Formative Questions Flashcards
The removal of a peptide sequence from a protein as a form of signal is called
Proteolytic Cleavage
The three basic parts of an operon are the
Promoter, the operator, and two or more structural genes
The following shows a partial sequence of events in the oxytocin signal signal transduction pathway in uterine smooth muscle cells:
Oxytocin > GPCR > G protein activation > … > … > increase in intracellular Ca2+ ion levels > Na+ ion channel opening.
How could this signal transduction pathway be switched off?
Degradation of Second Messengers: If second messengers (like inositol trisphosphate, IP3) are involved, enzymes can degrade these molecules, further diminishing the signal.
Which superfamily does the nicotinic acetylcholine receptor belong to based on its structure?
Ligand-gated ion channel receptors
Co-repressors are usually found in … systems, which tend to be found in … pathways
repressible; anabolic
In which human tissues are beta-2 adrenoreceptors normally expressed in sufficient density to evoke a dilation in response to binding by adrenaline?
Smooth Muscle of Blood Vessels,
Bronchial Smooth Muscle,
Uterine Smooth Muscle,
Liver
Which superfamily do the insulin receptors belong to based on their structure?
Kinase-linked receptors
In bacterial cells, the concentration of cAMP is … correlated with the concentration of glucose, hence, glucose concentrations should … correlated with the amount of transcription in the lac operon (assuming that lactose is abundant)
inversely; be inversely
How many peptide chains form a mature insulin
2
What is an example of a steroidal hormone synthesised from cholesterol
Cortisol, sex hormones, vitamin D
Which type of bond maintains the ring structure of hormones such as somastatin
Disulphide bond
Signals that travel to distant cells through the circulatory system are
Hormones
The presence of a stop signal on a protein usually means it is destined for
membrane of an organelle
In comparison with structural genes in bacterial operons, genes that encode for stress responses in plants
are not coordinately regulated
Which of the following enzymes converts cyclic adenosine monophosphate (cAMP) to adenosine monophosphate (AMP)
Phosphodieterase
How many protein subunits compose nicotinic acetylcholine receptors
5
Which would most likely be a gene under constitutive expression control
A gene that encodes for a portion of the ribosome
What is the normal sequence for the release of insulin from pancreatic beta cells
- Increased blood glucose levels lead to glucose being taken up by pancreatic beta cells through the glucose transporter (GLUT2).
- Once inside the cell, glucose undergoes glycolysis and is metabolized, increasing ATP levels.
- Closure of K+ Channels, rise in ATP causes this.
This leads to a decrease in potassium ion efflux, causing membrane depolarization. - Calcium Influx: The depolarization of the membrane opens voltage-gated calcium channels (Ca2+ channels), allowing calcium ions to flow into the beta cells.
- Insulin Granule Exocytosis: The influx of calcium triggers the exocytosis of insulin-containing secretory granules, leading to the release of insulin into the bloodstream.
- Insulin Action: Once released, insulin travels through the bloodstream to target tissues, where it promotes glucose uptake and regulates metabolism.
When proteins are modified after mRNA translation, this is called
Post-translation modification
What is normally exchanged following G-protein coupled receptor activation
GDP for GTP
What is the lac operon?
The lac operon of E. coli contains genes involved in lactose metabolism. It’s expressed only when lactose is present and glucose is absent.
