| Define extracellular or intercellular cell signaling | The communication that allows single cell to influence behavior of other cells in a specific manner |
| Define intracellular signal transduction | An intracellular events within a cell affects many molecular process and biochemical reactions |
| List all the basis mechanism used for the intercellular communication | -Via intercellular messenger
-Via gap junction
- Via surface protein |
| Give an example for intercellular communication via intercellular messenger | In low level of thyroid hormone Anterior pituitary secretes TSH ( Thyroid stimulating hormone ). Through blood flow it was sensed by thyroid stimulating hormone receptor on thyrocytes which then secretes tyroxine.
Other example :
In water deprivation ( plasma osmolality increases ) . Posterior pituitary secretes Antideuretic Hormone (ADH) . Through blood flow it was sense by ADH receptor on kidney cell which then decreases water excretion. |
| Give example on intercellular communication via Gap junction | Gap junction in gastrointestinal tract ( GIT ) allows ions movement for electrical activities such as peristalsis and also allows movement of metabolites from one cell to another cells
- In cardiac muscle also the similar mechanism is used to maintain the unison contraction |
| Give example on intercellular communication via surface protein | Direct communication between cell . Integrin receptor for cell migration . |
| List 3 types of extracellular communication | 1. Endocrine Signalling
2. Paracrine Signaling
3. Autocrine Signaling |
| Define Endocrine Signalling | These cells secrete their signal molecules, called hormones, into the bloodstream, which carries the signal to target cells distributed widely throughout the body. |
| Define Paracrine Signaling | Act as local mediators affecting only cell in immediate environment of the signaling cell. |
| Describe briefly Autocrine Signaling | send signals to other cells of the same type, as well as to themselves.In such autocrine signaling, a cell secretes signal molecules that can bind back to its own receptors. During development, for example, once a cell has been directed along a particular pathway of differentiation, it may begin to secrete autocrine signals to itself that reinforce this developmental decision.
Autocrine signaling is most effective when performed simultaneously by neighboring cells of the same type, and it is likely to be used to encourage groups of identical cells to make the same developmental decisions. |
| Explain the steps of intracellular signaling | 1. Signal known as first messenger is synthesized then transported to tearget cell
2. Upon receiving the signal ( growth factor ) , a membrane bound receptor become activated
3. Then results in activation of second messenger(s) which transmit the signal further downstream . As to transmit the signal further downstream the activated receptor passes the signal onto components signal use. Signaling proteins which can be activated or deactivated.
4. This then result in changes of cellular metabolism which then elicit response required by cell such as proliferation , survival , hypertrophy and so on.
5.Then signal attenuated which then terminates the response . |
| Describe first messenger | Involves extracellular cell signaling between cells . |
| Describe second messenger | Intracellular signaling molecules released by the cell in response to extracellular signaling molecules . It will trigger cellular response that may involve proliferation , differentiation , migration , survival , apoptosis and depolarization . |
| List 3 groups of second messenger | 1. Hydrophobic molecules
2.hydrophilic molecules
3. gases |
| what are the 2 types of ligands interaction | 1. Cell surface receptor
2. Nuclear receptor |
| Explain the significance ligand interaction through cell surface receptor | Cell surface receptor through ligand and cell surface receptor is used when the ligand is not able to pass the cell membrane or does not have to enter the cell. |
| Explain the significance ligand interaction through nuclear receptor | when the ligand are capable to pass through the cell membrane |
| What are the tools used for cell signaling ? list them | 1. Receptor
2.protein kinase
3. protein phosphate
4. Regulatory GTPase
5. adaptor proteins |
| What is the role of receptor | for detection of incoming signal |
| when is G-protein is used for activation ? | when membrane bound receptor have no cytoplasmic tyrosine kinase domain |
| what happen when protein kinase attaches phosphate to signaling proteins? | phosphorylation ( activates ) |
| what happen when protein phosphatase? | it remove phosphate from signaling proteins (dephosphorylation) which will deactivates the protein |
| what is the role of regulatory GTPase in intracellular signaling ? | as swithches and exist in active form to transmit signal while in inactive form to repress signal futher downstream |
| what is the role of adaptor protein in intracellular signalling? | mediates signal transmission between signaling proteins |
| How does signaling molecules are being activated and deactivated? | through phosphorylation and dephosphorylation |
