Biochemistry___Lesson-8___Chapter 3.12 thru 3.14

Question 1

A molecular machine built from a polymer of amino acids.

Answer 1

Protein

Question 2

A molecule that behaves as a biological catalyst in a cellular reaction.

Answer 2

Enzyme

Question 3

A process in which a protein unravels, losing its specific shape, and as a result, its function.

Answer 3

Denaturation

Question 4

The monomers of protein composed of a central carbon bonded to an amino group, a carboxyl group, a hydrogen, and an R group.

Answer 4

Amino acid

Question 5

A covalent bond between two amino acids.

Answer 5

Peptide bond

Question 6

Two bonded amino acids.

Answer 6

Dipeptide

Question 7

A polymer of amino acids.

Answer 7

Polypeptide

Question 8

The sequence of amino acids in a polypeptide.

Answer 8

Primary structure

Question 9

Folded segments of a polypeptide that take the shape of an alpha helix or a beta pleated sheet.

Answer 9

Secondary structure

Question 10

The overall three-dimensional shape of a protein made from the bonding of secondary structures to each other.

Answer 10

Tertiary structure

Question 11

The structure of a protein made from more than one polypeptide.

Answer 11

Quaternary structure

Question 12

Draw from memory the molecular structure of 2 amino acids (label an amino group and carboxyl group) undergoing a dehydration reaction to form a peptide bond.

Answer 12

Question 13

What is the monomer of proteins?

Answer 13

Amino acids

Question 14

Draw the molecular structure of an amino acid that has methyl as the R group. Label the amino group, carboxyl group, and R group. What chemical properties does this amino acid have: hydrophilic, hydrophobic, acidic, basic?

Answer 14

Hydrophobic
Amino group is NH2
Carboxyl group is COOH
Methyl is CH3

Question 15

How can a cell make many different kinds of proteins out of only 20 amino acids?

Answer 15

There is an unlimited combination of amino acids because the number of amino acids in a chain can vary, and the same amino acid can be used many times in a chain.

Question 16

What determines the function of a protein?

Answer 16

The shape of the protein.

Question 17

What can cause protein denaturation

Answer 17

Protein denaturation is when a protein unfolds and stops functioning. This can be caused by changes in temperature, pH, or ion concentration, each of which can interfere with the hydrogen bonds that hold together the secondary structure. When these bonds are destroyed the protein unfolds and stops functioning.

Question 18

What gives an amino acid the chemical properties of hydrophilic, hydrophobic, acidic, or basic?

Answer 18

The chemical nature of the R group. If the R group has an oxygen atom it will be hydrophilic. If the R group is a hydrocarbon, then it will be hydrophobic. Carboxyl groups are acidic and amino groups are basic.

Question 19

What are the 4 levels of protein structure?

Answer 19

1 - primary
2 - secondary
3 - tertiary
4 - quaternary

Question 20

What type of bond holds together the primary structure of a polypeptide?

Answer 20

A peptide bond (a type of covalent bond) between the carboxyl group of the backbone one amino acid and the amino group of the backbone another amino acid.

Question 21

What type of bond holds together the secondary structure of a polypeptide?

Answer 21

Hydrogen bonds between the atoms of the backbone.

Question 22

What are the 2 types of secondary structure?

Answer 22

Alpha helix and Beta pleated sheet.

Question 23

Which levels of protein structure requires R group interactions

Answer 23

3 - tertiary
4 - quaternary

Question 24

A genetic mutation can change the primary structure of a protein. How can this destroy the protein’s function?

Answer 24

R groups determine if the 2 structure will fold into an alpha helix or a beta pleated sheet, although they do not participate in the hydrogen bonds that make 2 structure.

R groups form bonds between each other to create 3 and 4 structure.

If an R group is changed by genetic mutation, and if this results in a change of 2 or 3 or 4 structure, and if that results in a change in the shape of the protein, then the protein will not work.

Question 25

What is one role that a protein could have in a cell?

Answer 25

enzyme

Question 26

What do enzymes do?

Answer 26

Act as catalyst to speed up chemical reaction

Question 27

Is a denatured protein active or inactive?

Answer 27

inactive

Question 28

Cells have homeostasis, which means that conditions in the cell are held within a small range. What condition would cause an enzyme to denature if that condition is outside the normal range?

Answer 28

• salt concentration
• pH
• temperature

Question 29

What atom, that is part of an R group, is typically responsible for making an amino acid hydrophilic?

Answer 29

oxygen

Question 30

What are the 4 different types of R group interactions?

Answer 30

• hydrophobic interactions
• ionic bonds
• hydrogen bonds
• disulfide bridge (covalent bond)