Chapter 9_Molecular Structure Of DNA and RNA

Question 1

To fulfill its role, the genetic material must meet four criteria:

Answer 1

• 1. Information: Must contain the information necessary to construct an entire organism.
• 2. Transmission: During reproduction, the genetic material must be passed from parents to offspring.
• 3. Replication: Because the genetic material is passed from parents to offspring, and from mother cell to daughter cells during cell division, it must be copied.
• 4. Variation: Within any species, a significant amount of phenotypic variability occurs.

Question 2

Nucleic Acids

Answer 2

DNA and RNA

Question 3

To fully appreciate the structures of DNA and RNA, we need to consider four levels of complexity.

Answer 3

• 1. Nucleotides form the repeating structural unit of nucleic acids.
• 2. Nucleotides are linked together in a linear manner to form a strand of DNA or RNA.
• 3. Two strands of DNA (and sometimes RNA) interact with each other to form a double helix.
• 4. The three-dimensional structure of DNA results from the folding and bending of the double helix. Within living cells, DNA is associated with a wide variety of proteins that influence its structure.

Question 4

The two types of sugars

Answer 4

Deoxyribose and ribose.

Question 5

The five different bases are subdivided into two categories

Answer 5

• Purines (A, G) Double ring structure

- Pyrimidines (T, C, U) Single ring structure

Question 6

Differences between Deoxyribose and Ribose

Answer 6

• Deoxyribose has H attached to 2’ carbon

- Ribose has OH attached to 2’ carbon

Question 7

Adenine, Guanine, Thymine, Cytosine, Uracil

Answer 7

• Adenine: NH2 attached to 6’ carbon
• Guanine: NH2 attached to 2’ carbon
• Thymine: CH2 attached to 5’ carbon
• Cytosine: NH2 attached to 4’ carbon
• Uracil: H attached to 5’ carbon

Question 8

What are nucleotides made up of?

Answer 8

A phosphate group, a sugar, and a base

Question 9

What are nucleosides made up of?

Answer 9

Base, sugar

Question 10

Phosphodiester Linkage

Answer 10

Linkage involves an ester bond between a phosphate group on one nucleotide and the sugar molecule on the adjacent nucleotide. Basically the phosphate group connects two sugar molecules.

Question 11

Backbone

Answer 11

The phosphate and sugar molecules form the backbone of a DNA or RNA strand. The bases project from the backbone. The backbone is negatively charged due to a negative charge on each phosphate.

Question 12

Chargaff’s Rule

Answer 12

The idea that the amount of A, in DNA equals the amount of T, and the amount of G equals C

Question 13

Complementary Strands

Answer 13

5’-ATGGCGGATTT-3’

3’-TACCGCCTAAA-5’

Question 14

Grooves

Answer 14

The indentations where the atoms of the bases are in contact with the surrounding water.

Question 15

A, B, Z DNA

Answer 15

• A DNA: Has right handed structure. Occurs under conditions of low humidity.
• B DNA: The normal structure of DNA. It is right handed.
• Z DNA: Left handed structure.

Question 16

Triplex DNA

Answer 16

Triple helix structure, 3rd strand is synthetic.

Question 17

RNA

Answer 17

Much shorter than DNA.