What is the role of DNA ligase in the elongation of the lagging strand during DNA replication? It joins leading strand fragments together It synthesizes RNA nucleotides to make a primer. It ensures that replication away form the fork results in one DNA molecule. It unwinds the parental double helix. It catalyzes the lengthening of telomeres.
Who predicted, but didn't perform the experiments that supported the semiconservative model of DNA replication? O Watson and Crick Hershey and Chase Meselson and Stahl Franklin and Tatum None of the other choices are correct.
The following question refers to this table of codons. 52 What amino acid sequence will be generated, based on the following mRNA codon sequence? 5-AUG-UCU-GAU-UUA-UCC-UUG-3 Met-Ser-Leu-Ser-Leu-Ser Met-Ser-Ser-Leu-Ser-Leu Met-Glu-Arg-Arg-Glu-Leu Met-Arg-Glu-Arg-Glu-Arg Met-Ser-Asp-Leu-Ser-Leu
Answer
1) Ans: It ensures that replication away from
the fork results in one DNA molecule
- In DNA replication there are two strands leading strand and
lagging strand. Leading strand is continuously synthesized where
the lagging strand is made in fragments because when the fork moves
forward the DNA polymerase must come and reattach to the newly
formed DNA, which results the formation of fragments of DNA ,called
lagging strand or Okazaki fragments. The DNA ligase joins the
lagging strand fragments.
2) Ans: Watson and crick
- Semi conservative replication hypothesis is proposed by Watson
and Crick. In semiconservative hypothesis proposed by Watson and
crick , the two strands pf DNA get separated during
DNA Replication and each strand will act as template for
the synthesis if new strand. - Meselson–Stahl experiment, done by Matthew Meselson and
Franklin Stahl in 1958, proved the semiconservative replication of
DNA. Alfred Hershey and Martha Chase conducted an experiment in
1952 which proven that DNA is the genetic material.
3) Ans: Met-Ser-Asp-Leu-Ser-Leu
- 5'-AUG-UCU-GAU-UUA-UCC-UUG-3' are the genetic code. Codon is a
sequence of three DNA or RNA nucleotides that corresponds to a
specific amino acid, each codon corresponds to single aminoacid and
the complete set of codons is called genetic code. 64 codons are
there in genetic code which codes for only 20 aminoacid.
figure shows the respective codons for aminoacid and from that
we could know the amino acids codes for the respective genetic code
5'-AUG-UCU-GAU-UUA-UCC-UUG-3'. From the options
Met-Ser-Asp-Leu-Ser-Leu is the correct answer because the peptide
5'-AUG-UCU-GAU-UUA-UCC-UUG-3' codes for that only.