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2013-04-21 15:28:05

MCAT Biology
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  1. What is the first filial generation?
    F1 generation - generation after parents 

    For Mendel, this generation was the heterozygous offspring of homozygous dominant and homozygous recessive parentage.
  2. When does the Mendelian ratio appear and what is it?
    When a heterozygous F1 generation is self-pollinated. 

    F2 generation expresses 3:1 dominant:recessive traits

    F2 = grandchildren to parent generation  
  3. What is the phenotype?
    The physical apperance/expression of a trait. Pink, blue, etc.
  4. What is genotype?
    The genetic makeup of a trait that produces a certain phenotype. i.e. Tt individual is heterozygous for being tall 
  5. Complete dominance 
    An individual has 2 chromosomes for any trait ... these chromosomes will be homologous, meaning that they code for the same trait and have the same gene loci BUT differ in the alleles that they express 

  6. What is an allele? 
    The unique contribution of each homologous chromosome - A is an allele and a is another allele
  7. The Law of Segregation 
    Alleles segregate independently to offspring. 

    i.e. even though each parent has two alleles for a given trait, they contribute only one allele to their offspring - this relates to meiosis
  8. What does inbreeding do?
    It increases the number of homozygous individuals but DOES NOT change the frequency of an allele
  9. Incomplete dominance vs. co-dominance
    Incomplete dominance - white and red flowers make pink flowers 

    Co-dominance- Human blood type AB antigens both expressed on blood cell membranes
  10. Law of Independent Assortment
    If genes coding for different traits are found on different chromosomes, they do not affect each other during gamete formation

    What is they're on the same chromosome? The closer together they are, the more likely they'll stay together...but if they're far apart, crossing-over may separate them

    • Independent assortment generates genetic variation. 
    • A cell has 2 copies of each somatic chromosome- one from mom, one from dad (homologous 
    • chromosomes). Independent assortment shuffles these chromosomes, and then places only one 
    • copy of each into the gamete. This way, the gamete may have chromosome 1 from mom, 
    • chromosome 2 from dad, chromosome 3 from dad, ... etc.
  11. What results in a 9:3:3:1 ratio? 
    A dihybrid cross - i.e something that is heterozygous (hybid) for TWO traits that are being passed together. 

    WwGg x WwGg

    The resulting PHENOTYPIC ratio will be 9:3:3:1 

    • 9- dominant, dominant
    • 3- dominant, recessive
    • 3- recessive, dominant
    • 1- recessive, recessive  
  12. The 23rd chromosome is the sex chromosome and establishes a person's gender 

  13. When is a gene considered to be sex-linked?
    When it appears on the 23rd chromosome pair, the sex chromosomes 

    Usually, the Y chromosome does not carry sex-linkage  
  14. Where is the allele for the sex-linked trait carried and what implications does it have? 
    On the X chromosome

    For men, the trait will always be expressed whether it's dominant or recessive because their Y chromosome does not carry a sex-link allele

    For women, expressage of sex-linked traits depends on whether the allele is dominant or recessive  
  15. What is the Barr body?
    The second X chromosome in somatic cells shrivels up and its genes inactivate 
  16. If a female is a carrier for a trait she must...
    Be carrying the recessive allele for a sex-linked trait on one of her sex chromosomes 
  17. What kind of disease is hemophilia?
    Sex-linked recessive 
  18. Are the X and Y chromosomes homologous to one another?
  19. Is evolution a change in:
    a.) an individual’s alleles?
    b.) a family’s alleles?
    c.) a population’s alleles? 
    d.) a species’ alleles?

    C - A population's alleles or GENE POOL 

    As long as the frequency of alleles in a gene pool remains constant, evolution has not occured  
  20. What is the order of taxonomical classification?

    King Philip Comes Over for Good Sex

    Within each are subgroups --- should know the subphylum Vertebra  
  21. What is Vertebra?
    A Subphylum falling under the Phylum Chordata 
  22. What is more specific, Vertebra of Chordata?
    Vertebra = subphylum 
  23. Organisms within the same ___ have similar genetic structures. 
  24. What is Mammalia? 
    A Class 
  25. What is Chordata?
    A phylum 
  26. What are domians? 
    New superkingdoms! 

