Chapter 5 Questions

Question 1

What are the four major classes of bio-molecules?

Answer 1

Carbohydrates, Lipids, Proteins, and Nucleic Acids

Question 2

Explain how organic polymers contribute to biological diversity.

Answer 2

Each class of polymers is made up of a specific set of monomers. Although organisms share the same limited number of monomer types, the number of arrangements is immense. A great variety of different polymers can be made from a small set of monomers.

Question 3

Explain how covalent linkages are formed and broken in organic molecules.

Answer 3

When a bond forms between two monomers, each monomer contributes part of the water molecule that is lost. One monomer provides the hydroxyl group(-OH) and the other provides the Hydrogen(-H). This process is repeated as more monomers are added. Covalent linkages are broken through hydrolysis, where a hydroxyl group bonds to one monomer, and the hydrogen bonds to the adjacent monomer.

Question 4

Describe the distinguishing characteristics of carbohydrates, and explain how they are classified.

Answer 4

Carbohydrates consist of a carbonyl group, multiple hydroxyl groups, and 3 to 7 carbon atoms. They are classified by the sugars, whether they are mono/Di/poly-saccharides and this is based on where the carbonyl group is and how many carbons there are.

Question 5

Describe the important biological functions of polysaccharides.

Answer 5

Polysaccharides are macro-molecules. They consist of a few hundred to a few thousand monosaccharides joined by glycosidic linkages. Some of the functions of a polysaccharide are structure and storage. Structural polysaccharides are used to build strong building material. An example of a structural polysaccharide is cellulose which is a major component of the cell wall of a plant. Storage polysaccharides are used to store starch in plants and glycogen in humans. Both starch and glycogen are branched, so as to allow for quick release.

Question 6

Distinguish between the glycosidic linkages found in starch and cellulose, and explain why the difference is biologically important.

Answer 6

Starch has a 1-4 linkage of A glucose monomers. All the -OH groups are found in a line, next to each other.
Cellulose has a 1-4 linkage of B glucose monomers. The angles of the bonds that link the rings make every other glucose monomer upside down in respect to its neighbors. The
-OH groups are not next to each other, but alternate from top to bottom.
*This is biologically important, because animals have the enzyme to digest only the alpha linkage, but not the beta linkage. Animals such as cows can digest beta linkages because they have bacteria in their stomach(I don’t know which one…) that aid in digesting it.

Question 7

Explain what distinguishes lipids from other major classes of macro-molecules.

Answer 7

The number one thing that makes lipids different than other macro-molecules is that lipids do not consist of monomers, so they are not polymers. Another thing that makes lipids different is that they are hydrophobic, they do not like water. If you look at oil in water, they separate. Lipids tend to be mostly hydrocarbons.

Question 8

Describe the unique properties, building block molecules, and biological importance of the three important groups of lipids: fats, phospholipids, and steroids.

Answer 8

Fats: A fatty acid consists of a long HYDROCARBON chain with a carboxyl group at one end. The non-polar hydrocarbons make a fat hydrophobic. (Saturated vs. Unsaturated)
Phospholipids: Consist of a glycerol linked to two fatty acids and a negatively charged phosphate group, to which other small molecules are attached. Head is hydrophilic and tail (two fatty acid chains) is hydrophobic.
Phospholipid bi-layer.
Steroids: Class of lipids distinguished by four connected carbon rings with various functional groups attached. Cholesterol used to maintain fluidity in skin cells.

Question 9

Identify an ester linkage and describe how it is formed.

Answer 9

In making a fat, three fatty acid molecules each join to a glycerol by an ester linkage, a bond between a hydroxyl group and a carboxyl group. An ester linkage is formed when one water molecule is removed for each fatty acid to be joined to the glycerol.

Question 10

Distinguish between a saturated and unsaturated fat, and list some emergent properties that are a consequence of these structural differences.

Answer 10

Saturated:
-No double bonds, because as many hydrogens as there can be are bonded to the carbon skeleton.
-Emergent prop=solid at room t.
Unsaturated:
-Double bond between 2 carbons, due to lack of hydrogens
-Emergent=liquid at room t.

Question 11

Describe the characteristics that distinguish proteins from the other major classes of macro-molecules, and explain the biologically important functions of this group.

