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General Biology I E2 > Chapter 11 > Flashcards

Chapter 11 Flashcards

1
Q

Cell-to-Cell Communication

A

absolutely essential for multicellular organisms

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2
Q

Biologists have discovered some universal mechanisms of cellular regulation involving a set of …

A

Cell-signaling pathways

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3
Q

Cellular signaling (pathways)

A

-cell communication
during cell communication, external signals are converted into responses within the cell

-takes info in, processes info, does something with the info

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4
Q

Signal transduction pathways

A
  • convert signals on a cell’s surface into cellular responses
  • are similar in microbes and mammals

-share chemical information

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5
Q

Chemical messengers

A

the way cells in a multicellular organism communicate through

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6
Q

Animals cells have …

A

cell junctions (gap junctions) that directly connect the cytoplasm of adjacent cells

  • cells talking to each other through gap junctions
  • receive chemical info and do something with it
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7
Q

Local signaling (in animal cells)

A

may communicate via direct contact of cell surface molecules or receptors

  • share molecular info with nearby cells
  • in cytoplasm, direct contact, membrane proteins (cell-to-cell recognition)
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8
Q

Local regulators or factors

A

Animal cells communicate through these that can influence cells in the local vicinity
-releases some sort of chemical or signal, i.e. ligand

-Paracrine or synaptic signaling

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9
Q

Paracrine signaling

A

a secreting cell acts on nearby target cells by discharging molecules of a local regulator a growth factor into the extracellular fluid

-secrete or produces local regulators, i.e. growth factors
not necessarily touching

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10
Q

Synaptic signaling

A

a nerve cell releases neurotransmitter molecules into a synapse, stimulating the target cell

  • specialized way how neurons talk to each other
  • cell can release chemicals at the synapse..target cell gets info and does something about it
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11
Q

Autocrine signaling

A

secrets a factor and circles back and (works) has an effect on the same cell

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12
Q

Growth Factors

A

molecules that function as local regulators to stimulate or trigger nearby cells to grow and multiply

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13
Q

Hormones (long distance signaling)

A
  • chemicals used in both plants and animals for long distance signaling (lock and key)
  • are highly specific for their receptors and cells
  • doesn’t affect all cells

(in animals, specialize endocrine cells release hormones into the circulatory system)

  • i.e. estrogen is specific for the estrogen receptor (only affect certain cells that contain the estrogen receptors)
  • mammary cells to tissues
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14
Q

Earl W Sutherland, Ed Krebs discovered

A

how the hormone Epinephrine acts on cells to stimulate the breakdown of the storage sugar glycogen in liver and muscle cells to be used for energy

  • Sutherland suggested that cells receiving signals went through three processes..
  • i.e. flight or fight response
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15
Q

adrenaline

A

synonymous with epinephrine

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16
Q

Ligand

A

naturally produced molecule

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17
Q

3 stages of cell signaling

A

1) Reception (ligand)
2) Transduction (intermediate or circuitry piece)
3) Response (activation of cellular response)

-suggested by Earl Sutherland

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18
Q

Theme Verses

A

Psalm 16:11: You have made known to me the path of life; you will fill me with joy in your presence, with eternal pleasures at your right hand.

Psalm 27:11: Teach me your way O Lord; lead me in a straight path…

Psalm 119:35: Direct me in the
path of your commands, for there I find delight

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19
Q

1) Reception

A
  • “lock and key” scenario
  • on surface of the cell
  • a signal molecule (ligand) binds to a cell surface receptor protein, causing it to change shape
  • is highly specific
  • causes a conformational change in the receptor to initiate transduction of the signal
  • get process started
  • “antenna”
  • receptors on surface of plasma membrane
  • intracellular receptors
  • i.e. estrogen produced in the ovary and can circulate in the blood but only affect cells that have an estrogen receptor
  • i.e. adrenaline produced by adrenal glands, circulate in body, but only affect cells with adrenaline receptors
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20
Q

Small or hydrophobic signal molecules

A

can readily cross the plasma membrane

-use intracellular receptors that may be either cytoplasmic or nuclear proteins

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21
Q

Steroid Hormones

A

bind to intracellular receptors to initiate their signals and regulate cellular activity

  • i.e. testosterone: move into nucleus and control behavior of cell
  • synthesis new proteins
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22
Q

3 main types of membrane receptors

A

1) G-protein-linked
2) Tyrosine kinase
3) Ion channel

23
Q

G-protein-linked

A
  • consists of a receptor protein associated with a G protein on the cytoplasmic side of the cell
  • the “lock”
  • on surface of plasma membrane
  • causes change in shape of receptor
  • act as an on/off switch to trigger the next step in the pathway leading to the cellular response
  • GDP –> GTP
  • type of plasma membrane receptor

i. e. epinephrin uses a G protein
i. e beta blockers, prevent receptors from being activated

24
Q

Receptor Tyrosine kinases

A
  • protein enzymes that are activated and then transfer phosphate groups (from ATP) to other molecules in the cytoplasm (inside the cell)
  • molecule binds to site, activates enzyme
  • trigger cellular response
  • type of plasma membrane receptor

i. e. Epidermal growth factor (EGF) (signal molecule) and EGF receptor
i. e. skin growth