    Bacteria ; Archea ; Eukarya 
  27. What is a species? 
    Organisms that can produce fertile offspring with one another 
  28. 1. Geographic isolation
    2. Habitat isolation
    3. Seasonal isolation
    4. Mechanical isolation
    5. Developmental isolation
    6. Behavioral isolation
    7. Gametic isolation  
    • 1. Geographic - separated in space 
    • 2. Habitat- live in the same region but occupy different habitats
    • 3. Seasonal - mate in different seasons
    • 4. Mechanical - physically impossible to mate with one another
    • 5.  Developmental - embryo unable to develop 
    • 6. Behavioral - different mating rituals
    • 7. Gametic - gametes are incompatible  
  29. Survival of the fittest 
    No two species can occupy the same niche indefinitely 

    The fittest organism can survive to produce progeny and ensure that reproduction continues  
    • Type I - K strategist : few offspring, parental care, slow to mature, SIGMOIDAL GROWTH CURVE THAT LEVELS OFF AT CARRYING CAPACITY , DENSITY-DEPENDENT factors 
    • Habitats that do not change very often characterize k strategists

    Type III - R strategist : many offspring, mature rapidly, no parental care, found in unpredictable environments affected by DENSITY INDEPENDENT FACTORES (environmental fluctuations)
  30. What is speciation and when does it occur?
    The formation of a new species 

    Occurs when gene flow in a population is cut off  
  31. What causes speciation?
    Geographic, seasonal, and behavioral isolation --- anything that affects gene flow 
  32. What is adaptive radiation?
    When several species arise from the same ancestral species 
  33. What is an evolutionary bottleneck?
    When an allelic shift occurs in the members of the species

    A SEVERE reduction in population size (natural disaster)  
  34. Divergent evolution
    When two species that have similar ancestry have homologous structures 

  35. Convergent evolution 
    When two unrelated species develop analogously similar structures 

    Ana = anew  
  36. Polymorphism 
    Distinct forms of a phenotypic trait 
  37. What satisfies HW equlibrium?
    • 1. Large population 
    • 2. Mutational equilibrium (backward=forward)
    • 3. Immigration or emmigration must not change gene pool
    • 4. Random mating
    • 5. No selection for the fittest organism  
  38. What is genetic drift?
    Where an allele in lost in a population because all people carrying that allele die off 

    Caused by random events, not selective pressures  
  39. p^2 + 2pq + q^2 = 1

    p + q = 1
    • Express frequencies in decimal terms 
    • p^2 = frequency of the homozygous pp
    • 2pq = frequency of the heterozygous pq
    • q^2 = frequency of the homozygous qq

    • p = frequency of p allele 
    • q = frequency of q allele 
  40. First attempt to recreate the atmosphere of early earth 
  41. Coacervates 
    Lipid/protein bubbles through to be the first cells evolved 
  42. Chordata is a phylum 

    Chordates have bilateral symmetry

    Chordates are deuterostomes = anus develops near blastopore

    Have coelom, notochors, pharyngeal slits, hollow nerve cord, and a tail
  43. What is a coelom?
    A characteristic of chordates : a body cavity with mesodermal tissue
  44. What are the classes of vertebra?
    • 1. Agnatha
    • 2. Cartilaginous fish
    • 3. Bony fish
    • 4. Amphibians
    • 5. Reptiles
    • 6. Birds
    • 7. Mammals
  45. Do catastrophic events change HW?
    No. Nothing like floods, earthquakes etc change HW 
  46. Can migratory birds be of the same species? 
    Yes, migratory birds aren't geographically isolated 
  47. What is mutualism?
    When both things depend on each other for survival or equal benefits 

    i.e. GM Corn cannot survive without human intervention so it benefits from humans just the way that we benefit from eating it
  48. The Molecular Clock Theory
    We can find how much time has passed by measuring the amount of neutral mutations
  49. From whom are cellular organelles inherited?
  50. Phenotype is affected by?
    Selective pressures
  51. Natural Selection
    Fitness = the ability to pass on traits to offspring. 

    If an individual is healthy, but cannot reproduce, he/she is not fit. It's all about the ability to reproduce and produce viable offspring!! Predation has nothing to do with it.
  52. Human taxonomical classification
    • Domain: Eukarya
    • Kingdom: Animalia
    • Phylum: Chordata
    • Class: Mammalia
    • Order: Primata
    • Family: Homididae
    • Genus: Homo
    • Species: Sapiens