3.8 - Nucleic Acids

Question 1

Name the pentose sugars in DNA and RNA

Answer 1

DNA - deoxyribose
RNA - ribose

Question 2

Describe how polynucleotide strands are formed and broken down

Answer 2

•Condensation reactions between nucleotides form strong phosphodiester bonds ( sugar - phosphate backbone)
• hydrolysis reactions use a molecule of water to break these bonds
• enzymes catalyse these reactions

Question 3

Describe the structure of DNA

Answer 3

• molecule twists to form a double Helix of 2 deoxyribose polynucleotide strands ( there are 2 sugar phosphate backbones )
• H- bonds firm between complimentary base pairs ( AT & GC ) on strands that run antiparallel

Question 4

What are the nitrogenous bases?

Answer 4

•Adenine
• guanine
• cytosine
• thymine

Question 5

What are purines?

Answer 5

Adenine and guanine - thru have a double ring structure

Question 6

What are pyrimidines ?

Answer 6

Cytosine, thymine and uracil - have a single ring structure

Question 7

How are polynucleotides formed?

Answer 7

Nucleotides are linked together by condensation reactions to form a polymer called a polynucleotide

Question 8

What is a phosphodiester bond?

Answer 8

A condensation reaction between two nucleotides it’s called a phosphodiester bond because it consists it a phosphate group and two ester bonds