Chapter 5- Biology Flashcards
3 components
Reception: message is transmitted via the extracellular environment of the cell and is detected by the cell.
Transduction: converts the message so that cellular response can occur
Response: physical, biochemical, physiological change in the cell
Stimulus response model
Signal, Reception, Signal Transduction, Effector, Cellular Response
Receptors on the cell surface
protein based ligands
Intracellular receptors
in cytosol or nucleus- lipophilic
Stages in Cell Comm
Cell migration (movement)
Cell division
Changes in cell metabolism
Apoptosis
Signal transduction
Converts signal from outside the cell into a response within the cell. Signalling molecule binds to specific receptor, changes its 3D shape and activates it
Transduction of lipophilic signals
Need carrier molecules when being transported through the blood,
Path of hydophobic signals
- Signalling molecule passes through phospholipid bilayer
- Signal binds with receptor
- Signal-receptor complex moves from the cytoplasm into the nucleus
- Activated region of receptor protein attaches to a DNA region which then activates genes
- Relatively longer-lasting response
e. g. steroids
Hydrophillic siganls
- Includes peptide and protein hormones (eg’s?)
- Transported in solution in blood plasma
- Signalling molecule cannot enter the cell, it binds to a surface receptor
- A secondary messenger within the cell amplifies the message and a relay or cascade of messages (reactions) occurs
- The message reaches the nucleus where specific genes are activated
- Shorter period of response
Hormone
A chemical messenger , secreted by specialised endocrine cells in one part of the body, and often travel via the bloodstream to a target organ/cell where it effects a response.
Resting potential
cytoplasm has a slight negative charge compared with the extracellular fluid as K+ channels open and leave the cell.
Action potential
exited neuron, positive cytoplasm. sodium ions flood into the cell
Cytokines
cell signalling molecules that aid cell to cell communication in the immune responses and stimulate the movement of cells towards sites of inflammation, infection and trauma
plant hormones
Animal hormones:
- chemical messengers
- only required in small quantities
Different to animal hormones
mode of transport
-produced in meristems (growing regions)
Necrosis
unplanned cell death,
- mechanical damage
- chemical trauma
