1.6 Nucleic Acids

Question 1

What are nucleic acids?

Answer 1

• Polymers made of nucleotide monomers

Question 2

What is a nucleic acid’s function?

Answer 2

• store, transmit, and express hereditary information (code for proteins)

Question 3

What are the two forms of nucleic acids?

Answer 3

Deoxyribonucleic acid and ribonucleic acid

Question 4

How do nucleic acids form, generally speaking? (2 steps)

Answer 4

Nucleotides to polynucleotides to nucleic acids

Question 5

What are the monomers of nucleic acids?

Answer 5

Nucleotides

Question 6

What are the 3 parts of nucleotides? (4)

Answer 6

• nitrogenous base
• five carbon sugar (pentose)
• phosphate group(s)
• in polynucleotides, each monomer only has one phosphate group

Question 7

What are the two types of nitrogenous bases?

Answer 7

Pyrimidines and purines

Question 8

What is a pyrimidine, and what nitrogenous bases are included?

Answer 8

• one ring with 6 atoms

- cytosine, thymine (DNA), Uracil (RNA)

Question 9

What is a purine, and which nitrogenous bases are included? (3)

Answer 9

• one ring with 6 atoms, bonded to one ring with 5 atoms
• adenine
• guanine

Question 10

What is a type of sugar is bonded to the nitrogenous base? What is it for DNA and RNA? (3)

Answer 10

• five carbon sugar
  In DNA, it’s deoxyribose
  In RNA, it’s ribose
  Note they all differ in structure and function

Question 11

What direction do we number our carbons in rings?

Answer 11

• clockwise from the oxygen

Question 12

Where is a phosphate group added to in a nucleotide?

Answer 12

• added to the 5 carbon (5’) of the sugar (sugar is attached to the base) to form a nucleotide

Question 13

What is a nucleoside?

Answer 13

• portion without phosphate group (sugar and nitrogenous base)

Question 14

Which group on the nucleotide links nucleotides together?

Answer 14

• phosphate group

Question 15

What type of linkage do polynucleotides have?

Answer 15

• phosphodiester linkage

- sugar/phosphate backbone bonded together

Question 16

What is the directionality of polynucleotides? (3)

Answer 16

• 5’ to 3’
• 5’ is phosphate end
• 3’ hydroxyl end

Question 17

The sequence of bases along the DNA or mRNA is unique for each gene. What does it dictate? (3)

Answer 17

• dictate AA sequence
• dictates primary structure of a protein
• therefore dictates 3D structure of a protein

Question 18

What is the structure of DNA?

Answer 18

• consists of two polynucleotides
• forms a double helix
• strands are antiparallel
  —Held together by H bonds between bases

Question 19

Which hydrogen bonds are weaker. AT or GC (3)

Answer 19

• AT because 2 hydrogen bonds
• GC is not because there are 3 H bonds, therefore stronger
  Note that increased AT bonding when DNA is unzipped

Question 20

What is the structure of RNA? (4)

Answer 20

• single stranded polynucleotide
• variable in shape due to base pairing WITHIN RNA
• adenine to uracil
• Guanine to cytosine