3.6 Structure of Proteins

Question 1

What structure results in different amino acids

Answer 1

R-groups

Question 2

How many different amino acids are commonly found in cells

Answer 2

20

Question 3

How and when do amino acids join

Answer 3

When the hydrogen in the amine group of one AA and hydroxyl in the carboxylic acid group of another AA react

Question 4

What is formed/produced when 2 AAs react (2)

Answer 4

-Peptide bond
-Water

Question 5

What is it called when many AAs are joined together by peptide bonds

Answer 5

Polypeptide

Question 6

Explain R-group interactions

Answer 6

When the diff R-group making up a protein interact forming different bonds

Question 7

What enzyme catalyses the formation of polypeptides and where does this happen?

Answer 7

-Peptidyl transferase
-Ribosomes

Question 8

Explain the primary structure

Answer 8

• the sequence in which amino acids are joined
• determines all other structural levels of the protein
• peptide bonds involved

Question 9

Explain secondary structure

Answer 9

• Hydrogen bonds form within amino acid chain
• pulled into coil shape called alpha helix
• lie parallel to form beta pleated sheets

Question 10

Explain tertiary structure

Answer 10

• folding of protein into overall 3D shape
• folding brings R-groups closer together so they react ->
  hydrophobic + hydrophilic reactions (weak interaction between polar/nonpolar R-groups
  hydrogen bonds
  ionic bonds
  disulfide bridges (interaction between R-Groups that contain sulfur)

Question 11

Explain Quaternary structure

Answer 11

• results from association of twomor more individual proteins
• same as tertiary structure except between diff protein molecules rather than within 1 molecule

Question 12

What enzymes/molecules are involved in the breakdown of peptides

Answer 12

-Protease enzyme catalyse reaction that turns peptide back into AA
- Water molecule used in hydrolysis reaction to break peptide bond