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1. Signal Transduction

2. Receptors
Receptors are macromolecules having chemorecognitive site for specific
endogenous or exogenous molecule;whose interaction with ligand(molecule)
initiates a chain of sequence leading to biological response

3. Adrenaline
Acetylcholine

4. Sequence of reactions to yield biological response
Adrenaline

5. Chemical nature of receptor
Protein

6. Classification
1. Ligand gated ion channel
2. G-Protein Coupled receptor
3. Enzyme linked receptor
4. Intracellular receptors

7. Ligand gated ion
channel

9. Sodium channel Potassium Channel
CalciumChannel Chloride channel

10. Location of ion channel : Dendrites
Acts as a sensor for impulses

13. Transmission of impulse towards CNS for interpretation

14. Examples
1. GABA receptor(Chloride ions)
2. 5HT3 Serotonin receptor
3. Nicotine receptor
4. Glycine receptor
5. NMDA-glutamate receptor

15. Neurotransmitters
Neurotransmitters are endogenous chemicals acting as signaling molecules
that enable transmission of signals across a synapse from one neuron to
another neuron, to a muscle cell, or to a gland cell.
Excitatory
Neurotransmitters
Inhibitory
Neurotransmitters
Inhibitory + Excitatory
Neurotransmitters

16. Excitatory Neurotransmitters
Glutamate Aspartate
Learning and Memory
NMDA-Glutamate receptor
Na,K,Ca

17. Inhibitory Neurotransmitters
1. GABA (gamma-Aminobutyric acid)
1. Glycine

18. Glycine receptor
Chloride ions
Chloride ions
GABA receptor

19. 1. Adrenaline
2. Acetylcholine
3. Dopamine
4. Serotonin
5. Histamine
Inhibitory + Excitatory
Neurotransmitters

20. GABA receptor Serotonin receptor
Nicotinic receptor NMDA-Glutamate receptor
Glycine receptor
Na,K,Ca
Na,K,Ca Na,K,Ca
Chloride ions
Chloride ions

21. GPCR : G-Protein Coupled Receptor
Metabotropic Receptor Serpentine Receptor
7-Transmembrane
Receptor

22. 7-Transmembrane Receptors
G-protein
binding region
Extracellular region
Intracellular region
Ligand Binding Region

23. G-Protein Receptor is also known as 7-
Transmembrane protein because it passes through
membrane 7 times.

24. GPCRs also known as Serpentine Receptor

25. Take 10 mins break , we will start at
12.15

26. GPCR : G-Protein Coupled Receptor
G-Protein
Guanine Nucleotide Binding
Protein

27. Nucleotide
1. Nitrogen base
2. Pentose sugar
3. Phosphate group
N
N

28. Purins Pyrimidines
ADENINE
GUANINE
CYTOSINE
THYMINE
URACIL
Nitrogen bases
Purins Pyrimidines
ADENINE
GUANINE

29. GUANINE
Nucleotide
Guanine Nucleotide Binding Protein (G-Protein):
Proteins which binds to Guanine nucleotide is known
as G-Protein
Protein

30. GPCR- 7 Transmembrane protein(Receptor) bonded to G-proteins
GUANINE
Nucleotide
Transmembrane
Protein(Receptor)
(G-Protein)
That means,Receptor
Coupled to G-Protein

31. GUANINE
Nucleotide
(G-Protein)
Guanosine
diphosphate(GDP)

32. Working Principle: Signal Transduction Mechanism

34. Working Principle: Signal Transduction Mechanism

35. Chemical messenger
Any compound that transmit
a message (Signal)
Primary Messenger
Secondary Messenger

36. Primary Messenger
Drug or Endogenous molecule

37. Secondary Messengers
Chemical messenger

38. Secondary Messengers
Kaun hai ye log kaha se aate
hai????
1. cAMP (Cyclic adenosine monophosphate)
2. IP3 (Inositol triphosphate)
3. DAG (Diacylglycerol)
4. cGMP(Cyclic Guanosine monophosphate)
5. Calcium ions
6. NO/CO
We are short lived
intracellular signaling
molecules

39. 1. cAMP (Cyclic adenosine monophosphate)
2. IP3 (Inositol triphosphate)
3. DAG (Diacylglycerol)
4. cGMP(Cyclic Guanosine monophosphate)
5. Calcium ions (Ca2+)
6. NO/CO
Elevated concentration of secondary messengers leads to rapid
alteration in the activity of cellular enzymes followed by cellular
function

