Grey Matter - Topic 8 Flashcards
(39 cards)
Distinguish between each of the following:
(a) Sensory neurone and motor neurone
- Sensory neurones carries impulses from the receptor where’s motor neurones carries impulses to a muscle/gland
- Sensory carry impulses to the CNS, motor carries away from CNS
- Motor has many short dendrites, sensory has one long dendron
What neurone is this and why?
Motor as the cell body is at one end
What neurone is this and give it’s function
Sensory and its function is to conduct impulses from receptor to the CNS
What is the structure of a myelin sheath?
Myelin sheath contains Schwann cells that wrap and fold around the axon.
They are fatty lipids in nature with nodes as gaps in the sheath and speed up the electrical impulses for a rapid responses.
Explain the effect of opioids on the diameter of the pupil, between one and five hours after exposure to a flash of light.
Pupils constrict as time passes with opioids, due to circular muscles stimulated and radial muscles are inhibited. Meaning the parasympathetic nerve pathway is inhibited whilst the sympathetic nerve pathway is stimulated
Describe the functions of the enzymes used to genetically modify bacteria.
- Restriction endonuclease used to cut the plasmid
- To form sticky ends
- Ligase enzyme used to add gene to plasmid
- Ligase forms phosphodiester bonds between nucleotides
- Recombinant DNA/ Plasmid is produced
Explain how an enzyme is involved in joining the two different genes together
- DNA ligase joins the two genes
- by forming phosphodiester bonds
- Via condenstation reactions
Which enzymes can be used to cut open the plasmids
Restriction endonuclease
Plamids are placed inside a type of bacteria and then exposed to an antibiotic.
(iii) Explain why antibiotic A is used in stage 3.
- So the bacteria with the antibiotic resistance gene will survive
- Therefore the bacteria will have the gene for (any characteristic named)
Glucosaminoglycans (GAGs) are the by-products of chemical reactions inside cells. GAGs are broken down by enzymes inside lysosomes in cells.
Mucopolysaccharidosis type I (MPS I) is a genetic condition that results in the build-up of GAGs inside cells.
MPS I affects the production of enzyme G that breaks down GAGs inside lysosomes.
More than 50 different mutations in the gene for enzyme G have been found to result in MPS I. Most of these mutations involve changing a single base in the gene.
(i) Explain how a single base mutation can lead to an altered primary structure of enzyme G.
- Changing a base results in a change in triplet code
- So the codon in the mRNA will change
- Resulting in different amino acid structure thus different primary structure.
(ii) Explain how human genome sequencing can be used to identify the mutations associated with MPS I.
- Sequence the genome of people with MPS1
- Sequence the genome of a number of people without the condition
- Compare the base sequences and work out mutations only found in individuals with this condition.
Explain why genetically modified bacteria delivering drugs ‘to the exact tissue in the body where they’re needed and nowhere else’ would decrease side effects.
- Drugs not delivered to other/healthy tissues. The drug does not deliver to the whole body
-Overall dosage is needed less and a higher concentration can be delivered to target area
What describes the genome of an adult male?
- All of his introns plus all of his exons
Which types of organism can be both genetically modified and be a
source of a gene to be used in GM?
Animal, bacteria and plant
The neurones of the central nervous system contain TAU proteins. These proteins help to maintain cell structure.
In humans, six different TAU proteins can be produced from a single gene.
Parkinson’s disease has been linked to the different forms of the TAU proteins present in neurones.
Scientists are studying the effect of these different TAU proteins in animal models. One model used is the fruit fly, Drosophila.
a) Describe how Drosophila flies could be genetically modified to produce one form of the human TAU protein.
- Extract mRNA for one form of the (tau protein)
-copy mRNA into DNA
-Use restriction enzymes to create sticky ends/ cut the DNA and a vector - ligate/integrate/insert the TAU DNA into the vector DNA
-Introduce vector into fertilised egg/embryonic stem/zygote/cells/neural cell stem cells.
Describe how bacteria can be genetically modified to produce a cytokine for the treatment of neurological and mental disorders
- Isolate gene for cytokine
- use a bacterial plasmid as a vector
- Cut the human DNA and the plasmid using the same restriction enzyme
- Splice the gene and plasmid together using DNA ligase
- Put the modified plasmids into bacterial cells
Spider silk is a very strong and flexible natural fibre. It is of interest to humans as a possible fibre for protective clothing.
Scientists have genetically modified a range of organisms to produce spider silk, including goats and plants such as alfalfa.
Give two reasons why some people may be concerned about the use of genetically modified alfalfa as a source of spider silk.
- The transfer of antibiotic-resistance gene to other microorganisms
- Could lead to pathogenic bacteria developing resistance to antibiotics
Glucosaminoglycans (GAGs) are the by-products of chemical reactions inside cells. GAGs are broken down by enzymes inside lysosomes in cells.
Mucopolysaccharidosis type I (MPS I) is a genetic condition that results in the build-up of GAGs inside cells.
MPS I affects the production of enzyme G that breaks down GAGs inside lysosomes.
More than 50 different mutations in the gene for enzyme G have been found to result in MPS I. Most of these mutations involve changing a single base in the gene.
A biotechnology company is developing a method of repairing the mutations in the gene for enzyme G.
The method being developed is called CRISPR-Cas9.
In this method, a short sequence of RNA binds to the DNA containing the mutation responsible for MPS I.
This RNA acts as a guide to enable the Cas9 enzyme to bind to DNA. This enzyme can then cut and repair the DNA, removing the mutation.
(i) Describe how scientists could produce this short sequence of RNA needed to treat someone with MPS I.
- Transcription of the DNA containing the mutation
- Using RNA nucleotides/ RNA polymerase
Explain why the use of CRISPR-Cas9 technology can be described as personalised medicine.
- Individuals have different mutations/ target an individual’s specific mutation
-The RNA molecule used will be specific to each mutation thus individual.
There are various ways to scan the brain.
Describe how positron emission tomography (PET) scans can be used to investigate brain structure.
- PET makes use of radioactive tracers/markers/glucose
- PET scan detects emission of positrons/production of gamma rays
- Provides 3D image
(ii) Name the type of learning behaviour shown by the child as they were repeatedly shown a cheeseburger.
Habituation
(iii) Explain what happens at the synapse to cause a decrease in saliva production
when the child was shown a cheeseburger on more than six occasions.
- Calcium ion channels become less responsive
- Fewer vesicles move towards/fuse with the presynaptic membrane
- Therefore less neurotransmitter binds to receptors on the post-synaptic membrane
- Thus membrane may not be depolarised/ action potential may not occur
Visual development requires exposure of the visual cortex to environmental signals during a critical period.
Describe the role of visual stimulation on the development of the visual cortex during the critical period.
- Ocular dominance columns develop in the visual cortex
- Neurones will form synapses with these columns
- Stimuli/action potentials/ impulses along neurones required to strengthen connections with cells of ocular dominance columns
- Stimulation during the critical period is needed to form effective connections in the visual cortex
(ii) Functional MRI (fMRI) measures brain activity by detecting changes in __________________?
Blood flow
