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Put the steps of the process of signal transduction in the order they occur:
1. A conformational change in the signal-receptor complex activates an enzyme.
2. Protein kinases are activated.
3. A signal molecule binds to a receptor.
4. Target proteins are phosphorylated.
5. Second messenger molecules are released.

3, 1, 5, 2, 4

Of the following, where would you expect to find tight junctions?

in the epithelium of an animals stomach

What does it mean to say that a signal is transduced?

The physical form of the signal changes between the outside of the cell and the inside.

Osteocytes are bone cells. Collagen fibers and calcium salts are found in abundance between and among the osteocytes. The collagen and calcium salts are _____.

part of the extracellular matrix

Which statement best describes what would happen if you treated cells in a developing frog embryo with a molecule that blocked a cadherin observed in muscle tissue?

Adhesion of muscle cells to cells of non-muscle tissues would be disrupted.
The formation of the middle lamella between adjacent muscle cells would be disrupted.
Connections between the cytoskeleton of muscle cells and the ECM would be disrupted.
Adhesion of muscle cells to other muscle cells would be disrupted.

Adhesion of muscle cells to other muscle cells would be disrupted.

Because each cadherin can bind only to cadherins of the same type, only adhesion of muscle cells to other muscle cells would be affected.

Why does a hormone only act on specific cell types in an organism and not others?

A cell must have the appropriate receptor before it can bind to the hormone.

One characteristic of life and living systems is that they are able to adapt. Toward this end, cells interact with other cells and their environment through the action of their _____.

plasma membrane and extracellular matrix

Which statement most accurately explains how some signals are amplified?

More hormone is produced.
Receptors are blocked.
Second messengers are produced.
Enzymes remove phosphate groups from proteins.

Second messengers are produced.

How can a hormone that is present in very small quantities within the bloodstream elicit such a large response within a cell?

The message from the hormone is amplified many times within the cell.

A gap junction is a channel that connects adjacent cells. From substances listed, which one cannot pass through a gap junction?
ions that can regulate heartbeat
amino acids


The receptors for steroid hormones are located inside the cell, instead of on the membrane surface like most other signal receptors. Why is this not a problem for steroids?

because steroid hormones are lipid soluble so can readily diffuse through the lipid bilayer of the cell membrane

Intercalated discs are cell-cell junctions found between cardiac muscle cells. One feature of these intercalated discs is that they contain a large number of gap junctions, which means that _____.

water ions and small molecules can readily pass from one cardiac muscle cell to the next

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