25
Ion (gated) channel receptors
- act as a gate to allow the flow of specific ions, such as Ca^2+ through the channel - allow charged elements to be moved though membranes - type of plasma membrane receptor i. e. glutamate bind to glutamate receptors, opens channel - common in neurons
26
Ligand binding changes the channel shape...
allowing ions to flow into the cell
27
Ion channels are essential for...
neurotransmitter molecules released between two neurons in the brain
28
2) Transduction
- cascades of molecular interactions relay signals from receptors to target molecules through a multistep pathway to accomplish 2 purposes: 1) Amplification of a signal: want a big response quickly 2) provide more opportunities for coordination and regulation of the signal input: "customized response" - "circuitry piece" - uses proteins and enzymes -at each step in a pathway, the signal is transduced into a different form, commonly a conformational change in a protein ultimately leading to a large cellular response
29
many signaling pathways include what two things
1) activation of enzymes and | 2) their subsequent phosphorylation of other enzymes or proteins in the cell
30
Cells can communicate by physically touching
sharing cytoplasmic contents
31
Phosphorylation
a process that involves a series of Protein Kinases (Enzyme) that add a phosphate to the next protein (substrate) in line thereby activating it; in the cell - addition of a PO4-2 functional group by kinases - important molecules - signals to transduce or process information
32
Protein Phosporylation
a cellular mechanism for regulating protein activity
33
what percent of (a person's) genes encode for Protein Kinases that in turn regulate thousands of cellular proteins and functions
over 2% code for different types of kinases
34
Phosphatase (Enzymes)
can remove the phosphates from phosphorylated molecules in the cell - participate in transduction phase - a way to control activity of some molecules - change structure and function of molecules - i.e. activation of lysozymes will switch it on
35
2nd Messengers
small, nonprotein, water-soluble molecules or ions that rapidly diffuse throughout the cell and participate in signaling pathways (cytoplasm and nucleus-sometime) - key molecule that receives info in the cell - amplification
36
2 best studied 2nd messengers
1) cyclic AMP (cAMP) | 2) Calcium (Ca^2+)
37
Earl Sutherland
identified cAMP and how adrenaline uses cAMP during fight or flight response
38
cAMP is made from
ATP by the enzyme adenylyl cyclase following the activation of G-protein-linked receptors, such as the Epinephrine receptor - needed for fight or flight - increased in cells exposed to adrenaline
39
Adenylyl Cyclase
converts ATP to cAMP | -enzyme
40
cAMP concentration
can be reduced by phosphodiesterase (enzymes)
41
Caffeine
blocks the conversation of cAMP to AMP, maintaining the system in a state of "activation" (high cAMP) - blocks phosphodiesterase - acts like adrenaline - [cAMP] will increase in cells exposed to caffeine
42
Many G-proteins trigger the formation of
cAMP, which then acts as a 2nd messenger in cellular pathways
43
protein kinase A (PKA)
cAMP diffuses throughout the cell and activates this ...
44
Calcium (Ca^2+) ion
an important second messenger and its concentration is rapidly regulated in the cytosol of cells -when released into the cytosol of a cell, it acts as a second messenger in many different pathways - found in ER, important in estrogen signaling - controlled inside of cells - important signaling molecule - stored in different places - control of breast cancer cell growth - helps transduction in cells
45
3) (Cellular) response
Cell signaling leads to regulation of cytoplasmic activities such as protein translation (synthesis), generating cellular energy, or nuclear transcription - i.e. epinephrine triggers glycogen (sugar) breakdown in a cell for energy - i.e. muscle contraction; or fight or flight; regulation of genes; cell growth
46
in the cytoplasm signaling pathways regulate a variety of cellular activities including ...
the synthesis of new proteins or translation | -or new enzymes
47
Signaling pathways also regulate ...
genes by activating transcription factors that turn genes on or off
48
Transcription factors
nuclear proteins that bind DNA and turn genes on and off | -control of genes/regulation of DNA in cells
49
Signal pathways with multiple steps can..
1) amplify the signal - each protein in a signaling pathway amplifies the signal by activating multiple copies of the next component in the pathway - make something bigger i. e. epinephrine signaling 2) contribute to the specificity of the cellular response - the different combinations of proteins in a cell gives the cell great specificity in both the signals it detects and the responses it carries out
50
Signal response is terminated quickly by ...
or switching off a signal | -removing a ligand or signal molecule from receptor itself
51
Fine-tuning the signaling pathway
branching and "cross-talk" between signaling pathways further help the cell coordinate incoming signals and the response Cell A: pathway leads to a single response Cell B: pathway branches, leading to two response Cell C: Cross-talk occurs between two pathways Cell D: Different receptor leads to different response
52
Scaffolding Proteins
(tethering transduction pathways together) - proteins inside cell - can increase the signal transduction efficiency by physically linking together signal pathway molecules - increase efficiency by enhancing signaling speed, accuracy, and proximity of signal transfer - "molecular boat dock" -i.e. AKAP-PKA scaffolding protein
53
1st messenger
- ligand/agonist - produced by cell or tissue - binds to receptor on surface of plasma membrane: change shape sticks to receptor; molecular info gets transferred to a relay molecule (i.e. G protein molecules)
54
Phosphorylation cascade
uses kinase enzymes -ligand/receptor -> relay molecule (usually kinase or phosphatase) couple to G-protein-> can switch on kinase/ kinases use ATP phosphate (ATP -> ADP) change structure/function-> info moves transduced or move along activate many kinases until cellular response is done what its done to do

General Biology I E2 (5 decks)

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