ch 10 - nucleotides and nucleic acids

Question 1

what are nucleotides?

Answer 1

• building blocks of nucleic acid
• energy currency (ATP)
• signaling molecules
• enzyme co-factors

Question 2

what is nucleic acid?

Answer 2

• genetic information in all stages of protein synthesis

Question 3

what composes a nucleotide?

Answer 3

• 5 carbon pentose sugar (ribose or deoxyribose)
• a nitrogenous base (purine or pyrimidine)
• phosphate(s)

Question 4

a purine has ___ ring(s), where a pyrimidine has ___ ring(s)

Answer 4

2, 1

Question 5

what is epigenetics?

Answer 5

• study of changes in organisms caused by modification of gene expression rather than altering genetic code
• heritable changes

Question 6

what steps are used to name a nucleotide or nucleoside?

Answer 6

1. what base is present?
2. ribose or deoxyribose sugar?
3. is a phosphate in position 5? (yes = olate if its tide. no = osine for sine and idne for tide)

Question 7

what are Chargaff’s rules?

Answer 7

• gave strong hints, but never revealed structure of DNA
  1. Base composition of DNA varies between species
  2. DNA from different tissues of same species have same composition
  3. base composition is stable in species and doesn’t change in environment, age, nutrition, etc.

Question 8

Describe the following ways of structural stabilization:

a. Hydrophobic effects
b. Stacking interactions
c. Hydrogen bonds
d. Charge-Charge interactions

Answer 8

a. Hydrophobic effects: purine and pyrimidine rinds burry in interior of double helix
b. Stacking interactions: stacked base pairs form van der Waals contact
c. Hydrogen bonds: H bonding between base pairs
d. Charge-Charge interactions: electrostatic repulsion of negatively charged phosphate groups is decreased by cations and cationic proteins

Question 9

what is denaturation?

Answer 9

• the complete unwinding and separation of double-stranded DNA by heat or chemical agents

Question 10

what is annealing?

Answer 10

the reforming of double-stranded helix from single strands

Question 11

how does the polymerase chain reaction (PCR) occur?

Answer 11

• takes advantage of ability for each DNA strand to serve as template for production of a complementary strand
• reproduces short DNA segments rapidly
• process involves heat, cool, make primers, repeat

Question 12

how do restriction enzymes work?

Answer 12

• cut DNA at a very specific point
• serve as bacterial defense against viral invaders
• utilized for specific manipulation of DNA

Question 13

true or false. prokaryotic DNA is long and needs to be packages into higher order structure where eukaryotic DNA is short and doesnt need to

Answer 13

False. Eukaryotic DNA is long and needs to be packages into higher order structure where prokaryotic DNA is short and doesnt need to

Question 14

how does RNA differ from DNA structurally?

Answer 14

• RNA contains ribose as the pentose sugar rather than deoxyribose
• RNA generally contains uracil rather than thymine
• RNA usually is single stranded, however some adopt 3D structures

Question 15

what are introns?

Answer 15

• eukaryotic genes interrupted by non-coding intervening sequences
• can vary in size, number, position
• removed from mRNA before translation