Cell Communication
How do animal and plant cells communicate when in direct contact with each other?
Plant cells: plasmodesmata
What is the main job of second messengers?
What is the most common second messenger?
To amplify the signal that the ligand brought to the cell.
cAMP - Cyclic AMP (adenosine monophosphate)
Define homeostasis.
A state of relatively stable internal conditions.
What type macromolecule is glucose?
Carbohydrate!
What's the difference between paracrine and synaptic signaling?
Both are types of local signaling.
Paracrine typically deals with growth factors/hormones that release via exocytosis to a nearby cell.
Synaptic deals specifically with the nervous system - neurotransmitters diffusing across the synaptic cleft
What are the 2 types of receptors?
G protein coupled receptors (GPCRs)
Ligand Gated Ion Channels
What are set points?
Give me an example.
Set Point: Values for various physiological conditions that the body tries to maintain
Temperature: 98.6 degrees Farenheit
Heartrate: 60 bpm (there is more of a range on heartrate depending on bmi, etc.)
Which one of Santa's reindeer has the same name as another holiday mascot?
Cupid!
There are 2 places that receptors can be located, where are those 2 places?
AND which molecules bind to which ones?
Plasma Membrane - Hydrophilic, large/polar molecules
Intracellular - Hydrophobic, small/nonpolar molecules
What does it mean when it says that ligand-receptor binding is highly specific?
It means that only certain ligands can bind with certain receptors. Insulin ligands would bind with insulin receptors.
Think of enzymes and their active sites. It's like a lock-and-key model.
Define negative feedback.
Give me an example.
Negative feedback: when the effect of the stimulus (input) is reduced.
Ex: Sweating, Shivering, Insulin/Glucagon production for blood sugar
What organelle packages and ships proteins?
Golgi apparatus!
What are 3 possible responses at the end of a signal transduction pathway?
1. Proteins will alter membrane permeability
2. Enzymes will change a metabolic process
3. Proteins will turn genes on or off
What's the difference between kinase and phosphatases?
Kinase - relays message by phosphorylating
Phosphatase - shuts off pathways by dephosphorylating them
Define positive feedback.
Give me an example.
Positive feedback: when the effect of the stimulus is amplified/increased.
Ex: childbirth, fruit ripening (ethylene), blood clotting
What organelle is responsible for protein synthesis?
Compare and contrast how plant and animal cells communicate via long-distance.
Both use hormones.
Plants release hormones which travel their tissues OR the air to other plants
endocrine signaling - releases hormones into the blood stream
What are the 3 stages of cell signaling? Briefly describe all 3 stages.
1. Reception: ligand binds to receptor
2. Transduction: the message from the ligand is transferred from an extracellular to an intracellular message (cell is processing what the message actually means)
3. Response: something is going to happen in the cell in response to whatever message the ligand sent
What can happen if phosphatase is mutated?
Pathways will not be shut off properly, and the messages will still go through. - Could lead to cancer cells that divide uncontrollably.
Where does Transcription occur in the cell?
The nucleus