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biology year 2 - exam q > Nerve Coordination > Flashcards

Nerve Coordination Flashcards

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1
Q

when the sarcomeres contract, what happens to the length of the I band?

A

shortens

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2
Q

when the sarcomeres contract, what happens to the length of

the A-band?

A

stays same

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3
Q

people who have Mcardles disease produce less ATP than healthy people.

as a result, they are not able to maintain strong muscle contraction during exercise.

use your knowledge of sliding filament theory to suggest why?

A

ATP needed for:

  • formation of crossbridges between actin and myosin
  • power stroke movement of myosin heads
  • detachment of myosin heads
  • recovery stroke
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4
Q

what causes the I band and H zone to decrease in length?

A
  • actin filaments slide in between myosin filaments
  • pull Z line closer
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5
Q

what is the role of ATP in myofibril contraction?

A
  • provides energy for movement of myosin head
  • provides energy for breaking of actin-myosin crossbridge
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6
Q

describe the role of calcium ions and ATP in the contraction of a myofibril?

A
  • Ca2+ diffuse into myofibrils from SR
  • Ca2+ cause movement of tropomyosin
  • movement causes exposure of binding site on actin
  • myosin head attach to binding sites on actin
  • hydrolysis of ATP causes myosin head to bend
  • bending causes pulling on actin filaments
  • attachment of new ATP mol to each myosin head causes myosin head to detach from actin site
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7
Q

when nerve impulse arrives at a synapse, it causes the release of neurotransmitter from vesicles in presynaptic knob.

describe how?

A
  • nerve impulse causes Ca2+ ion channels to open
  • Ca2+ enter by FD
  • causes synaptic vesicle to FUSE with ps-m
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8
Q

use your knowledge of how myosin and actin interact to suggest how the myosin molecule moves the mitochondrion towards ps-m?

do NOT include roles of Ca2+ ions and tropomyosin in your answer?

A
  • myosin head attaches to actin AND bends
  • pulls mitochondria along ACTIN
  • next myosin head attaches to actin and bends
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9
Q

the movement of mitochondria happens when nerve impulses arrive at synapse.

suggest and explain one advantage of movement of mitochondria towards pre-sm when nerve impulses arrive at synapse?

A
  • provide ATP
  • for active transport of ions
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10
Q

describe the sequence of events leading to the release of ACh and its binding to the post-sm?

A
  • AP arrives at synaptic knob of pre-sm
  • Ca2+ diffuses into synaptic knob
  • vesicles fuse with membrane
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11
Q

the binding of GABA to receptors on post-sm causes negatively charged chloride ions to enter post-sn.

explain how this will inhibit transmission of nerve impulses by post-sn?

A
  • makes inside of neurone more neg
  • threshold not reached - no AP fired
  • no depolarisation
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12
Q

epilepsy may result when there is increased neuronal activity in the brain.

one form of epilepsy is due to insufficient GABA. GABA is broken down on the post-sm by the enzyme GABA transaminase. vigabatrin is a new drug being used to treat this form of epilepsy. the drug has a similar molecular structure to GABA.

suggest how vigabatrin may be effective in treating this form of epilepsy?

A
  • binds to GABA receptors
  • inihibits neuronal activity
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13
Q

a different form of epilepsy has been linked to an abnormality in GABA receptors.

suggest and explain how an abnormality in GABA receptors may result in epilepsy?

A
  • receptors have diff TS
  • GABA cannot bind - inhibition of neuronal activity doesnt occur
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14
Q

during an epileptic seizure, muscular contractions may not occur.

in whic part of the brain would neuronal activity produce muscular contractions of the right leg?

A
  • MOTOR AREA
  • left cerebral hemisphere
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15
Q

explain the shape of a curve which shows increase in sodium ions between 0.5ms and 0.7ms?

A
  • Na+ ions enter
  • changes membrane potential
  • more channels open
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16
Q

multiple sclerosis is a disease that involves damage to the myelin sheaths of neurones.

movement in MS sufferers may be jerky or slow.

damage to the myelin sheaths of neurones can lead to problems controlling the contraction of muscles.

suggest one reason why?

A
  • AP travel more slowly
  • delay in muscle contraction
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17
Q

cannabinoids are hydrophobic molecules.

in the body, they easily pass into neurones.

why?

A

can bypass fatty acid portion of phospholipid bilayer

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18
Q

cannabinoid receptors are found in the pre-synaptic membrane of neuromuscular junctions.

when a cannabinoid binds to its receptor, it closes Ca2+ ion channels.

suggest how cannabinoids could prevent muscle contraction?

A
  • prevents influx of Ca2+ ions
  • synaptic vesicles dont fuse with membrane
  • neurotransmitter doesnt diffuse across synaptic cleft
  • no AP
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19
Q

suggest why artificial cannabinoids would be better to use than cannabis when treating someone with MS?

