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28 Cards in this Set
- Front
- Back
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Why is it important for Animals and Plants to respond to changes to the external and internal environments?
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It increases their chance of survival.
Response to internal changes means that optimum conditions are kept for chemical reactions to take place. Any change to the environments is called a STIMULUS. |
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What are receptors and effectors?
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Receptors - they are cells/proteins on the cell surface membranes that detect the stimuli.
Effectors - are cells that bring about the response to a stimulus to produce an effect (muscles or glands). |
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What are the 3 main types of neurones?
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SENSORY NEURONE - transmit electrical impulses from receptor to the CNS.
MOTOR NEURONE - transmit electrical impluses from CNS to effectors. RELAY NEURONE - transmit electrical impulses between sensory neurones. |
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What are the two different Nervous Systems?
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CENTRAL NERVOUS SYSTEM - made up of brain and spinal cord.
PERIPHERAL NERVOUS SYSTEM - made of neurones which connect CNS to the rest of the body. |
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What the the two different systems of Peripheral Nervous System?
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SOMATIC NERVOUS SYSTEM - controls conscious activities.
AUTONOMIC NERVOUS SYSTEMS - controls unconsciou activities ( e.g. digestion). |
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What is Parasympathetic and Sympathetic Nervous Systems?
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Parasympathetic - calms the body down( 'rest and digest' system).
Sympathetic - gets body ready for action ( 'flight or fight' system). |
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What is the difference in Nervous System and Hormonal System Communications?
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Nervous - LOCALISED (neurotransmitters are secreted directly onto cells), SHORT-LIVED, RAPID.
Hormonal - SLOWER (as travel in blood and is slower than electrical impulses), LONG-LASTING ( dont breakdown as quick as quickly as neurotransmitters) and WIDESPREAD. |
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How do receptor cells communicate information via the nervous sytem?
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Receptor cells are specific to one stimulus (e.g. light, pressure or glucose concentration)
When receptor is in resting state there is a POTENTIAL DIFFERENCE (p.d) between the inside and outside of the cell. P.d when cell is at rest is called the RESTING POTENTIAL. Stimulus detected - cell membrane excited - becomes more permeable - allowing more ions to move in and out of cells - altering the p.d Change in p.d due to a stimulus is called the GENERATOR POTENTIAL (g.p). Bigger stimulus - bigger movement of ions - bigger change in p.d - bigger g.p produced. if g.p is big enough then will trigger an ACTION POTENTIAL (a.p) - an electrical impulse along a neurone. A.p only triggered if g.p reaches a THRESHOLD level Strength of stimulus is measured by FREQUENCY of a.ps If stimulus too weak the g.p doesnt meat threshold and so no a.p. |
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What are Pacinian Corpuscles and how do they work?
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They are receptors in the skin which detect a mechanical stimuli (e.g pressure)
Contain the end of a sensory neurone - wrapped in layers of LAMELLAE Pressure on the lamellae - presses the sensory nerve ending - causes deformation of the STRETCH-MEDIATED sodium channels in the cell membrane - Na+ channels open - Na+ ions difuse out - create a g.p - which meets threshold - creating an a.p. |
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What are Photoreceptors?
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Light receptors in the eye
light enters eye - amount of light that enters in controled by muscles of the IRIS - light focused by lens onto retina - retina contains photoreceptor cells. FOVEA - an area in the eye where there are lots of photoreceptors. Never impulses carried out from the photoreceptor cells to the brain by the OPTICAL NERVE (a bundle of neurones). Where the optical nerve leaves the eye is called a BLIND SPOT - no photoreceptor cells present so no light detected. |
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How is light converted into an electrical impluse?
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Light enters eye - hit the photoreceptor cells - get absorbed by light-sensitive pigments.
Light bleaches the pigment - causes chemical change - altering membrane permeability to sodium G.p created - if reaches threshold - nerve impluse sent along a BIPOLAR NEURONE. Bipolar neurones connect photoreceptors to the optic nerve - which then takes it to the brain. 2 types of photoreceptors - CONE and ROD cells. |
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Describe rod cells....
