UNIT 7: CELL SIGNALING AND IMMUNOLOGY
Cell Signaling (5.6)
● The three stages of cell signaling, inc. signaling cascades (phosphorylation
cascades) and second messengers
- Reception: ligand binds to the receptor (intracellular/extracellular)
- Transduction:
→ phosphorylation cascade:
1. signaling molecule binds with receptor ⇒ active relay molecule
2. activates inactive protein kinase 1
3. the now activated protein kinase activates the inactive protein kinase 2
with the help of ATP’s phosphate group ⇒ ATP → ADP
4. Active protein kinase 2 activates the last protein kinase with the help
of ATP’s phosphate group ⇒ ATP → ADP
→ active relay:
1. Ligand binds with receptor
2. Activates relay protein
3. 1 activated relay protein creates multiple pathways b/c of one binding
⇒ multiple responses
→ secondary messenger:
→ molecules that relay signals from receptors on the cell surface to target
molecules inside the cell, in the cytoplasm or nucleus.
- Response: takes place in nucleus
1. Initiates transcription and translation
2. Response turns on and off genes
● How signal transduction pathways differ in single-celled organisms vs. multicellular
organisms
- Multicellular organisms: cell signaling allows cells to coordinate their
activities ⇒ ensure that tissues, organs, and organ systems function
- Single-celled organisms: belong to the same population ⇒ allows populations
of cells to coordinate with one another and work like a team to accomplish
tasks no single cells could carry out on its own
The Immune System (Ch. 35)
- Pathogen: anything that can cause disease (ex: bacteria, viruses)
- Antigen: particle of pathogen that can be detected by the immune system + used
to break into host cells (like a key)
- innate/nonspecific: immunity an organism is born with
- adaptive/specific:
● Lines of defense
- 1st line of defense: prevents pathogen from entering the body (ex: skin,
mucus, hair, sweat tears)
- 2nd line of defense: after pathogen has entered and prevent any more harm it
does to the body (ex: macrophages, fever, inflammatory response)
→ macrophages: white blood cell that engulfs + clears out debris + dead cells
→ inflammatory response: bacteria ⇒ chemical alarm signals ⇒ wound swells +
blood clots ⇒ phagocytes eat the bacteria
- 3rd line of defense: after pathogen has entered and prevent any more harm it
does to the body
● Functions of T cells and B cells
- In adaptive/specific immunity cells, B and T cells, that have receptors to
certain antigens, are multiplied
- Genes activated by B and /t cells are genes that control cell division
- B cells undergo humoral response: antibodies bind to and neutralize antigens
- T cells undergo mediated response: involves T cells destroying infected cells
Cell Signaling (5.6)
● The three stages of cell signaling, inc. signaling cascades (phosphorylation
cascades) and second messengers
- Reception: ligand binds to the receptor (intracellular/extracellular)
- Transduction:
→ phosphorylation cascade:
1. signaling molecule binds with receptor ⇒ active relay molecule
2. activates inactive protein kinase 1
3. the now activated protein kinase activates the inactive protein kinase 2
with the help of ATP’s phosphate group ⇒ ATP → ADP
4. Active protein kinase 2 activates the last protein kinase with the help
of ATP’s phosphate group ⇒ ATP → ADP
→ active relay:
1. Ligand binds with receptor
2. Activates relay protein
3. 1 activated relay protein creates multiple pathways b/c of one binding
⇒ multiple responses
→ secondary messenger:
→ molecules that relay signals from receptors on the cell surface to target
molecules inside the cell, in the cytoplasm or nucleus.
- Response: takes place in nucleus
1. Initiates transcription and translation
2. Response turns on and off genes
● How signal transduction pathways differ in single-celled organisms vs. multicellular
organisms
- Multicellular organisms: cell signaling allows cells to coordinate their
activities ⇒ ensure that tissues, organs, and organ systems function
- Single-celled organisms: belong to the same population ⇒ allows populations
of cells to coordinate with one another and work like a team to accomplish
tasks no single cells could carry out on its own
The Immune System (Ch. 35)
- Pathogen: anything that can cause disease (ex: bacteria, viruses)
- Antigen: particle of pathogen that can be detected by the immune system + used
to break into host cells (like a key)
- innate/nonspecific: immunity an organism is born with
- adaptive/specific:
● Lines of defense
- 1st line of defense: prevents pathogen from entering the body (ex: skin,
mucus, hair, sweat tears)
- 2nd line of defense: after pathogen has entered and prevent any more harm it
does to the body (ex: macrophages, fever, inflammatory response)
→ macrophages: white blood cell that engulfs + clears out debris + dead cells
→ inflammatory response: bacteria ⇒ chemical alarm signals ⇒ wound swells +
blood clots ⇒ phagocytes eat the bacteria
- 3rd line of defense: after pathogen has entered and prevent any more harm it
does to the body
● Functions of T cells and B cells
- In adaptive/specific immunity cells, B and T cells, that have receptors to
certain antigens, are multiplied
- Genes activated by B and /t cells are genes that control cell division
- B cells undergo humoral response: antibodies bind to and neutralize antigens
- T cells undergo mediated response: involves T cells destroying infected cells
