1.4 a) Coordination, Hydrophobic and Hydrophilic Signals Flashcards
Multicellular organisms signal between cells using ___ ___.
extracellular signalling
What are the three types of extracellular signalling molecules?
peptide hormones, steroid hormones, neurotransmitters
Some proteins in the plasma membrane act as ___, with a binding site for specific ___ molecules.
receptors, signal
The act of ___ a signal molecule causes a ___ change of the receptor, which initiates a ___ within the cell.
binding, conformational, response
Different cell types produce different ___ ___ which can only be detected by cells with the specific ___.
These cells then…
signal molecules, receptor.
respond to the signal
Signalling molecules have ___ effects on different ___ types, due to differences in the ___ involved within the cell.
different, cell, pathways
In multicellular organisms, different cell types can show a tissue-___ response to the ___ signal.
tissue-specific, same
Hydrophobic signalling molecules can…
And so, can bind to ___ ___.
diffuse directly through the plasma membrane.
intracellular receptors
The receptors for hydrophobic signalling molecules are ___ ___.
transcription factors
What are transcription factors?
molecules that bind to HREs on DNA and either stimulate or inhibit the initiation of transcription (or: ‘they affect gene expression’)
The steroid hormones ___ and ___ are examples of ___ signalling molecules.
oestrogen and testosterone, hydrophobic
These steroid hormones bind to specific ___, in the ___ or ___.
receptors, cytosol, nucleus.
The hormone-receptor complex then moves to the ___ where it binds to specific sites on ___, affecting ___ expression.
nucleus, DNA, expression
What are the sites on DNA (that hormone-receptor complexes bind to) called?
Hormone Response Elements (HREs)
What does binding at HREs affect?
The rate of transcription (aka gene expression)
Each ___ hormone can affect the gene expression of many ___ genes.
steroid, different
Hydrophilic signalling molecules bind to ___ ___, and do not ___ the cell.
membrane receptors (or transmembrane receptors), enter
Examples of extracellular signalling molecules are ___ and ___ ___.
neurotransmitters, peptide hormones
Sort the following three signalling molecules into either 1) or 2).
Neurotransmitters, steroid hormones, peptide hormones.
- Hydrophobic signalling molecule
- Hydrophilic signalling molecule
- Steroid hormones (oestrogen and testosterone) are hydrophobic, and so diffuse through the membrane and bind to intracellular receptors (which may create a transcription factor which binds to HREs affecting the rate of transcription)
- neurotransmitters and peptide hormones are hydrophilic, and so bind to transmembrane receptors
Transmembrane receptors change ___ when a ___ binds to its extracellular face.
conformation, ligand
Hydrophilic signalling molecules do not ___ the cell, but the signal is ___ across the ___.
enter, transduced, membrane
Transmembrane receptors act as ___ ___, when a ligand/hydrophilic signalling molecule binds to it from ___ the cell.
signal transducers, outside
Transmembrane receptors transduce ___ by converting the ___ binding event into intracellular ___, which activates a cellular ___.
signals, ligand, signals, response
Transduced hydrophilic signals often involve _-__ or cascades of ___ by kinase enzymes.
G-proteins, phosphorylation
