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BDS1 BAMS molecules and cells > molecular basis of health > Flashcards

molecular basis of health Flashcards

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Organic Chemistry 101 flashcards
1
Q

how do cells communicate?

A

via cell signalling pathways

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2
Q

what are the four categories of chemical signalling?

A
  • paracrine
  • autocrine
  • endocrine
  • juxtacrine
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3
Q

what is paracrine chemical signalling?

A

cell targets a nearby cell

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4
Q

what is autocrine chemical signalling?

A

cell targets itself

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5
Q

what is endocrine chemical signalling?

A

a cell targets a distant cell through the blood stream

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6
Q

what is juxtacrine chemical signalling?

A

a cell targets a cell connected by gap junctions

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7
Q

how do cells recognise signals?

A
  • Cells have protein receptors that recognise and bind ligands​
    ​- Target cells must have the right receptor to bind the ligands​
    ​- Most signal molecules are large and hydrophilic and bind cell-surface receptors​
    ​- Some small hydrophobic molecules bind intracellular receptors (as they can diffuse through the plasma membrane)​
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8
Q

what type of molecules can enter/exit cells?

A

hydrophobic molecules

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9
Q

describe the steps involved in a signalling pathways

A
  • ligand binds to receptor
  • receptor is activated
  • the signal is tranduced to relay the signal
  • cell response
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10
Q

what is key to remember about ligand-receptor interactions?

A

they are highly specific

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11
Q

what type of molecule are receptors normally?

A

trans-membrane proteins

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12
Q

what are the three classes of membrane receptors?

A
  • G-protein coupled
  • Enzyme-linked
  • Ion channel
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13
Q

what are receptors within the cell called?

A

intracellular receptors

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14
Q

describe G protein coupled receptors

A
  • Largest and most diverse group of membrane receptors​
  • Interact with G-proteins (GTP)​
  • Active G-proteins activate cell membrane proteins​
  • Up to 1000 different GPCRs- each highly specific for a particular signal​
  • ~34% (475) FDA approved drugs target GPCRs (Nat Rev Drug Dis, 2017)​
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15
Q

describe enzyme-coupled receptors

A
  • Receptor with intrinsic enzyme activity​
    ​- Receptor Tyrosine Kinases (RTKs) largest family​
    ​- Tyrosine kinases add PO4 to tyrosine​
    ​- RTKs typically bind proteins at low concentrations​
    ​- Important role in regulating cell growth, differentiation and survival​
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16
Q

describe Ion-channel receptors

A
  • Convert chemical messages into electrical messages​
    ​- Ligand-gated/voltage-gated​
    ​- Important in neuronal and muscular action potentials​
    ​- Lidocaine blocks voltage-gated Na2+​
17
Q

describe Ion-channel receptors

A
  • Convert chemical messages into electrical messages​
    ​- Ligand-gated/voltage-gated​
    ​- Important in neuronal and muscular action potentials​
    ​- Lidocaine blocks voltage-gated Na2+​
18
Q

what is signal tranduction?

A
  • Receptor ligation causes intracellular domain to change shape​
    ​- The message is delivered to inside the cell through a series of biochemical reactions​
    ​- Sets off a chain of biochemical reactions (signal transduction cascades) within the cell​
    • Second messengers (small-non protein molecules)​
    • Phosphorylation (modifies protein activity)​
    • Action potentials (mediated by ion influx)​
19
Q

what are second messengers?

A
  • cAMP is a common second messenger​
    ​- Converted from ATP by active adenylyl cyclase​
    ​- cAMP activates protein kinase A​
    ​- Effect changes in gene expression via the activation of transcription factors​
20
Q

what are possible cell responses?

A
  • Ultimately cell communication leads to regulation of cellular responses​
  • Regulate protein translation by turning genes on or off​
  • Final target molecule may be a transcription factor – a protein that binds DNA to regulate gene transcription​
21
Q

what are examples of breakdowns in cellular communication which cause molecular disease?

A

Loss of the signal​ eg type 1 diabetes
Failure to respond to a signal​ eg type 2 diabetes
Failure of signal to reach target cell​ eg multiple sclerosis
Over/under expression of signal​ eg (over) periodontitis
Multiple breakdowns may occur- cancer

22
Q

what is the treatment for type I diabetes?

A
  • Replenish insulin​
    ​- Not a cure- only targets the symptoms of the disease​
    ​- Patients may also take immune-modifying drugs to limit further β-cell destruction ​
23
Q

what is the treatment for type II diabetes?

A
  • Diet and exercise to regulate blood glucose​
    ​- Insulin receptor is RTK​
    ​- Metformin inhibits tyrosine phosphatase​
    ​- Increases insulin receptor expression​
24
Q

what is the treatment for multiple sclerosis?

A

use of steroids and immune-modifying drugs to prevent/limit cell destruction​
​

25
Q

what happens in periodontitis to bone formation?

A

bone resorption exceeds bone formation

26
Q

describe how cancer arises

A
  • Despite tight controls breakdown in cell communication can lead to uncontrolled cell growth​
    ​- Often occurs in absence of signal​
    ​- Usually leads to apoptosis​
    ​- BUT if cell loses ability to respond to death signals it divides out of control​
    ​- Cancer always involves multiple breakdowns in communication​
27
Q

what are possible cancer treatments?

A

Surgery - mainstay of cancer treatment ​
Chemotherapy – Systemic administration of one or more anti-cancer drugs​
​Radiotherapy – Radiation damages DNA in cancer cells​
​Immune therapy – Immune system capable of recognising and killing faulty cells​
Monoclonal antibodies – targeted immune therapy​
​Vaccines - HPV viruses are DNA tumour viruses,​
Responsible for nearly all cervical cancers​

28
Q

describe the molecular basis of theraputics

A
  • Drugs must interact chemically with a target to induce a therapeutic effect​
    ​- Typically through binding proteins in cell membrane to induce a cellular response​
    ​- Drugs manipulate existing cell communication pathways for therapeutic benefit​

BDS1 BAMS molecules and cells (20 decks)

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