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Mainly found in the peripheral parts of the retina.
Only give black and white informtion. They are very sensitive to light - this is because manly rods join ONE neurone (many weak g.ps combine to reach threshold and trigger an a.p). Low sensitivity because many rod cells to one neurones - this means that light from 2 objects close together can't be told apart. |
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Describ cone cells....
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Mainly packed together in the fovea.
Gives coloured information. 3 types - red-sensative, green-sensative and blue-sensative. Not as sensitive as rod cells ( one cone cell to one neurone - so takes more light to reach a threshold). Give a hight visual activity because cones are close together and one cone is connected to one neurone. When light hits 2 cone cells - reaches 2 threshold - 2 a.ps sent to brain - so can distinguish between 2 points that are close together as 2 separate points. |
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What is Gene Technology?
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techniques that can be used to study genes and their functions.
e.g. POLYMERASE CHAIN REACTION (PCR) - produce lotes of identicle copies of a specific gene IN VIVO gene cloing - produces lots of copies of a specific gene. DNA PROBES - identifies specific genes. |
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What are th e ways that DNA Fragments can be produced and how do they work?
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1) REVERSE TRANSCIPASE
Difficul to obtain DNA Fragment containing target genes mRNA molecules are complemary and so is easier to obtain - used as templates to make lots of DNA called COMPLEMENTARY DAN (cDNA) mRNA is isolated - mixed with free DNA nucleotides and REVERSE TRANSCRIPTASE - use mRNA as templates to form new strand. 2) RESTRICTION ENDONULEASE ENZYMES some dna contains PALINDROMIC SEQUENCES (antiparallel based pairs) Enzymes recornise specific palindromic sequances - cut the DNA at these places. different enzymes cut at differnet places by HYDROLYSIS REACTIONS leave STICKY ENDS - small tail of unparied bases at each end ( first base is always left attached) 3) PCR (vitro) several stages - repeated over to produce many copies reaction mixture contains- free nucleotides, primers, DNA sample, and DNA polymerase4 mixture heated to 95*C (breaks hydrogen bonds) - then cooled to around 50-65*C (so primers can attach to DNA strands) |
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Describe In Vivo Cloning....
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(copied with an organism)
1) Gene INSERTED into a VECTOR vector is cut open using the same restiction enzyme as was used to isolate DNA vector + DNA mixed togethr with DNA LIGASE - which joins sticky ends together v new DNA formed called RECOMBINANT DNA 2) TRANSFER of vectors vectors with recombinant DNA is tranfered into cells host cells ar eplaced in an ice-cod solution of calcium chloride so cell walls become more permeable - then heatshock given of 42*C to encourage take up of vector plasmids. 3) IDENTIFYING transformed cells not all cells will have tken up the wanted gene MARKER GENES can be added to help identify the cells host cells are added to agar plates to form colonies the marker gene can code for an antibiotic resistance - host cells with antibiotic will survive and others will die. FLORESCENCE MARKERS will show genes that dont have the gene under UV light. |
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What are the advantages and disadvantages of Vivo Cloning?
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ADVANTAGES
can produce protain + mRNA as done in cells - as has the ribosome to do so + the enzymes. produce modified DNA/mRNA Large fragments of DNA can be cloned relatively cheap DISADVANTAGE DNA has to be isolated may not want modified DNA Slow process - some bacteria grows quiet slowly. |
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What are teh advantages and disadvantages of Vitro Cloning (PCR)?
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ADVANTAGES
can produce lots of DNA - but not mRNA isnt modified if dont want it onlyreplicated DNA fragment of interest - dont have to isolate fast process DISADVANTAGE only replicates small DNA fragments may want modified products mRNA and protein arnt made aswell can be expensive |
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What is Genetic Engineering?
