

What is the primary structure of proteins?

Answer 5

The amino acid sequence

Question 6

What is the secondary structure of proteins?

Answer 6

The amino acids then fold into secondary structures such as a-helices and B-sheets.

Question 7

What is the tertiary structure of proteins?

Answer 7

The proper folding of the protein into its final shape.

Question 8

What is the quaternary structure of proteins?

Answer 8

Is the coming together of sub-units to form the overall functional protein.

Question 9

How and why do proteins fold?

Answer 9

They fold due to:
-hydrphobicity/hydrofillicity
-disulfide bonds (covalent bonds that hold structures together
Folding is essential for protein function.

Question 10

What is the importance of amino acid R groups fro function?

Answer 10

Amino acids can be polar, non polar, positively or negatively charged.
These features are important as they play a major role in protein folding and 3D structure which impacts function.

Question 11

What are examples of post translational modifications impacting function?

Answer 11

• Glycosylation (addition of sugar chains)

- Phosphorylation (addition of phosphate group)

Question 12

How does glycosylation impact protein function?

Answer 12

• Help it to interact with partner proteins, they are also very large so help protect the protein as enzymes cant reach it.
• Increases half life
• Important for orientation

Question 13

How does phosphorylation impact protein function?

Answer 13

• Receptor signalling is dependant on this
• Helps in intracellular communication
• Important for control of enzyme function, some enzymes dont activte until phosphorylated.

Question 14

What are the phases of assembling a protein?

Answer 14

The genome is transcribed to mRNA then translated to protein (large parts are not translated)

Question 15

What phases can translation be split into?

Answer 15

• Initiation
• Elongation
• Termination

Question 16

What happens in initiation?

Answer 16

-Initiation- tRNA carrying amino acid methionine binds to start codon of mRNA sequence.
Large ribosomal subunit binds to form complete initiation complex

Question 17

What happens in elongation?

Answer 17

Ribosome continues to translate each codon in turn, this continues until all codons are read.

Question 18

What happens in termination?

Answer 18

Ribosome reads stop codon, protein is released and translation complex comes apart.

Question 19

How are proteins localised?

Answer 19

Proteins carry signal peptides that are recognised by signal receptors that guide them to their target site.

Question 20

What are some mutations that alter protein function?

Answer 20

• Sickle cell disease

- Cancer

Question 21

How is sickle cell disease called?

Answer 21

It is caused by a mutation in B-globin gene (one base in 1 codon), this changes an amino acid and totally changes the structure and function of cells produced.

Question 22

What happens in sickle cell disease?

Answer 22

Red blood cells become sickle shaped, causing blockages and damaging vital organs and tissue, the sickle cells are destroyed rapidly, causing anemia.

Question 23

How are some cancers caused by mutation?

Answer 23

Ras (a signalling molecule) is mutated, usually a mutation in codon 12, 13, 59, 61 as they are key regulatory parts of the protein.
In cancer Ras becomes hyperactive.

Question 24

Why is knowledge of protein structure important?

Answer 24

Helps rational drug design

Question 25

Why do all protein structural alterations from mutation not cause damage?

Answer 25

The mutation needs to be very specific to cause damage.

Question 26

How can you get more than 1 protein per gene?

Answer 26

Proteins are decorated with molecular suffixes and prefixes

Question 27

What is the start codon called?

Answer 27

Methionine