Choose the transcript created if RNA polymerase transcribes the following template strand.

5'-ACTTGCAGGCC-3' 

What is the mRNA transcript of the given DNA sequence?

3' ACCTGTTAC 5'

If a gene has a sequence of 5'-AGCTGCCTT-3', what would be the complementary mRNA sequence that leaves the nucleus to be translated?

The base sequence of one strand of tRNA is v. What is the corresponding sequence of DNA?

You are a student researcher cloning a gene that is around 1500 bases long into a vector for recombinant expression. Starting with cDNA, you succesfully clone and transfect bacterial cells to propogate the plasmid. You sequence the plasmid to check and make sure that the target gene has been succesfully incoorporated into the vector. After checking the sequence, you notice that there is a single nucleotide that has been switched from an A to a G several hundred basepairs after the start codon. You express the protein anyway. After subjecting the protein to SDS-page, you learn that it exists at its expected length, but in a functional asssay, the protein seems to have lost its function. What type of mutation is this called?

In the DNA component of a chromosome, changes such as methylation result in alterations in how DNA is processed without changing its sequence. This is known as __________.

The concept of genomic imprinting is important in human genetics. In genomic imprinting, a certain region of DNA is only expressed by one of the two chromosomes that make up a typical homologous pair. In healthy individuals, genomic imprinting results in the silencing of genes in a certain section of the maternal chromosome 15. The DNA in this part of the chromosome is "turned off" by the addition of methyl groups to the DNA molecule. Healthy people will thus only have expression of this section of chromosome 15 from paternally-derived DNA.

The two classic human diseases that illustrate defects in genomic imprinting are Prader-Willi and Angelman Syndromes. In Prader-Willi Syndrome, the section of paternal chromosome 15 that is usually expressed is disrupted, such as by a chromosomal deletion. In Angelman Syndrome, maternal genes in this section are deleted, while paternal genes are silenced. Prader-Willi Syndrome is thus closely linked to paternal inheritance, while Angelman Syndrome is linked to maternal inheritance.

Figure 1 shows the chromosome 15 homologous pair for a child with Prader-Willi Syndrome. The parental chromosomes are also shown. The genes on the mother’s chromosomes are silenced normally, as represented by the black boxes. At once, there is also a chromosomal deletion on one of the paternal chromosomes. The result is that the child does not have any genes expressed that are normally found on that region of this chromosome.

The passage indicates that genomic imprinting can be the result of silencing genes by adding methyl groups to DNA sequences. Which of the following is true of methyl groups?

Histones are important components of chromosomes that help to form the scaffolding around which DNA wraps while organizing. Considering the structure of DNA, what is most likely true of histones?

The cell is the most basic functional unit of life.  Everything that we consider to be living is made up of cells, and while there are different kinds of cells, they all have some essential features that link them all together under the category of "life."  One of the most important parts of a cell is the membrane that surrounds it, seperating it from the rest of the environment.

While organisms from the three main domains live in incredibly different environments, they all possess similar cell membranes.  This phospholipid bilayer protects the cell, giving it a way to allow certain things in while keeping other things out.  Though organisms from different domains have different kinds of fatty linkages in their membranes, they all serve this essential purpose.

Membranes contain all kinds of essential proteins and signal molecules that allow the inside of the cell to respond to the outside of the cell.  In a multicellular eukaryote, this ability can be used to allow cells to communicate.  In a bacterial colony, an extracellular signal could be used to signal other bacteria.  Signals cascade through a series of molecular pathways that go from the outside of the cell all the way to the nucleus and back out again, giving the cell control on a genetic level.  This allows cellular responses to be quick and effective, and it also allows the cell to control how long it stays in that state.

What is an important aspect of the control a cell has over its molecular responses?

One component of the immune system is the neutrophil, a professional phagocyte that consumes invading cells. The neutrophil is ferried to the site of infection via the blood as pre-neutrophils, or monocytes, ready to differentiate as needed to defend their host.

In order to leave the blood and migrate to the tissues, where infection is active, the monocyte undergoes a process called diapedesis. Diapedesis is a process of extravasation, where the monocyte leaves the circulation by moving in between endothelial cells, enters the tissue, and matures into a neutrophil.

Diapedesis is mediated by a class of proteins called selectins, present on the monocyte membrane and the endothelium. These selectins interact, attract the monocyte to the endothelium, and allow the monocytes to roll along the endothelium until they are able to complete diapedesis by leaving the vasculature and entering the tissues.

The image below shows monocytes moving in the blood vessel, "rolling" along the vessel wall, and eventually leaving the vessel to migrate to the site of infection.

The maturation of monocytes into neutrophils requires the expression of new segments of DNA. The expression of these genes is mediated by demethylation of the needed DNA sequences. This is an example of __________.