DNA: Discovery and Basics

Question 1

when and by whom was DNA discovered?

Answer 1

Friedrich Miescher discovered nuclein in 1869

nuclein –> nucleic acid –> dna

Question 2

what are nucleotides composed of?

Answer 2

1 of 4 nitrogen containing bases, sugar molecule and a phosphate grp

Question 3

what did watson and crick identify?

Answer 3

the double helix structure of dna

Question 4

describe the structure of dna

Answer 4

macromolecule
2 polynucleotide chain polymers of nucleotides
major/minor grove
2nm wide
3.4nm rise
10-10.5 bases per turn

Question 5

why is dna a helix?

Answer 5

to save space

Question 6

why a double helix?

Answer 6

for replication an stability

Question 7

difference between nucleotide and nucleoside

Answer 7

nucleotide:
base + ribose + phosphate

nucleoside:
base + ribose

Question 8

what are the four types of bases?

Answer 8

adenine
cytosine
guanine
thymine uracil (rna)

Question 9

what are the two types of pentose sugars?

Answer 9

purines (double ring)
pyrimidines (single ring)

Question 10

what are the two bases for purine and pyrimidine?

Answer 10

purine : adenine and guanine
pyrimidine: cytosine and thymine

Question 11

describe the structure of the double helix

Answer 11

sugar-phosphate backbone (has strong covalent bonds)

paired bases inside (weak hydrogen bonds- 2 for A-T and 3 for C-G)