DNA and RNA AS

Question 1

structures in a neucleotide

Answer 1

nitrogenous bases A,T,C or G, a deoxyribose pentose sugar backbone and a phosphate.

Question 2

what reaction and bond joins parts of DNA?

Answer 2

condensation reaction and phosphodiester bond

Question 3

adaptations of DNA

Answer 3

sugar phosphate backbone gives strength. coiling makes compact. long molecule for lots of information. complementary base pairs allow accurate replication. many H bonds provide strength, easily broken for replication

Question 4

word for when one strand runs in the 5’ 3’ direction and the other runs in the 3’ 5’ direction.

Answer 4

antiparallel

Question 5

what pairs with adenine

Answer 5

thymine

Question 6

what pairs with guanine

Answer 6

cytosine

Question 7

how many H bonds with Adenine

Answer 7

2

Question 8

how many H bonds with guanine

Answer 8

3

Question 9

how many bases code for an amino acid

Answer 9

3

Question 10

name of sections of DNA which are non-coding

Answer 10

introns

Question 11

name for discrete triplet codes

Answer 11

non-overlapping code

Question 12

how do mutations stop enzymes from working

Answer 12

change in base. amino acid sequence changed. change in H/ionic bonds. tertiary structure altered and thus shape of active site

Question 13

semi conservative replication

Answer 13

DNA strands separate

new molecules formed from one old strand and one new strand

Question 14

How is RNA adapted for function?

Answer 14

stable

single stranded to allow bonding at the ribosome

Question 15

comparison between DNA and RNA

Answer 15

DNA double stranded RNA single stranded
DNA deoxyribose sugar RNA ribose sugar
DNA has thymine base RNA has uracil base

Question 16

Structures in RNA

Answer 16

nitrogenous base, A, U, C and G. ribose sugar, and a phosphate.

Question 17

purpose of RNA

Answer 17

messenger RNA transfers the genetic code from the DNA to the ribosomes

Question 18

steps in DNA replication

Answer 18

chains separate, breaking H bonds
with DNA helicase
each chain acts as a template
nucleotides line up with complementary bases and join to template strand
DNA polymerase joins sugar phosphate groups of adjacent nucleotides in the 5’ 3’ direction
phosphodiester bonds form

Question 19

why does DNA polymerase work in the 5’ 3’ direction only

Answer 19

its active site only bonds to the 3’ end (5’ and 3’ end are different shapes)