Chapter 9: Cell Communication

Question 1

effective cell signaling requires:

Answer 1

1. ligand
2. receptor protein
3. transduction pathway (produces cellular response)

Question 2

the ligand is a ______

Answer 2

signaling molecule that binds to a specific receptor protein

Question 3

the 2 types of ligands are:

Answer 3

1. hydrophilic (cannot cross the cell membrane)
2. hydrophobic (can cross the cell membrane)

Question 4

transduction is _________

Answer 4

the conversion of a signal from outside the cell to a form that causes a specific cellular response

Question 5

the location of the receptor for hydrophobic ligands is _______

Answer 5

intracellular

Question 6

the location of the receptor for hydrophilic ligands is ________

Answer 6

cell surface

Question 7

the methods of signaling based on distance from source to receptors are:

Answer 7

1. direct contact
2. paracrine signaling
3. endocrine signaling
4. synaptic signaling
5. autocrine signaling

Question 8

direct contact is _______

Answer 8

the direct contact of adjacent plasma membranes for cellular communication

Question 9

an example of direct contact is ______

Answer 9

a gap junction, which is a junction between adjacent animal cells that allows for the passage of signals between cells

Question 10

direct contact is important in _______

Answer 10

embryonic development and immune response

Question 11

paracrine signaling is ________

Answer 11

local signaling where secretion from one cell has an effect on cells in the immediate area

Question 12

paracrine signaling is _______ and can be destroyed by ________

Answer 12

1. short lived
2. extracellular enzymes

Question 13

an example of paracrine signaling is ________

Answer 13

growth factors, which are local regulators in animals that stimulate nearby target cells to grow and divide

Question 14

endocrine signaling is _________

Answer 14

long distance signaling where hormones are released into the blood stream, which carries them to the target cell

Question 15

a hormone is _____

Answer 15

a molecule (usually peptide or steroid) that is produced in one part of an organism and triggers a specific reaction in target tissues or organs some distance away

Question 16

hormones are released from ______

Answer 16

glands

Question 17

the 2 types of glands are:

Answer 17

1. endocrine gland
2. exocrine gland

Question 18

the endocrine gland is a ________

Answer 18

ductless gland that secretes hormones into the extracellular space, where they diffuse into the circulatory system

Question 19

the exocrine gland is a _______

Answer 19

type of gland that releases its secretion through a duct, such as a digestive gland of a sweat gland

Question 20

synaptic signaling is ________

Answer 20

the transmission of neurotransmitters from a nerve cell to a synaptic gap (or synaptic clift)

Question 21

a synaptic gap is ________

Answer 21

the gap between a nerve cell (signaling cell) and a target cell (another nerve cell or muscle cell)

Question 22

autocrine signaling is when _____

Answer 22

cells send signals to themselves, which will bind the secreting signals to specific receptors on the cells own membrane

Question 23

the 2 types of receptors are:

Answer 23

1. intracellular receptors
2. cell surface receptors

Question 24

intracellular receptors are found in the _______

Answer 24

nucleus or cytoplasm

Question 25

intracellular receptors are specific for _______

Answer 25

hydrophobic ligands

Question 26

process of intracellular receptors:

Answer 26

1. hormones cross plasma membrane and bind to cytoplasmic receptors 2. hormone binding alters receptor conformation so it no longer binds inhibitor 3. hormone-receptor complex translocates to nucleus (acts as transcription factor) 4. hormone-receptor complex binds to DNA, usually turning on transcription but can also turn it off 5. cellular response is change in gene expression

Question 27

transcription is _______

Answer 27

when dna is used to create mrna, which will exit to the cytoplasm and translate to a protein, bringing about a specific cellular response

Question 28

an example of an intracellular receptor is _______

Answer 28

the receptor for nitric oxide (NO), which is a ligand released by neurons that innervates the penis, gastrointestinal tract, and cerebral blood vessels

Question 29

nitric oxide works in the body by _______

Answer 29

crossing the cell membrane of the muscle cells that line blood vessels and binding to the enzyme **guanylyl cyclase**, which acts as a receptor and catalyzes the synthesis of cGMP which, in the smooth lining, the walls of vertebrate blood vessels cause the relaxation of muscle cells, allowing for blood vessels to expand so more blood can flow in.

Question 30

some additional examples of an intracellular receptor are _______

Answer 30

receptors for testosterone, cortisol, estrogen, and progesterone. these receptors act as regulators of gene transcription