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is he manipulation of an organisms DNA
organisms that have had their DNA altered are called TRANSFORMED ORGANISMS - have recombinant DNA plants, bacteria and animals are genetically modified to benifit humans produce disirable characteristics in off spring as modified plasmids placed into embryos. |
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What 3 ways can GMO benefit humans?
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1) Agriculture
transformed to give HIGHER YIELD or more NUTRIENTS - reduce risk of famine and malnutrition PEST RESISTANCE - so fewer pesticides needed - reduce cost + environmental problems associated with it. e.g golden rice - vit A - s.asia and s.africa 2) Industry BIOLOGICAL CATALYSTS - produced in large quantities - less money 3) Medicine produce DRUGS and VACCINES - quickly, cheaply, large quantites e.g insulin for type 1 diabetes ( bacteria) |
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What are the issues with genetically engineering?
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1) Agriculture
farmers may only plant one type of crop - MONOCULURE - could make whole crop vunrable to a disease as they are all genetically the same. People concerned about posability of 'superweeds' - become resistant to herbicides - could occur if plant was to breed with wild plants. 2) Industry without proper labelling some people think wont have choice about whether to consume genetcally modified or not some people worried process could puify proteains - could lead to roduction of toxins. 3) Medicine limit technology to save lives used unethically - make disired off springs |
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People
Vs Environment (Genetic Engineering) |
PEOPLE:
reduce risk of famine + malnutrition - drought resistant crops helpful in producing vaccines for everyone even in areas of none frigeration. medicine produced cheaply so more can afford them. ENVIRONMENTALISTS: harm environment - decrease in biodiveristy - disease cant be stopped in 'superweeds'. forces small companies outof buisness. |
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What are Genomes?
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all genetic material in an organism.
some genomes contain repetitive, non-coding base sequence the number of repeats is differet between each individual - the number of repeats allows comparason betwen person to person. individuals have a low chance of having the same genetic fingure print as chances of the same number of repeats is highly unlikely. |
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What is the process of making a DNA fingerprint?
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1) cut up DNA sample (blood/semen/hair/skin/saliva)
2) PCR - provide a big enough sample of DNA 3) Restriction enxymes - cut out specific core sequences 4) gel electrolesis - separation 5) add alkalin solution - separate double strands into single strands. 6) SOUTHERN BLOTTING - nylon membrane - UV light sticks DNA 7) Radioactive DNA probes added which join to DNA strands - single stranded pieces - complementary base sequence to core sequence- PO4- (radioactive) 8) X-ray film - darkening due to radioactive emmisions |
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What are the uses of DNA Fingure Printing?
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Determine relationships (biological father etc)
Determine genetic variablity of population - greater no. of bands = more variability Crime scenes - find suspect who killed Medical Diagnosis - diagnose genetic disorders and cancer Animal + Plant breeding - prevent decrease in gene pool - animals/plant with similar bands wont be breed together and ones with lots different ones will be. |
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How can genes be located and separated?
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DNA PROBES
short strands of DNA have specific base sequence that complements the base sequence on the target gene. bind to the target gene - label attached so can be detected - radioactive or florescence. DNA SEQUENCING restriction enzymes cut sequence into small bits DNA fragments separated - electropholesis |
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What is gene therapy and how does it work?
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How it works:
altering the defective genes inside cells to treat the disorder if caused by 2 recessive alleles then can add a working dominant allele. if caused by a dominant allele then you can 'silence' it - stick DNA in the middle so stops working. 2 types Somatic therapy - altering alleles in the body cells Germlin therapy - altering alleles in the sex cells ( illegal though) |
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What are the Advantages and Disadvantages to gene therapy?
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ADVANTAGES
prolong lives of people with genetic disorders give people wiht disorders a better qualitly of life conceive babies without disorders (germline) could decrease the number of people that suffer from the disorder or cancer DISADVANTAGES treatment may be short term might undergo multiple treatments (somatic) difficult to get alleles into cell body could identify it as a foregn cells and so immune response kills them. allele could insert in the wrong place - causing more problems dissorders caused by multiple genes would be difficult to treat. |
