Chapter 11 Flashcards

1
Q

What is quorum sensing?

A

Concentration of signaling molecules allows bacteria to sense local population density

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2
Q

What is biofilm?

A

An aggregation of bacterial cells adhered to a surface

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3
Q

Types of local signaling

A

Paracrine signaling ; synaptic signaling

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4
Q

Paracrine signaling

A

Animal cells communicate using secreted messenger molecules that travel only short distances

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5
Q

Synaptic signaling

A

Occurs in the animal nervous system when a neurotransmitter is released in response to an electric signal

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6
Q

Long-distance signaling

A

Used hormones ; endocrine signaling (bloodstream)

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7
Q

Three stages of cell signaling

A

Signal reception, signal transduction, cellular response

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8
Q

Signal reception

A

Binding of ligand (signaling molecule) and receptor

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9
Q

Cell surface receptors

A

Membrane receptors located on cell surface ; heir large or polar ligands can’t diffuse through the membrane

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10
Q

Intracellular receptor

A

Located inside cell ; their ligands are small or nonpolar and can diffuse across the membrane

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11
Q

GPCRs

A

G Protein-coupled receptors

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12
Q

RTKs

A

Receptor tyrosine kinases

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13
Q

Receptor tyrosine kinases

A

Membrane receptors that transfer phosphate groups from ATP to another protein

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14
Q

Ion channel receptors (ligand-gates)

A

Contain a region that can act as a gate, opening or closing the channel, when the receptor changes shape

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15
Q

Intracellular receptors

A

Receptor proteins found in cytoplasm or nucleus

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16
Q

What can activated hormone-receptor complexes do?

A

They can act as a transcription factor, turning on or off specific genes

17
Q

What is phosphorylation?

A

Protein kinases transfers phosphates from ATP to protein

18
Q

Examples of second messengers

A

Cyclic AMP and Ca 2+ (spread by diffusion)

19
Q

What does adenylyl cyclase do?

A

Converts ATP to cAMP in response to an extracellular signal

20
Q

What does cAMP do?

A

Activates protein kinase A which then phosphorylates various other proteins

21
Q

What does adenylyl cyclase do?

A

Makes cAMP from ATP

22
Q

What happens in cholera bacterium?

A

Vibrio cholerae produces a toxin that modifies G proteins so that it is stuck in its active form ; leads to continuous production of cAMP, causing intestinal cells to secrete lots of salt which is fallowed by water ; untreated the person can die

23
Q

Why is Ca 2+ a good second messenger?

A

It’s concentration in the cytosol is normally much lower than the concentration outside the cells and in certain organelles within the cell ; small change in # represents larger % change

24
Q

IP3 & DAG and where they are produced

A

Inositol triphosphate & diacylglycerol ; produced by cleavage of a certain kind of phospholipid in the plasma membrane

25
4 aspects of signal regulation
Amplification of signal, specificity of response, overall efficiency of response, termination of signal
26
What happens in Signal amplification?
At each step the number of activated products can be greater than the proceeding step
27
What is specificity of cell signaling?
Proteins allow cells to detect and respond to different signals ; same signal can have different effects with different proteins
28
What is a scaffolding protein?
Large relay protein to which several other relay proteins are attached ; increase efficiency by grouping together different proteins involved in same pathway
29
4 ways to shut off signal
Ligand unbinds from receptor ; ligand/receptor complex is internalized and degrades ; second messengers are degraded ; protein phosphates remove phosphate off previously phosphorylated proteins