Cellular Signals Flashcards
The stimulus response model
- stimulus(change in environment)
- receptor (specialised cell detects change)
- coordination centre (brain spinal cord)
- effector(specialised cell organ response to message)
- response (opposite effect of the stimulus)
What do hormones do
Endocrine cells produce hormones which are Carried in the blood stream to exert a specific metabolic effect on a target cell.
Differences of hormones
Protien based- eg human growth protien
Lipid based hormone- pass through membrane easily eg steroids
What are types of chemical signals
Hormones
Neurotransmitters
Plant regulators
Pheromones
What is signal transduction in hydrophilic, protein based hormones
Process where a cell converts one kind of signal or stimulus to another. The chemical events are carried out by the presence of secondary messengers that will bind with specific cellular components that produce a specific response.
Signal reception
The first step of cellular communication where protein receptors bind to one signalling molecule with a specific shape
Cellular response
Effector proteins are produced be gene regulation stimulated directly by hormone or indirectly by protein hormone. The effector proteins produce cellular responses to the original external signal molecule
Transduction pathway diagram
Photos
Lipid soluble, hydrophobic, steroid, cell signalling process
Are able to pass through cell membrane. Will interact with protein receptor molecule found in cell cytoplasm. Moves from cytoplasm to nucleus where joins with DNA and gene activation process will begin protein synthesis
Lipid signaling process
Photos
What does amplification mean
1 signal molecule to produce lots of molecules
Step 1 of chemical signal
Arrival of action potential at pre synaptic neurone and causes an influx of calcium ions (facilitated diffusion) and induces vesicles to release their neurotransmitters into synapse (exocytosis)
Step 2 chemical signals
The neurotransmitters diffuse across the synapse to receptors on post synaptic membrane
Step 3 chemical signal
Neurotransmitters binds to receptors on post synaptic membrane
Step 4 chemical signal
Ion channels in the membrane open causing an influx of sodium. May or may not reach threshold to activate neural impulse
Step 5 of chemical signal
Neurotransmitters is deactivated by enzyme located on membrane. Components of neurotransmitters are reabsorbed (active transport) back into axon terminal recycled and repacked. Uses mitrocondria
How do plant regulators differ from animal hormones
Plant regulators are less specific and can bring about a number of responses based on the environmental conditions.
Whereas hormones can only bring one specific response
What are plant chemical messengers called
Plant regulators
What is a pheromone
A chemical messenger that are produced within an organism and released to the environment. These signals are received by another organism using specific receptor cites
What’s some types of pheromones
Trail phermones
Alarm pheromones
Territorial pheromones
Sex pheromones
What is apoptosis
The process of programmed cell death that involved a series of biochemical events and is an example of a transduction bathway
What is intrinsic apoptosis
Programmed cell death that begins within the cell.
How does intrinsic apoptosis occur
Driven by the mitrochondria and involved enzymes called (capase) that destroys internal organelles and produces chemicals that attract phagocytic cells to engulf cellular parts
What is extrinsic apoptosis
When an individual cell is instructed to destroy itself from an external messenger.
When does extrinsic aptopis occur
If a cell does not develop correctly (cancer cells) or if there are too many of the type of cell
How does extrinsic apoptosis occur
The cell recieves a “death message signal” and the message is recognised by the programmed death cell receptors on the membrane
What is the rule for apoptosis
Rate of cell renewal = rate of cell death
Cell changes in apoptosis
Cell shrinks
Plasma membrane forms bubbles
The nucleus and oraganelles condense and fragment
The cell breaks up, contents forms parcels
Remnants are engulfed by phagocytic cells- this prevents damage to other cells
Examples of aptoptis
Dysfunctional, damaged or diseased cells- prevents a virus from replicating or spreading to other cells
Embryonic development- final shaping of body parts depends on programmed cell death of excess cells eg skin cells joining toes
What are the 5 kinds of plant regulators
Auxins Gibberellins Ethylene Cytokinins Absisic acid
Similarities and differences between animal hormones and plant regulators
Sim- organic and signaling molecules
Differences- don’t travel in general circulation, are not produced in endocrine glands, are much smaller compared to animal hormones
Function of auxin plant hormone
Causes cells to elongate, and more away from the light, this causes ts to grow towards the light
Function of gibberellins plant hormones
Cause growth of tissues by causing cells to get longer
Function of cytokinins plant regulators
Cause growth by stimulating cells to divide by mitosis
Eythylene plant regulators
Helps plants/fruits ripen and mature
Helps flowers open
Abscisic acid plant regulators
Brings on dormancy eg autum leaves fall off
Malfunction of apoptosis with cancer
Cancer cells can appear from too little apoptosis. Mutations present in cancer cells enable the cells to rapidly grow forming tumours, the cancer cells does not respond to normal apoptosis signal of self destruct
Malfunction of apoptosis with Parkinson’s and Alzheimer’s
Parkinson’s disease and alzheimers result form exessive cell death from apoptosis in nerve cells in the brain.
