Chapter 11: Cell Communication

Question 1

Quorum Sensing

Answer 1

allows bacterial populations to coordinate the behavior of cells in a population, requires cells with given densities to be acting at the same time

Question 2

Biofilm

Answer 2

example of quorum sensing, aggregation of bacteria cells attached to a surface by molecules secreted by the cell, only after the cells have reached a certain density

Question 3

Saccharomyces Cerevisiae

Answer 3

cells of yeast, used to make bread, wine, and beer, identify sexual mates when they chemically signal reproduction, 2 sexual mating types are a and aplha

Question 4

Sexual Mating Types in Yeast

Answer 4

each type secretes specific factors that bind only to receptors on the other cell, unique match between mating factors and receptors is key in mating only within the same species of yeast cells

Question 5

Steps in Binding Mating Factors and Receptors

Answer 5

1: signal reception
2: signal transduction
3: cell response

Question 6

Local Signaling

Answer 6

eukaryotic cells communicating through direct contact, cell junctions directly connect the cytoplasm of adjacent cells, cell surface molecules can also interlock, key to embryonic development, immune responses, and stem cell production

Question 7

Paracrine Signaling

Answer 7

local regulators that influence nearby cells

Question 8

Growth Factors

Answer 8

local regulator class, in animal cells, stimulates nearby target cells to grow and divide

Question 9

Synaptic Signaling

Answer 9

very specialized type of local signaling, occurs in the animal nervous system, nerve cell releases the neurotransmitter molecules into the synapse and stimulates the target cells

Question 10

Hormones

Answer 10

molecule in plant and animal cells, long-distance signaling, also known as endocrine signaling in animals

Question 11

Effects of Epinephrine

Answer 11

mobilizes fuel reserves which help signal fight or flight responses, breaks down glycogen

Question 12

Signal Reception

Answer 12

the target cell’s detection of a signaling molecule coming from outside a cell, chemical signal is “detected” when a signaling molecule is bonded to a receptor protein on the cell’s surface

Question 13

Signal Transduction

Answer 13

the binding of a signaling molecule changes the receptor protein to initiate the transduction, this stage converts the signal into a form that can bring a specific cellular response, often requires a sequence of changes in a series of molecules

Question 14

Cellular Response

Answer 14

the transduced signal finally triggers a specific response that can be almost any imaginable action in the body, ensures that crucial activities occur at the right time and place

Question 15

Ligand

Answer 15

molecule that specifically binds to another molecule that binds to another molecule, causes a receptor protein to change the shape which directly activates the receptor so it can interact with another molecule

Question 16

G-Protein Coupled Receptor

Answer 16

GPCR, largest family of human cell surface receptors, more than 800GPCR

Question 17

3 Major Types of Transmembrane Receptors

Answer 17

GPCR, receptor tyrosine kinase (RTK), ion gated channels

Question 18

Ligand Gated Ion Channels

Answer 18

membrane channel, key to the nervous system, opens and closes as the channel changes shape, ion flow triggers an electrical signal that flows down the length of the receiving cell

Question 19

Transcription Factors

Answer 19

protein that controls which gene is turned on in a cell at a specific time

Question 20

Signal Transduction Factors

Answer 20

found in the cytoplasm or nucleus of target cells, to reach the receptors a signaling molecule passes through the target cell’s plasma membrane, once a hormone or signaling molecule enters a cell, its binding to an intracellular receptor changes the receptor into a hormone receptor complex that causes a response, signal activated receptor activates another molecule and so on until the protein that produces the final cellular response is activated

Question 21

Relay Molecules

Answer 21

relays signals from receptors to responses, often proteins

Question 22

Protein Kinase

Answer 22

enzyme that transfers a phosphate group from ATP to a protein, act on proteins different from themselves, phosphorylate two amino acids (serine, threonine) instead of tyrosine like in RTK

Question 23

Phosphorylation Cascade

Answer 23

a series of different proteins in a pathway that are phosphorylated, each protein adding a phosphate group to the next one in line, phosphorylation activates the protein and dephosphorylation returns it to its inactive form

Question 24

Protein Phosphatases

Answer 24

enzyme that can rapidly remove phosphate groups from proteins through dephosphorylation, provide the mechanism for turning off the signal transduction pathway when the initial sign is no longer present, makes protein kinase available for reuse

Question 25

Second Messengers

Answer 25

small, non-protein, water-soluble component to the signal transduction pathway, moves through cells quickly through diffusion, participates in pathways initiated by both GPCR and RTK

Question 26

2 Most Common Second Messengers

Answer 26

cyclic AMP and calcium ions

Question 27

Cyclic AMP

Answer 27

cAMP, small molecule produced from ATP, adenyl cyclase is the enzyme embedded in the plasma membrane that converts ATP into cAMP in response to extracellular signals

Question 28

Phosphodiestrase

Answer 28

enzyme that converts cAMP into AMP

Question 29

Inhibitory G-Protein

Answer 29

blocks the activation of adenylyl cyclase

Question 30

Cyclic GMP

Answer 30

second messenger, causes muscle relaxation

Question 31

Calcium Ions

Answer 31

widely used second messenger, causes muscle contractions, exocytosis of molecules, and cell division, cells use Ca2+ ions as a second messenger in pathways triggered by GPCR and RTK, actively transported in and out of cells and their cytosol into the endoplasmic reticulum

Question 32

Inositol Triphosphate

Answer 32

IP3, second messenger produced by a certain kind of phospholipid in the plasma membrane

Question 33

Diaglycerol

Answer 33

DAG, second messenger produced by a certain kind of phospholipid in the plasma membrane

Question 34

Transcription Factor

Answer 34

final activated molecule in a signaling pathway, may function as a transcription factor, turns genes on, regulates a gene by turning it off, regulates protein activity

Question 35

4 Aspects of Regulation

Answer 35

amplification, regulation, response, termination

Question 36

Amplification

Answer 36

caused by signal cascades, effect stems from the fact that the proteins are able to process multiple molecules of substrate before becoming inactive again

Question 37

Specificity of Cell Signaling and Coordination of the Response

Answer 37

different kinds of cells turn on different genes and have different collections of proteins, responses of a cell to a signal depends on its particular collection of signal receptor proteins, relay proteins, and response proteins

Question 38

Signaling Efficiency: Scaffolding Proteins and Signaling Complexes

Answer 38

most relay molecules are proteins and proteins are too large to diffuse quickly through the cytosol, relay proteins serve as points of branching or intersecting in signaling pathways, when they malfunction it causes many issues like bleeding, eczema, and cancer

Question 39

Scaffolding Proteins

Answer 39

increases efficiency of signal transduction, large relay proteins that several other relay proteins are attached to

Question 40

Termination of the Signal

Answer 40

when the amount of active receptors falls below that the cellular responses stop all together

Question 41

Apoptosis

Answer 41

controlled cell suicide, happens when a cell has reached its programmed life span or it is infected/damaged, cellular agents chop up DNA and fragment other organelles and cytoplasmic components, cell shrinks and becomes lobed, dead parts are placed into vesicles and are engulfed and digested by specialized cells

Question 42

Proteins Used in Mitochondrial Apoptosis

Answer 42

Ced-3, Ced-4, Ced-9, thought of as relay proteins capable of transducing apoptotic signals

Question 43

Uses of Apoptosis

Answer 43

development and maintenance of all animal cells, evolved early in evolution of eukaryotes, no apoptosis can lead to webbed fingers and toes, also can be linked to alzheimers and parkinsons due to the accumulation of proteins in neural cells