Chapter 11

Question 1

Prokaryotic single-cell communication: Baker’s yeast

Answer 1

Ex: A Saccharomyces cerevisiae cell uses chemical signaling to identify mates.
1) 2 cells exchange specific mating factors
2) binding of the specific factors to receptors leads to cell fusion (mating)
3) both cells completely fuse; the nucleus of the fused cell includes the gene/DNA from both the cells (a+α)

Question 2

Prokaryotic single-celled communication: Bacterial cells - biofilms

Answer 2

Quorum sensing: allows bacteria populations to coordinate behavior of all cells in a population.
Example of this are biofilms, which is an aggregation of bacteria cells attached to a surface by molecules secreted by the cells, but only after the cells reach a certain density.

Question 3

An eukaryotic multicellular organism’s need for communication

Answer 3

Specifically important in embryonic development, the immune response, and in maintaining adult stem cell populations.

Question 4

External signals

Answer 4

Responses within the cell :) and come front outside the “target” cell
- Steroid molecules
- glycoproteins
- dipeptides
- Amino Acids - CO, NO

Question 5

Signal Transduction Pathway

Answer 5

A series of 3 steps: SIGNAL RECEPTION, SIGNAL TRANSDUCTION, and CELLULAR RESPONSE.
Explains how the binding of a mating factor by the yeast cell receptor initiates the cellular response of mating.

Question 6

Local signaling

Answer 6

up to a few cells’ distance
ex: paracrine & synaptic

Question 7

Long distance signaling

Answer 7

up to body-length distance
ex: endocrine

Question 8

Paracrine signaling

Answer 8

a signaling cell acts on nearby target cells by secreting molecules of a local receptor (ex: a growth factor)
(Just to neighboring cells, fast - just into ECF, only a handful of target cells)

Question 9

Synaptic signaling

Answer 9

a nerve cell releases neurotransmitter molecules into a synapse, stimulating the target cell, such as a muscle or another nerve cell
(sort of a subset of paracrine, super fast - because it is just from 1 target cell across the synaptic cleft)

Question 10

Endocrine signaling

Answer 10

specialized endocrine cells secret hormones into bodily fluids, often blood to travel throughout the body. The hormones reach most body cells, but are bound by and affect only some cells.
(Long distance, slow-ish, highest number of target cells - only can respond if the cells have specific receptors)
PRIMARY MESSENGER = 1° messenger

Question 11

Autocrine signaling

Answer 11

sort of a subset of paracrine signaling
cell secrets signal
PRIMARY MESSENGER = 1° messenger

Question 12

Cell to cell communication via cytosol

Answer 12

gap junctions (between animal cells) & plasmodesmata (between plant cells)

Question 13

Cell to cell communication via surface molecules

Answer 13

cell surface molecules
- in many animal cells, cell-surface molecules on adjacent cells interact with each other, resulting in a signal passing between the cells

Question 14

Reception

Answer 14

The target cell’s detection of a signaling molecule coming from the outside. A chemical signal is “detected” when the signaling molecule binds to a receptor protein located on the cell’s surface.

Question 15

Transduction

Answer 15

The binding of the signal molecule to the receptor protein changes the protein’s shape which initiates the transduction process. This stage converts the chemical “signal” to a form that can bring about a specific cellular response.

Question 16

Response

Answer 16

After the chemical signal undergoes transduction, the response can be any imaginable cellular activity.
The cellular response to a transduced signal.

Question 17

G-Protein coupled receptors (GPCRs)

Answer 17

G-protein = GTP - binding protein

Question 18

Signal Reception

Answer 18

Requires a receptor.
Plasma membrane receptors are required by