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Bio 1113 > Chapter 11: Cell-Cell Interactions > Flashcards

Chapter 11: Cell-Cell Interactions Flashcards

1
Q

What can quorum sensing lead to?

A

Large populations of unicellular organisms working together to form one thing like a multicellular organism. Like biofilms and slime molds

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2
Q

How does signaling occur in unicellular organisms?

A

The process of reception and signal transduction very similar between unicellular and multicellular organisms. The unicellular organisms sort of act as one multicellular organism

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3
Q

Adrenaline (epinephrine) signaling molecule example

A

Binds to cells with receptors for it. Cells respond differently depending on what proteins are present. Inhibit digestion, excite heart rate, etc.

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4
Q

What is quorum sensing?

A

Unicellular organisms way of giving cells an idea of what’s around them. Their response to population density

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5
Q

What does a nuclear response do?

A

Protein synthesis

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6
Q

Overview of transaction in cell signaling

A

The signal is converted into a form that can cause some type of cellular response (relay it inside)

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7
Q

What are protein kinases? What do they do?

A

In phosphorylation. They are critical proteins that add phosphate groups to turn on

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8
Q

What do plasmodesmata do?

A

In plants, tube/tunnel that connects two cytoplasms to allow passage of ions and small molecules between neighboring cells

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9
Q

What is a phosphorylation cascade and how does it work?

A

One kinase phosphorylates the next, which does the next, etc. This makes it a cascade. It could activate multiple kinases and not just one to amplify the signal

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10
Q

What do gap junctions do?

A

In animals, allow passage of ions and small molecules between neighboring cells

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11
Q

What does Ca+2 do?

A

It is used as a second messenger in both G proton and tyrosine kinase receptor pathways

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12
Q

What are the two ways messages are passed in transduction?

A

Activates enzyme to produce second messengers or activates phosphorylation cascade

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13
Q

When are G proteins on?

A

When GTP is bound

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14
Q

What do G proteins act as?

A

An on/off switch

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15
Q

What is response in cell-signaling?

A

The whole point of the signal is to tell the cell to do something. This is the cell doing something

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16
Q

What do desmosomes do?

A

Bind the cytoskeletons of adjacent cells together with deep connections. Like bolts that work with the cytoskeletons. Cell-cell adhesions are selective

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17
Q

Two types of cell-cell attachments

A

Tight junctions and desmosomes

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18
Q

What happens in reception of cell signaling?

A

A receptor protein on the surface of the cell (or inside the cell) binds the signaling molecule (ligand) and transmits the signal

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19
Q

Where does Ca+2 flow in and out of?

A

Out of the cell, into smooth ER, into mitochondria

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20
Q

Whats outside of a cell?

A

The extracellular matrix in humans and other animals and cell walls in plants

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21
Q

How do gap junctions form?

A

In animals, membrane proteins line up to form channels between cells

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22
Q

What are the functions of the extracellular matrix?

A

Support, segregate tissues (different extracellular matrix in different tissues and blood, bone, and other connective tissues), and regulation of intercellular communication

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23
Q

How specific is binding and what does binding cause?

A

Very specific and causes the receptor to change shape

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24
Q

Is the binding of signaling molecules to receptors reversible?

