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The brain Flashcards

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1
Q

Describe how dopamine acts as a neurotransmitter

A
  • complains released from presynaptic membrane, from the synaptic knob and diffuses across synaptic cleft
  • binds to receptors on post-synaptic membrane
  • opens sodium ion channels
  • initiating depolarisation/action potential in post synaptic neurone
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2
Q

Describe how use of MDMA could affect transmission of impulses in brain

A

MDMA binds to serotonin receptors
MDMA prevents reuptake of serotonin
(Blocking presynaptic receptors/binding to postsynaptic receptors)
More serotonin binds to postsynaptic membrane receptors
More action potentials produced

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3
Q

Explain how use of MDMA may cause development of symptoms of depression

A

MDMA use results in depletion of serotonin
Loss of receptors on post synaptic membrane
Lack of serotonin associated with depression

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4
Q

Describe how low serotonin levels can affect transmission of impulses in brain

A

Serotonin is a neurotransmitter
Less serotonin means fewer depolarisations of post synaptic membranes
Threshold not met
Less chance of action potential being produced

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5
Q

Explain how difficulty of treating Parkinson’s disease overcomes difficulty of drugs passing from blood into brain

A

L- dopa that can cross blood brain barrier
It is converted into dopamine

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6
Q

Explain how nicotine causes an action potential in the post-synaptic neurone that releases noradrenaline

A

Nicotine is similar in shape to acetylcholine
Increases permeability of membrane to sodium ions
Nicotine causes depolarisation of post-synaptic membrane
Depolarisation reaches threshold level

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7
Q

How can an increase in calcium ion uptake by the neurone lead to release in noradrenaline

A

Vesicles containing noradrenaline fuse with presynaptic membrane

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8
Q

Explain why inhibitors of acetylcholinisterase could be useful in treatments of Alzheimer’s disease

A

Acetylcholinesterase breaks down acetylcholine
Inhibitors prevent break down of acetylcholine
More acetylcholine is available to bind to post synaptic membrane
Therefore compensating for reduced production of acetylcholine

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9
Q

What happens at synapse leading to habituation

A

Repeated stimulus decreases permeability of presynaptic membrane
Fewer calcium ions moving into pre synaptic neurone
Fewer vesicles fusing with presyanptic membrane
Less neurotransmitters can bind to receptors in post synaptic membrane
Less neurotransmitter released and diffuse across gap
Action potential less likely to occur in post synaptic neurone

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10
Q

describe how PET scans can be used to investigate brain structure

A

radioactive tracer is absorbed in tissues
detects production of gamma rays
produces a 3D image

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11
Q

describe role of visual stimulation on development of visual cortex during critical period

A

occular dominance columns develop
neurones form synapses with these cells
impulses along neurones required to strengthen connections
stimulation during ciritical period is needed to form connections in viusal cortex

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12
Q

describe how ions and neurotransmitter molecules are involved in the transmission of an impulse

A

calcium ions are entering presynaptic neurone
vesicles fuse with presynaptic membrane
vesicles release neurotransmitters that diffuse across presynaptic cleft
neurotransmitter binds to receptors on post-synaptic membrane
sodium ions diffuse into post synaptic cell
action potential on post synaptic membrane occurs

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13
Q

explain how fMRI can be used to identify part of brain involved with interpreting information from visual cortex

A

detects blood flow in brain
increased blood flow = increased brain activity
oxyhaemoglobin absorbs fewer radio waves

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14
Q

cerebrum

A

vision and thinking

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15
Q

hypothalamus

A

thermoregulation

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16
Q

medulla

A

controls breathing and heart rate

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17
Q

cerebellum

A

movement and balance

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18
Q

Describe the functions of the enzymes used to genetically modify bacteria

A

restriction endonuclease used to cut plasmid
forming sticky ends
ligase enzymes used to add isolated gene to plasmid
ligase forms phopshodiester bonds by condensation reaction
recombinant DNA produced

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19
Q

IAA

A

causes cell elongation
alters pH of cell wall
regulates transcriprtion
makes cellulose cell wall more plastic

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20
Q

Explain how a single base mutation can lead to an altered primary structure of enzyme

A

change in triplet code
changes codon in mRNA
resulting in different amino acid

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21
Q

Explain how human genome sequencing can be used to identify the mutations associated with the condition

A

sequence the genome of people with the condition
sequence the genome of a number of people without the condition
compare base sequences to identify mutations found only in individuals with the condition

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22
Q

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

A

drugs not delivered to other tissues
overall dosage needed is less

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23
Q

Describe how flies could be genetically modified to produce one form of the
human TAU protein.

Study These Flashcards
A

extract mRNA for one form of the TAU protein
copy mRNA into DNA
use restriction enzymes to cut the DNA
insert the TAU DNA into the vector DNA
introduce vector into fertilised egg cell

24
Q

Describe how bacteria can be genetically modified to produce a cytokine

Study These Flashcards
A

isolate the gene for the cytokine
use a bacterial plasmid
cut the human DNA and plasmid using the same restriction enzyme
splice the gene and plasmid together using DNA ligase
put modified plasmids in bacterial cell

