What does quorum cell signaling do?
- monitor local cell density
- coordinate behavior that requires a certain density (e.g., forming spores to lie dormant, forming biofilms, secreting toxins)
What are biofilms?
aggregation of bacterical cells attached to a surface by secretions from the cells
What kind of signaling is in yeasts? What does it do?
sex signaling; identify mates by chemical signaling
What are the 3 steps of cell signaling?
- signal reception
- signal transduction
- cellular response
details of these steps are similar in simple and complex orgsnisms
Early versions of cell signaling likely evolved before…
the first multicellular organisms
What are the characteristics of local cell signaling?
- signaling molecules travel a short distance between cells
- direct connection
- surface signaling molecules andd receptors
What are the characteristics of long-distance cell signaling?
- often small molecules that can diffuse through cell walls in plants
- mostly hormones that travel in the bloodstream in animals
What 3 stages occur when a signal is recieved by a cell?
- reception
- transduction
- cellular response
What happens in the reception stage of cell signaling?
- a cell detects a signaling molecule from outside of the cell
- a signal is detected when the chemical signal (ligand) binds to a receptor protein inthe surface of the cell of inside the cell
What happens in the transduction stage of cell signaling?
- when the signaling molecule binds the receptor, it changes the receptor protein in some way
- this change initiates the process of transduction
- each relay molecuule in the signal transduction pathway changes the next molecule in the pathway
What happens in the cellular response stage of cell signaling?
the signal triggers a specific cellular response
What are the benefits of having multiple relay molecules in transduction?
- the signal caused by a small number of signaling molecules can be greatly amplified
- signal can be transferred to multiple molecules in the next step of the pathway
- more opportunities for coordination and control than simpler systems
- allows for regulation of the response
What is a first messenger and second messenger?
first messenger: signaling molecule
second messenger: smaller non-protein relay molecules
How are responses regulated?
- controls in the relay
- threshold met
- presence of scaffolding proteins
What is apoptosis?
a type of cell death where a series of molecular steps in a cell can lead to its death
What happens during apoptosis?
- DNA, organelles, and cytoplasm chopped up and fragmented
- cell shrinks and becomes lobed
- cells parts packaged in vesicles and engulfed/digested by specialized scavenger cells
- protects surrounding cells from cell just breaking apart and leaking its contents out
What happens when apoptosis isn’t regulated?
it can be involved in diseases like Parkinson’s and Alzheimers
killing cells that shouldn’t be marked for destruciton yet
What happens when apoptosis doesn’t remove damaged cells?
diseases like cancer can occur
buildup of damaged cells
