2.6 Structure of DNA and RNA

Question 1

What are Nucleic Acids?

Answer 1

they are a group of chemicals in cells concerned with the transmission of inherited information
two types:
DNA - deoxyribose nucleic acid
RNA - ribose nucleic acid
they are polymers of nucleotides

Question 2

Components of a Nucleotide

Answer 2

• a 5C sugar
• a phosphate group
• nitrogen base (adenine, guanine, cytosine, thymine or uracil)
  all bonds within nucleotides are covalent bonds
  all bonds between nucleotides are hydrogen bonds

Question 3

What is DNA?

Answer 3

carries the genetic message for the functioning of the organism
a gene is a length of DNA that codes for a polypeptide, which forms protein
found in:
- chromosomes in the nucleus of eukaryotes and plastids for prokaryotes
- in mitochondria
- in chloroplasts
(sugar is deoxyribose)
double helix shape made of two antiparallel strands of nucleotides linked by hydrogen bonding between complementary base pairs
three bases (triplet) codes for one amino acid

Question 4

Approximate Sizes of DNA

Answer 4

viruses - 5 - 200 kilo base pairs
bacteria - 500 - 5000 kb
yeast - 13,500 kb
fruit fly - 165,000 kb
human - 2,900,000 kb

Question 5

How did Crick and Watson find structure of DNA?

Answer 5

they took paper shapes for the bases and used them to make a model of DNA that fitted with the images of a double helix

Question 6

RNA structure

Answer 6

• sugar is ribose
• has the base uracil instead of thymine
• single-stranded
• less stable than DNA
• much smaller than DNA