Exam 7: Cell Communication and Multicellularity

In a signal transduction pathway involving G protein-coupled receptors, the receptor first binds the ligand and activates a G protein.After the GTP-bound subunit of the G protein separates from the rest of the G protein, it travels until it encounters

The second messengers inositol trisphosphate, calcium ions, and nitric oxide are all similar in that they can

Refer to the table below. This table was created to summarize features of ligands, agonists, and antagonists.How many cells in the table contain an error?

Refer to the figure and table below. A researcher treated mouse kidney cells growing in culture so that they took up a fluorescent dye into their cytosols without losing viability.(This dye undergoes a change in fluorescence intensity upon binding calcium ions.) The treated cells were then incubated with and without a compound thought to act as a signaling molecule, and the cells were observed for changes in fluorescence.The researcher hypothesizes that the signaling molecule functions according to the pathway shown in the diagram above.As a next step, the researcher wants to acquire evidence that IP₃ is involved in this pathway.Which procedure will provide needed evidence about IP₃ as the entire experiment is repeated?

Gap junctions that span the gap between plasma membranes of two cells are composed of

In some signal transduction pathways, a small nonprotein molecule or ion known as a(n) _______ diffuses through the cytoplasm and mediates the interaction between the receptor and the response of the cell.

Which statement about plasmodesmata is true?

Refer to the two figures below. The receptor portions of two signal transduction pathways are shown.The two mechanisms underlying these pathways are similar in that they both involve

A biologist discovers a new signal transduction pathway in fruit flies that involves a protein kinase cascade.As part of a grant proposal he writes to obtain funding for further work on this pathway, the biologist proposes research to look for phosphatase enzymes.Why?

A researcher discovered a small protein secreted by the pituitary that functions as a growth factor to stimulate cell division in mouse skin cells.The skin cells of mice that have a mutation in a particular gene do not respond to this growth factor.When the researcher isolated and sequenced the gene, she found that it coded for a protein kinase.Which statement best explains this?

Which of the following has its receptors on a gated ion channel for sodium ions (Na⁺)?

Refer to the figure below. Consider that each time a growth factor binds to its receptor as shown in the figure, two ras G proteins are activated and each ras G protein activates one raf protein.If each raf then activates ten MEK molecules and each activated MEK activates ten molecules of MAP kinase, the original signal will be amplified by a factor of

Compare direct communication via plasmodesmata or gap junctions with receptor-mediated communication between cells.What are the advantages of one method over the other?

A molecule that binds to the particular three-dimensional structure of a receptor site is known as a(n)

Refer to the figure below. Given the steps shown, what happens next?

Refer to the table below. The table shows data collected from studies comparing normal and mutant cells.Mutant cells differ from normal cells in having a mutation in the gene encoding a receptor protein.The mutation results in a single amino acid change from a serine to a cysteine.A possible effect of the mutation is that receptor protein

Which molecule binds directly to a protein kinase receptor?

A sequence of chemical reactions that occurs within a cell in response to a signal is a(n)

Which statement about calcium ions is true?

Three types of cell membrane receptors are