Chapter 19

Question 1

Explain Proteins.

Answer 1

Proteins…
- in the body are polymers from 20 different amino acids
- form structural components such as cartilage, muscle, hair, and nails
- transport oxygen into the blood

Question 2

What are Amino Acids?

Answer 2

Amino acids are molecular building blocks of proteins. They have a central atom called the alpha carbon.

Question 3

What is the alpha carbon bonded to within amino acids?

Answer 3

The alpha carbon is bonded to…
- two functional groups: an ammonium group and a carboxylate group
- a hydrogen atom and a R group or side chain in addition to the carboxylate and ammonium group.

Question 4

What are the classifications of Amino Acids?

Answer 4

Hydrophobic (water fearing)
- nonpolar neutral

Hydrophilic (water loving)
- polar neutral

Question 5

T/F Our bodies can only metabolize the “L” form of amino acids.

Answer 5

True

Question 6

How do you identify a Nonpolar Amino Acid?

Answer 6

An amino acid is nonpolar when the R group is H, alkyl, or aromatic.

Question 7

How do you identify a Polar Amino Acid?

Answer 7

An amino acid is polar when the R group is an alcohol, thiol, or amide.

Question 8

How do you identify a Polar Acidic Amino Acid?

Answer 8

An amino acid is polar acidic when the R group is a carboxylate group (when its negative).

Question 9

How do you identify a Polar Basic Amino Acid?

Answer 9

An amino acid is polar basic when the R group is a ammonium group (when its postive).

Question 10

Classify this Amino Acid.

Answer 10

Nonpolar

Question 11

Classify this Amino Acid.

Answer 11

Nonpolar

Question 12

Classify this Amino Acid.

Answer 12

Nonpolar

Question 13

Classify this Amino Acid.

Answer 13

Nonpolar

Question 14

Classify this Amino Acid.

Answer 14

Nonpolar

Question 15

Classify this Amino Acid.

Answer 15

Nonpolar

Question 16

Classify this Amino Acid.

Answer 16

Nonpolar

Question 17

Classify this Amino Acid.

Answer 17

Nonpolar

Question 18

Classify this Amino Acid.

Answer 18

Nonpolar

Question 19

Classify this Amino Acid.

Answer 19

Polar

Question 20

Classify this Amino Acid.

Answer 20

Polar

Question 21

Classify this Amino Acid.

Answer 21

Polar

Question 22

Classify this Amino Acid.

Answer 22

Polar

Question 23

Classify this Amino Acid.

Answer 23

Polar

Question 24

Classify this Amino Acid.

Answer 24

Polar

Question 25

Classify this Amino Acid.

Answer 25

Polar Acidic

Question 26

Classify this Amino Acid.

Answer 26

Polar Acidic

Question 27

Classify this Amino Acid.

Answer 27

Polar Basic

Question 28

Classify this Amino Acid.

Answer 28

Polar Basic

Question 29

Classify this Amino Acid.

Answer 29

Polar Basic

Question 30

What are Peptides?

Answer 30

Shorter chains of amino acids are called peptides - Longer chains are called polypeptides - The N terminal amino acid is written on the left and the C terminal is written on the right.

Question 31

What is a Peptide Bond?

Answer 31

Peptide bonds are amide bonds between the alpha carbon group of one amino acid and the carboxylic acid group of another amino acid.

Question 32

Explain how to draw Peptides.

Answer 32

1. Draw the structure for each amino acid peptide 2. Remove the O- atom from the carboxylate group 3. Remove two H+ atoms from the ammonium group 4. Use peptide bonds to connect the amino acids

Question 33

Explain Primary Structure of Proteins.

Answer 33

- a sequence of amino acids in a protein - slight changes in the sequence can greatly affect protein function - sickle cell anemia is caused by substitution of a single amino acid.

Question 34

Explain Insulin.

Answer 34

Insulin was the first protein to have its primary structure determined. It has a primary structure of two polypeptide chains linked by disulfide bonds.

Question 35

Explain Secondary Structure of Proteins.

Answer 35

- These structures are maintained by numerous hydrogen bonds between the C=O and NH groups of the peptide bonds. - Two common types include alpha helices and beta pleated sheets. - The formation of many hydrogen bonds along the polypeptide chain gives the helical shape.

Question 36

Explain a Triple Helix.

Answer 36

- Three polypeptide chains woven together - Hydrogen bonds hold the chains together giving the polypeptide the added strength collagen, connective tissue, and tendons.

Question 37

Explain Tertiary Structure of Proteins.

Answer 37

Its a three dimensional shape formed by the interactions of amino acids readiness in different parts of the chain. There are 5 stabilizing interactions: 1. Hydrophobic Interactions 2. Hydrophilic Interactions 3. Salt Bridges 4. Hydrogen Bonds 5. Disulfide Bonds

Question 38

Explain Hydrophobic Interactions.

Answer 38

Occur between two amino acids that have nonpolar R groups, forming a nonpolar center at the interior of the protein.

Question 39

Explain Hydrophilic Interactions.

Answer 39

Occur between the external aqueous environment and the R groups of the polar amino acid residues that are pulled to the outer surface of most proteins.

Question 40

Explain Salt Bridges.

Answer 40

Are ionic attractions between ionized R groups of polar basic and polar acidic amino acids.

Question 41

Explain Hydrogen Bonds.

Answer 41

Form between the H of a polar R group and the O and N of another polar amino acid.

Question 42

Explain Disulfide Bonds.

Answer 42

Are covalent bonds that form between SH groups of cysteine residues in a polypeptide chain.

Question 43

Explain Quaternary Structure of Proteins.

Answer 43

- Biologically active proteins with two or more polypeptide chains or subunits. - Hemoglobin (a globular protein that transports oxygen in blood) consist of four polypeptide chains: two alpha and two beta chains.

Question 44

What is Denaturation of a Protein?

Answer 44

Denaturation of a protein occurs when the interaction that stabilizes secondary, tertiary, or quaternary structures are disrupted. - it destroy the shape and renders the protein biological inactive - it does not alter the primary structure of the protein

Question 45

How does Denaturation of a Protein occur?

Answer 45

- Increasing temperature - Making the pH very acidic or basic - Adding a certain organic compound - Adding a heavy metal ion - Adding mechanical agitation