Genetics.txt

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Author:
songbirds
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216301
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Genetics.txt
Updated:
2013-04-28 08:51:52
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biology genetics
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Genetics
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  1. What is variation
    Variation means that there are differences between species
  2. What is species
    A group of organisms capable of interbreeding and producing fertile offspring
  3. Two types of variation
    Inherited and acquired

    • Inherited: genes inherited from parents
    • Can be passed onto next generation
    • Inherit different traits from each parent

    • Acquired variation: not born with these
    • Learned and not passed on
  4. What is heredity
    Heredity is the passing on of features from parents to offspring by means of genes
  5. What is a gene
    A gene is length of DNA that codes for a specific protein
  6. What is a chromosome
    A chromosome is a structure composed of DNA and protein
  7. What is gene expression
    Gene expression is using a gene to produce a specific protein
  8. A single piece of DNA is called a..
    Nucleotide
  9. What does DNA stand for
    Deoxy-ribonucleic acid
  10. Each nucleotide is made up of 3 parts
    • 1) a nitrogen containing base
    • 2) a sugar called deoxy-ribose
    • 3) a phosphate backbone
  11. Four different bases of DNA
    • Adenine - thymine
    • Guanine - cytosine

    • A and G are purine bases
    • C and T are pyrimidine bases

    • A and T form 2 hydrogen bonds
    • C and G form 3 hydr bases
  12. Differences between DNA and RNA
    DNA double stranded, RNA single strand

    DNA sugar is deoxy-ribose, RNA sugar is ribose

    DNA has thymine, RNA has uracil

    DNA is very long, RNA is short

    DNA is found only in nucleus RNA is found in nucleus and cytoplasm
  13. DNA extraction
    • Chop
    • Washing up liquid
    • Salt
    • Water bath 60
    • Ice bath 0
    • Blend
    • Filter
    • Protease
    • Ethanol ice cold


    CWSHCBFPE
  14. Why chop kiwi in DNA extraction
    Break down cell wall
  15. Why add washing up liquid
    Break down phospholipids in cell membrane
  16. Why add salt in DNA extraction experiment
    Causes DNA to clump together affecting osmosid
  17. Why water bath at 60C in DNA extraction experiment
    Denatures enzymes that could breakdown the DNA
  18. Why ice bath at 0C
    Slow down any cellular reactions that could effect DNA
  19. Why blend for 3s in DNA extraction
    Fully break down all cell walls and membranes
  20. Why filter in DNA extraction experiment
    Remove any large cell contents/organelles
  21. Why add protease in DNA extraction experiment
    Breakdown proteins/enzymes to further stop DNA damage
  22. Why add ice cold ethanol in DNA extraction experiment
    Makes DNA insoluble and as a result visible
  23. What is DNA replication
    • A process when DNA produces an exact copy of
    • itself

    Occurs in nucleus

    Occurs during interphase
  24. DNA replication steps
    1. DNA double helix unwinds. Enzymes breakdown hydrogen bonds between bases. Room for new complimentary bases.

    2. New complimentary bases come from the cytoplasm. New bases join with old ones.

    3. New bases continue to join along entire length of DNA. Forms 3 identical double stranded lengths of DNA. Half of each strand is made of old bases and the other of new.

    4. Strands recoil to form double helix. 2 strands are identical to one original strand.
  25. Types of RNA
    • mRNA
    • tRNA
    • rRNA
  26. Function of mRNA and where found
    Carries protein code from DNA to ribosomes

    Found in nucleus and cytoplasm
  27. Function of tRNA and where found
    Carries amino acids to ribosome

    Found in the cytoplasm
  28. Function of rRNA and where found
    Used to make ribosomes

    Found in the cytoplasm
  29. What is a codon
    A codon is 3 DNA bases that code for 1 amino acid
  30. What is an anticodon
    An anticodon contains 3 complimentary bases to a codon
  31. Stages of protein synthesis
    • Transcription
    • RNA Processing
    • Translating
  32. What happens in transcription
    Takes place: nucleus

    Information from DNA is transferred to RNA

    DNA double helix uncoils and unzips. Exposed bases match up with RNA bases in the nucleus to form mRNA
  33. What happens in RNA processing
    Takes place: nucleus

    Non coding regions taken out by enzymes

    Coding regions come together

    End product is mRNA molecule that goes from nucleus to cytoplasm
  34. Translating
    • 1. mRNA attaches to ribosome
    • 2. tRNA arrives, brings amino acid to the first three bases (codon) on the RNA
    • 3. Three unpaired bases (anti-codon) on tRNA link up with each codon.
    • 4. Another tRNA molecule brings second amino acid, links up with codons etc.
    • 5. Peptide bond joins amino acids to form polypeptide chain.
    • 6. Process continues until stop codon is reached.
  35. Possible outcomes for codons
    1. Start codon to identify start of gene

