2.4 Proteins

Question 1

What are polypeptides?

Answer 1

Chains of amino acids that are made by linking together aas by condensation reactions. Happens in ribosome. Main component of proteins.

Question 2

What is a lysozyme?

Answer 2

Enzyme composed of only one polypeptide chain found in nasal mucous and tears.

Question 3

What is integrin?

Answer 3

Membrane protein with 2 polypeptides, each of which has a hydrophobic portion embedded in the membrane.

Question 4

What is collagen?

Answer 4

Composed of 3 polypeptides

Question 5

What is hemoglobin?

Answer 5

Transports protein in red blood cells. Composed of 4 polypeptides chains as well as a haeme group

Question 6

What determines the conformation of a protein?

Answer 6

Aa sequence of its polypeptides. 2 mains shapes -> fibrous and globular.

Question 7

What is the primary structure of a polypeptide chain?

Answer 7

The number and sequence of aas. Determined by base sequence in DNA

Question 8

What is the secondary structure of a polypeptide chain?

Answer 8

Regular repeated structures in chain of aas. Ex. Beta-pleated sheets and alpha helices

Question 9

What is the tertiary structure of a polypeptide chain?

Answer 9

3D shape of one polypeptide chain. Stabilized by intermolecular bonds.

Question 10

What is the quaternary structure of a polypeptide chain?

Answer 10

Linking together of 2 or more polypeptides or linking of polypeptide chain w a prosthetic group. (Ex. Hemoglobin)

Question 11

What are some of the functions of proteins?

Answer 11

Catalysis, muscle contractions, cytoskeletons, tensile strengthening, blood clotting, transports of nutrients and gases, cell adhesion, membrane transport, hormones (insulin, FSH), receptors, packing of DNA (histones), immunity

Question 12

What is a proteome?

Answer 12

All of the proteins produced by a cell, a tissue or an organism. Variable because different cells make different proteins, vary over time

Question 13

What is a genome?

Answer 13

All of the genes of a cell, tissue, or an organism. Fixed: all cells have same genes.

Question 14

What is denaturation?

Answer 14

A change in the confirmation of the protein (changing in shape of molecule)

Question 15

What makes proteins denature?

Answer 15

Effect of temperature (heat breaks bonds required for enzyme to maintain its structure), and effect of pH (enzyme activity is reduced if pH deviates from optimum)

Question 16

How does substrate concentration affect the activity of enzymes?

Answer 16

At low substrate concentrations, random collisions between substrate and active site are rare. At higher concentrations enzyme activity peaks. When concentration is too high activity plateaus -> active sites are all occupied so increasing conc has little effect on activity.

Question 17

How are amino acids linked?

Answer 17

Peptide bonds (carboxyl group of one aa and amino group of another)