A
  • wont affect synapses in brain
  • wont damage brain
20
Q

a myelinated axon conducts conducts impulses faster than non-myelinated axon.

explain this difference?

A
  • in myelinated AP only at nodes
  • in myelinated AP jumps from node to node
  • in myelinated, AP doesnt travel along whole length of memb
21
Q

a student who read this investigation concluded that there was a relationship between the amount of myelin in a persons brain and whether or not they had dementia.

do these data support this conclusion?

give reasons

A
  • dementia results lower than control
  • error bars dont overlap - so differences significant
  • dementia may be due to other factors
  • because big difference in myelin in diff dementia
  • only small sample size
22
Q
A
  • probability difference in mean level of myelin caused by chance = 0.047
  • difference = significant
23
Q
A
  • sodium ion channels open
  • influx of sodium ions in post-sm causes depolarisation
24
Q
A
  • if not removed, keeps binding to receptor
  • keeps causing depolarisation
25
Q
A
  • movement in all groups same before MDMA
  • MDMA inc movement in group L
  • group K shows MDMA causes movement
  • little inc in group M
26
Q
A
  • ATPase required for fast hydrolysis of ATP
  • to provide energy needed for muscle contraction
27
Q
A
  • fast
  • lots of ATPase
  • for fast hydrolysis of ATP
28
Q
A
  • unable see organelles
  • only light microscope allows viewing of images in colour
29
Q
A
  • myosin filaments unable form
  • cant pull actin along
  • sarcomeres wont shorten
30
Q

give 4 precautions that researchers took to make their calc of mean number of capillaries per fibre reliable?

A
  • all same species
  • same muscle used
  • fields of view randomly chosen
  • used at least 8 animals in each group
31
Q

the leg muscles of long distance cyclists are usually larger than leg muscles of non-athletes.

why?

A
  • have more capillaries
  • more mitochondria
  • inc in diameter of fibres
32
Q

what is the role of phosphocreatine in providing energy during muscle contraction?

A
  • provides phosphate
  • make ATP
33
Q

explain how a lower temperature leads to slower nerve impulse conduction?

A
  • slower diffusion
  • of Na+
34
Q

suggest the conditions a researcher could use when obtaining her data for 0 seconds?

A

keep everything at room temp

35
Q

suggest the effect a taser has on a suspects muscle?

A
  • contractions
  • relaxations
  • rapidly
36
Q

suggest how tasers of 40-80 per second are dangerous to a suspect?

A
  • causes continuous mucle contraction
  • at high force
  • leads to heart failure
37
Q

role of tropomyosin in myofibril contraction?

A
  • moves out of way when Ca2+ bind
  • allowing formation of actin-myosin CB
38
Q

part played by myosin in myofibril contraction?

A
  • head bends to pull actin along in rowing action
  • head detaches and resits further along actin filament
39
Q

insecticide DFP combines with active site of enzyme AChE.

the muscles stay contracted until the insecticide is lost from the neuromuscular junction.

explain how?

A
  • AChE unable break down ACh
  • ACh still availabe to depolarise membrane
40
Q

epilepsy

A
  • brain contains millions of neurones communicating with one another
  • nerve imp regulated in brain to prevent excitation
  • inability to regulate AP in brain neurones results in epilepsy
41
Q

explain how donepezil could improve communication between nerve cells?

A
  • less ACh broken down
  • ACh binds to receptors
  • more Na+ enters to reach threshold
42
Q

suggest and explain 2 reasons why there is a high frequency of the E280A mutation in yaramul?

A
  • isolated to smaller gene pool
  • allele inherited from common ancestor
43
Q

explain why natural selection has not reduced the frequency of the E280A mutation in population?

A
  • symptoms develop late
  • have already reproduced
44
Q

the age at which the E280A mutation is expressed to cause AD can vary.

suggest and explain one reason for this?

A
  • due to enviro
  • methylation of genes
45
Q

suggest why a DNA probe for the mutated triplet was not considered a suitable method for detection of the E280A mutation?

A
  • produces false positives
  • would not know if it was the mutation
46
Q

cocaine is a highly addictive and illegal drug

the release of the neurotransmitter dopamine in specific synapses in the brain leads to feelings of pleasure

dopamine is removed from synapses by dopamine transporter proteins in the plasma membrane of neurones.

cocaine binds to the dopamine transporter protein

use all info to suggest how cocaine leads to feelings of pleasure?

A
  • prevents dopamine binding
  • transporter cannot move dopamine through membrane
  • dopamine remains in synapse
47
Q

explain how a mutation leads to the production of a protein that transports dopamine but is NOT affected by cocaine?

A
  • cocaine cannot bind
  • mutation changes base sequence of dna
  • change in amino acid base sequence of protein
  • change in tertiary structure (hydrogen, ionic and disulfide bonds)
  • dopamine can still bind

biology year 2 - exam q (27 decks)

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