DNA vs RNA

Question 1

Messenger RNA (mRNA)

Answer 1

responsible for transfer of information from nucleus to cytoplasm

Question 2

Transfer RNA (tRNA)

Answer 2

construction of proteins at the ribosomes in the cytoplasm

o Anticodon in tRNA is complementary to the codon of mRNA that codes for the specific amino acid (attached to the tRNA)

Question 3

Ribosomal RNA (rRNA)

Answer 3

forms the structural and functional components of ribosomes

Question 4

DNA

Answer 4

• Consists of 2 polynucleotide strands in the form of a double helix with complementary base pairs: C with G and A with T
• held by hydrogen bonds
  Occurs in the chromosomes of the nucleus

Question 5

RNA

Answer 5

• Consists of single strands and exist in 2 functional forms: messenger RNA (mRNA) and transfer RNA (tRNA)
• Some RNA also occurs in the nucleus, most are found in the cytoplasm – particularly in the ribosomes

Question 6

Main features of genetic code

Answer 6

• Universal
• Continuous and non-overlapping
  o Ribosomes are read continuously as successive groups of 3 (ribo)nucleotides, one DNA triplet/codon at a time without skipping any (ribo)nucleotides
• Degenerate, but unambiguous
  o A single amino acid can be coded by more than 1 different DNA triplet/codon BUT every DNA triplet/codon codes for just 1 amino acid and thus the code is unambiguous
  o Most of the amino acids are encoded by degenerate DNA triplets/codon that differ in the 3rd position of the DNA triplet/codon
• Has punctuation DNA triplets/codons – start and stop DNA triplets/codons

Question 7

ribosomes

Answer 7

o Ribosome moves along the mRNA one triplet codon at a time
o tRNA anticodons align with mRNA codons by complementary base pairing in ribosomes  amino acid attached to tRNA forms peptide bond by condensation reaction with 2nd amino acid while the 2 amino acids are held close together within the ribosome