Chapter 10.3

Question 1

primary structure of DNA

Answer 1

refers to- the string of nucleotides joined together by phosphodiester linkages

Question 2

three components of each DNA nucleotide

Answer 2

sugar
phosphate group
nitrogen containing base

Question 3

what are the two types of nitrogenous bases?

Answer 3

purine

pyrimidine

Question 4

name the purines

Answer 4

consist of a 5 member ring attached to a 6 member ring
adenine
guanine

Question 5

name the pyrimidines

Answer 5

consist of a 6 member ring only
cytosine
thymine
uracil

Question 6

what is the difference between ribose and deoxyribose?

Answer 6

deoxyribose- (DNA’s sugar)

• has a hydrogen atom (-H) attached to the 2’ carbon atom
• has one fewer oxygen atom overall
• less reactive than RNA, more stable for long term genetic coding

ribose- (RNA’s sugar)

• has hydroxyl group (-OH) attached to the 2’ carbon atom
• more reactive than DNA because of additional oxygen atom

Question 7

nucleoside

Answer 7

a term referring to a deoxyribose/ribose sugar joined with a nitrogenous base

Question 8

what makes up the phosphate group?

Answer 8

• phosphorous atom bonded to four oxygen atoms
• always bonded to the 5’ carbon atom of the sugar
• usually carry a negative charge = making DNA acidic

Question 9

what are deoxyribonucleotides?

Answer 9

nucleotides in DNA containing deoxyribose

Question 10

ribonucleotides

Answer 10

nucleotides in RNA containing ribose

Question 11

phosphodiester linkages

Answer 11

Phosphodiester bond connecting two nucleotides in a polynucleotide strand.

connect the 3’ carbon atom of one nucleotide to the 5’phosphate group of the next
-always goes 5’ —> 3’

Question 12

how many hydrogen bonds do C-G pairs have?

Answer 12

3

Question 13

how many hydrogen bonds to T-A pairs have?

Answer 13

2

Question 14

secondary structure of DNA

Answer 14

refers to its 3 dimensional configuration
(fundamental helical structure)
-antiparallel double helix

Question 15

what are the 3 secondary structures of DNA?

Answer 15

A form
B form -
Z form

Question 16

what is A-DNA structure?

Answer 16

• forms when less water is present
• right-handed double helix
• shorter and wider than B-DNA

Question 17

what is B-DNA structure?

Answer 17

Right-handed helical structure of DNA that exists when water is abundant; the secondary structure described by Watson and Crick and probably the most common DNA structure in cells.

Question 18

what is Z-DNA structure?

Answer 18

Secondary structure of DNA characterized by 12 bases per turn, a left-handed helix, and a sugar-phosphate backbone that zigzags back and forth.