Elysia chlorotica is a sea slug that acquires chloroplasts by consuming an algal food source, Vaucheria litorea. The ingested chloroplasts are sequestered in the sea slug's digestive epithelium, where they actively photosynthesize for months after ingestion. In the algae, the algal nuclear genome encodes more than 90% but not all of the proteins required for chloroplast metabolism. Thus it is suspected that the sea slug actively maintains ingested chloroplasts, supplying them with photosynthetic proteins encoded in the sea slug genome. How would you determine whether the sea slug has acquired photosynthetic genes by horizontal gene transfer from its algal food source? Discuss the steps required for heritable endosymbiosis to eventuate, and their plausibility.

The interphase nucleus is a highly structured organelle with chromosome territories, interchromatin compartments, and transcription factories. In cultured human cells, researchers have identified approximately 8000 transcription factories per cell, each containing an average of eight tightly associated RNAP II molecules actively transcribing RNA. If each RNAP II molecule is transcribing a different gene, how might such a transcription factory appear? Provide a simple diagram that shows eight different genes being transcribed in a transcription factory and include the promoters, structural genes, and nascent transcripts in your presentation.

The accompanying illustration shows a portion of a gene undergoing transcription. The template and coding strands for the gene are labeled, and a segment of DNA sequence is given. For this gene segment:

Write the polarity and sequence [TIP 1] of the RNA transcript from the DNA sequence given.

The accompanying illustration shows a portion of a gene undergoing transcription. The template and coding strands for the gene are labeled, and a segment of DNA sequence is given. For this gene segment:

Indicate the direction in which RNA polymerase moves as it transcribes this gene.

The accompanying illustration shows a portion of a gene undergoing transcription. The template and coding strands for the gene are labeled, and a segment of DNA sequence is given. For this gene segment:

Superimpose a drawing of RNA polymerase as it nears the end of transcription of the DNA sequence.

The accompanying illustration shows a portion of a gene undergoing transcription. The template and coding strands for the gene are labeled, and a segment of DNA sequence is given. For this gene segment:

Identify the direction in which the promoter [TIP 2] for this gene is located. [Diagram below appears here] 

Most large protein complexes in mitochondria and chloroplasts are composed both of proteins encoded in the organelle genome and proteins encoded in the nuclear genome. What complexities does this introduce for gene regulation (i.e., for ensuring that the appropriate relative numbers of the proteins in a complex are produced)?

The DNA sequence below gives the first 12 base pairs of the transcribed region of a gene, and the template and nontemplate strands of DNA are identified. The transcription start is the thymine nucleotide at the end of the sequence given. Use the diagram to answer the list of questions. Make a copy of the diagram before you begin answering the questions, or have one group member diagram the answers for bacteria and another group member diagram the answers for eukaryotes.

Nontemplate strand  ___________TTGCTACGGTCA___________
Template strand        ___________AACGATGCCAGT___________

Write the anticipated eukaryotic consensus sequence(s) in the approximate position(s) on the diagram.

The DNA sequence below gives the first 12 base pairs of the transcribed region of a gene, and the template and nontemplate strands of DNA are identified. The transcription start is the thymine nucleotide at the end of the sequence given. Use the diagram to answer the list of questions. Make a copy of the diagram before you begin answering the questions, or have one group member diagram the answers for bacteria and another group member diagram the answers for eukaryotes.

Nontemplate strand  ___________TTGCTACGGTCA___________
Template strand        ___________AACGATGCCAGT___________

Assuming the sequence shown is part of a eukaryotic gene, what consensus sequence(s) would you expect to identify within about 100 base pairs of the start of transcription?