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| The signals received by cells, whether originating from other cells or from changes in the physical environment, take various forms, including light and touch. However, cells most often communicate with each other by _____ signals. | chemical |
| Scientific evidence that shows similarities between cell signaling mechanisms in many different types of organisms suggests that these signaling pathways first evolved in ____________. | single-celled organisms |
| The process by which a signal on a cell's surface is converted into a specific cellular response is a series of steps called a(n) ______________. | signal transduction pathway,  |
The type of signaling called cell-cell recognition is important in such processes as ______ and ______.,  | embryonic development and immune response (Cells in developing embryos start to differentiate due to their location and proximity to other cells, so they have to know what other cells they are near. Immune cells need to be able to tell the difference between cells that belong and invading cells) |
| Messenger molecules that travel only short distances are called _________. | local regulators (the red molecules below),  |
| Local signaling involves the secretion of signaling molecules that act on ______ cells. | nearby, |
| Signaling molecules that communicate with distantly located cells by entering and travelling through the circulatory (in animals) system until their target is reached are called _____. | hormones (plants have hormones also),  |
| The transmission of a signal from one end of a long neuron to the other end is accomplished by transmitting a(n) ______ signal down the neuron. | electrical signal (This can be considered a form of long distance communication due to the long length of most nerve cells) |
| The process going on at the receiving end of a cellular conversation can be broken down into three steps; ______, ______, and _______. | reception, transduction, and response, |
| A chemical signal is "detected" when it binds to a _____ protein located at the cell's surface or inside the cell. | receptor protein |
| During the reception stage, a signal molecule binds to a ________ protein, causing it to ____________ | receptor protein, change shape |
| Most receptors are found on the _______. | outside of the plasma membrane |
| The three major types of membrane receptors are _____, ______, and ______. | G-protein-linked receptors, receptor tyrosine kinases, and ion channel receptors |
| What type of signaling is being shown in the picture below, | hormonal (or endocrine) signaling, |
| What type of signaling is being shown in the picture below?, | local signaling, |
What type of signaling is being shown in the picture below?,  | long-distance signaling, |
Which of the three stages of a signal transduction pathway is shown under the #1?,  | reception, |
| Which of the three stages of a signal transduction pathway is shown under the #2?, | transduction, |
| Which of the three stages of a signal transduction pathway is shown under the #3?, | response, |
The space between the two cells in the picture below is called the ______.,  | synapse, |
