7 - Cell Cell Interactions

Question 0

What does ECM stand for?

Answer 0

extracellular matrix found in animals

Question 1

What are integral proteins?

Answer 1

transmembrane proteins intracellular connection with actin - in they cytoskeleton binds with fironectins

Question 2

Where would the ECM components be synthesized?

Answer 2

Rough ER

Question 3

_______ bind with actin intracellurally and __________ fibers extracellularly

Answer 3

Integrins Fibronectin

Question 4

ECM varies in the amount present based on what?

Answer 4

ECM varies upon which tissues - highly found in areas requiring structural support - skin & bones

Question 5

Cartilage secretes what?

Answer 5

collagen

Question 6

What is a tight junction?

Answer 6

The proteins that stitch cells together, like quilting

Question 7

Which ECM does leaky gut syndrome affect?

Answer 7

it breaks tight junctions

Question 8

What is the adhesion protein that rivets the cells together called?

Answer 8

desmosomes

Question 9

What are the three characteristics of a desmosome?

Answer 9

1. contains cadherin proteins - trans membrane protein that binds it
2. only binds to the same kind of cadherin
3. intracellularly binds to intermediate filaments

Question 10

___________ channels are between animals cells and allow for communication and exchange of ions

Answer 10

Gap Junctions

Question 11

What are the gaps between plant cells that allow for passage of ions and small molecules

Answer 11

plamodesmata

Question 12

Where in the body do you find a prevalence of gap junctions?

Answer 12

in the heart tissue

Question 13

Define gap junctions

Answer 13

they are the connection between adjacent calls specialized as protein channels, allow H20, a-a sugar and nucleotides to move

Question 14

list the three main forms of communication between cells

Answer 14

1 - paracrine - localized chemical signals 2 - nerves - neurotransmitters 3- hormones & growth factors

Question 15

Why do only some cells react to cellular communication?

Answer 15

signal receptors are specific and determine the response

Question 17

briefly describe how lipid soluble signal transduction works this may be incorrect - standby

Answer 17

hormonal -> lipid soluble interacts directly inter-cellularly through direct signaling processing

Question 17

The bacteria vibrio cholera permanently turns on a G protein resulting in the activation a pumps that secrete Na +, Cl-, K+ and other ions. What are the implications of this?

Answer 17

the cell is loosing hydrophilic ions which would draw out H20 from the body and encourage elimination

Question 18

briefly describe how lipid insoluble signal processing works

Answer 18

• cannot x mb Reception
• Reception:
  
  • binds @ mb surface
  • changes shape reception site
• Processing:
  
  • signal transduced from one form to another, eg G protein linked
  • Amplifies = 2^nd messanger turns on pumps, genes

Question 19

What is signal amplification?

name the major types

Answer 19

how a small message can turn on a huge response

intracellularly

2 types: enzyme linked & G Proteins

Question 20

name the two general actions of signal transduction

Answer 20

1. reception
2. processing

Question 21

Great question for the final: describe the process of either G protein related cell to cell interaction, or communication via enzyme linked receptors

Answer 21

know how to do this

Question 22

Why would a G Protein be non-responsive?

Answer 22

hhmmmm - I can’t remember the answer to this, but I was sure that it would be a test Q possibly from cross talk

Question 23

What is cross talk?

Answer 23

the interaction of simultaneous communication between cells that can be excitatory, inhibitory or hold a response

Question 24

How are G Proteins and Enzyme linked receptors similar?

Answer 24

The both can cause both or either Phosphoralization cascades or 2nd messangers

Question 25

How is an enzyme linked receptor different than a G protein receptor?

Answer 25

the receptor acts as an enzyme (changes shape) & has a higher capacity to activate more transduction pathways

Question 26

How is the signal transduction phosphorylation cascade turned off?

Answer 26

1. ligand moves away from the receptor 2. enzymes deactivate in the cells eg in the G protein GTP -\> GDP 3. PHOSPHATASES protein - removes Pi from enzyme or **dephosphoralates** 4. to stay operational - extracellular signal ahs to contine or it`s shut down

Question 27

Name the three 2nd messengers reviewed in class

Answer 27

Ca+ cyclic GMP cyclic AMP

Question 28

What do 2nd messangers do?

Answer 28

1. turned on by an activated enzyme 2. Change which genes are being expressed in a target cell 3. Activate**/**deactivate target protein that already exists in a cell eg mb channel, activating gene

Question 29

What is protein kinase?

Answer 29

an enzyme that phosphorylates - that crops Pi's off

Question 30

Signal transduction has 2 responses, what are they?

