Genetics exam 1

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Genetics exam 1
2014-09-21 21:27:22

Genetics exam 1, ch 1, 2, 3
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  1. genetics
    the study of all aspects of genes (cell, organism, population)
  2. genes
    • fundamental units of biological information
    • composed of DNA
  3. Molecular genetics
    • the study of the molecular processes underlying gene structure and function
    • discovery of DNA allowed this to exist.
  4. What kind of information is held within cells that allows them to rebuild an entire complex adult organism?
    DNA lies within chromosomes within nucleus of every cell, passed from generation to generation through nuclear divisions (meiosis and mitosis)
  5. What constitutes biological information?
    Life regenerates every generation from single cells
  6. genomics
    study of complete gene sets (genomes).
  7. James Watson and Francis Crick
    • 1953, solved structure of DNA (double helix)
    • Inferred that DNA has info written in genetic code (4 nucleotides) which passes from generation to generation.
  8. genome
    organism's complete set of genetic information
  9. "genetic code"
    • linear series of 4 molecular building blocks (nucleotides)
    • passes from generation to generation
    • inferred by Watson and Crick
  10. diploid
    • 2 identical chromosome sets/copies of genome (pairs of homologous chromosomes or homologs)
    • humans 2n=46
  11. homologous chromosomes
    or homologs, 2 copies of same chromosome, as seen in diploid organism
  12. haploid
    • number of chromosomes in basic set. 
    • Only one copy of each gene.  
    • Human sex cells (n=23)
  13. chromosomes consist of:
    DNA (~1m) wrapped around histone protein until 4cm "supercoil"
  14. heterochromatin
    Centromere and telomeres of chromosome, tightly wrapped so less gene expression
  15. telomere
    • tips of chromosome
    • made of heterochromatin
  16. centromere
    center of chromosome, made of heterochromatin
  17. euchromatin
    • "legs" of X chromosome, cross of X and tips are heterochromatin
    • More loosely wrapped, more expressed
  18. protein
    main element of form in organisms (structural, enzymatic, regulatory)
  19. 3 types of proteins
    • structural - keratin
    • enzymatic - amylase, polymerase
    • regulatory - turns on and off to regulate expression
  20. Main task of living system
    • convert info of DNA into proteins
    • process and "language" is same in all organisms
  21. The Central Dogma
    DNA --(transcription)--> RNA --(translation)--> Protein
  22. Transcription
    DNA to RNA, occurs in nucleus
  23. Translation
    mRNA to Ribosomes, occurs in cytoplasm/ER
  24. Replication
    the way life perpetuates over time, producing new organisms and regenerating new organisms from single progenitor cell
  25. proteome
    complete study of all proteins
  26. connectome
    complete study of neuron connections
  27. tight supercoil
    not very expressed chromosome
  28. loose supercoil
    expressed chromosome/gene.
  29. introns
    get cut out of gene in replication
  30. exons
    stay in in gene replication
  31. Bacterial chromosomes
    Only have one, everything is required.  Also have plasmids floating in cell, not required but specialized, passed.  Extrachromosomal
  32. plasmids
    extrachromosomal DNA floating in cell, not required but specialized and passed
  33. Viral genome
    NOT ALWAYS DNA, only thing that can use RNA instead, not alive because cannot procreate alone.
  34. "well conserved"
    • process and language pretty much same in all organisms.  Evolutionarily as good as it gets.  
    • If mammal and fish are the same, pretty good bet.
  35. free ribosome proteins
    make cytoplasmic proteins that work inside the cell
  36. ER proteins
    leave cell
  37. semi-conservative
    post-meiosis, each daughter chromosome has 1 old and 1 new strand.
  38. somatic
    every cell that isn't a sex cell.
