topic 7

Question 1

signal transduction pathways used for

Answer 1

converting extracellular signals into cellular responses

Question 2

two types of cell communication

Answer 2

local signaling and long-distance signaling

Question 3

what are the ways cells can communicate through local signaling (3)?

Answer 3

• direct contact
• cell-cell recognition
• local regulators

Question 4

what type(s) of local signaling do we see in both animal & plant cells?

Answer 4

direct contact

Question 5

what type(s) of local signaling do we see in only animal cells?

Answer 5

cell-cell recognition and local regulators

Question 6

what are cell junctions responsible for in direct contact signaling?

Answer 6

to allow molecules to pass readily between two adjacent cells without crossing the plasma membrane

Question 7

what is cell-cell recognition?

Answer 7

when animal cells communicate & recognize each other via direct contact using surface molecules (ex: carbohydrates)

Question 8

what are local regulators?

Answer 8

messenger molecules that travel only short distances (ex: neurotransmitters/growth factors)

Question 9

what two types of signaling use local regulators?

Answer 9

paracrine and synaptic signaling

Question 10

what is paracrine signaling?

Answer 10

a secreting cell acts on nearby target cells by discharging molecules of a local regulator (ex: growth factor) into the extracellular fluid

Question 11

what is synaptic signaling?

Answer 11

a nerve cell releases neurotransmitter molecules into a synapse, stimulating the target cell

Question 12

what are the types of cell junctions?

Answer 12

• communicating junctions
• occluding junctions
• anchoring junctions

Question 13

what are the type(s) of communicating junctions?

Answer 13

• gap junctions
• plasmodesmata

Question 14

what is the function of gap junctions?

Answer 14

allow molecule and ion exchange between animal cells

Question 15

where are gap junctions located?

Answer 15

along the apical surfaces of cells of various tissues (ex: epithelial)

Question 16

what are connexins?

Answer 16

membrane proteins that form gap junction channels

Question 17

where does the transport of Ca+2 between neighboring smooth muscle cells takes place?

Answer 17

Gap junctions

Question 18

what is the function of plasmodesmata?

Answer 18

allow molecule exchange in plant cells (ex: water)

Question 19

what are the type(s) of occluding junctions?

Answer 19

tight junctions

Question 20

what is the function of tight junctions?

Answer 20

• inhibit cell-to-cell communication (molecule exchange)
• create an exclusion zone around cells to prevent leakage of ECF from a layer of epithelial cells

Question 21

tight junctions connect to ____

Answer 21

actin microfilaments

Question 22

where are tight junctions located?

Answer 22

underneath the apical surface of epithelial cells

Question 23

the 2 transmembrane proteins are tight junctions made from?

Answer 23

• claudin
• occludin (linked to actin microfilaments)

Question 24

type(s) of anchoring junctions (cell-cell)

Answer 24

• desmosomes
• adherens junctions

Question 25

type(s) of anchoring junctions (cell-ECM)

Answer 25

• focal adhesion
• hemisdesmosomes

Question 26

actin filaments are present in

Answer 26

adherens junctions / focal adhesions

Question 27

intermediate filaments are present in

Answer 27

desmosomes/hemidesmosomes

Question 28

the function of desmosomes

Answer 28

anchor to the cytoplasm through intermediate filaments (ex: keratin)