Yeast cells, plant cells, and mammal cells all share many similarities in cell signaling. This provides evidence that (2 points) cell-signaling mechanisms are only found in organisms that use methods of sexual reproduction

intercellular communication evolved as a way for multicellular organisms to coordinate cell functions

eukaryotic cells use signal transduction pathways while prokaryotic cells use a more primitive form of signaling

signal transduction pathways appeared in cells before the evolution of multicellular organisms

2.
What type of signaling is represented in the figure? (2 points)

An elongated cell releases small molecules into a very narrow space between it and the target cell.
© 2012 FLVS

autocrine

hormonal

paracrine

synaptic

3.
Cells can use different types of signaling to achieve different goals. Which of the following best describes hormonal signaling in animals? (2 points)

A hormonal signal can be directed to a very specific target because a narrow space separates the target cell from the transmitting cell.

A concentration gradient between the signaling and target cells is established, causing cells along the gradient to respond differently.

Numerous cells can receive and respond to the hormonal signal produced in their local vicinity.

Specialized cells release hormone molecules into the circulatory system, allowing distant target cells to be affected.

4.
Dioxin, a by-product of various industrial chemical processes, is suspected of contributing to the development of cancer and birth defects in animals and humans. It enters the cells by simple diffusion, binds to proteins in the cytoplasm, and alters the pattern of gene expression. Based on this description, which of the following are most likely to be the cytoplasmic proteins to which dioxin binds? (2 points)

DNA polymerases

enhancers

nucleosomes

transcription factors

5.
What type of receptor is described in the following paragraph? (2 points)

Binding of a signaling molecule to this type of receptor uses an enzyme to remove a phosphate group from an ATP molecule to activate another receptor. The activated receptor can be recognized by relay proteins inside the cell, which bind to the receptor and change shape. These activated proteins then trigger a transduction pathway that leads to some sort of cellular response.

intracellular receptor

ligand-gated ion channel

g protein-coupled receptor

receptor tyrosine kinase

6.
For each of the three types of cell-surface transmembrane receptors listed below, explain how the receptor operates and state an example of where this type of receptor can be found. (5 points)
Ion channel receptors
Receptor tyrosine kinases
G protein-coupled receptors

7.
Biological recognition is important in processes at the molecular, cellular, and organismal levels. Choose ONE of the following, explain how the process of recognition occurs, and discuss a specific example. (5 points)
Neurotransmitters are recognized in the synapse.
Target cells respond to specific hormones.