Proteins

Question 1

What is the structure of an amino acid?
(Search up to check its correct)

Answer 1

H R O
\ | /
N—-C—-C
/ | \
H H OH

Question 2

What are the three main parts of an amino acid?

Answer 2

Amine group, carboxyl group, R (residual) group

Question 3

What are the elements present in proteins?

Answer 3

Carbon, hydrogen, nitrogen, oxygen and sulfur

Question 4

Define monomer

Answer 4

A monomer is a small molecule that can be joined together to make larger molecules called polymers.

Question 5

Define polymers

Answer 5

Polymers are molecules made from a large number of monomers joined together (many parts)

Question 6

What is a condensation reaction?

Answer 6

A condensation reaction is a chemical reaction in which two molecules join together forming a larger molecule and release a smaller molecule (often water) in the process.

Question 7

What is a polypeptide?

Answer 7

Polypeptide is a chain of a large number of amino acids, bonded together by peptide bonds

Question 8

What is a peptide bond? (search up what it looks like) (and dont forget the charges)

Answer 8

When two amino acids react together and form a chemical bond

Question 9

What is the primary structure of a protein? What does it give the protein?

Answer 9

• primary structure is simply the specific order of amino acids in a polypeptide
• it is important as it helps to determine the three dimensional shape (shape is really important for a proteins function)
• primary structures is determined by the DNA sequence of the gene which encodes that polypeptide

Question 10

What is the secondary structure of a protein?

Answer 10

(- secondary structure is the formation of hydrogen bonds between positively and negatively charged atoms which cause the polypeptide chain to twist and fold into shape) (they can fold into an alpha helix or a beta pleated sheet)
- C == O (in amino acids) = small negative charge
- N –H (in amino acids) = small positive charge
- these positive and negative charges can attract each other
-when this happens hydrogen bonds form between the amino acids all along polypeptide chain
- these hydrogen bonds cause chain to twist and fold into shape

Question 11

What are the two main types of secondary structure? What holds these shapes in place

Answer 11

• alpha-helix
• Beta pleated sheets
• Hydrogen bonds is what holds the shapes in place

Question 12

What is the tertiary structure of a protein?

Answer 12

• tertiary structure is the overall 3 dimensional shape of a polypeptide chain
• tertiary structure is critical for how a protein functions (e.g. changing the tertiary structure by heating it causes it to denature)

Question 13

What is the quaternary structure

Answer 13

• quaternary structure only applies to proteins with at least two subunits
• this is a large molecule (e.g. haemoglobin)
• these proteins may contain prosthetic groups

Question 14

What is the name of the polypeptide chains in a large molecule?

Answer 14

• the polypeptides in a large molecule are called ‘subunits’
• quaternary structure shows how the individual subunits are arranged to form a larger three dimensional structure

Question 15

What is a conjugated protein?

Answer 15

• proteins that contain other non-protein molecules
• these are called prosthetic groups
• proteins with prosthetic groups are called conjugated proteins

Question 16

What is the functional difference between globular and fibrous proteins?

Answer 16

• globular proteins are involved in metabolic and functional processes whereas fibrous are involved in structural and supportive processes
• globular proteins are more sensitive to factors such as temperature and pH whereas fibrous are more stable and resistant

Question 17

Compare and contrast the molecular structures of globular and fibrous proteins?

Answer 17

• globular proteins have a spherical, compact shape whereas fibrous proteins have a long, thin shape
• globular proteins are soluble which means they are hydrophilic whereas fibrous proteins are insoluble which means they are hydrophobic
• both are chains of amino acids joined by peptide bonds
• both contain hydrogen bonds which hold the molecules three dimensional shape together

Question 18

Why are fibrous proteins insoluble? (links to the structure of fibrous protein)

Answer 18

• fibrous proteins are insoluble because the hydrophobic parts of the polypeptide chains are exposed to the external environment

Question 19

Why is water said to be dipolar? What does the dipole nature of water create?

Answer 19

• water is said to be dipolar because it has a positive and negative pole (as a result of the uneven distribution of electrons within it)
• the dipole nature within a water molecule creates attractive forces known as hydrogen bonding, allowing them to stick together