5.6: The plasma membrane plays a key role in most cell signaling

Question 1

local regulators

Answer 1

they are signaling molecules dissolved in the cytosol that are used to communicate short distances, growth factors are good examples of these

Question 2

Where do signaling molecules typically come from

Answer 2

from other signaling cells

Question 3

Types of local signaling include…

Answer 3

direct contact through junctions, cell to cell rec. , paracrine, and synaptic signaling

Question 4

Cell Junction

Answer 4

directly connect cytoplasms of very close cells, type of local signaling

Question 5

Plasmodesmata

Answer 5

cell junctions but for plants

Question 6

Paracrine signaling

Answer 6

where local regulators influence the cells in a certain vicinity

Question 7

synaptic signaling

Answer 7

in the nervous system, a nerve cell is triggered by an electrical signal which makes the nerve cells secrete a neurotransmitter molecule carrying a chemical signal, these molecules then diffuse into the synapses

Question 8

An example of long distance signaling is…

Answer 8

endocrine signaling

Question 9

endocrine signaling

Answer 9

specialized cells release hormones, in animals, these hormones travel through the circulatory system, in plants they move through air and gas

Question 10

hormones

Answer 10

used for long-distance signaling, many types

Question 11

What are the 3 stages of cell signaling?

Answer 11

Reception, Transduction, and Response

Question 12

Reception

Answer 12

The target cell’s detection of signal molecules when they bind

Question 13

Where does reception usually take place

Answer 13

in the cell or on its membrane

Question 14

ligand

Answer 14

general term for a signaling molecule with a receptor protein causes shape change in the protein when binded

Question 15

Transduction

Answer 15

The conversion of the signal to a for that can bring about a specific cellular response, basically series of reactions happen to where it can make a response

Question 16

signal transduction pathway

Answer 16

series of steps where a signal on a cell’s surface is converted into a specific response

Question 17

Response

Answer 17

The specific cellular response to the signal molecules

Question 18

What is the significance of the receptor protein changing shape when it binds to the signaling molecule

Answer 18

The binding of ligand and a receptor is very specific, the following shape change of the receptor molecule causes it to react with other cellular molecules

Question 19

Intracellular receptors

Answer 19

found inside the plasma membrane in the cytoplasm/most often in the nucleus, ligand must be small and hydrophobic

Question 20

Plasma membrane receptors

Answer 20

found in the plasma membrane, hydrophilic ligands

Question 21

G protein-coupled receptor(GPCR)

Answer 21

surface transmembrane receptor that works with the help of a G protein, this type of reception is used by other hormones and neurotransmitters

Question 22

G protein

Answer 22

Protein that is activated by exchanging its GDP with GTP

Question 23

Step of 1 of G-protein-linked reception

Answer 23

1. Ligand binds to G proteins-couples receptor(type of receptor)
2. Makes a shape change in the receptor so it binds to inactive G protein
3. This causes a GTP to replace GDP, thus activating the G protein(happens when G protein binds to the receptor)

Question 24

Step of 2 of G-protein-linked reception

Answer 24

4. The newly activated G protein binds to a specific enzyme(activates enzyme)
5. This activation of the enzyme causes a cellular response(only one)
6. The shape change is back to normal and the G protein hydrolyzes its GTP back to GDP to repeat the process after the receptor leaves

Question 25

How does the G-protein-linked reception cause cholera

Answer 25

a high concentration of cAMP causes intestinal cells to secrete large amounts of waste

Question 26

Step 1 and 2 of receptor tyrosine kinases

Answer 26

1. The binding of signal molecules(two of the same type) to the receptors 2. This causes the formation of a dimer 3. dimer: structure of many tyrosine kinases that receives an ATP(phosphorylation) molecule

Question 27

Step 3 and 4 of receptor tyrosine kinases

Answer 27

The inactive relay model becomes active by attaching to the receptor tyrosine kinase proteins(multiple responses based on number of Tyrosines)

