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bioe4s > 4.1,2,3,4 Cell Communication > Flashcards

4.1,2,3,4 Cell Communication Flashcards

1
Q

Why is cell-to-cell communication critical? (2)

A

Critical for the function and survival of cells

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2
Q

What is cell-to-cell communication responsible for? (2)

A

-the growth and development of multicellular organisms

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3
Q

What are the three general ways that cells communicate?

A
  1. direct contact
  2. Local Signaling
  3. Long-distance signaling
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4
Q

What is the direct contact way of cells communicating?

A

Communication through cell junctions

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5
Q

What occurs in direct contact?

A
  • signaling substances and other material dissolved in the cytoplasm can freely move between adjacent cells
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6
Q

Which gap junctions do animals and plants use in direct contact?

A
  • animals use gap junctions

- plants use plasmodesmata

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7
Q

An example of direct contact would be immune cells. What occurs in this process?

A
  • antigen (protein markers on cell surface) presenting cells (APCs, ex. macrophages) communicate to T cells through direct contact
  • (see diagram page 4)
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8
Q

What are happens in local signaling?

A
  • A secreting cell will release chemical messages (local regulators/ligands) that travel a short distance through the extracellular fluid (outside cell)
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9
Q

What is a ligand?

A
  • A term used for a molecule that specifically binds to another larger molecule (a signal)
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10
Q

How do local regulators/ligands work?

A

The chemical messages will cause a response in a target cell

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11
Q

What are two examples of local signaling?

A

paracrine and synaptic signaling

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12
Q

What is paracrine signaling (local)?

A
  • secretory cells release local regulators (ie. growth factors) via exocytosis to adjacent cell
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13
Q

What is synaptic signaling? (2)

A
  • occurs in animal nervous system

- Neurons secrete neurotransmitters, which diffuse across the synaptic cleft

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14
Q

What is the synaptic cleft?

A

The space between the nerve cell and target cell

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15
Q

What do animals and plants use for long-distance signaling?

A

hormones

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16
Q

How does long-distance signaling occur in plants?

A
  • plants release hormones that travel in the plant vascular (vessel) tissue (xylem and phloem) or through the air to reach target tissues
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17
Q

What is xylem?

A

transports water and nutrients from roots

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18
Q

What is phloem?

A
  • transports sugars and other metabolic products down from leaves
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19
Q

How do animals do long-distance signaling? (2)

A
  • use endocrine signaling
    – specialized cells release hormones into the circulatory system where they reach target cells
    (slow b/c rely on circ. system for transport)
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20
Q

The mechanism of insulin regulation is an example of long-distance signaling. How does it work? (2)

A
  • insulin is released by the pancreas into the bloodstream where it circulates through the body and binds to target cells
  • insulin decreases blood sugar, promoting cellular respiration
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21
Q

What are the three stages of cell-to-cell signaling?

A
  1. reception (ligand binds to receptors)
  2. transduction (signal is converted)
  3. response (a cell process is altered)
22
Q

What is reception?

A

The detection and receiving of a ligand by a receptor in the target cell

23
Q

What are receptors?

A

macromolecule that binds to a signal molecule (ligand)

24
Q

What do all receptors have, in terms of ligands? (2)

A
  • have an area that interacts with the ligand

- an area that transmits a signal to another protein

25
Q

Ligand and receptor binding is highly _____?

A

specific

26
Q

What happens when the ligand binds to the receptor?

A
  1. the receptor activates via conformational change and allows the receptor to interact with other cellular molecules
  2. initiates a transduction signal
27
Q

Where can receptors be found? (2)

A

in plasma membrane or intracellular space (cytoplasm)

28
Q

What are plasma membrane receptors, and what do they bind to?

A
  • most common type of receptor involved in signal pathways

- Binds to ligand that are polar, water-soluble, and large

29
Q

What are two examples of plasma membrane receptors?

A
  • G Protein couple receptors (GPCRs)

- ligand-gated ion channels

30
Q

What are G Protein coupled receptors (stated in chart)?

