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Cell Signaling Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Signaling cells secrete——— that bind——to initiate a change of events in the cell/

A

Ligands molecule/ receptors

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2
Q

What is the action of epinephrine ?

A

Epinephrine is used in anti inflammatory response
But when glucose level is low, epinephrine is released, they covert glycogen to glucose in the liver.

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3
Q

What kinds of cellular junctions allow the passage of signaling molecules between neighboring cells?

A

Gap junction and plasmodesmata

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4
Q

Stages involved in cellular pathway

A

Reception——>signal transduction——>cellular response

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5
Q

How does ligands such as steroids bind to receptor?

A

They fuse into the cell and bind with the internal receptor. Ligand- receptor complex moves to the nucleus and interacts with the cellular DNA and influenced the genes it expressed.

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6
Q

How does polar ligands interact with the receptors?

A

By binding to the membrane receptor. Some membrane receptors change conformation so that certain ions such Na+ and K+ can pass through the membrane. Other membrane receptors interact with the G protein on the cytoplasmic part of the membrane, which causes series f reactions inside the c ell.

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7
Q

Some receptors can bind several ligands true or false?

A

Yes. Smell receptors

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8
Q

A specific ligands only bind to a specific receptor/ true or false

A

True

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9
Q

How many types of signaling are there?

A

There are four categories of chemical signaling found in multicellular organisms: paracrine signaling, endocrine signaling, autocrine signaling, and direct signaling across gap junctions

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10
Q

What are the main difference between auto, para, endo and gap junctions signaling?

A

The distance that signals travel

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11
Q

What are paracrine signals?

A

Signals that act locally between cells that are close together are called paracrine signals. Paracrine signals move by diffusion through the extracellular matrix

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12
Q

Paracrine cells are quickly removed or degraded by enzymes or neighboring cells. Why?

A

To restablish the conc gradient for the signals

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13
Q

Endocrine signals originate from———

A

Endocrine cells
Hypothalamus, pituitary and thyroid gland

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14
Q

The response from endocrine gland is ——

A

Slow but long lasting

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15
Q

The ligands of the endocrine glands are—— and they travel via ——

A

Hormones And blood

Because of their form of transport, hormones get diluted and are present in low concentrations when they act on their target cells. This is different from paracrine signaling, in which local concentrations of ligands can be very high.

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16
Q

When do autocrine signalling take place ?

A

This type of signaling often occurs during the early development of an organism to ensure that cells develop into the correct tissues and take on the proper function

this process of stimulating a group of neighboring cells may help to direct the differentiation of identical cells into the same cell type, thus ensuring the proper developmental outcome.

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17
Q

Where do paracrine signals act on?

A

On the same cell or a similar cell.

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18
Q

What does autocrine signalling also regulate?

A

Regulates the pain sensation and inflammatory responses. Further if a cell is infected with a virus , can signal itself to programmed cell death apoptosis.

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19
Q

Direct signalling through cell junction interact between what type of cells

A

Adjacent cells.

The transfer of signaling molecules communicates the current state of the cell that is directly next to the target cell; this allows a group of cells to coordinate their response to a signal that only one of them may have received. In plants, plasmodesmata are ubiquitous, making the entire plant into a giant communication network.

Gap junction allow small signaling molecules called intracellalar mediators to diffuse between two cells.

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20
Q

Two types of receptors are—— and ——

A

Internal receptor and cell surface receptor

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21
Q

Intracellular receptors are located in the——- and respond to —— molecules

A

Cytoplasm a of the cell and hydrophobic molecules that can travel across the membrane

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22
Q

When the intracellular receptor binds to ligand, what happens next?

A

Conformational change in the receptor protein and exposes DNA binding site and interfere with the gene expression.

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23
Q

What type of cell signaling influence the green expression without having to pass the signals on to the other receptors or messengers?

A

Intercellular receptor+non polar ligands

Directly interfere with the gene expression

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24
Q

Cell surface-receptors are ———or——- proteins

A

Transmembrane receptor or integral proteins

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25
Q

What happened when the receptors proteins are defect?