Answer 30

1. converts extracellular messages to intracellular messages 2. in many cases it causes the message to amplify

Question 31

T/F Are send messengers proteins?

Answer 31

no they are enzymes

Question 32

When a ligand binds to an enzyme linked receptor on two inactive monomer, what is formed?

Answer 32

a dimer

Question 33

What must be completed before a dimer can become an enzyme?

Answer 33

needs to be Phosphorylated

Question 34

list the sequence of events in the signal transduction pathway

Answer 34

1. signal is received 2. signal is transduced 3. signal is amplified 4. cellular response

Question 35

What is cross talk?

Answer 35

* diverse signals can increase * decrease signal response

Question 36

Where can ECM be found in plants

Answer 36

they can`t, ECM is a fibre composite of protein found in animals

Question 37

In the animal world how are cells connected

Answer 37

desmosomes gap junctions tight junctions

Question 38

How are plant cells held together

Answer 38

tight junctions plasmodesmata held together by gelatenous proteins & sugars hydrophiliic keeps lamina wet

Question 39

List the steps of how a G Protein triggers the production of a 2^nd messanger

Answer 39

1. ligand binds to mb R = binding of inactive G protein (+GDP) - R 2. GTP displaced GTP = activation station for the G protein 3. Activates G Protein to bind to Enzyme =\> change of shape E 4. Activated E =\> response -\> amplification 5. Ligand leaves -\> G protein hydrolyses GTP -\>GDP = inactive

Question 40

list the steps in signal transduction via enzyme-linked receptors

Answer 40

1. 2 Ligands bind to 2 inactive monomers =\> dimer 2. Dimerized + Pi = phosphorlated =\> enzyme 3. + inactive protein =\> activation cellular responce =\> phosphorylation cascade

Question 41

some phosphorylation cascades cause what

Answer 41

production of 2^nd messangers

Question 42

how does signal transduction help the system

Answer 42

* increases the response time * can be shut down quickly * highly sensitive to small changes in hormones or signals

Question 43

What is the correct order for the following events in the interaction of a cell with a signal? 1. Alteration of cell function 2. signal binds to receptor 3. signal released from source 4. signal transduction Select one: A. 1234 B. 2314 C. 3214 D. 3241 E. 3421

Answer 43

which one is it D

Question 44

Why do some signals (first messengers) trigger second messengers to activate target cells? Select one: 1. The first messenger requires activation by ATP 2. The first messenger is not water soluble 3. The first messenger binds to many types of cells 4. The first messenger cannot cross the plasma membrane 5. There are no receptors for the first messenger.

Question 45

The function of the extracellular matrix (ECM) in most multicellular organisms is Select one: 1. To provide structural support 2. To provide strength 3. To organize cells 4. Cell signalling 5. All answers apply

Question 46

The activation of receptor tyrosine kinases is characterized by Select one: 1. Dimerization and phosphorylation 2. Dimerization and calcium release 3. A phosphorylation cascade 4. GTP hydrolysis 5. Channel protein shape change

Answer 46

1

Question 47

Plasmodesmata and gap junctions Select one: 1. Allow small molecules and ions to pass rapidly between cells 2. Are both membrane-lined channels 3. Are present only on either side of a cell 4. Are involved in cell recognition

Answer 47

1

Question 48

Clostridium perfringens is a bacterium wich secretes several toxins, one which causes the break down of collagen and another which causes the breakdown of cell adhesion molecules. Explain the impact these toxins would have on cells

Answer 48

* the matrix would start to disintigrate * the binding between gap junctions and desmosomes would break. terrible outcomes of bleeding, keeping things out that are supposed to stay out * intracellular communication difficult

Question 49

A cell receives a signal to manufacture integrins. Where in the cell would these proteins be produced

Answer 49

indomembrane system

Question 50

Compare and contrast gap junctions and plasmodesmata

Answer 50

They both are pores between cells for the passage of small molecules and ions gap junctions = animal cells plasmodesmata = plant cells

Question 51

Where would you expect to find te receptor for the teroid hormone aldosterone - inside the cell or in the mb. Why

Answer 51

intracellularly lipid soluble = passes through mb and directly to receptors

Question 52

What is protein kinase, and what is its role in a signal transduction pathway

Answer 52

an enzyme that phosphorylates from ATM to another protein usually protein kinase = turns on the phosphorylated protein = series = cellular response therefore carrying the signal from outside the cell to the protein that brings about the cellular response

Question 53

Excessive levels of an enzyme-linked receptor called HER2 has been found in some breast cancers. When activated, this receptor stimulates cell proliferation. How could you develop a drug to thwart cancer cell growth in HER2 positive cancers

Answer 53

bind down the receptor sites where HER2 binds