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Bs3033 essay questions, Study notes of Biology

essay questions for brain and behaviour

Typology: Study notes

2018/2019

Uploaded on 12/17/2019

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2010
Question 1. Classify and characterize various types of memories. What brain regions are
responsible for their acquisition?
Classify and characterize various types of memories. What brain regions are responsible for
their acquisition?
1. Declarative (explicit) o Semantic (facts) – hippocampuso Events (events) -
hippocampus, amygdala
2. Nondeclarative (implicit)o Procedural(skillsandhabits)-cerebellumo
Priming(neocortex)o Classicalconditioning(hippocampus,amygdala,cerebellum)
3. Non-associative learning – reflex pathways
4.
Question 3. Describe the approaches used to determine (i) the localization of P2X
receptors in the body, (ii) which P2X receptors can form heteromeric channels and (iii)
whether P2X receptors interact with other receptors/proteins?
(i) determine the localization of P2X receptors in the body
Use of the amino acid sequence of the seven P2X receptor subunits can be used to map
localization. This can be done at the level of mRNA through Northern blotting (will show
what tissues can be expressed in but not detail on which cell types within the tissue). Can
use the sequence to design oligos for in situ hybridization that should give localization to
particular cell types within a tissue but still only looking at mRNA . Use of the amino acid
sequence to generate selective antibody for the receptor that can be used for
immunohistochemistry – advantages that will give cellular distribution. May also suggest
that could deveop knock-in mice with tagged P2X receptors.
Could also characterize P2X receptor properties of a particular tissue and compare to
properties of recombinant receptors.
(ii) which P2X receptors can form heteromeric channels
Approaches rely on co-expression of P2X receptor subunits. One approach is to look for
novel phenotype on expression of different subunits – were given the example of P2X2 and
P2X3 co-expression to give channels with the time course of P2X2 and the pharmacology of
P2X3. More general approach is to co-express the proteins and look to see whether they can
co-immunoprecipitate. Would need to give some information here on how to do an IP and
appropriate controls.
(iii) whether P2X receptors interact with other receptors/proteins?
Two examples that could be used here. (1) Interaction of P2X and nicotinic receptors – lack
of addition of the currents when co-stimulated, P2X blocks the nicotinic component and (2)
Use o f immunoprecipitation and mass spectrometry to identify interacting proteins. The
example given was of the P2X7 receptor.
The aim for this question is for the student to think about and demonstrate their
understanding of the methods/approaches that can be used to characterize receptors.
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Question 1. Classify and characterize various types of memories. What brain regions are

responsible for their acquisition?

Classify and characterize various types of memories. What brain regions are responsible for

their acquisition?

1. Declarative (explicit) o Semantic (facts) – hippocampuso Events (events) -

hippocampus, amygdala

2. Nondeclarative (implicit)o Procedural(skillsandhabits)-cerebellumo

Priming(neocortex)o Classicalconditioning(hippocampus,amygdala,cerebellum)

3. Non-associative learning – reflex pathways

Question 3. Describe the approaches used to determine (i) the localization of P2X

receptors in the body, (ii) which P2X receptors can form heteromeric channels and (iii)

whether P2X receptors interact with other receptors/proteins?

(i) determine the localization of P2X receptors in the body

Use of the amino acid sequence of the seven P2X receptor subunits can be used to map

localization. This can be done at the level of mRNA through Northern blotting (will show

what tissues can be expressed in but not detail on which cell types within the tissue). Can

use the sequence to design oligos for in situ hybridization that should give localization to

particular cell types within a tissue but still only looking at mRNA. Use of the amino acid

sequence to generate selective antibody for the receptor that can be used for

immunohistochemistry – advantages that will give cellular distribution. May also suggest

that could deveop knock-in mice with tagged P2X receptors.

Could also characterize P2X receptor properties of a particular tissue and compare to

properties of recombinant receptors.

(ii) which P2X receptors can form heteromeric channels

Approaches rely on co-expression of P2X receptor subunits. One approach is to look for

novel phenotype on expression of different subunits – were given the example of P2X2 and

P2X3 co-expression to give channels with the time course of P2X2 and the pharmacology of

P2X3. More general approach is to co-express the proteins and look to see whether they can

co-immunoprecipitate. Would need to give some information here on how to do an IP and

appropriate controls.

(iii) whether P2X receptors interact with other receptors/proteins?

Two examples that could be used here. (1) Interaction of P2X and nicotinic receptors – lack

of addition of the currents when co-stimulated, P2X blocks the nicotinic component and (2)

Use o f immunoprecipitation and mass spectrometry to identify interacting proteins. The

example given was of the P2X7 receptor.

The aim for this question is for the student to think about and demonstrate their

understanding of the methods/approaches that can be used to characterize receptors.

Question 1. Describe the general structure and properties of voltage-gated potassium

channels and discuss how these properties contribute to setting resting membrane

potentials and other aspects of neuronal function. How could dysfunction of these

channels contribute to disease?

Key points:• Explanation of basic structure: subunits, tetramerisation, pore specificity for potassium over sodium, origin of voltage-dependence; perhaps contrast with other channels (Na/Ca).

  • Provide overview of the diversity of different genes for subunits 40 Kvs; over 100 K

channel subunits overall divided into around 12 families.

  • Likely focus on Kv1-4 as the archetypalchannels; low-voltage-activated, high voltage-activated; setting threshold and AP duration, respectively.
  1. May provide a broad and therefore superficial explanation of most families; may include Kir and K2p (this will indicate cross-talk as I did not cover this in my lectures) or may also concentrate on the Kv’s alone. Either approach is acceptable.
  2. The details on the function need to be integrated with their explanation of the channel properties to some extent. This could include RMP, AP threshold, AP duration, firing frequency; AHPs.
  3. Should mention location of ion channels; node of Ranvier, initial segment; somatic versus dendritic location. Could use auditory pathway as example of function of Kv1 and Kv3 in terms of auditory processing.
  4. In terms of disease: Might mention epilepsy, MS, perhaps diabetes or LQT (if capable of including cardiovascular knowledge)

Question 2. Using specific examples to illustrate your answer, describe how various

proteins within the active zone of the presynpatic terminal control the process of vesicle

recycling, transmitter release and

vesicle re-uptake.

The essay may be structured around the vesicle cycle which should be described. The key steps are outlined in the diagram shown. The elements required are uptake, translocation, docking, priming and calcium dependent fusion/release. Mechanisms of re-uptake following release should also be considered as

Question 4. Describe the experimental evidence that the second transmembrane domain

contributes to the pore of the P2X receptor ion channel.

Points that should be included in the answer.

  • P2X novel family of channels with two transmembrane domains associated with the pore (different from cys-loop and glutamate superfamilies).
    • Non- selective cation channel with reversal at ~ 0 mV
    • Second TM and ionic conduction determined with cysteine scanning mutagenesis and methanethiosulphonate or cadmium block T * Wild type channels unaffected by MTS reagents T * MTS reagents show block of P2X channel when at particular residues indicating that these face the channel pore (I328, N333, T336, L338)
  • By using different MTS reagents of different size can identify how wide parts of the ion conduction pore are* Some effects of MTS reagents are dependent on the channel opening (mutant D349C) indicating that this residue is internal to the gate of the channel* Recent work with measuring rate of cadmium block of cysteine mutants indicates different rates for some mutants whether ATP present (i.e. channel open) or not.* The structure of the zebra fish P2X4 receptor shows that TM lines the pore.