Structure of DNA and RNA

Question 1

describe the function of DNA

Answer 1

-holds genetic information which codes for polypeptides (proteins)

Question 2

describe the function of RNA

Answer 2

-transfers genetic information from DNA to ribosomes

Question 3

name the two types of molecule from which a ribosome is made

Answer 3

-DNA
-proteins

Question 4

describe a DNA nucleotide

Answer 4

-phosphate group
-deoxyribose sugar
-nitrogen containing organic base

Question 5

describe an RNA nucleotide

Answer 5

-phosphate group
-ribose sugar
-nitrogen containing organic base

Question 6

what are the names of the possible bases in a DNA nucleotide

Answer 6

-adenine
-thymine
-guanine
-cytosine

Question 7

what are the names of the possible bases in an RNA nucleotide

Answer 7

-adenine
-uracil
-guanine
-cytosine

Question 8

describe the differences between a DNA nucleotide and an RNA nucleotide

Answer 8

-pentose sugar is deoxyribose in DNA, and ribose in RNA
-base can be thymine in DNA, and base can be uracil in RNA

Question 9

describe how nucleotides join together to form polynucleotides

Answer 9

-condensation reactions, removing water molecules
-between phosphate group of one nucleotide and deoxyribose/ribose of another
-forming phosphodiester bonds

Question 10

why did scientists initially doubt that DNA carried the genetic code

Answer 10

-the relative simplicity of DNA
-chemically simple molecule with few components

Question 11

describe the structure of DNA

Answer 11

-polymer of nucleotides (polynucleotide)
-each nucleotide formed from deoxyribose, a phosphate group and a nitrogen containing organic base
-phosphodiester bonds join adjacent nucleotides
-2 polynucleotide chains held together by hydrogen bonds
-between specific complementary base pairs (A-T) (G-C)
-double helix

Question 12

describe the structure of (messenger) RNA

Answer 12

-polymer of nucleotides (polynucleotide)
-each nucleotide formed from ribose, a phosphate group and a nitrogen containing base
-bases are uracil, adenine, cytosine and guanine
-phosphodiester bonds join adjacent nucleotides
-single helix

Question 13

compare and contrast the structure of DNA and (messenger) RNA

Answer 13

-dna has deoxyribose, rna has ribose
-dna has thymine, rna has uracil
-dna is double stranded/double helix, rna is single stranded/single helix
-dna is long with many nucleotides, rna is shorter with fewer nucleotides
-dna has hydrogen bonds/base pairing, rna has no hydrogen bonds/base pairings

Question 14

how many hydrogen bonds are between A and T

Answer 14

2

Question 15

how many hydrogen bonds are between G and C

Answer 15

3

Question 16

suggest how the structure of DNA relates to its functions

Answer 16

-two strands which both act as a template for semi conservative replication
-hydrogen bonds between bases are weak so strands can be separated for replication
-complementary base pairing for accurate replication
-many hydrogen bonds between bases for a stable and strong molecule
-double helix with sugar phosphate backbone to protect bases/hydrogen bonds
-long molecule to store lots of genetic information
-double helix (coiled) so is compact

Question 17

suggest how you can use incomplete information about the frequency of bases on DNA strands to find the frequency of other bases

Answer 17

-% of adenine in strand one =% of thymine in strand 2 and vice versa
-% of guanine in strand one = % of cytosine in strand 2 and vice cersa
-because of specific complementary base pairing between 2 strands