3.1.5.1 Structure of DNA and RNA

Question 1

what is the function of DNA?

Answer 1

to hold genetic information

Question 2

what is a nucleotide made up of?

Answer 2

a phosphate, a pentose sugar and nitrogen-containing organic base

Question 3

how do nucleotides join to form polynucleotides?

Answer 3

they bind together through a condensation reaction

Question 4

what bond is formed between nucleotides?

Answer 4

a phosphodiester bond

Question 5

how do phosphodiester bonds form?

Answer 5

• condensation reaction
• between phosphate and deoxyribose
• catalysed by DNA polymerase

Question 6

what are the four different bases in DNA?

Answer 6

A, T, C and G

Question 7

bases pair up though…

Answer 7

complementary base pairing

Question 8

what does the base A stand for?

Answer 8

adenine

Question 9

what does the base T stand for?

Answer 9

thymine

Question 10

what does the base C stand for?

Answer 10

cytosine

Question 11

what does the base G stand for?

Answer 11

guanine

Question 12

which bases pair together?

Answer 12

• A and T
• C and G

Question 13

complementary base pairing means that there will always be…

Answer 13

equal amounts of A and T and equal amounts of C and G in each DNA molecule

Question 14

which bonds hold DNA bases together?

Answer 14

hydrogen bonds

Question 15

which pair of bases has more hydrogen bonds between them?

Answer 15

C and G so the more of these there are, the more stable the DNA molecule

Question 16

describe the structure of DNA

Answer 16

• polymer of nucleotides (polynucleotides)
• each nucleotide formed from deoxyribose, a phosphate group and a nitrogenous base
• phosphodiester bonds between nucleotides
• double helix held by hydrogen bonds
• H bonds between adenine—thymine and cytosine—guanine

Question 17

what is the function of RNA?

Answer 17

to transfer genetic information from DNA to the ribosomes

Question 18

what are ribosomes formed from?

Answer 18

RNA and proteins

Question 19

RNA is a relatively ___ polynucleotide chain

Answer 19

short

Question 20

the sugar in DNA is ___ whereas the sugar in RNA is ___

Answer 20

• deoxyribose
• ribose

Question 21

the nucleotide strand in DNA is ___ whereas the nucleotide strand in RNA is ___

Answer 21

• double
• single

Question 22

in RNA, thymine is replaced with…

Answer 22

uracil (U)

Question 23

what are the two types of RNA?

Answer 23

messenger RNA (mRNA) and transfer RNA (tRNA)