Nucleic Acids

Question 1

How are nucleotides joined and what does it form?

Answer 1

• condensation reaction
• phosphate group on carbon 5 of the pentose sugar forms covalent bond with OH group of 3 carbon on the adjacent pentose sugar.
• phosphodiester bonds
• polymer called polynucleotide

Question 2

How are phosphodiester bonds broken?

Answer 2

• hydrolysis
• release individual nucleotides
• water released

Question 3

What do the phosphodiester bonds provide in a polynucleotide?

Answer 3

• a long, strong sugar phosphate ‘backbone’ with a base attached to each sugar

Question 4

What are nucleic acids?

Answer 4

• large molecules in cell nuclei
• two types: RNA and DNA
• roles in storage and transfer of genetic information and the synthesis of polypeptides (proteins)

Question 5

What elements do nucleic acids contain?

Answer 5

• carbon
• hydrogen
• oxygen
• nitrogen
• phosphorus

Question 6

How are nucleic acids formed?

Answer 6

• large polymers formed from many nucleotides (monomers) linked together in a chain

Question 7

What are individual nucleotides components?

Answer 7

• pentose sugar
• phosphate group
• nitrogenous base

Question 8

What makes DNA’s sugar different from RNA’s?

Answer 8

• lacks one oxygen on carbon 2

Question 9

How is DNA’s structure different from RNA’s?

Answer 9

• has T base instead of U
• sugar is deoxyribose
• double stranded

Question 10

How is RNA’s structure different from DNA’s?

Answer 10

• has U base instead of T
• sugar is ribose
• smaller molecule
• single stranded

Question 11

How are DNA’s and RNA’s structure the same?

Answer 11

• form polymers in the same way
• phosphodiester bonds
• linear molecules
• both have sugar, base and phosphate
• have A,C and G bases

Question 12

What are pyrimidines and which bases are pyrimidines?

Answer 12

• smaller bases
• contain single carbon ring structures
• thymine and cytosine and uracil

Question 13

What are purines and which bases are purines?

Answer 13

• larger bases
• contain double carbon ring structures
• adenine and guanine

Question 14

How are the nitrogenous bases bonded together?

Answer 14

• hydrogen bonds
• A-T has 2 H bonds
• C-G has 3 H bonds

Question 15

What does antiparallel mean?

Answer 15

• each strand has a phosphate group (5’) at one end and OH group (3’) at the the other end
• the two parallel strands of the double helix are arranged so they run in opposite directions

Question 16

Why do pyrimidine bases always pair with purine bases

Answer 16

• maintains constant distance between DNA ‘backbones’ resulting in parallel polynucleotide chains

Question 17

What is complementary base pairing?

Answer 17

• A and T always bond and C and G always bond

- means there’s always equal amounts of the bases that are paired

Question 18

What is the method of extracting DNA?

Answer 18

1. Grind sample in pestle and mortar
2. mix sample with detergent
3. add salt
4. add protease enzymes
5. add layer of ethanol on top of sample
6. DNA seen as white strands, forming between layer of sample and alcohol. DNA can be picked up by ‘spooling’ it onto a glass rod.

Question 19

What does grinding the sample in DNA extraction do?

Answer 19

• breaks down cell walls

Question 20

What does mixing the sample with detergent do in DNA extraction do?

Answer 20

• breaks down cell membrane, releasing cell contents into solution

Question 21

What does adding salt to the sample in DNA extraction do?

Answer 21

• breaks hydrogen bonds between DNA and water molecules

Question 22

What does adding protease enzymes to the sample in DNA extraction do?

Answer 22

• breaks down proteins in DNA

Question 23

What does adding ethanol to the sample in DNA extraction do?

Answer 23

• alcohol causes DNA to precipitate out of solution