Blog

T2 phage viruses are very simple; they are composed of DNA or RNA enclosed by a protein coat. When the phages are grown it is possible to radioactively label the DNA component only. For the second part of their experiment, Hershey and Chase allowed bacteria to be infected by the radioactively labeled T2 phage virus.  After allowing them to grow and reproduce, the bacterial cells were processed by centrifugation and the resulting pellet and supernatant were tested for radioactivity. What result do you expect?

Duplicated genes can lead to genome evolution primarily because they

Regulation of gene expression occurs first at the DNA structural level, and is even more tightly regulated at the transcription level, but even after a gene has been transcribed there are mechanisms at work to regulate expression.  ” At the top, a long horizontal pink DNA strand contains five colored exons interspersed throughout its length. From left to right, the exons are: a teal section labeled Exon 1, a purple section labeled Exon 2, a brown section labeled Exon 3, a yellow section labeled Exon 4, and a blue section labeled Exon 5, with long pink sections of DNA between each exon. Below this are three different splicing variants. The left variant shows a horizontal strand with sections labeled Exon 1, Exon 2, Exon 3, Exon 4, and Exon 5 in teal, purple, brown, yellow, and blue respectively. Below this strand are protein structures shown as folded ribbons. The teal structure consists of a coiled region forming a compact shape. The purple structure is a coiled region forming a loop-like shape. The orange-brown structure forms a larger loop. The yellow structure forms an elongated loop shape. The blue structure is a small coiled region. These same colored structures with identical shapes appear in the other two variants below. The middle variant shows a horizontal strand with sections labeled Exon 1, Exon 2, Exon 4, and Exon 5 in teal, purple, yellow, and blue respectively, with Exon 3 omitted. Below this strand are the corresponding protein structures in teal, purple, yellow, and blue. The right variant shows a horizontal strand with sections labeled Exon 1, Exon 2, Exon 3, and Exon 5 in teal, purple, brown, and blue respectively, with Exon 4 omitted. Below this strand are the corresponding protein structures in teal, purple, orange-brown, and blue.” This image best illustrates ______.

The Trp operon is a repressible system. Tryptophan is the co-repressor for the operon.  Which correctly describes the Trp operon when tryptophan is not present?

How would an error with DNA ligase interfere with the replication of DNA?

If aminoacyl-tRNA synthetase fails to function properly, what part of protein synthesis will cease?

Regulation of gene expression occurs first at the DNA structural level, but it is even more tightly regulated at the transcription level. ______ are proteins that interact with the transcription factors and mediator proteins, allowing the trancription initiation complex to assemble and transcribe at a high level.

Genetic fingerprinting, the unique banding pattern of an individual, is possible because

Analysis of DNA sequences from two individuals of the same species results in a greater estimate of genetic variability than does analysis of amino acid sequences from the same two individuals because

Individual nucleotides in the nucleoplasm exist as nucleoside triphosphates, meaning they are composed of a nitrogenous base, a sugar, and three phosphates—just like ATP, except that the sugar is deoxyribose.  During DNA synthesis, the exergonic removal of the 2 unstable phosphate ions on the nucleotide drives the polymerization reaction, as the remaining phosphate is joined to the ___ end of the sugar before it.