    2. To produce an amino acid.

    3. To stop protein synthesis
  36. What is DNA Profiling
    DNA profiling is the process of making a unit of bands from a sample of DNA for a purpose of comparison
  37. Basic steps of DNA profiling
    EXCUSE STAN

    • EXtract DNA from sample of cells
    • CUt DNA into fragments with restriction enzyme
    • SEparate fragments on the basis of size
    • STain DNA bands to make pattern visible
    • ANalyse pattern of bands
  38. Uses of DNA Profilinh
    • Forensic analysis
    • Paternity tests
  39. What is evolution
    Evolution is the change of one species into a new species occurring over a long period of time
  40. Theory of evolution discovered by
    Charles Darwin and Alfred Wallace
  41. Natural selection theory
    • 3 observations:
    • -overbreeding
    • -population numbers remain constant
    • -inherited variations occur in populations

    • 2 conclusions:
    • -there is a struggle for existence (competition)
    • -natural selection (organisms with traits that allow them to adapt to environment will survive and reproduce, passed on. Unfavourable variations are not passed on.)
  42. Evidence for evolution
    • Fossil records
    • Comparative anatomy
    • Comparing DNA sequences
  43. Inherited variations are caused by
    • Sexual reproduction
    • Mutation
  44. 3 possible causes of sexual reproduction variation
    1. Independent assortment of chromosomes (different chromosomes, different gametes)

    2. Crossing over (occurs during meiosis and allows combination of parental genes on one chromosome, allows for variation in offspring)

    3. Fertilisation (different gametes from each parent)
  45. What is a mutation
    A mutation is the change in the amount or structure of DNA
  46. What are mutagens
    Mutagens are agents that cause mutations
  47. Main types of mutagens are
    Radiation (x rays, UV light, unprotected exposure to UV radiation lead to cancer/skin tumor)

    Chemicals (caffeine, tobacco smoke, effect gene that suppresses tumours)
  48. 2 types of mutations
    • Gene / point mutations
    • Chromosome mutations
  49. What are gene/point mutations
    Gene/point mutations are mutations in a single gene
  50. Example of gene/point mutation
    Cystic fibrosis/haemophilia/sickle cell anemia
  51. Gene/point mutations are caused by
    • Addition of extra vase
    • Change of a base to a different and incorrect base
    • Removal of a necessary base
  52. What is a chromosome mutation
    A chromosome mutation is a change in the number or structure of a chromosome
  53. Cause of chromosome mutation
    2 chromosomes being passed on from egg due to fault in meiosis
  54. Example chromosome mutations
    Down's syndrome
  55. What is genetic engineering
    Genetic engineering is the artificial manipulation of alteration of genes
  56. Steps involved in genetic engineering
    • Isolation
    • Cutting
    • Ligation and insertion
    • Transformation
    • Expression
  57. Applications of genetic engineering
    1. Animals - human gene to clot blood DNA of sheep. Produce haemophiliacs in their milk.

    2. Microorganisms - gene for insulin inserted in bacteria, produce for diabetics

    3. Plants - gene for vitamin a inserted into rice plant. Vitamin a enriched rice
  58. What are alleles
    Alleles are different forms of the same gene
  59. What does dominant mean
    Dominant means that the allele prevents the working of the recessive allele
  60. What does recessive allele
    Recessive means that the allele is prevented from working by a dominant allele
  61. What is genotype
    Genotype means the genetic make-up of an organism
  62. What does homozygous mean
    Homozygous means that the two alleles are the same
  63. What does heterozygous mean?
    Heterozygous means that the alleles are different
  64. What does phenotype mean
    Phenotype means the physical make-up or appearance of an organism
  65. What does progeny mean?
    Progeny refers to the offspring that are produced
  66. What is a mono hybrid cross
    A breeding experiment that tracks the inheritance of a single trait
  67. What is a Punnett square
    A Punnett square is used to show the possible combinations of gametes
  68. What is a dihybrid cross
    A dihybrid cross is one where two traits are incolved
  69. What is sex linkage
    Sex linkage is when a gene is found on a sex (x or y) chromosome
  70. What is linkage
    Linkage is when genes are located on the same chromosome
  71. Law of segregation
    Monohybrid crosses

    Pairs of factors (alleles) separate at gamete formation
  72. Law of independent assortment
    Dihybrid crosses

    During gamete formation either of a pair of factors is equally likely to combine with either of another pair of factors

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