1.5.2 Nucleotide Structure & the Phosphodiester Bond

Question 1

Both DNA and RNA are

Answer 1

polymers

Question 2

Both DNA and RNA are polymers that are made up of

Answer 2

many repeating units called nucleotides

Question 3

Each nucleotide is formed from

Answer 3

• a pentose sugar (a sugar with 5 carbon atoms)
• a nitrogen-containing organic base
• a phosphate group

Question 4

The basic structure of a nucleotide

Answer 4

Question 5

The components of a DNA nucleotide are

Answer 5

• a deoxyribose sugar with hydrogen at the 2’ position
• a phosphate group
• one of four nitrogenous bases - adenine (A), cytosine(C), guanine(G) or thymine(T)

Question 6

The components of an RNA nucleotide are

Answer 6

• a ribose sugar with a hydroxyl (OH) group at the 2’ position
• a phosphate group
• one of four nitrogenous bases - adenine (A), cytosine(C), guanine(G) or uracil (U)

Question 7

What makes RNA more susceptible to hydrolysis

Answer 7

the presence of the 2’ hydroxyl group

Question 8

The presence of the 2’ hydroxyl group makes RNA more susceptible to

Answer 8

hydrolysis (this is why DNA is the storage molecule and RNA is the transport molecule with a shorter molecular lifespan)

Question 9

RNA nucleotide

Answer 9

Question 10

DNA nucleotide

Answer 10

Question 11

An RNA nucleotide compared with a DNA nucleotide

Answer 11

Question 12

The nitrogenous base molecules that are found in the nucleotides of DNA (A, T, C, G) and RNA (A, U, C, G) occur in two structural forms

Answer 12

purines and pyrimidines

Question 13

The bases adenine and guanine are

Answer 13

purines

Question 14

Which bases are purines

Answer 14

adenine and guanine

Question 15

The bases adenine and guanine are purines, they have a

Answer 15

double ring structure

Question 16

The bases cytosine, thymine and uracil are

Answer 16

pyrimidines

Question 17

Which bases are pyrimidines

Answer 17

cytosine, thymine and uracil

Question 18

The bases cytosine, thymine and uracil are pyrimidines, they have a

Answer 18

single ring structure

Question 19

The molecular structures of purines and pyrimidines are slightly different

Answer 19

Question 20

Answer 20

Question 21

Nucleotide Structure Table

Answer 21

Question 22

DNA and RNA are polymers (polynucleotides), meaning that they are made up of

Answer 22

many nucleotides joined together in long chains

Question 23

Separate nucleotides are joined via

Answer 23

condensation reactions

Question 24

nucleotides are joined via condensation reactions, these occur between

Answer 24

the phosphate group of one nucleotide and the pentose sugar of the next nucleotide

Question 25

A condensation reaction between two nucleotides forms a

Answer 25

phosphodiester bond

Question 26

It is called a phosphodiester bond because it consists of

Answer 26

a phosphate group and two ester bonds (phosphate with double bond oxygen attached - oxygen - carbon)

Question 27

The chain of alternating phosphate groups and pentose sugars produced as a result of many phosphodiester bonds is known as the

Answer 27

sugar-phosphate backbone (of the DNA or RNA molecule)

Question 28

A section of a single polynucleotide strand showing a phosphodiester bond (and the positioning of the two ester bonds and the phosphate group that make up the phosphodiester bond)

Answer 28