Chapter 11 Flashcards
- cell junctions allow signaling molecules to pass freely between adjacent cells
- cell-cell recognition via cell-surface molecules
- paragons signaling
Local signaling
- uses hormones
- travel through bloodstream to reach target cells
Long distance signaling
Ability of a cell to respond depends on whether it has ____ that can bind the signaling molecule
Receptors
3 stages of cell signaling
- Reception
- Transduction
- Response
Receptor protein on surface of cell (or inside) binds the signaling molecule (ligand) and transmits the signal
Reception
Binding is very specific and can cause receptor to:
Change shape
3 main types of membrane receptors
- g protein-coupled receptors
- tyrosine kinase receptors
- ion channel receptor
-plasma membrane receptors that are associated with G proteins
G protein-coupled receptor (GPCR)
G protein acts as:
On/off switch
Membrane receptors w/enzymatic activity which attach phosphate to tyrosine residues
Receptor tyrosine kinases (RTK)
One RTK can activate ____ or more pathways (#)
10
Associated w/many types of cancer
Abnormally activated RTKs
When gate opens specific ions can pass through
Ion channel receptors
Binding of ligand causes:
Conformational change
- Found in either the cytoplasm or nucleus
- kind of receptor
Intercellular receptor
Signaling molecules must be able to:
Pass through membrane
Be hydrophobic
- Relay of signals from receptors to target molecules in the cell
- allows signal to be amplified
- allows for more regulation
Transduction
Message is often passed through a change in _______
Protein conformation
Phosphorylation=protein _____
Kinases
Dephosphorylation= protein_____
Phosphates
Small, non protein, water soluble molecules
Can easily spread message throughout cell
Second messenger
2 most common second messengers:
- Cyclic AMP (cAMP)
2. calcium ions (Ca2+)
Adenylyl cyclase+ATP–>
cAMP
Used as a second messenger in both G-protein and tyrosine kinase receptor pathways
Ca2+
_____ causes: muscle contraction, secretion, cell division
Increasing Ca2+
Whole point of signal is to tell cell to do something
- usually regulate gene expression
- regulate activity of protein
Step 3: response
All cells in your body contain _______ DNA
The SAME
Why is a heart cell dif. From a liver cell?
-Dif. genes are turned on in dif. Cells
Dif. cells therefore have dif. proteins
Apoptosis
- programmed cell death “Cell suicide”
- eliminates cells that are damaged, infected or at the end of their life span
DNA &organelles are chopped up &packaged into vesicles which are engulfed &digested by:
Scavenging cells
How could cancer result from a defect in apoptosis?
A damaged cell wouldn’t die because of the defect so it would grow and multiply and become a tumor