Question 28

What is the key difference between G-protein-linked reception and receptor tyrosine kinases

Answer 28

single ligand can activate with G-protein so single response, multiple cellular responses in tyrosine kinase depends on the number of phosphates attached

Question 29

ligand-gated ion channel

Answer 29

Is a gate for ions when the receptor changes shape(gated ion channel)

Question 30

explain how the ligand-gated ion channel works

Answer 30

when a receptor is bound to a ligand, the ion gate allows for specific ions to come in (opens and closes),these ions are moving down their electronegative gradient(facilitated diffusion), the process is reset through the receptor leaving

Question 31

what systems require the ligand-gated ion channel

Answer 31

very important in the nervous system, diffusion of ions can cause an electrical signal

Question 32

What are the 3 membrane receptors

Answer 32

G-protein-linked receptors, Receptor tyrosine kinases, and ligand-gated ion channel

Question 33

What is an example of an intracellular receptor

Answer 33

Steroid Hormone Interacting with an Intracellular Receptor

Question 34

Explain how a Steroid Hormone Interacting with an Intracellular Receptor works

Answer 34

1. Aldosterone(steroid), can pass through the plasma membrane(hydrophobic ligand) 2. This steroid binds to a receptor protein in the cytoplasm activating it(since in the cytoplasm, the transduction pathway is short) 3. Hormone receptor complex(receptor bound to protein) enters the nucleus and binds to specific genes 4. This steroid/hormone acts as a transcription factor, stimulates the transcription of the gene/DNA into mRNA 5. mRNA is translated into a specific protein

Question 35

Protein kinases

Answer 35

at each step these phosphorylate/activate many proteins at the next level(an enzyme that activates another enzyme until inactive protein is activated, info/phosphates are passed on)

Question 36

Phosphorylation cascade

Answer 36

multistep pathway which amplifies the signal as the process goes on,phophoralyzation occurs as the name implies

Question 37

when does the phosphorylation cascade stop

Answer 37

Goes until the protein that turns on the response is activated

Question 38

benefits of a phosphorlation cascade

Answer 38

allows for a larger cellular response and more coordination opportunities

Question 39

typically how many protein kinases are use

Answer 39

3

Question 40

Protein phosphatases

Answer 40

removes the phosphate from protein kinases, a process called dephosphorylating(turns off signal)

Question 41

what are the benefits of protein phophotases(pp)

Answer 41

They also make protein kinases available for reuse, enabling the cell to respond to the signal again

Question 42

Second messengers

Answer 42

small, nonproteins, water-soluble molecules, or ions(Cyclic amp, Calcium ions)(only for plasma membrane receptors)

Question 43

What is the main duty of the secondary messengers

Answer 43

The second messenger activates protein kinase A which then starts the phosphorylation cascade

Question 44

What are examples of places where secondary messengers are used

Answer 44

These messengers can participate in pathways of G and tyrosine receptors

Question 45

Cyclic AMP(cAMP)

Answer 45

is one of the most widely used second messengers, causes the start of protein kinase or protein kinase A

Question 46

Adenylyl cyclase

Answer 46

an enzyme in the plasma membrane, converts ATP to cAMP(is ending in -ase then enzyme)

Question 47

Phosphodiesterase

Answer 47

turns off cAMP

Question 48

where is the cellular response the shortest?

Answer 48

the cytoplasm

Question 49

Where does a cellular response usually occur

Answer 49

The response typically occurs in the cytoplasm(enzyme) or nucleus(protein)

Question 50

what is the usual cellular response in the nucleus

Answer 50

The final activated molecules is usually a transcription factor

Question 51

what is the usual cellular response in the cytoplasm

Answer 51

Activities in the cytoplasm include activating or inhibiting an enzyme, or cause cytoskeleton rearrangement

Question 52

What is apoptosis

Answer 52

It is programmed cell suicide, can be triggered by, death signaling ligand, DNA damage in the nucleus, and protein misfolding in the endoplasmic reticulum