Proteins

Question 1

What are proteins composed of?

Answer 1

Proteins are comprised of long chains of recurring monomers called amino acids

Question 2

What is the structure of a generalised amino acid? (5 components) Draw the structure

Answer 2

Amino acids all share a common basic structure, with a central carbon atom bound to:

An amine group (NH2)
A carboxylic acid group (COOH)
A hydrogen atom (H)
A variable side chain (R)

Question 3

How many different amino acids are there?

Answer 3

There are 20 different amino acids which are universal to all living organisms

Question 4

How are proteins created?

Answer 4

Amino acids are joined together on the ribosome to form long chains called polypeptides, which make up proteins

Question 5

How do amino acids differ?

Answer 5

Each type of amino acid differs in the composition of the variable side chain

Question 6

Why do the side chains affect the type of protein?

Answer 6

These side chains will have distinct chemical properties (e.g. charged, non-polar, etc.) and hence cause the protein to fold and function differently according to its specific position within the polypeptide chain

Question 7

How can amino acids be joined together to form a protein?

Answer 7

Amino acids can be covalently joined together in a condensation reaction to form a dipeptide bond

Question 8

What is the covalent bond between amino acids is called?

Answer 8

The covalent bond between the amino acids is called a peptide bond

Question 9

What are long chains of amino acids called?

Answer 9

long chains of covalently bonded amino acids are called polypeptides

Question 10

How can polypeptide chains be broken down?

Answer 10

Polypeptide chains can be broken down via hydrolysis reactions, which requires water to reverse the process

Question 11

What is the primary structure?

Answer 11

The order of the amino acid sequence is called the primary structure and determines the way the chain will fold

Question 12

Do all amino acids fold the same? Why?

Answer 12

NO
Different amino acid sequences will fold into different configurations due to the chemical properties of the variable side chains

Question 13

What two types of secondary structures are there?

Answer 13

Alpha helices

Beta-pleated sheets

Question 14

When do amino acids fold in alpha-helices?

Answer 14

Alpha helices occur when the amino acid sequence folds into a coil/spiral arrangement

Question 15

When do amino acids fold into beta-pleated sheets?

Answer 15

Beta-pleated sheets occur when the amino acid sequence adopts a directionally-oriented staggered strand conformation

Question 16

What is tertiary structure?

Answer 16

The overall three-dimensional configuration of the protein casued by the R-groups ineracting to form new bonds

Question 17

What determines the tertiary structure of a protein?

Answer 17

The tertiary structure of a polypeptide chain will be determined by the interactions between the variable side chains

Question 18

What are examples of interactions of side chains which result in a tertiary structure?

Answer 18

These interactions may include hydrogen bonds, disulphide bridges, ionic interactions, polar associations, etc.

Question 19

What is Quaternary structure?

Answer 19

Arrangement and interaction of two or more polypeptide chains to form a functional protein. Each subunit is a fully folded polypeptide (from the tertiary structure).

Question 20

What is conjugated or nonconjugated?

Answer 20

Conjugated proteins have a prosthetic group (e.g., hemoglobin with heme). Non-conjugated proteins are made only of amino acids (e.g., albumin).

Question 21

Insulin

Answer 21

Type of Protein: Globular protein
Structure: Quaternary structure (two polypeptide chains held together by disulfide bonds).
Function: Regulates blood sugar levels by signaling cells to absorb glucose.

Question 22

Collagen

Answer 22

Type of Protein: Fibrous protein
Structure: Tertiary structure for individual chains, and quaternary structure for the triple helix.
Function: Provides structural support to tissues like skin, tendons, and bone

Question 23

Glycoprotein A and B solubility

Answer 23

Glycoproteins called A and B are embedded in the phospholipid bilayer where the non-polar(hydrophobic) amino acid are folded so it can interact with the hydrophobic layer of the membrane to remain embedded.

Question 24

Denaturation

Answer 24

The process where a protein loses its shape and, therefore, its function.
Cause: Heat, pH changes, or chemicals can disrupt bonds (e.g., hydrogen bonds, disulfide bridges).