Unit 1 - Nucleic Acids

Question 1

What are the 2 types of nucleic acids?

Answer 1

1. DNA - Deoxyribonucleic Acid
2. RNA - Ribonucleic Acid

Question 2

Describe the functions of nucleic acids in general

Answer 2

• Informational molecules
• Polymers of nucleotides (100’s - 1000’s) which are the monomer units
• Used by all organisms to store hereditary info that determines structural/functional characteristics
• (Only molecules that make identical copies of themselves w/ reproduction)

Question 3

What are the functions of DNA?

Answer 3

1. Long-term storage of hereditary info
2. Carries genetic instructions/blueprints for the building parts of the cell
3. Segments of DNA are responsible for carrying genes, have structural purposes, or regulate the use of genetic info

To summarize:
1. Protein expression (Phenotypes)
2. Inheritance (Genotypes)
3. Evolution (Mutations)

Question 4

What are the functions of RNA?

Answer 4

1. Involved in the process of transcribing genetic info from DNA into proteins
2. Protein synthesis (process of making proteins) is carried out by organelles called ribosomes which take instructions from RNA

To summarize:
1. Used in protein synthesis
2. Structural in ribosomes

Question 5

How do nucleic acids store and transmit hereditary info?

Answer 5

• The amino acid sequence of a polypeptide is programmed by a gene
• A gene consists of a region of DNA
• DNA provides direction for its own replication
• DNA also directs RNA synthesis and through RNA, controls protein synthesis
• DNA (and its genes) is passed by the mechanisms of inheritance
• Only molecule that can make identical copies of itself

Question 6

What are the nitrogen bases of DNA?

Answer 6

• Purines:
  1. Adenine (A)
  2. Guanine (G)

-Pyrimidines:
3. Thymine (T)
4. Cytosine (C)

• Adenine pairs w/ Thymine (double bond)
• Guanine pairs w/ Cytosine (triple bond)

Question 7

What are the nitrogen bases of RNA?

Answer 7

• Purines:
  1. Adenine (A)
  2. Guanine (G)

-Pyrimidines:
3. Uracil (U)
4. Cytosine (C)

• Adenine pairs w/ Uracil
• Guanine pairs w/ Cytosine

Question 8

What is the difference b/w the shape of DNA vs. RNA?

Answer 8

• DNA = double helix (2 strands)
  ~ H bonds b/w nitrogen base pairs (C + G, A +T)
• RNA = single stranded

Question 9

What is a phosphodiester bond and what role does it play in building nucleic acids?

Answer 9

• A phosphodiester bond happens when the hydroxyl group of one nucleotide is bonded to the phosphate of the next
• These bonds create a repeating backbone of sugar-phosphate units with the nitrogen bases as “appendages” sticking out

Question 10

Why are only H-bonds used in DNA’s double helix structure?

Answer 10

• In order to replicate, the strands must separate to make new DNA strands (cannot be broken if the strands are covalently bonded)

Question 11

What are the main differences b/w DNA and RNA?

Answer 11

• An RNA molecule is a single polynucleotide chain while DNA molecules have 2 polynucleotide strands that spiral around an imaginary axis to form a double helix
• The pentose (sugar) found in nucleotides of RNA is ribose while in DNA it is deoxyribose
• Nitrogen bases - thymine is replaced by uracil in RNA molecules