40. Mystery 1:Sequence of reactions to yield biological response
Adrenaline

41. 1. Adrenaline
2. Acetylcholine
3. Dopamine
4. Serotonin
5. Histamine
Mystery 2 :Inhibitory + Excitatory Neurotransmitters

42. Keywords :
Receptor (Protein)
GPCR( 7 transmembrane protein coupled to G-Protein)
G-Protein having 3 subunits-(Alpha,Beta,Gamma)

43. Guanosine
diphosphate(GDP)
Alpha
Subunit
Gs Gq Gi
Gs/Gq Both are stimulatory
Gi is inhibitory

44. Stimulatory
Inhibitory

45. Stimulatory Pathway

47. Inhibitory Pathway

49. Stimulatory Pathway

51. Classification
1. Ligand gated ion channel
2. G-Protein Coupled receptor
3. Enzyme linked receptor
4. Intracellular receptors

60. Conclusion
● Extracellular signaling molecule/stimuli interacts with receptor and initiates
sequence of reaction(intracellular s to yield biological response

61. Intracellular signaling
● There are four basic categories of chemical signaling
found in multicellular organisms:
● Paracrine signaling- Ex. Synaptic
● Autocrine signaling
● Endocrine signaling
● Signaling by Direct contact (Contact-Dependant)

62. Paracrine signaling
● Cells that are near to one another communicate through the release of chemical messengers(molecule).
This type of signaling, in which cells communicate over relatively short distances, is known
as Paracrine signaling.
● Paracrine signaling allows cells to locally coordinate activities with their neighbors.
● Best example : Synaptic signaling
Synaptic signaling, in which nerve cells transmit signals. This process is named for the synapse, the
junction between two nerve cells where signal transmission occurs.
● Sensory neuron receives an electrical impulse and moves it rapidly through the cell, traveling down a
long, fiber-like extension called an axon. When the impulse reaches the synapse, it triggers the release
of ligands called neurotransmitters, which quickly cross the small gap between the nerve cells. When
the neurotransmitters arrive at the receiving cell(second neuron) , they bind to receptors and cause a
chemical change inside of the cell (often, opening ion channels and changing the electrical potential
across the membrane).
● The neurotransmitters that are released into the chemical synapse are quickly degraded or taken back up
by the sending cell. This "resets" the system so they synapse is prepared to respond quickly to the next
signal.

63. 1.Paracrine signaling

65. ● In Autocrine signaling, a cell signals to itself, releasing a ligand that binds to
receptors on its own surface.
● If a cell is infected with a virus, the cell can signal itself to undergo programmed cell
death, killing the virus in the process.
● Lysozyme : Suicidal bags of cell
2. Autocrine signaling

66. ● When cells need to transmit signals over long distances, they often use the circulatory
system as a distribution network for the transfer of signal.
● In long-distance endocrine signaling, signals are produced by specialized cells and
released into the bloodstream, which carries them to target cells in distant parts of the
body.
● Signals that are produced in one part of the body and travel through the circulation to
reach far-away targets are known as hormones.
3. Endocrinesignaling

67. ● In humans, endocrine glands that release hormones include pituitary , thyroid, para
thyroid, adrenal as well as the gonads (testes and ovaries) and the pancreas. Each
endocrine gland releases one or more types of hormones.
● Ex : 1. The Pituitary releases growth hormone (GH), which promotes growth,
particularly growth of the skeleton and cartilages
● 2. Insulin is a hormone made by one of the body's organs called the Pancreas.
Insulin helps your body turn blood sugar (glucose) into energy. It also helps your
body store it in your muscles, fat cells, and liver to use later, when your body needs it.
● After you eat, your blood sugar (glucose) rises. This rise in glucose triggers your
pancreas to release insulin into the bloodstream. Insulin travels through the blood to
your body's cells. It tells the cells to open up and let the glucose in. Once inside, the
cells convert glucose into energy or store it to use later.
● Without insulin, your body can't use or store glucose for energy. Instead, the glucose
stays in your blood.

69. Signaling through cell-cell contact
● Gap junctions are a type of cell junction found in animal cells in which adjacent
cells are connected through protein channels.
● Plasmodesmata are microscopic channels which traverse the cell walls of plant
cells(small channels that directly connect the cytoplasm of neighboring plant cells to
each other)
Gap junctions

70. ● Gap junctions in animals and plasmodesmata in plants are tiny channels that directly
connect neighboring cells. These channels allow small signaling molecules,
called intracellular mediators, to diffuse between the two cells. Small molecules
and ions are able to move between cells, but large molecules like proteins and DNA
cannot fit through the channels.
Signaling through cell-cell contact

71. The End

72. Any Question