Exam 7: Cell Communication and Multicellularity

Calcium ions can serve as second messengers in signal transduction pathways.Mechanisms in the cell can regulate calcium signals that have been activated during a signal transduction pathway.Which is a calcium regulation mechanism by which the cell returns to the state it was in before the pathway was initiated?

Lipid-derived second messengers such as IP₃

Vitamin D is a relatively small, lipid-soluble molecule that can behave as a hormone.Its receptor, therefore, most likely

Which graph portrays the change in number of molecules activated at each successive step in a signal transduction pathway?

Which statement about plasmodesmata is false?

The receptor for estrogen is

Connexons are channel structures that make up

Refer to the figure below. Write an equation to express the chemical reaction shown, and explain how this reaction is involved in signal transduction.

The drug sildenafil (Viagra) increases cGMP levels, so which enzyme is most likely inhibited by Viagra?

Sometimes a transcription factor within the cytoplasm can act as an intracellular receptor for a ligand.When activated, such transcription factors can alter gene expression by

Refer to the figures below. Each of the four figures represents a different type of cell signal.Which of the following correctly matches each figure with its cell signal type?

Refer to the figure below. Part of the signal transduction mechanism common to G protein-coupled receptors is shown.Which step occurs next?

Many G proteins have three polypeptide subunits that can bind a

A signal made by a cell that affects that same cell is a(n)

Refer to the figure below, which represents structures connecting adjacent cells in multicellular organisms. The structures shown are found in (plants/animals) _______.

The second messenger that is not formed as the result of a chemical reaction is

A juxtacrine signal affects

Which statement about nitric oxide is true?

Which statement about protein kinase receptors is false?

Refer to the figure below. Based on the figure, which statement about the acetylcholine receptor is true?