Module 20 Flashcards
Cell commuication and cell cycle
Population
All the individuals of a given species that live and reproduce in a particular geographic area
Steps of communication
A stimulus
The release of the signal
The reception of the signal
Response
What does the signalling cell do
Receives and responds to a STIMULUS
How do signalling cells respond to stimulus
By making and releasing signalling molecules
Signalling Molecules
chemicals released by cells that alter the activity of other cells
AKA Ligands
Receptor Protiens
Proteins on a cells surface or in a cell’s interior that bind specific signalling molecules
The Target Cell
The cell that receives the signal released by a signal cell
Ligands
Signalling Molecules; chemicals released by cells that alter the activities of other cells
Ligand-receptor interaction
The signalling molecule must be specifically matched or must complement the receptor protein
What is the purpose of ligand-receptor interactions
To make sure that a signal is received ONLY by the appropriate cell
What kind of bond hold ligand-receptor interactions
Weak, noncovalent bonds
Quorum sensing
Communication among bacteria that leads to a response ONLY when there are a HIGH number of bacteria present in a given area
Why must there be high population density in order for Quorum sensing to work
It turns on a communication pathway
At low population density there is very little signal in the environment, so they are unlikely to bind to bacteria’s protein receptors
At high population density, more signal molecules are released and are able to bind to protein receptors.
Bacteria then respond by synthesizing chemicals like bioluminescence
All target cells respond the same
False, for example target cells triggered by adrenaline increases heart rate , increasing the amount of oxygen delivered throughout the body. when target cells in the lung receives the signal molecule, the lungs cells relax
Identify the four steps of cell communication in the fight or flight
Stimulus: being startled
Signalling Cells produce signalling molecules: adrenal glands and adrenaline
Molecule binds to receptor: Receptor proteins on the heart and lungs
Response: increased heart rate and relaxed lung cells
What determines what a target cell is
The corresponding receptor protien
Hormone
A type of signaling molecule that travels in the CIRCULATORY system and effects DISTANT cells
Endocrine Signalling
Signalling by hormones that travel through the circulatory system
Paracrine Signalling
Signalling molecules move by diffusion over a short distance
Diffusion
Movement from an area of high to low consentration
Growth Factor
Causes cells to grow, divide and differentiate
Often in embryos
Autocrine Signalling
The signalling cell and target cell are the same
What kind of communication is Quorum sensing
Autocrine signaling
Contact-dependent signalling
Requires the two communicating cells to be in physical contact with each other
Describe one way contact-dependent signaling works with transmembrane proteins
A transmembrane protein acts as a signaling molecule on one cell and a transmembrane protein acts as a receptor protein on another
Which type of cell communication does not not a receptor protein
Contact-dependent signaling that uses passage or channels to connect the interior of adjacent cells
How do animal cells communicate with adjacent cells through passages
They use GAP JUNCTIONS to send signals to one another
What are gap junctions
transmembrane protein between two neighboring cells
What do plant cells have that animal cells dont
Cell wall
Plasmodesmata
The way that plant cells use contact-dependent signalling
Openings that cross through the membranes and the cell walls of two plant cells
Similarities between gap junctions and plasmodesmata
allow cells to exchange IONS and SIGNALLING MOLECULES
How are plasmodesmata different from gap junctions
The cell membranes of the connect cells are CONTINUOUS
The size of the openings is LARGER
Parts of the feedback loop in homeostasis
- Stimulus, or a difference in the set point
- Sensor
- Effector
- Response
Sensor
Detects stimulus and sends signals to the effector
Sense the cool air (the stimulus) or when conditions have moved away from a particular level
Set Point
Particular level set for conditions, that if changed becomes a stimulus
Effector
Restores a normal condition following the disturbance of those conditions
Initiates response
The heater would be the effector
Reponse
Brings system back to a SET POINT
A heaters response would be to heat the air in the room
Negative Feedback
A stimulus that acts on a sensor that signals to the effector
The effector will produce a RESPONSE THAT OPPOSES the initial STIMULUS, and TURNS OFF THE SIGNAL
DECREASES THE ACTIVITY OF A SYSTEM
Positive Feedback
Output or response of a system INCREASES THE ACTIVITY OF THE SYSTEM
What does negative feedback maintain
It maintains the set point
What does positive feedback maintain
It maintains the activity of the system, reinforcing it
MOVES AWAY FROM THE SET POINT
Example of positive feedback in childbirth
Signalling molecules contract the uterus causing the release of more signals and more contractions
Thermoregulation
The ability to maintain a constant body temperature
What kind of feedback does homeostasis rely on
Negative Feedback
