2.4 Proteins

Question 1

What results from amino acids linked by a condensation reaction?

Answer 1

Polypeptides

Question 2

What is a peptide bond?

Answer 2

A bond formed between the carboxyl group of one amino acid and the amino group of another, releasing a molecule of water.

Question 3

How many different amino acids are there in polypeptides synthesized on ribosomes?

Answer 3

20

Question 4

How does the amino acid sequence of polypeptides relate to genes?

Answer 4

The amino acid sequence of polypeptides is coded for by genes.

Question 5

Can a protein consist of more than one polypeptide?

Answer 5

Yes, a protein may consist of a single polypeptide or more than one polypeptide linked together.

Question 6

How does the amino acid sequence determine a protein’s conformation?

Answer 6

The amino acid sequence determines the three-dimensional conformation of a protein through the folding and interaction of its amino acids.

Question 7

What is a proteome?

Answer 7

The unique set of proteins produced by an organism, coded by their genome.

Question 8

Name two main causes of protein denaturation.

Answer 8

Heat and deviation of pH from the optimum.

Question 9

What is the function of rubisco?

Answer 9

An enzyme involved in the fixation of carbon dioxide in chloroplasts.

Question 10

What role does insulin play in the body?

Answer 10

A hormone involved in glucose uptake from the blood.

Question 11

Define immunoglobulins.

Answer 11

Antibodies that fight infections by recognising and binding to specific antigens.

Question 12

What is the structural significance of collagen?

Answer 12

A fibrous protein providing tensile strength in tendons, ligaments, skin, and bones.

Question 13

How is spider silk characterized?

Answer 13

A fibrous protein known for its resistance to breaking and extensibility, used by spiders for their webs.

Question 14

What causes sickle cell anemia at the molecular level?

Answer 14

A single amino acid change in hemoglobin, where glutamic acid is substituted by valine.

Question 15

What is the significance of the proteome in medical research?

Answer 15

Proteome analysis can inform cancer treatment by determining the effectiveness of chemotherapy.

Question 16

Explain how amino acids can be linked together in any sequence giving a huge range of possible polypeptides.

Answer 16

Amino acids can be linked in any sequence during protein synthesis, creating a vast diversity of polypeptides. Since there are 20 different amino acids, the number of possible sequences and thus polypeptides is virtually limitless, enabling the formation of a wide array of proteins with unique structures and functions.

Question 17

Outline that every individual has a unique proteome.

Answer 17

Every individual has a unique proteome, reflecting the distinct set of proteins expressed by their genome. This uniqueness is due to variations in genes between individuals, influencing which proteins are produced and how they’re expressed, contributing to individual physiological differences and responses to the environment.

Question 18

State that living organisms synthesize many different proteins with a wide range of functions.

Answer 18

Living organisms synthesize a vast array of proteins, each serving diverse functions crucial for life. These functions include enzymatic catalysis, structural support, transport, cell signaling, immune responses, and movement, among others. The versatility of proteins underpins the complexity and adaptability of biological systems.

Question 19

Outline the function of rhodopsin.

Answer 19

Rhodopsin is a light-sensitive receptor protein found in the rod cells of the retina. It plays a crucial role in the mechanism of vision by detecting low light levels, enabling night vision. Upon absorbing light, rhodopsin triggers a signal transduction cascade that ultimately results in a visual signal being sent to the brain.