25
Give reasons why some people may be concerned about the use of genetically modified plant
transfer of antibitoic resistance gene to other microorganisms
26
Describe how scientists could produce this short sequence of RNA needed to treat someone with a condition
transcription of DNA containing mutation to produce mRNA using RNA polymerase and RNA nucleotides
27
Explain why the use of RNA technology can be described as personalised medicine.
targets an individual's specific mutation RNA molecule used will be specific to each mutation/individual
28
Explain the electrical changes in an axon that allow these nerve impulses to be detected.
potential difference across axon changing (-70 to -55) voltage gated sodium channels open soidum ions move into axon, causing depolarisation Sodium channels close and potassium channels open potassium ions move out of axon, causing repolarisation of membrane
29
Compare and contrast the structure of a sensory neurone and a motor neurone
both have: cell body containing a nucleus, both have an axon, both have dendirtes at one end of neurone and terminal branches at the other end. different location of cell body
30
glycolipids
sugar molecules joined by glycosidic bonds
31
describe the role of dendrites in a neurone
forms synapses with other neurones receive impulses from other neurones involved in summation initiate an action potential to the axon
32
describe how adrenlaine changes the heart rate
adrenaline carried in blood acts on sinoatrial node increasing frequency of impulses produced by SAN that spread across heart increasing rate at which heart cintracts
33
Describe the role of sodium ions in the functioning of a mammalian rod cell
sodium ions are pumped out the rod cell in the light, sodiudm ions do not move back into rod cell so it is hyperpolarised in the dark, sodium ions can move back into rod cell so it is depolarised
34
Explain why the plants were placed in a box in complete darkness.
plants respond to light and show phototropic responses therefore light must be excluded to study geotropism/effects of gravity putting plants in the dark prevents light having an effect. light is controlled
35
Explain how the IAA affects the growth of the coleoptile
IAA diffuses from the tip of the coleoptile therefore can be taken up by cells in zone of elongation which causes cell to elongate this lowers pH in cellulose cell wall causing coleoptile to grow towards light
36
Explain the effect of increasing light intensity on the current produced by a rod cell.
increasing light intensity decreases current rhodopsin is broken down more opsin binds to sodium-gated voltage channels these close making membrane impermeable to sodium ions
37
Describe the role of IAA (auxin) in the phototropic response of plants
IAA is produced in the tip of shoot accumulates on the dark side of the shoot stimulates cell elongation causing shoot to grow towards light source
38
Dim light
Antagonistic interaction of muscles Radial muscles contract and circular muscles relax to dilate pupils
39
Rod cells in dark
Sodium ions are pumped out They diffuse back in so cell membrane is depolarised Triggers release of neurotransmitters, which inhibit bipolar neurone so action potential isn’t fired
40
Rod cells in light
Light energy causes rhodopsin to break into retinal and opsin by bleaching Sodidum ionn channels close so sodium ions can’t diffuse back in Cell membrane is hyperpolarised Bipolar neurone isn’t inhibited so it depolarises and if threshold is met, action potential is transmitted
41
How is myelinated neurone different
Depolarisation only happens at Nodes of Ranvier Neurones cytoplasm conducts enough electrical charge to depolarise next node so impulse jumps from node to node This is saltatory conduction
42
Red light
Pr is quickly converted into Pfr in red light
43
Far red light
Pfr is quickly converted into Pr
44
Darkness (photoreceptors)
Pfr is slowly converted into Pr
45
Daylight contains more
Red light
46
Describe role of enzymes involved in synthesis of personalised proteins in GMOs
DNA helicase breaks hydrogen bonds RNA polymerase involved in making mRNA forming phosphodiester bonds Enzymes join amino acids together
47
Explain role of nervous system in bringing about increase in temperature of fingertip
Thermoreceptors detect increase in temperature Hypothalamus detects it More impulses sent along sympathetic begets Leads to vasodilation So more warm blood flowed near the skin surface
48
Why there might be a lighter part in fMRI scan
Due to more activity Increase in blood flow to this region fMRI signals not absorbed by oxygenated blood
49
Compare and contrast use of PET and CT
Both give info on function and structure PET shows areas that are active CT gives location/ size CT uses X rays but PET uses radioactively labelled metabolite
50
Why does neurone become hyperpolarised
Potassium ions continue leaving axon Preventing another depolarisation occurring - refractory period Allowing time for neurone to reset So nerve impulses travel in only one direction
51
Explain why a person successfully treated using genetically modified virus may still have a child with the recessive condition
Genetic modification has not occurred in gametes Person treated has gametes with allele for condition Other gamete also supplies a recessive allele Mutation occurs in gene of offspring
52
How nervous system responds to stimuli
Receptor cells detect stimuli Electrical impulse sent along sensory neurone to CNS Impulses sent along motor neurones to effectors
53
Explain the role of ATP in the transmission of impulses along neurones
ATP required for sodium:potassium pumps To move ions against concentration gradient To maintain potential difference across axon membrane
54
role of lipids in schwann cell
- Part of myelin sheath / electrical insulation - Stops sodium and potassium ions moving across membrane - So no depolarisation where {Schwann cell / myelin} is present / depolarisation only occurs at nodes of Ranvier - Allows saltatory conduction
55
describe how movement of sodium ions in a rod cell affects depolarisation in a bipolar neurone
-in the dark sodium ions moving {in through sodium ion channels -sodium ions {removed / pumped out} at inner segment -so rod cell depolarises -causing neurotransmitter / glutamate to be released - inhibits depolarisation in (adjacent bipolar neurone
56
describe role of phytocrome in flowering of long day plants
- increased red light (due to a long day - phytochrome red converted to phytochrome far-red in the day - accumulation / high concentration} of phytochrome far red stimulates flowering
57

biology (12 decks)

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