Nucleotides and Phosphodiester Bonds (Part 2)

Question 1

What are nucleotides?

Answer 1

Nucleotides are the monomers from which DNA and RNA polymers are built

Question 2

What are monomers and polymers?

Answer 2

Monomers = Small subunits, that combine to make a polymer.

Polymers = large molecule made from many repeating subunits, known as monomers.

Question 3

What is the nucleotide structure?

Answer 3

Nucleotide structure includes:
1. a pentose sugar
2. a nitrogen-containing organic base
3. a phosphate group

Question 4

What are the components of a DNA nucleotide?

Answer 4

1. a deoxyribose sugar
2. a phosphate group
3. one of four nitrogenous bases:
   - adenine (A)
   - cytosine (C)
   - guanine (G)
   - thymine (T)

Question 5

What are the components of an RNA nucleotide?

Answer 5

1. a ribose sugar
2. a phosphate group
3. one of four nitrogenous bases:
   - adenine (A)
   - cytosine (C)
   - guanine (G)
   - uracil (U)

Question 6

Draw what an RNA nucleotide looks like.

Question 7

Draw what a DNA nucleotide looks like.

Question 8

What are the two structural forms of the nitrogenous base mo9lecules in DNA and RNA?

Answer 8

purines
pyrimidines

Question 9

What is a purine, and give the two examples?

Answer 9

Adenine and guanine are purines: they have a double ring structure

Question 10

What is a pyrimidines, and give the three examples?

Answer 10

Cytosine, thymine and uracil are pyrimidines: they have a single ring structure

Question 11

What is a pentose sugar?

Answer 11

contains 5 carbon atoms

Question 12

Where is deoxyribose sugar found?

Answer 12

DNA

Question 13

Where is Ribose sugar found?

Answer 13

RNA

Question 14

What is the difference between deoxyribose and ribose, in terms of structure?

Answer 14

Deoxyribose contains one fewer oxygen atom that ribose
- In ribose carbon 2 has an OH group, while in deoxyribose carbon 2 has an H group.

Question 15

What type of polymers are DNA and RNA?

Answer 15

DNA and RNA are polymers (polynucleotides), meaning that they are made up of many nucleotides joined together in long chains

Question 16

How are nucleotides joined together, and what parts does it occur between?

Answer 16

Separate nucleotides are joined together via condensation reactions
- These condensation reactions occur between the phosphate group of one nucleotide and the pentose sugar of the next nucleotide

Question 17

How is a phosphodiester bond formed?

Answer 17

A condensation reaction between two nucleotides forms a phosphodiester bond
- It is called a phosphodiester bond because it consists of a phosphate group and two ester bonds

Question 18

What is a sugar-phosphate backbone?

Answer 18

The chain of alternating phosphate groups and pentose sugars produced as a result of many phosphodiester bonds is known as the sugar-phosphate backbone (of the DNA or RNA molecule)

Question 19

What bonds allow polynucleotides to be synthesised?

Answer 19

As the synthesis of polynucleotides requires the formation of phosphodiester bonds, the same is true for the reverse process: the breakdown of polynucleotides requires the breakage of phosphodiester bonds