Unit 1 - A & P Module - Cell Signaling and Transduction

Question 1

Which of the following statements about lipophilic hormones is true?

Answer 1

All answers are true.
1. The hormone-receptor complex forms in the nucleus.
2. The hormone-receptor complex forms in the cytosol.
3. The binding of the hormone-receptor complex to DNA can promote or inhibit transcription.
4. The effects of lipophilic messengers hormones are long lasting.

The majority of lipophilic hormone receptors are transcription factors that are either located in the cytosol and move to the cell nucleus upon activation, or remain in the nucleus waiting for the steroid hormone to enter and activate them.

Question 2

Lipophobic chemical messengers are also hydrophilic. The following describes lipophobic chemical messengers.

Answer 2

1. Fast from onset to response
2. Receptors are on the plasma membrane
3. Activate membrane-bound enzymes
4. Relatively short duration of response

Question 3

Up regulation allows a target cell to __________.

Answer 3

increase the sensitivity of a target cell to a ligand

Question 4

During peptide synthesis, a propeptide may be found in the __________.

Answer 4

endoplasmic reticulum, Golgi apparatus, or secretory vesicle

Question 5

The interaction between chemical messengers and their receptors is similar to the interaction between __________.

Answer 5

substrates and enzymes, ions and pore-type channels, and glucose transporter proteins in the cell membrane

Question 6

Steroid hormones found in the human body are varied, but the manner in which they act on target cells is quite similar, in that they have an affinity for binding sites located __________.

Answer 6

within the cytosol, on the outside of the plasma membrane, and in the nuclear envelope

Question 7

The cellular response to the second messenger cAMP can be inhibited by activating __________.

Answer 7

phosphodiesterase and Gi protein (an inhibitory G protein)

Question 8

Lipophilic hormones __________.

Answer 8

bind to receptors inside the cytoplasm or nucleoplasm

Question 9

In contrast to fast ligand-gated channels, slow ligand-gated channels __________.

Answer 9

are directly linked to enzymes such as guanylate cyclase and interact with G proteins

Question 10

Signal amplification can occur at the level of the __________.

Answer 10

G protein, protein kinase, and second messenger

Question 11

Which of the organ systems is known for producing a more focused, fast and directed response from target cells?

Answer 11

Nervous system

Question 12

When adenylate cyclase is activated, __________.

Answer 12

ATP is converted into cAMP (cyclic AMP)

Question 13

An intracellular signaling molecule produced by the binding of a ligand to a membrane-bound receptor is called a __________.

Answer 13

second messenger

Question 14

Intracellular calcium levels are kept in the submicromolar range (<10-6 molar) by the following mechanisms.

Answer 14

1. Binding to cytosolic proteins
2. Active transport across the cell membrane
3. Active transport into mitochondria