Biology, 07.04.2020 19:58, gdeorsey

The Meselson and Stahl experiment starts with E. coli containing 15N/15N labeled DNA grown in 14N media. Which result did Meselson and Stahl observe by sedimentation equilibrium centrifugation to provide strong evidence for the semiconservative model of DNA replication?

Answers: 1

Show answers

Answers

answered: kutsarver

No 15N/15N labeled DNA was observed in second generation

Explanation:

Meselson and Stahl were doing an experiment to find out the semi-conservative mode of replication of DNA. The first cultured bacteria in 15N medium which was containing a heavy isotope of nitrogen. The DNA synthesized here had more density. After that they transferred the bacteria to the 14N containing medium. When bacteria reproduced and new strands of DNA were synthesized, they observed the following -

The first generation had hybrid DNA with 15N/14N strandsThe second generation had both hybrid 15N/14N DNA and 14N/14N DNA strandsThere was no 15N/15N DNA observed.

In this way they proved that one strand of DNA is kept conserved during the replication.

answered: ximena68

The first generation has DNA with 15N/14N strands, Second generation has both type of DNA, one contain 15N/14N strands and other with14N/14N strands.

Explanation:

In DNA replication, the newly formed dsDNA contains one parental type strand and the other newly formed strand, which is formed during replication.

The mode of DNA replication is semi-conservative in which one strand is parental and other is new.

As given, E.coli contain 15N/15N labeled DNA and it was grown in 14N media.

So, here during DNA replication, the first generation has hybrid 15N/14N DNA, one strand( 15N) is parental and other (14N) in newly formed, and the second generation has both hybrid 15N/14N DNA and 14N/14N DNA. There is no DNA containing 15N/15N strands was observed.

answered: Guest

they are known to reach a speed of 21 miles per hour

answered: Guest

Proteins are the workhorses of the cell, controlling virtually every reaction within as well as providing structure and serving as signals to other cells. proteins are long chains of amino acids , and the exact sequence of the amino acids determines the final structure and function of the protein. instructions for that sequence are encoded in genes . to make a particular protein, a messenger ribonucleic acid (mrna) copy is made from the gene (in the process called transcription ), and the mrna is transported to the ribosome . protein synthesis, also called translation , begins when the two ribosomal subunits link onto the mrna. this step, called initiation, is followed by elongation, in which successive amino acids are added to the growing chain, brought in by transfer rnas (trnas). in this step, the ribosome reads the nucleotides of mrna three by three, in units called codons , and matches each to three nucleotides on the trna, called the anticodon. finally, during termination, the ribosome unbinds from the mrna, and the amino acid chain goes on to be processed and folded to make the final, functional protein