What is the 3 purposes of mitosis and name the stages of the cell cycle
1) Growth, repair, development
2) Growth, DNA replication, Mitosis, Cytokinesis
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What are the stages of mitosis?
Interphase= DNA replicates
Prophase= DNA condenses= chromo., membrane and nucleus disappear
Metaphase= chromo. and copies line up in middle of cell
Anaphase= cell fibres pull each sc
Telophase= chromosomes uncoil
cytokinesis=nuclear membrane reforms
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Uses of stem cells in medicine
(type 1 diabetes, paralysis, sickle cell anaemia)
1) extract from early embryos
2) grow in a lab
3) stimulate them to differentiate into desired specialised cell
4) give to patient to replace their faulty cells
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pros and cons of stem cells
e= immune system rejection (diff. genomes) =>
(though this risk could be reduced by giving patient medication to suppress their immune system, doesn't always work, often has side effects)
a= no rejection, but can only diff. into blood cells
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how do scientists study the brain
1) study people w. brain damage
2) electrically stimulate parts of brain (using electrodes, i.e visual/muscle contractions)
3)brain scans (CT= use x-rays to see damaged areas, PET= use radioactive chemicals (to measure underlying activity) MRI= magnetic f
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Why is treating the brain so difficult?
1) tumours
2) infections
3) trauma
4) mental health problems
(physically hard= encase within skull and surrounding brain tissue= fragile, i.e surgery)
(complexity= we do not understand the underlying processes, i.e drugs and chemicals)
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What is the reflex arc
stimuli=>receptor=>sensory neurone(i.e change in temp or CO2 in blood)=>spinal cord=>relay neurone=>motor neurone=>effector(i.e muscles or glands, contract or relax)
whenever electrical impulse hits nerve ending, it causes a release of some chemicals
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what is the iris reflex and how does it work
it controls pupil size
constricts= smaller in bright light (avoid retina damage)
dilates= larger in low light (see in the dark)
circular muscles= in bright light= c.m contract, r.m relax
radial muscles= in low light= c.m relax, r.m contract
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close objects vs. distant objects and refraction
close= large refraction, c.m contracts and the s.l slacken
distant= less refraction, c.m relax and pull s.l taut
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what is hyperopia and myopia and what lenses are required to correct them
hyperopia= can't refract enough, can't focus on near objects bc. image appears behind retina= blurry)=> convex (stronger refraction)
myopia= refracts too much, can't focus on distant objects bc. image forms b4 retina= blurry=> concave lens (refracts light
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Other cards in this set
Card 2
Front
What are the stages of mitosis?
Back
Interphase= DNA replicates
Prophase= DNA condenses= chromo., membrane and nucleus disappear
Metaphase= chromo. and copies line up in middle of cell
Anaphase= cell fibres pull each sc
Telophase= chromosomes uncoil
cytokinesis=nuclear membrane reforms
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