A
  • these proteins act as an “inbox”

- They receive messages in the form of light energy (autotrophs) and as nutrients from the environment

31
Q

What are ligand-gated ion channels in terms of the nervous system?

A
  • in the nervous system, neurotransmitters are the ligand that a receiving dendrite binds to, so the Na+ gates will open and a continuation of action potential occurs
32
Q

Where can intracellular receptors be found, and what do they bind to?

A
  • found in cytoplasm or nucleus or target cells

- bind to ligands that can pass through the plasma membrane (hydrophobic molecules)

33
Q

What are examples of ligands that can pass through intracellular receptors?

A
  • steroid hormones (type of lipid ex. estrogen, testosterone, cholesterol)
  • thyroid hormones
  • gasses like nitric oxide
34
Q

What is transduction?

A
  • The conversion of an extracellular signal to an intracellular signal that will bring about a cellular response
35
Q

What does transduction require?

A
  • A sequence of changes in a series of molecules known as a signal transduction pathway
36
Q

What does the signal transduction pathway regulate?

A
  • protein activity
37
Q

How does a signal transduction pathway regulate protein activity?

A
  • through phosphorylation and dephosphorylation
38
Q

What does the enzyme protein kinase do?

A
  • relays signal inside the cell (activates signal by gaining phosphate group)
39
Q

What does the enzyme protein phosphatase do?

A
  • shuts off pathway as dephosphorylation occurs, shutting down the pathway
40
Q

During transduction, the signal is amplified by second messengers. What are second messengers? (2)

A
  • small, non-protein molecules and ions that help relay the message and amplify the response
  • cyclic AMP (cAMP, adenosine monophosphate) is a common second messenger
41
Q

What is stage 3 response?

A
  • The final molecule in the signaling pathway that converts the signal to a response that will ALTER a cellular process
42
Q

What are three examples of response?

A
  1. Protein that can alter membrane permeability (ex. insulin increases glucose uptake)
  2. Enzymes that will change a metabolic process (Promote or shut it down)
  3. proteins that turn genes on or off
43
Q

What can signal transduction pathways influence?

A
  • how a cell responds to its environment
44
Q

What can signal transduction pathways cause changes in? (2)

A
  1. gene expression and cell function
    - (what protein will be made/not made)
  2. can alter phenotypes (characteristics such as physical appearance or making that protein) or result in cell death
45
Q

What are mutations, and what do mutations to receptor proteins or any component of the signaling pathway result in? (2)

A
  • mutations are changes in nucleotide sequence of DNA or mRNA
  • change to the transduction pathway of the signal
46
Q

What are the two main categories of cell membrane receptors in eukaryotes?

A
  1. G protein couple receptors (GPCRS)

2. Ion channels

47
Q

What are G protein couple receptors? (3)

A
  • Largest category of cell surface receptors
  • important in animal sensory systems
  • Binds to G protein that can bind to GTP, which is an energy molecule similae to ATP
48
Q

The GPCR, enzyme, and G protein are inactive until _____

A

ligand binding to GPCR on the extracellular side (see pg 16)

49
Q

When the ligand binds to GPCR, what does it cause, and allow for? (7)

A
  1. cytoplasmic side to change shape
  2. allows G protein to bind to GPCR
  3. Activates the GPCR and G protein
  4. GDP becomes GTP
  5. Part of the activated G protein can then bind to the enzyme
  6. enzyme activated
  7. amplifies signal and leads to a cellular esponse
50
Q

What is the polarity of ligand gated ion channels, and what type of transport does this indicate?

A
  • hydrophilic, therefore facilitated diffusion or active transport
51
Q

Where are ligand gated ions channels located, what are they important for, and what do they act as? (3)

A
  • located in the plasma membrane
  • important in the nervous system
  • receptors that act as a gate for ions
52
Q

What happens when a ligand binds to the receptor/ion channel? (2)

A
  1. the “gate” opens or closes, allowing diffusion of specific ions
  2. initiates a series of events that lead to a cellular response
    EXAMPLE ACTION POTENTIAL

bioe4s (96 decks)

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