chapter 5

  1. genome
    a complete set of chromosomes 
  2. genotype 
    the genetic composition of an organism 
  3. phenotype
    the observable appearance of an organism
  4. chromosome
    the strand of DNA found within a nucleus of a cell
  5. DNA (Deoxyribonucleic Acid)
    Molecules that compose chromosomes
  6. gene
    a functional hereditary unit made up of dna that occupies a fixed location on a chromosone
  7. gene expression
    the translation of the genotype into the phenotype of an organism
  8. allele
    alternative version of a particular gene
  9. homozygous
    having two identical alleles for a given gene
  10. heterozygous
    having t wo different alleles for a given gene
  11. recessive allelea 
    gene that will reproduceits characteristic phenotype only when it occurs in a homozygous pair
  12. dominant allele
    a gene that produces its phenotype regardless of wether its paired allele is heterozygous or homozygous
  13. imprinted gene
    a gene of which only the mothers or the fathers copy is expressed but not both in the normal mendelian sense
  14. ribonucleic acid (RNA)
    a molecule that is similar to DNA that participates in the translation of genetic sequences into proteins.
  15. codon
    a sequence of three bases on the DNA molecule that encode one of 20 amino acids
  16. proteome
    the set of proteins encoded by the genome
  17. meiosis
    cell division in sexually reproducing organisms that reduces the number of chromosomes in half in the reproductive cells such as sperm eggs and spores.
  18. linkage
    the characteristic of genes located adjacent to one another to be passed along as a group
  19. crossing over
    a proccess occuring during meiosis in which chromosomes exchange equivalent segments of DNA material
  20. mutation
    a heritable alteration of genes
  21. sex linked characteristics
    phenotypical characteristics that result from expression of genes on the x chromosome that are not duplicated on the y-chromosome.
  22. x chromosome inactivation
    the pprocess by which one X chromosome in each female cell is silenced to equalize the amount of proteins procuced by males and femalse
  23. single nucleotide polymorphism (SNP)
    variation that occurs in a gene when  a single based is changed from one version to the next
  24. alzheimer's disease
    a degenative, ultimately fatal condition marked initially by memory loss.
  25. zygote
    the cell formed by the two merged reproductive cells
  26. embryo
    an organism in its early stage of development; in humans, the developing individual is reffered to as an embryo between two and eight weeks following conception
  27. fetus
    the unborn offspring; used to refer in humas to the developing individual following the embryonic stage until birth 
  28. germ layer
    one of the first three layers (endoderm, mesodem and ectoderm) that differintiate in the developing embryo 
  29. ectoderm
    one of the initial three germ layers of the embryo the source of the skin and neural tissue
  30. mesoderm
    one of the initial three germ layers the embryo that will form connective tissue such as ligaments, muscles, blood vessels, and the urogenital systems
  31. endoderm
    one of the initial three germ layers of the embryo that source of many internal organs
  32. neural plate
    a layer formed by the differentiating neural cells within the embryonic ectoderm
  33. inducing factor 
    a chemical that produces celll differentiation
  34. neural tube
    a structure formed by the developing embryonic neural plate that will eventually form the brain and spinal cord, with the interior of the tube forming the ventricle system of the adult brain.
  35. ventricular zone
    the layer of cells within the lining of the neural tube that give rise to the new neural cells
  36. progenitor cell
    a stem cell in the ventricular layer that gives rise to either additional progenitor cells or migrating neural cells
  37. mitosis
    the process of a cell division that produces two identical daughter cells
  38. radial glia
    special glia that radiate from the ventricular layer to the outer edge of the cerebral cortex, serving as a pathway for migrating neurons.
  39. notochord
    an embryonic mesodermic structure lying under the neural tube that will eventually develop into the spinal vertebrae
  40. growth cone
    the swelling at the tip of a growing azon or dendrite that helps the branch reach its synaptic target
  41. filopodia
    long, fingerlike extensions from growth cones of axons and dendrites
  42. lamellipodia
    flat, sheetlike extensions from the core of growth cones located between the filopodia
  43. fasiculation
    the process by which azonos growing in the same direction stick together
  44. cell adhesion molecule (CAM)
    a molecule on the surface of a grwoing azon that promotes fasciculation
  45. apoptosis
    programmed cell death
  46. nerve growth factor
    the first identified neurotophin
  47. neurotrophin
    substance released by target cells that contributes to the survival of presynaptic neurons
  48. cell death gene
    a gene responsible for triggering the activity of capases leading to apoptosis
  49. caspase
    an enxyme within a cell that cuts up DNA and produces cell death
  50. synaptic pruning
    the process in which functional synapses are maintained and nonfucntional synapses are lost
  51. plasticity
    the ability to change
  52. critical period
    a segment of time during development in which a particular experience is influential and after which experience has little or no effect
  53. hebb synapse
    a synapse strenghtened by simultaneous activity. Named after Donald hebb
  54. imprinting
    the process by which baby animals, particularly birds, learn to follow their mother immediately upon seeing her after birth or hatching.
  55. anencephaly
    a neural tube in which the rostral neural tube does not develop normally, resulting in incomplete formation of the brain and skul.
  56. spina bifidia
    a neural tube defect in which the caudal part of the tube does not close properly
  57. down syndrome
    an abnormal genetic condtiion resulting from a genotype with three copies of chromosome 21 responsiible for moderate mental retardation and a characteristic physical appearance
  58. fragile x syndrome
    a heritable genetic disorder that produces cognitive and physical abnormalities
  59. phenylketonuria (PKU)
    a heritable condition in which the individual does not produce enzymes necessary for the breakdown of phenylalanine; left untreated the condition producess mental retarrdation
  60. fetal alcohol syndrome
    a set of physical and cognitive characteristics that result from maternal use of alcohol during pregnancy
  61. anterograde degeneration
    the deterioration of the axon segment separated from the cell body by the damage to the axon
  62. thetrograde degeneration
    the deterioration of postsynaptic cells in response to loss of input from damaged presynaptic neurons.
  63. nogo
    a substance that normally prevents further sprouting by mature axons
  64. dementia
    deterioration of cognitive abilities resulting from brain disorders.
  65. neurogenesis
    the birth of new neural cells
  66. neurofibrrillary tangle
    an abnormal internal structure of neurons found in cases of alzheimers disease
  67. tau
    an intracellular protein responsible for maintaining the structure of microtubules; broken down in conditions such as alzheimers disease
  68. amyloid
    a protein structure associated with the degeneration of tissue, such as in patients with alzheimers and other types of dimentia.
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chapter 5
behavioral Neuroscience