Biology3 FINAL B

  1. cell cycle, stages
    • interphase:
    • G1... growth phase
    • S ... the time of synthesis, DNA replication
    • G2... gap preparing for mitosis
    • mitosis
  2. prokaryotic cell cycle (binary fission)
    • 1. the circular DNA attaches to plasma membrane
    • 2. DNA replicates itself
    • 3. bacterial cell begins to elongate
    • 4. plasma membrane grows inward
    • 5. divides into two daughter cells
  3. mitosis prophase:
    • chromosomes condense
    • spindle microtubules attach to chromosomes
    • nuclear envelope breaks apart
  4. mitosis metaphase:
    chromosomes line up along the equator of the cell
  5. mitosis anaphase:
    • sister chromatids separate and move to opposite poles of the cell
    • kinetochores pull the chromosomes poleward along the spindle microtubules
  6. mitosis telophase
    • chromosomes reach the poles
    • nuclear envelopes form around both groups of chromosomes
    • spindle microtubules disintegrate
  7. mitosis cytokinesis
    • cytoplasm is divided between two daughter cells:
    • --micro filaments form a ring around the cell's equator
    • --the ring contracts, pinching in the cell's "waist"
    • --two new daughter cells are formed
  8. meiosis I vs meiosis II
    • I: homologous chromosomes pair up, but sister chromatids remain connected to each other
    • II: like mitosis, sister chromosomes separate and are pulled to opposite poles of the cell
  9. meiosis prophase I
    • homologous pairs come together (synapsis) to form a tetrad, consisting of two homologs
    • chromosomes condense
    • nuclear envelope disintegrates
    • crossing over between homologous pairs
    • form spindle fibers
  10. crossing over
    recombination between nonsister chromatids of homologous chromosomes which produces new combinations of parental alleles
  11. meiosis metaphase I
    • homologous pairs line up along the equator
    • recombination = independent assortment
  12. independent assortment
    chromosomes of homologous pairs arrange themselves independent of chromosomes of other homologous pairs
  13. meiosis anaphase I
    paired homologs separate and begin to migrate to opposite ends of the cell
  14. meiosis telophase I
    • homologs reach poles
    • cell divides by cytokinesis
  15. meiosis prophase II
    • spindle apparatus forms and attaches to each side of the chromosomes, one spindle fiber to each sister chromatid
    • nuclear membrane disintegrates
  16. meiosis metaphase II
    replicated chromosomes line up at the metaphase plate
  17. meiosis anaphase II
    sister chromatids separate and move to opposite ends of the cell
  18. meiosis telophase II
    • chromosomes reach poles
    • nuclear envelope forms around each haploid set of chromosomes
  19. meiosis cytokinesis
    cytoplasm splits into 4 haploid cells
  20. gene
    segment of DNA that codes for a specific trait
  21. chromosome
    a condensed structure made of DNA with genes
  22. allele
    form expression of a gene
  23. dominant
    refers to an allele that masks the effect of a recessive allele paired with it
  24. recessive
    refers to an allele with an effect that is masked by a dominant allele paired with it
  25. co-dominance
    • both alleles express themselves
    • i.e. blood type
  26. incomplete dominance
    • when a heterozygote is expressed by an intermediate phenotype
    • i.e. snapdragon color
  27. genotype
    the particular alleles carried by an individual
  28. phenotype
    an individual's observable traits
  29. homozygous
    having identical alleles of a gene
  30. heterozygous
    having two different alleles of a gene
  31. radioactive dating
    estimates age of rock or fossil by measuring the ratio of a radioisotope and daughter elements
  32. vestigial structures
    structures with little or no use in the current organism, but was of use in an ancestor
  33. Jean-Baptiste Lamarck
    • new structures from need: an organism would develop a structure if needed
    • use/disuse: structures used in life got larger
    • inheritance of acquired characteristics: characteristics develop in life
  34. Carl Linnaeus
    not evolutionist but named organism based on similarities
  35. George Cuvier
    • advanced the idea of catastrophism
    • that a vast supply of species was created initially, and that successive catastrophes destroyed some species
  36. Charles Lyell
    proposed that geological processes have occurred over a long period of time and gradually changed the landscape
  37. Charles Darwin
    • populations have variability: individuals are not all the same
    • variability is inherited
    • populations overproduce: more than the environment can support
    • fierce competition
    • evolution occurs by the process of natural selection
  38. genetic equilibrium
    • theoretical state in which a population is not evolving (allele frequencies do not change)
    • ---does not occur in nature because of mutation, natural selection, genetic drift, gene flow, selective mating, unequal success
  39. genetic drift
    two types
    • any change in allele frequencies in a population due to chance
    • founder effect: small number of individuals start new population; colonization of isolated habitats (islands, caves, etc)
    • bottleneck: sudden decrease in population size; commonly caused by disease outbreaks and natural catastrophes
  40. mutation
    • mutation restores genetic diversity by creating new alleles
    • germinal - (in gametes) are evolutionarily important
  41. adaptive radiation
    a burst of genetic divergences from a lineage gives rise to many new species
  42. convergent vs divergent evolution
    • convergent: two species become more similar due to a similar niche ==> involves analogous structures: similar body parts that evolved separately
    • divergent: two organisms become less similar as they evolve into niches. evolutionary pattern in which a body part of an ancestor changes in its descendants ==> homologous structures: similar body parts that reflect shared ancestry
  43. speciation
    two types
    • process by which new species arise from existing species
    • sympatric: pattern in which speciation occurs in the absence of a physical barrier
    • allopatric: pattern in which a physical barrier that separates members of a population ends gene flow between them
  44. reproductive isolation
    members of one population are unable to breed with members of another population (no gene flow)
  45. disruptive selection
    • mode of natural selection that favors extreme phenotypes in a range of variation
    • intermediate forms are selected against
    • e.g., African seedcrackers
  46. stabilizing selection
    • mode of natural selection in which intermediate phenotypes are favored and extreme forms are eliminated
    • e.g., body mass of sociable weavers
  47. directional selection
    • mode of natural selection in which phenotypes at one end of a range of variation are favored
    • allele frequencies shift in a consistent direction in response to selection pressure
    • e.g., peppered moths
Card Set
Biology3 FINAL B
Biology3 FINAL B