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General Biology I E2 > Chapter 11 > Flashcards

Chapter 11 Flashcards

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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
Q

Ion (gated) channel receptors

A
  • 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
Q

Ligand binding changes the channel shape…

A

allowing ions to flow into the cell

27
Q

Ion channels are essential for…

A

neurotransmitter molecules released between two neurons in the brain

28
Q

2) Transduction

A
  • 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
Q

many signaling pathways include what two things

A

1) activation of enzymes and

2) their subsequent phosphorylation of other enzymes or proteins in the cell

30
Q

Cells can communicate by physically touching

A

sharing cytoplasmic contents

31
Q

Phosphorylation

A

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
Q

Protein Phosporylation

A

a cellular mechanism for regulating protein activity

33
Q

what percent of (a person’s) genes encode for Protein Kinases that in turn regulate thousands of cellular proteins and functions

A

over 2% code for different types of kinases

34
Q

Phosphatase (Enzymes)

A

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
Q

2nd Messengers

A

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
Q

2 best studied 2nd messengers

A

1) cyclic AMP (cAMP)

2) Calcium (Ca^2+)

37
Q

Earl Sutherland

A

identified cAMP and how adrenaline uses cAMP during fight or flight response

38
Q

cAMP is made from

A

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
Q

Adenylyl Cyclase

A

converts ATP to cAMP

-enzyme

40
Q

cAMP concentration

A

can be reduced by phosphodiesterase (enzymes)

41
Q

Caffeine

A

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
Q

Many G-proteins trigger the formation of

A

cAMP, which then acts as a 2nd messenger in cellular pathways

43
Q

protein kinase A (PKA)

A

cAMP diffuses throughout the cell and activates this …

44
Q

Calcium (Ca^2+) ion

A

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
Q

3) (Cellular) response

A

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
Q

in the cytoplasm signaling pathways regulate a variety of cellular activities including …

A

the synthesis of new proteins or translation

-or new enzymes

47
Q

Signaling pathways also regulate …

A

genes by activating transcription factors that turn genes on or off

48
Q

Transcription factors

A

nuclear proteins that bind DNA and turn genes on and off

-control of genes/regulation of DNA in cells

49
Q

Signal pathways with multiple steps can..

A

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
Q

Signal response is terminated quickly by …

A

or switching off a signal

-removing a ligand or signal molecule from receptor itself

51
Q

Fine-tuning the signaling pathway

A

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
Q

Scaffolding Proteins

A

(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
Q

1st messenger

A
  • 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
Q

Phosphorylation cascade

A

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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