A

Yes

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25
What are cadherins?
Proteins in desmosomes that link cells (adhesion molecules). They are calcium dependent and vary between tissues.
26
How do intracellular receptors work?
The signaling molecules binds to the receptor in the cytoplasm, the receptor is transported to the nucleus, and it triggers a change in gene expression (on or off)
27
Two types of cell-cell gaps
Gap junctions in animals and plasmodesmata in plants
28
How is the message often passed in transduction?
A change in protein conformation
29
What does vibrio cholerae do?
Produces a toxin that causes a G protein to be unable to hydrolyze GTP to GDP so it remains stuck in on position, continually activating cAMP. Levels of cAMP causes salt to be excreted into the intestines and water follows = diarrhea
30
When are G proteins off?
When GDP is bound
31
What does being amplified mean?
Small signal can get a big response
32
Two ways cells respond to signals
Change in gene expression (protein synthesis) and regulate the activity of a protein (turn on already made protein)
33
What do multiple steps allow in transduction?
Allows the signal to be amplified and allows for more regulation
34
What does more regulation mean?
Multiple players in the pathway, the cell weighs them to get a response
35
Is a nuclear or cytoplasmic response quicker and why?
Cytoplasmic because you don't have to wait for a protein to be synthesized
36
What is transduction?
The relay of signals from receptors to target molecules in the cell
37
What do second messengers do?
They play a role in passing along messages
38
What do GPCRs often activate?
The production of second messengers
39
What do RTKs activate?
Ras (G protein)
40
Are cells self contained?
No, they must interact with other cells and the environment
41
What is the middle lamella?
Part that holds two cell walls from two cells together
42
What do GPCRs contain and what does it do?
GTPase domain that shuts itself off
43
What do tight junctions restrict?
Passive movement.
44
Relationship of number of second messengers and pathways?
More than one second messenger in one pathway and one second messenger can be involved in multiple pathways
45
Properties of tight junctions
Can vary between tissues and they are dynamic (they can change. Loosen up in stomach after eating then tighten later)
46
Main components of cell walls?
Cellulose in plants and peptidoglycan in bacteria
47
What are the main components of the extracellular matrix?
Collagen and proteoglycans
48
What makes cAMP?
Adenylyl cyclase and ATP
49
What are the functions of cell walls?
Protection, maintain shape, prevent excess water uptake (can't expand past a certain point)
50
Where are cell walls found?
Plants, bacteria, fungi, and some protists
51
What are the extracellular/intercellular levels of Ca+2 and how is it transported?
Ca+2 10,000 times higher outside the cell. It is actively transported out of the cell or into the smooth ER
52
What do RTKs do?
Attach phosphates to tyrosine residues
53
How does long distance signaling work?
Hormones travel through bloodstream to reach target cells
54
How do plasmodesmata form?
In plants, membrane lined channels through cell walls connect adjacent cells with tube/tunnel structures
55
What turns off cAMP (turns it back to AMP)
Phosphodiesterase
56
2 most common second messengers
Cyclic AMP (cAMP) and calcium ions (Ca+2)
57
What are the two changes in protein conformation in transduction that pass a message?
Phosphorylation and dephosphorylation
58
What are GPCRs?
G-protein coupled receptors that are plasma membrane receptors that are associated with G proteins
59
Overview of response in cell signaling
The cell responds in some way to the signal
60
What are abnormally activated RTKs associated with?
Many types of cancer
61
What are RTKs?
Receptor tyrosine kinases that are membrane receptors with enzymatic activity which attach phosphates to tyrosine residues
62
What do ion channel receptors do?
Binding of ligand causes conformational change that open a gate to allow specific ions to pass
63
What are second messengers?
Small, non-polar, water soluble molecules that can easily spread messages throughout the cell because they are water soluble
64
How do signaling molecules get to intracellular receptors? What types of molecules must they be?
They have to pass through the membrane. They include steroid hormones, thyroid hormones, nitric oxide, small, non-polar, and hydrophobic molecules
65
What must happen in order to respond to new signals?
Old signals must be shut off
66
What are the 3 stages of cell signaling?
Reception, transduction, and response
67
What are the three main types of membrane receptors?
G-protein coupled receptors, tyrosine kinase receptors, and ion channel receptors
68
What is cAMP?
Cyclic adenosine monophosphate. Its a second messenger
69
What does increasing Ca+2 concentrations cause?
Muscle contraction, secretion, cell division
70
How is it determined if a cell can respond to a certain signaling molecule?
If it has receptors that can bind the signaling molecule
71
How is a signal terminated? Examples?
The messengers return to their inactive forms GTP hydrolyzes to GDP cAMP is converted to AMP Phosphatases remove phosphates to deactivate proteins
72
What does a cytoplasmic response do?
Activation of an already made protein
73
What is used in long distance cell signaling?
Hormones (endocrine signaling)
74
What is the extracellular matrix? Where is it found?
The stuff found outside of the cell in animal tissues
75
Why is a hear cell different from a liver cell in they share the same DNA?
Different genes are turned on in different cells and different cells therefore have different proteins
76
What are protein phosphatases?
In dephosphorylation. They are proteins that take off phosphate groups to turn off
77
Overview of reception in cell signaling
The signal is detected by the cell
78
What are kinases?
Enzymes that add phosphates
79
What is crosstalk?
Multiple pathways interact to modify a response. Pathways are complex and cross over and have multiple parts. The outcome of crosstalk is which path has the strongest signal
80
What do tight junctions do?
Form water tight seals between cells. No leaking or fluid movement
81
What are proteoglycans?
One of two main components of extracellular matrix made of protein and sugar

Bio 1113 (22 decks)

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