A

Lead to many diseases such as hypertension, asthma and heart disease

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26
Q

What are the components of the cell surface receptor?

A

Three components

  1. Extracellular domain (external ligand binding domain)
  2. Hydrophobic membrane spanning region
  3. Intracellular domain
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27
Q

What are the three categories of the cell surface receptor?

A

Ion-channel linked receptor
G protein linked receptor
Enzyme linked receptor

28
Q

Ion channel linked receptor mechanisms

A

Allow the passage of ions through the membranes . When a ligand binds to the extracellular domain of the channel, conformational changes occur and allow ions such as sodium, calcium, magnesium to pass through

29
Q

The membrane spanning regions of the cell surface receptors are ———

A

Hydrophobic to interact with the non polar phospholipid membrane

30
Q

What is G protein linked receptor and its mechanism

A

G-protein-linked receptors bind a ligand and activate a membrane protein called a G-protein. The activated G-protein then interacts with either an ion channel or an enzyme in the membrane

31
Q

Cause of cholera

A

Cholera virus produce toxin that atteach the G protein that controls the opening of the chlorine channel, resulting in large losses of fluids from the body and potentially fatal and dehydration as a result

32
Q

What are enxyme linked receptors>

A

Enzyme-linked receptors are cell-surface receptors with intracellular domains that are associated with an enzyme. In some cases, the intracellular domain of the receptor itself is an enzyme. Other enzyme-linked receptors have a small intracellular domain that interacts directly with an enzyme

Enzyme linked receptor normally have large Intracellular and extrecellualr domains but the membrane spanning region consists of a single alpha-helical region of the peptide strand.

33
Q

What type of molecules are ligands?

A

Ligands can be varied, from a small molecule such as small proteins and small Ca2+ ions

34
Q

Examples of water insoluble hydrophobic ligands

A
  1. Steroids

4 fuse rings carbon with different functional groups Include, sex hormones, vitamin D

  1. Thyroid hormones
35
Q

How are hydrophobic ligands carried in blood stream

A

By binding to the carrier proteins

36
Q

Can NO act as ligand?

A

Yes. Gas and can diffuse directly through the membrane .Receptors in smooth muscle and induce the relaxation of the tissue, very short half-life and functional over short distances

37
Q

Signal transduction occurs only in———— . Why?

A

Cell surface receptors . Bcuz internal receptors directly interact with DNA.

38
Q

What is dimerization?

A

Binding of the ligand causes dimerization of the receptors in some cases, which means that two receptors bind to each other to form a complex called a dimer.

The binding of the receptor enables their intracellular domain to come close and activate each other

39
Q

Same ligands can be used to initiate different signals in the different cells. T or F

A

T. Bcuz differences in protein expression in different cell types

40
Q

Signals from two or more receptors can merge to activate the same response in the cell. What can this ensure?

A

Ensure the multiple external requirements are met before a cell commits a specific response

41
Q

What is phosphorylation done by and what can be its effects?

A

Phosphorylation of enzymes and molecules is done by enzyme kinase.

Can activate or inactivate the enzyme and the reversal of phosphorylation, dephospho rylation by a phosphate will reverse the effect.

Can phosphorylated GDP or GTP to form GTP, also acid to serine, threonine, tyrosine to replace OH group.

Phosphorylation of tyrosine either active/inactivate the enzymatic activity or create a binding site downstream components in signaling cascades.

42
Q

What are second messengers?

A

Second messengers are small molecules that propagate a signal after it has been initiated by the binding of the signaling molecule to the receptor. These molecules help to spread a signal through the cytoplasm by altering the behavior of certain cellular proteins.

43
Q

Why is calcium low in cytosol?

A

Bcuz ions pumps in plasma membranes use ATP to remove it. For signaling purposes, calcium is stored in cytoplasmic vesicles such as ER .

44
Q

When signalling occurs, how does calcium enter the cell?

A

When signaling occurs, ligand-gated calcium ion channels allow the higher levels of Ca2+ that are present outside the cell (or in intracellular storage compartments) to flow into the cytoplasm, which raises the concentration of cytoplasmic Ca2+

45
Q

Release of calcium as second messenger examples

A

Insulin from beta cells of pancreas

Muscle contraction

46
Q

Where does cAMP comes from?

