Cell signaling Flashcards
Neural signals
Diffuse a long distance between neurons
Neuroendocrine signals
Released from neutrons but act on distant cells
Pheromones
Released into the environment and act on a different individual
How do cells in multicellular organisms communicate
By chemical messengers
Describe contact based interaction
The gap junctions between adjacent cells allow for the transfer of chemicals
Describe autocrine signaling
When a cell signals and targets itself
Describe paracrine signaling
When a cell signals a nearby cell
Describe endocrine signaling
A cell targets a distant cell by secreting hormones into the bloodstream
How do steroid hormones work
They diffuse across the plasma membrane and bind to receptors in the nucleus or cytoplasm
What are steroids hormones synthesised from
They’re synthesised from cholesterol
What is the steroid receptor superfamily
They’re transcription factors that function either as activators or repressors of transcription
How does testosterone initiate protein synthesis
Once testosterone has passed through the plasma membrane
- testosterone binds to a receptor protein in the cytoplasm activating it
- the hormone receptor complex binds to specific genes
- the bound protein stimulates the transcription of the genes into mRNA
- the mRNA is transited into a specific protein
Give an example of a signaling molecule and its use
NO (nitric oxide) - it signals the dilation of blood vessels
What are the 3 steps in cell signaling
1 reception
2 transduction
3 response
Describe the steps that occur in the reception stage of cell signalling
Signal molecule binds to a receptor protein ( it changes shape)
- its highly specific
What are the 3 main types of membrane receptors
G-protein-linked receptors
- receptor tyrosine kinases
- ion channel receptors
What are G proteins
They’re specialised proteins with the ability to bind GTP and GDP
- which allows it to act as an on or off switch
- if GDP is bound to the G protein, the G protein is inactive
What are Receptor tyrosine kinases
They are membrane receptors that attach
phosphates to tyrosine - can trigger multiple signal transduction pathways at once.
What is Signal Amplification -
At each step, the number
of activated products is much greater than in the
preceding step
What is The Specificity of Cell Signalling
Different kinds of cells
have different collections of proteins, so cell specificity in
detecting and responding to signals. Pathway branching and
“cross-talk” further help the cell coordinate incoming signals
What are the 4 aspects of fine - tuning
Amplifying the signal (and thus the response)
– Specificity of the response
– Overall efficiency of response, enhanced by
scaffolding proteins
– Termination of the signal
