Indicate the true statements and then correct the false statements so that they are true.
a. DNA is replicated in a 3' to 5' direction.
b. DNA has a parallel arrangement.
c. RNA primase is required on the leading and the lagging strand.
d. DNA ligase forms phosphodiester bonds between Okazaki fragments on the lagging strand.
e. Prokaryotic mRNA requires processing before it is translated.
f. In RNA, A bonds to U.
g. In DNA, C bonds with G.
h. RNA contains deoxyribonucleotides.

Verified step by step guidance

1. Step 1: Analyze statement (a): DNA replication occurs by adding nucleotides to the 3' end of the new strand, so the new strand is synthesized in the 5' to 3' direction. The template strand is read in the 3' to 5' direction. Therefore, the statement 'DNA is replicated in a 3' to 5' direction' is false. Correct it to: 'DNA is replicated in the 5' to 3' direction.'
2. Step 2: Analyze statement (b): DNA strands in the double helix are antiparallel, meaning one strand runs 5' to 3' and the other runs 3' to 5'. The statement 'DNA has a parallel arrangement' is false. Correct it to: 'DNA has an antiparallel arrangement.'
3. Step 3: Analyze statement (c): RNA primase synthesizes RNA primers on both the leading and lagging strands to initiate DNA synthesis. This statement is true.
4. Step 4: Analyze statement (d): DNA ligase forms phosphodiester bonds between Okazaki fragments on the lagging strand to join them into a continuous strand. This statement is true.
5. Step 5: Analyze statement (e): Prokaryotic mRNA is typically polycistronic and does not require extensive processing like eukaryotic mRNA (no splicing, 5' cap, or poly-A tail). Therefore, the statement 'Prokaryotic mRNA requires processing before it is translated' is false. Correct it to: 'Prokaryotic mRNA does not require processing before it is translated.'

Key Concepts

DNA Replication Directionality

DNA strands have directionality, running from 5' to 3' ends. DNA polymerase synthesizes new DNA only in the 5' to 3' direction by adding nucleotides to the 3' end of the growing strand. The template strand is read in the 3' to 5' direction, but the new strand is built 5' to 3'.

Structure and Function of RNA Primase and DNA Ligase

RNA primase synthesizes short RNA primers needed to start DNA synthesis on both leading and lagging strands. DNA ligase seals gaps between Okazaki fragments on the lagging strand by forming phosphodiester bonds, ensuring a continuous DNA strand.

Differences Between Prokaryotic and Eukaryotic mRNA and Base Pairing Rules

Prokaryotic mRNA is typically ready for translation immediately after transcription, lacking extensive processing seen in eukaryotes. Base pairing rules state that in RNA, adenine pairs with uracil (A-U), and in DNA, cytosine pairs with guanine (C-G). RNA contains ribonucleotides, not deoxyribonucleotides.