Answer 11

A protein is made up of many amino acids, and thus is made up of all the components of an amino acid, including a carbon in the middle, bonded to a carboxyl group, and amino group, and a hydrogen. Look at the vocab for protein to see all the different types of proteins and their functions.

Question 12

List and recognize four major components of an amino acid, and explain how amino acids may be grouped according to the physical and chemical properties of the side chains.

Answer 12

amino group, carboxyl group, a hydrogen atom, and variable group (R)

grouped according to side chains
1 group can be hydrophobic
1 group can have sides that are hydrophilic
with a carboxyl group, could have a negative charge
but would normally have a positive charge

acidic and basic only refer to groups on side chains

because they are charged, acidic and basic side chains are also hydrophilic

Question 13

Identify a peptide bond and explain how it is formed.

Answer 13

To make a peptide bond, the amino group of one amino acid is joined with the carboxylic acid of another.

Question 14

Explain what determines protein conformation and why it is important.

Answer 14

Protein conformation is determined by the set of amino acids assigned to it, this is important because it specializes the protein to become either a transport protein, enzyme,etc.

Question 15

Define primary structure and how it may be deduced in the laboratory.

Answer 15

The primary structure is the formation of the amino acid sequence within a protein. It can be deduced in a laboratory by hydrolyzing the protein into small peptide chains, determining their amino acid sequences, and then overlapping the sequences of small fragments created with different agents to reconstruct the whole polypeptide

Question 16

Describe the two types of secondary protein structure, and explain the role of hydrogen bonds in maintaining its structure.

Answer 16

The two types of secondary protein structures are an Alpha Helix and a Beta Sheet. The Alpha Helix has a coiled shape and the Beta sheet has a zig-zag pattern. The hydrogen bonds hold the structures together and keep them from denaturing.

Question 17

Explain how weak interactions and disulfide bridges contribute to tertiary protein structure.

Answer 17

Hydrogen bonding aids the formation of the secondary structures. Once these structures are formed, the R groups now can interact with other R groups. In the tertiary structure, the weak interactions aid in the 3D structure of the protein. Di-sulfide bonds form in the tertiary structure which add extra stability to the overall 3D shape of the protein.

Question 18

Using collagen and hemoglobin as examples, describe Quaternary protein structure.

Answer 18

Collagen is a fibrous protein that has helical sub-units intertwined into a larger triple helix, giving the long fibers great strength. Hemoglobin is a globular protein with Quaternary structure. It consists of four polypeptide sub-units(2 a chains and 2 B chains). Both a and B sub-units consist of a helical secondary structure. Each sub-unit has a nonpolypedtide component, called heme, with an iron atom that binds oxygen.

Question 19

Describe the characteristics that distinguish nucleic acids from the other major groups of macro-molecules.

Answer 19

Nucleic Acids consist of a phosphate group, a pentose sugar, and a nitrogenous base.
P - {} - N - - - N - {} - P

Question 20

Summarize the functions of nucleic acids.

Answer 20

1. Storage of genetic inheritance (DNA).

2. Controlling other functions of the body and cells by translating into proteins (RNA).

Question 21

List the major components of a nucleotide, and describe how these monomers are linked together to form a nucleic acid.`

Answer 21

As these nucleic acids are joined together (thus making a polymer, either DNA or RNA) via phosphodiester linkages, the phosphate and sugar components will be have interacting forces between them (to bind them), forming a sugar-phosphate backbone. This polymer will have two distinct ends, with the top part (consisting of a phosphate group) serving as the 5’ end and the bottom end (with hydroxyl group, OH, from the pentose sugar) serving as the 3’ end.

Question 22

List the functions of nucleotides.

Answer 22

1. Components of nucleic acids (DNA, RNA)

2. Carriers of chemical energy in the cell (ATP)

Question 23

Briefly describe the three-dimensional structure of DNA.

Answer 23

DNA is double helical in structure. each spiral strand, composed of a sugar phosphate backbone and attached bases, is connected to a complementary strand by hydrogen bonding (non- covalent) between paired bases, adenine (A) with thymine (T) and guanine (G) with cytosine (C). As well as Uracil with Adenine.

Question 24

Protein Diagram

Answer 24

H           R          O
     \         |         /
       N -   C   - C
     /         |       \
H            H     OH