A

Synthesized by adenyl Cyclase enzyme from ATP.

47
Q

What is the main role of cAMP?

A

Binds and activates cAMP dependent kinase. A kinase

A kinase activates serine and threonine residues by
phosphorylation.

A-kinase is found in many different types of cells, and the target proteins in each kind of cell are different. Differences give rise to the variation of the responses to cAMP in different cells.

48
Q

How is cAMP converted back to AMP?

A

By the enzyme called phosphodiesterase

49
Q

——- are lipids that can be converted to second messenger.

A

Inositol phospholipids. Because they are bound near the membrane receptors, can easily interact with them.

50
Q

What are G protein receptors also called?

A

7 transmembrane receptor

51
Q

Cell division and growth are stimulated by ——-=, left unregulated cell growth leads to ——

A

Growth factors, cancer

52
Q

The role of apoptosis——- and ——— or digits

A

Cell removal or elimination and involved in morphogenesis of fingers and toes in development by removing unnecessary cells

53
Q

How can signialing molecules be terminated within the cell?

A

By degradation or dephosphorylation

54
Q

Conditions where signaling pathways are blocked can be—— or ———

A

Deleterious (harmful ) or preventive (helpful)

Such as birth control pills, anesthetic, heart disease, autoimmune disease

55
Q

Some signal transduction pathway regulate —— others regulate the———.

A

Transcription of mRNA , translation

Example MAP kinase ERK

56
Q

What is the inhibitor molecule?

A

An inhibitor is a molecule that binds to a protein and prevents it from functioning or reduces its function.

57
Q

Many growth factors that bind to cell-surface receptors are linked to _____ and they are called _____

A

Tyrosine kinases / receptor tyrosine kinase RTK

58
Q

Explain the role of receptor tyrosine kinase in cell growth

A

Tyrosine kinase receptors- enzyme linked receptors—->form cross linked dimers when growth factors bind to its receptor——> phosphorylates Tyrosine——> initiate G proteins called RAS——> activates MAP kinase ——-> phosphorylates protein kinase——>regulate the signal transduction

59
Q

What does apoptosis allow?

A

Apoptosis allows a cell to die in a controlled manner that prevents the release of potentially damaging molecules from inside the cell. There are many internal checkpoints that monitor a cell’s health; if abnormalities are observed, a cell can spontaneously initiate the process of apoptosis

Apoptosis, or cell death, can be pathological, a sign of disease and damage, or physiological, a process essential for normal health.

60
Q

ECF interacts with the cell surface receptors and initiates the signaling cascades, what happened when the cell moves away from ECF?

A

The cell undergoes apoptosis , to keep the cell from traveling throughout the body and proliferating out of control

61
Q

How are fingers and toes developed and shaped during developmental stage

A

By apoptosis by eliminating unnecessary cells during the formation of web like tissue between the individual fingers and toes.

A cell signaling mechanism triggers apoptosis, which destroys the cells between the developing digits.

62
Q

What happened when T cells bind to self proteins

A

T cells- remove foreign macromolecules and foreign particles, and target them for the destruction by the immune system.

T cells scan between foreign and self proteins and normally do not attack cell proteins.

If T cells bind to self proteins- autoimmune disease

63
Q

What is the reason why endocrine signal hormones produce prolonged effects?

A

Because hydrophobic hormones are carried by the carriers in the blood which protect them from degradation by cellular enz. Bcuz ligands are normally removed to terminate signals

64
Q

What is bacterial biofilms >

A

Complex colonies of bacteria that exchange chemical signals to coordinate the release of toxins that will attack the host.

When bacteria form biofilm , they create barriers that prevent toxins and antibacterial drugs from affecting the population living in biofilm, therefore more likely to survive even in the presence of antibiotics.

65
Q

Some bacteria use ——- as signaling molecules

A

Autoinducers which help bacteria to communicate with the same kind,inducers can be small or large

66
Q

How do yeasts use cell signaling

A

To find another haploid budding mate by binding to their cell surface receptor

Biology (16 decks)

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