Lecture 14 Flashcards
Whats a signal transduction path
It converts a signal at a cells surface into a specific cellular response.
Or it is the process where one type f signal is converted to another
Eg - an extracellular signal converted to an intracellular signal through transmembrane receptors.
Flight and fight signal is by which molecule
Epinephrine
How can one signal create more than one response.
The signal can target a different target cell to produce different response
What is the importance of signalling
Signals for cell division and differentiation help them stay alive and functioning.
Gene expression and protein activity in response to environmental signals.
Communication between cells of organism, single and multicelled
Allows cells to adapt to the environment
Describe the communication in a yeast cell
The yeast has 2 mating factors a and ā Mating occurs between a and ā Each type secrete a specific type of mating factor that binds to the other types if mating factor This help locate each other Mate
What happens if yeast mates with a wrong mate
They are usually spherical but will extend a protrusion toward the source of the factor.
State the general principles of cell signalling.
Signals can act over a long or short range
Limited set of extracellular signals can produce a huge variety of response
A cells response to a signal can be fast or slow
Cell - surface receptors relay extracellular signals via intracellular signalling pathways
Some intracellular signalling proteins act as molecular switches
Cell surface RECEPTORS fall into three main classes.
Which type of signals do animals use to communicate mostly ? Extracellular or intracellular ?
Extracellular most of the time,
What are the two types of signalling molecules
1- contact dependent signalling.
2- local cell signalling between nearby cells.
Examples of Contact dependent signalling
A- cell junctions
B- cell cell recognition
Examples of local cell signalling between nearby cells
A- paracrine signalling
B- endocrine signalling
C- neuronal/ synapting signalling
Cell junctions
junctions btw adjacent cells that directly pas signalling molecules .
Animals- cell junction
Plants - plasmodesmata btw cell wall
Cell cell recognition
Animal cells communicate via membrane bound cell surface proteins/ receptors
eg - immune response, embryonic development , blood groups antigens and antibodies.
Difference between cell signalling and cell cell recognition
A- In cell signalling a signalling molecule is secreted however in the cell cell recognition signalling molecule is attached to the cell membrane.
B- signal molecule on one membrane and receptor on another.
Similarities between cell cell recognition and cell signalling
Both
1- immediate neighbours /adjacent cells
2- direct contact
Local signalling between nearby cells
A- paracrine signalling
B- endocrine signalling
C- neuronal signalling
A- Paracrine signalling
Special cell- secreting cells
Secretes- local regulators
Via- extracellular
Distance- at short distances
Eg - growth factor
B- endocrine signalling
Special cells- secretory glands Secretes - hormones Via- blood and lymph Distance- longer Eg - plant growth regulator, insulin
C- neuronal synaptic signalling
Special cells- neurone cells Secrete - neurotransmitter Via - synapse Distance - longer Eg - nerve to nerve or nerve to muscLe cells
Which of the signals are electric
Neuronal signalling
Describe a bit about neuron signalling
Neuronal signal are transmitted electrically along an exon
When they reach the terminal they release a neurotransmitter in the synapse
That then binds to the receptor on the post neural cell
List the Site of origin Chemical nature Response Of epinephrine
Epinephrine
Site of origin - adrenal gland
Chemical nature- derivative of amino acid tyrosine
Response- increases blood pressure, heart rate and metabolism
List the Site of origin Chemical nature Response Of insulin
Site of origin - B cells of pancreas
Chemical nature- protein
Response- stimulates glucose uptake , protein synthesis, lipid synthesis in many cell types
What type of signalling molecule binds to cell surface receptors
The signals molecules that bind to cell surface receptors are called extracellular signals
Hydrophilic and large Binds to the receptor
Stimulating 1 or 2 more intracellular signals
What type of signalling molecule binds to the intracellular receptors?
Small and hydrophobic eg steroids- cytosol
They also acts as molecular switches to gene express
And the intracellular receptor acts as transcription reg
Same signalling molecule can bring about different response if bound to different target molecules. Give an example of acetylcholine
Binds to pacemaker cells - dec rate of firing
Binds to salivary gland - secretion
In animal cells , extracellular also work in comb to bring about some response ,briefly explain and give example
A cell may require more then one signal to survive( eg A,B,C)
Addition signals require to grow and divide (eg A,B,C,D, E)
Addition signals required to differentiate. ( eg A,B,C,D,E,F)
Many responses can occur fast and many occur slow , give examples of fast and slow responses
It really depends on if the response requires a change in gene expression bcz requires
- activation of transcription factors
- binds to gene
- formation of protein
If yes eg cell growth, division or differentiation - slow
If no eg movement secretion , metabolism - fast