  39. Epigenetic modification
    • shape physical structure of genome.  Has to do with loosely or tightly wrapped, making transcription possible or impossible.  "switched on" or "switched off"
    • NON-ALLELIC, heritable but not based on mutations in DNA
  40. epigenic: OFF
    • silent (condensed) chromatin
    • methylated cytosines (red circles)
    • deacetylated histones
  41. Epigenic: ON
    • active, open chromatin
    • unmethylated cytosines (white circles)
    • acetylated histones
  42. Natural Selection
    • the process whereby individuals with a particular characteristic may reproduce better than others in a given environment. 
    • Make more offspring, more people with trait
  43. homology
    similarity due to shared ancestry due to common ancestor
  44. Theory of Evolution
    • notion of natural selection acting on variation.  
    • Change in DNA generates variation, which is raw material for evolution
  45. Evolutionary tree
    • phylogenic tree showing how far apart or close species are genetically and where they branched.
    • shows descent of various species through ancestral forms over time
    • Differences in DNA sequences are quantified and species with similar sequences are placed closer together
    • used to test patterns of evolutionary relationships previously proposed exclusively in physical homology
  46. mutant
    altered form of normal property
  47. useful transgenes
    • crops modified for insecticide and herbicide resistance
    • goats produce anti-blood-clotting protein antithrombin and secrete it in milk
    • bacteria synthesize important drugs like human insulin and growth hormone
    • yeast for bread/wine
    • gene therapy
    • forensics
  48. How do geneticists analyze biological properties?
    to find the subset of genes in the genome that influence the property (gene discovery)
  49. Detection of single-gene inhertiance patterns
    • 1)mate a wild type and a mutant
    • 2) mate their progeny
    • the ratio fo mutant to wt will reveal if the difference is held in a single gene
  50. wild type
    normal form
  51. Gregor Mendel
    • Father of Genetics
    • 1860, Czech
    • Garden Pea (psium sativum) (shape/color of pea, of pod, color of flower, plant height, position of flower).
    • studied contrasting phenotypes
  52. Selfing
    • Breeding with self, pollenate stigma with own pollen
    • Opposite of cross-pollination
  53. F1
    first filial generation
  54. Law of Equal Segregation
    • Mendel's 1st
    • Genes come in two forms, called alleles
    • Meiosis, gene pair separate EQUALLY into eggs or sperm
    • One gamete has only one copy of gene
  55. zygote
    fertilized egg
  56. homozygote
    A pair of identical alleles
  57. heterozygote
    pair of different alleles
  58. homozygous dominant
  59. Heterozygous
  60. homozygous recessive
  61. phenotypes
    VISIBLE characteristic (3:1)
  62. Genotypes
    GENETIC characteristic, 1:2:1
  63. What are alleles at molecular level
    different variations of same gene.  Can be mutation.
  64. Why are alleles with mutation normally recessive?
    Bad for species
  65. kinetochore
    at centromere on chromosome
  66. synaptonemal complex
    between homologous chromosomes, holds together
  67. null
    gene does not work, mutation likely at active site (or promoter)
  68. leaky
    • gene is active but not great, semi-functional. 
    • Mutation likely at end, or on edge of active site
  69. primary phenotype of a gene
    protein it produces (and functional differences)
  70. PKU (phenylketonuria)
    • Defective allele of phenylananine hydroxylase (PAH), doesn't turn phenylalanine into tyrosine, instead gets turned into phenylpyruvic acid, which cause neuronal degeneration/lack of development.
