Loren's bio 3

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Loren's bio 3
2012-04-19 01:31:21
Loren bio

Lorens bio 3 "genetics"
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  1. The basic unit of heredity
    The gene
  2. What are genes composed of?
    Where are they located at?
    • DNA
    • on the chromosomes
  3. What's an allele?
    When a gene exists in more than one form the alternative forms are called alleles
  4. What's a genotype?
    the genetic makeup of an individual
  5. The phenotype is?
    the physical make up of a person....
  6. A true breeding individual is....
    if self crossed will only produce offspring with the same phenotype
  7. Mendels 4 laws of inheritance...
    • 1. genes exist in alternative forms (alleles)
    • 2. organisms have two alleles for each trait, one from each parent
    • 3. the two alleles segregate during meiosis.
    • 4. if two alleles are different, only one will be fully expressed (dominant, recessive)
  8. Monohybrid cross
    only one trait being studied in a particular cross
  9. What's a test cross?
    a homozygous recessive (dd) organism is crossed with an unknown dominant organism (DD, or Dd) to find out what the dominant organism really is.
  10. Dihybrid Cross
    When the parents differ in two different traits.
  11. what is crossing over?
    it exchanges information between chromosomes and may break the linkage of certain patterns
  12. What's an example of codominance?
    • ABO blood groups
    • specifically AB blood (they're both dominant)
  13. Sex linked chromosomes are located.....?
    on the X and Y chromosomes
  14. Do environmental factors affect gene expression?
    • yes, the himalayan hare (dark fur)
    • (drosophila have crooked wings in low temp)
  15. What is nondisjunction?
    • the failure of homologous chromosomes to separate properly during meiosis I
    • the resulting zygote would have 3 copies or a single copy
  16. What's a mutation?
    a change in the genetic info of a cell, coded in the DNA
  17. What genetic malfunction causes sickle cell anemia?
    a substitution of valine (GUA or GUG) for glutamic acid (GAA or GAG)
  18. CUT the PIE
    Cytosine/ Urasil/ Thymine are all PYrimidines
  19. Purines consist of ???
    Adenine and Guanine
  20. What are the stop codons?
    • UAU
    • UAC
    • UAA
    • UAG
  21. What are the stops codons
    • UGU
    • UGC
    • UGA
    • UGG
  22. What does RNA contain that DNA doesn't have?
    • Uracil.....U
    • instead of Thymine
  23. Is RNA usually single stranded?
  24. mRNA
    • messenger RNA
    • it is the complement of the DNA sequence (it has the copy of the DNA sequence but opposite or backwards, kinda like a mirror)
    • it goes from the nucleus to the ribosomes where protein synthesis occurs
  25. tRNA
    • transfer RNA
    • found in the cytoplasm
    • helps in the translation of mRNA's code into amino acids.
    • helps bring amino acids to the ribosomes during protein synthesis
    • it recognizes and snags mRNA and amino acids (attaches them)
  26. rRNA
    • ribosomal RNA
    • a structural component of ribosomes
    • the most abundant, made in the nucleolus
  27. What's transcription?
    when information on DNA is transcribed into a strand of mRNA which then leaves the nucleus
  28. Translation
    • the process whereby mRNA codons are translated into a sequence of amino acids
    • in the cytoplasm
  29. Ribosomes
    • There are two subunits. Like a sandwich
    • they bind together during protein synthesis
  30. Polypeptide synthesis has three stages...?
    • 1. initiation
    • 2. elongation
    • 3. termination
  31. Start Codon
  32. Initiation of synthesis...
    • ribosome binds to mRNA near 5' end.
    • scans the mRNA til it gets to AUG
  33. Elongation of synthesis....
    hydrogen bonds form between mRNA codon and it's anti codon (the opposite complements of mRNA codon)
  34. Termination of synthesis...
    When one of the stop codons (UAA, UAG, UGA) arrives, they signal the ribosome to stop translation
  35. Bacterial genomes have circular DNA rings called....
  36. Episomes are plasmids that are capable of integration into thhe bacterial genome