Structure Of DNA and RNA

Question 1

What are the components that each individual nucleotide made up of?

Answer 1

— A pentose sugar
— A phosphate group
— A nitrogen containing base

Question 2

How is the pentose sugar, phosphate group and nitrogen base joined together?

Answer 2

It’s joined together during a condensation reaction to form a mononucleotide

Question 3

What is the bond called that’s between the deoxyribose sugar and phosphate group?

Answer 3

Phosphodiester bond

Question 4

What’s a dinucleotide?

Answer 4

2 mononucleotides joined together

Question 5

What’s a polynucleotide

Answer 5

It’s 3 or more mononucleotides joined together during a condensation reaction

Question 6

Structure of RNA?

Answer 6

— RNA is a polymer made up of nucleotides. It’s a single, short polynucleotide chain.
— The pentose sugar is always ribose
— The organic bases are adenine, guanine, cytosine and uracil

Question 7

Structure of DNA?

Answer 7

— The pentose sugar deoxyribose
— The organic bases are thymine, adenine, guanine and cytosine
— DNA is made up of 2 strands of nucleotides. Each strand is extremely long and they are joined together by hydrogen bonds formed between certain bases
— The phosphate and deoxyribose molecules alternate

Question 8

What does thymine always pair with

Answer 8

If it’s RNA uracil. If it’s DNA adenine

Question 9

What does guanine always pair with

Answer 9

Cytosine

Question 10

What is the double helix?

Answer 10

The phosphate and the deoxyribose wind round each other to form a double helix

Question 11

Why is DNA a stable molecule?

Answer 11

— The phosphodiester backbone protects the more chemically reactive organic bases inside the double helix
— Hydrogen bonds link the organic base pairs forming bridges between the phosphodiester uprights. As there are 3 hydrogen bonds between cytosine and guanine, the higher the proportion of C—G pairings the more stable the DNA molecule

Question 12

What is the function of DNA?

Answer 12

— It’s a very stable structure which normally passes from generation to generation without significant change.
— It’s 2 separate strands that are joined only with hydrogen bonds, which allows them to separate during DNA replication and protein synthesis
— It’s an extremely large molecule and therefore carries a lot of genetic information
— By having base pairs within the helical structure, the genetic information is to some extent protected from outside chemical and physical forces
— Base pairings leads to DNA being able to replicate and to transfer information such as mRNA