  71. silent
    mutation at very end, not on active site.  Gene functions normally
  72. Haplosufficient
    one copy is enough to have wild type phenotype
  73. haploinsufficient
    single wild type allele does not provide normal function
  74. human # of chromosomes (autosomal and sex)
    • 46 chromosomes
    • 22 homologous pairs of autosomes + 2 sex chromosomes
  75. homogametic
    females (XX)
  76. heterogametic
    Males (XY)
  77. Telomere areas of sex chromosomes are called
    pseudoautosomal region 1 and 2, on either side of the differential region
  78. Thomas Hunt Morgan
    • early 1900s
    • worked with Drosophilia eye color.  Reciprocal crosses did not make same phenotypic ratios
    • proved existance of chromosomes and that genes are on them "the chromosome theory of inheritence
    • sex-linked inheritance
  79. chromosomal theory of inheritance
    Thomas Hunt Morgan and Drosophilia
  80. propositus
    member of family who first comes to attention of geneticist (person requesting info, usually)
  81. autosomal recessive disorders
    • progeny of unaffected parents
    • affected progeny include both male and female
    • pedigree looks bare, few affected
  82. autosomal dominant disorders
    • phenotype appears in every generation of pedigree
    • affected parents transmit to offspring of both genders
    • (pseudoachondroplasia=dwarfism)
  83. Ability to taste PTC (Phenylthiocarbamide)
    Dominant taste allele, dimorphism
  84. autosomal polymorphisms
    in population, polymorphism is coexistance of two or more common phenotypes of a character (eye color, hair color, chin dimple, widow's peak, earlobes, etc).  Dominant is written first.
  85. X-linked recessive disorders
    • many more males than females affected
    • none of offspring of affected male show the phenotype but all daughters are carriers
    • no sons of affected male show phenotype and cannot pass condition on
    • (red-green color blind, hemophilia)
  86. X-linked dominant
    • Very rare
    • affected males pass to all daughters but no sons
    • affected (heterozygous) females married to unaffected males pass to half of sons and daughters
    • (Hypophospahtemia, hypertrichosis)
  87. Y-linked inheritance
    • fathers pass to sons
    • no cases of nonsexual phenotypic variants associated with Y
    • (Hairy ears)
  88. Product rule
    the probability of two independant events both occurring is the product of their individual probabilities
  89. sum rule
    • probabilities of either of two mutually exclusive events occurring is the sum of their individual probabilities 
    • (Roll 2 4s OR 2 5s.  1/36 + 1/36 = 1/18)
  90. Pleuralistic ignorance
    belief that you are the only one who doesn't understand, prevalent in large groups
  91. Independant Assortment
    • Mendel
    • Two genes on different chromosomes will act independantly at meiosis
  92. "linked" genes
    on same chromosome, will always match up
  93. "unlinked" genes
    on different chromosomes, will assort independantly.
  94. Monohybrid
    analysis of one gene
  95. dihybrid
    • analysis includes 2 genes
    • semicolon indicates different chromosomes (A/a;B/b)
    • 9:3:3:1
  96. trihybrid
    • analysis includes 3 genes
    • semicolon indicates different chromosomes (A/a;B/b)
  97. 9:3:3:1
    result of 2 hets, dihybrid cross.  Creates 2 3:1 ratios in phenotypes
  98. Branch diagram
    used instead of punnet square in dihybrid cross, punnet is too hard
  99. Elinor Caruthers
    • 1913
    • Heteromorphic chromosomes, one had a truncated end so could tell apart.  Also had single chromosome (grasshopper).  Found 50% ratio, proved INDEPENDANT ASSORTMENT
  100. Which meiotic stage generates mendel's second law?
    Anaphase (independant assortment)
  101. Test Cross
    cross with recessive to determine genotype of unknown
  102. Hybrid Vigor
    • The F1 heterozygote hybrid shows greater size and vigor than contributing lines
    • can't make itself, have to keep crossbreeding parents
  103. Polygenes
    • A group of non-allelic genes that, together, influence a phenotypic trait.  
    • non-alleleic, more than one gene that come together to influence one trait, also includes environmental factors.
  104. Why are mitochondria and chloroplasts special?
    • Have own DNA (nucleoids), not associated with (histone) proteins.  Not functionally autonomous, but make ATP
    • Uniparental inheritance (ONLY MOM)
  105. Uniparental inheritance
    Mitochondrial DNA,  can be mutant and cause phenotypic variants.  No histone proteins, very small
  106. p-value
    The number that determines if something is significant or insignificant (5% in chi square test).  If greater than 5%, non-significant.
  107. Chi-squared test
    • used to compare data with expected results, quantifies acceptable deviation.  
    • Reject hypothesis with less than 5% (p-value)(numbers to the right)
    • (O-E)2/E
    • df = phenotypes you can see -1