Wk 6 Lecture 2 Flashcards
What are the 5 categories of cell signaling events?
- Direct intercellular signaling
- Contact-dependent signaling
- Autocrine signaling
- Paracrine signaling
- Endocrine signaling
What is direct intercellular signaling?
Cell junctions allow signaling molecules to pass from one cell to another at rate of diffusion via gap junction
What is contact dependent signaling?
-Molecules bound to surface of cells serve as signals to cells coming in contact with them
-Receptors on adjacent cells bind to cell surface molecules
What is the difference between direct intercellular and contact-dependent signaling
Direct intercellular: Passed between cytoplasm to cytoplasm
Contact-dependent: Passed between adjacent cell membranes
What is autocrine signaling?
-Cells secrete signaling molecules that bind to their own cell surface or similar neighboring cells
-Affects locally - self and nearby cells
Real life example of autocrine signaling?
Screaming fire to a large crowd of people
What is paracrine signaling?
-Signal does not affect originating cell, but still affects nearby cells
What is endocrine signaling?
-Signals travel longer distances via blood stream and take longer to fade
What is a hormone?
A signaling molecule in blood stream
What are the four stages of cell signaling?
- Signal Reception (receive signal)
- Signal processing/transduction (transmit the signal)
- Signal response (carry out the signal’s instructions)
- Signal deactivation (stop signal)
What are signal receptors? (step 1-signal reception)
Proteins that change their shape or activity after binding to a signaling molecule
3 characteristics of signal receptors
- Dynamic
- May change in their sensitivity to particular hormones
- Can be blocked
What are signal receptors bound by? (step 1-signal reception)
- Hormones
- Other cell-cell signals
What is a hormone?
A long distance messenger; an information carrying molecule that is secreted from a cell, circulates in the body, and acts on target cells far from the signaling cell
Characteristics of a hormone (5 things)
- Small
- Present in extremely low concentrations
- Have a large impact on the condition of the organism as a whole
- Function/chemical structure of hormones vary widely
- Two types: lipid soluble and lipid insoluble
The presence of ____ dictates which cells will be able to respond to a particular hormone (step 1-signal reception)
An appropriate receptor protein
Identical receptors in diverse cells and tissues can ____ (step1-signal reception)
Allow long-distance signals to coordinate the activities of cells throughout a multicellular organism
What 3 things are protein function dependent on?
- Binding
- Shape
- Location
How does signal processing differ between lipid soluble and lipid insoluble horomones?
Different cell responses are produced
Lipid soluble hormones cross plasma membrane
Lipid insoluble hormones bind to membrane receptors
Describe lipid soluble steroid hormones
-Hydrophobic
Diffuse across membrane and bind to receptors in cell
=> Hormone receptor complex binds to Hormone Response Elements (HRE; ex: estrogen, progesterone, glucocorticoids, ecdysone)
Where does the hormone receptor complex get transported to? What does it do there? (step 2-signal processing-lipid soluble steroid hormones)
Transported to nucleus where it alters gene expression
