Lec 1

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Lec 1
2015-04-15 08:23:21
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  1. What is physiological change? Give examples
    • Physiological changes are reversible
    • e.g. HR, rate of breathing
  2. What are developmental changes? Give examples
    • irreversible normal changes in a living organism as time passes
    • the same change is expected to occur in all members of a particular organism
    • e.g. growth in height, sexual maturation, graying of hair
  3. Examples of developmental changes (4)
    • embryological changes
    • maturation 
    • ageing
    • senescence
  4. What are embryological changes? Give an example
    • Changes which occur before birth
    • e.g. formation of organs
  5. What is maturation? Give an example
    • changes that result in the transformation of a child into an adult
    • geared to improve ability of a person to survive
    • e.g. strengthening of muscles
  6. What is ageing?
    Developmental changes that occur in later years
  7. What is senescence?
    progressive deterioration of physiogical function
  8. Ageing vs senescence
    • everyone experiences ageing but not senescence
    • ageing and senescence are linked
    • e.g. ageing = change in amp; senescence = yellowing of the lens
  9. The "working" definition of ageing is?
    maturation consists of  the progressive changes in size, shape and function during the life of an organism by which its genetic potentials (genotype) are translated into functioning mature systems (phenotype)
  10. What is developmental biology?
    the study of the genetic control of cell growth, differentiation and morphogenesis
  11. Define DNA
    • Deoxyribonucleic acid
    • carries instructions for synthesis of other compounds e.g. proteins, fats, carbohydrates and
    • how they should be assembled into appropriate structures to form a metabolically functioning body or soma
  12. Define genotype
    hereditary instructions passed from one generation to the next in genes
  13. Define phenotype
    functioning organisms produced by the genotype
  14. Define cell growth
    • increase in cytoplasmic volume in a cell
    • the increase in size or population of cells as in mitosis
  15. Define differentiation
    the normal process by which a less specialized cell develops/matures to a more specific form and function
  16. Define morphogenesis
    the biological processes that cause an organism to develop its shape
  17. The term "genetic potential" encompasses?
    recognition that development in many organisms may exhibit plasticity
  18. Define plasticity
    the capacity of cells, organs and systems to change their function/state
  19. Define gene expression plasticity/phenotypic plasticity
    the ability of one genotype to produce a range of different, relatively fit phenotypes in multiple environments
  20. How is the phenotypic plasticity of development modified?
    Through internal or external environmental conditions
  21. Why have gene expression plasticity?
    it is an evolutionary mechanism to match a phenotype suitable to surviving the envioronment
  22. What are the two mechanisms by which directional selection of a trait in a population may be achieved?
    • gene expression plasticity
    • random mutations
  23. What are the three outcomes of directional gene expression?
    • aids fitness for the environment
    • no effect
    • negative effect on fitness
  24. Features of gene expression plasticity
    • evolves very slowly
    • no env cue will be perfectly predictable of the presence of a particular stress so the fittest genotype in the long run will be one that does not completely commit to the presence of the stress
  25. Benefit of adaptive phenotypic plasticity
    ability to produce a better phenotype environment match for multiple environments
  26. Limits to benefits of adaptive phenotypic plasticity
    • plasticity may result in a plastic organism exhibiting lower fitness to an environment
    • non-plastic organisms also suffer this same disadvantage
  27. What are the limits to benefits of adaptive phenotype plasticity? (4)
    • variable reliability of env cues
    • lag-time limits
    • developmental range limits
    • epiphenotype problem
  28. Variable reliability of env cues may result in?
    expression of poor phenotype-env matching
  29. What can occur as a result of lag-time limits?
    poor phenotype-environment matching
  30. The lag time limit is between?
    sensing and responding to environmental cues
  31. What has a shorter time lag than changes in morphology?
    behaviour and physiology
  32. What is the epiphenotype problem?
    where traits that are expressed later may be weaker than a trait expressed earlier in development
  33. What are the costs of adaptive phenotypic plasticity? (5)
    • maintenance costs
    • production costs
    • information acquisition costs: process of sampling the env
    • developmental instability
    • genetic costs
  34. Why does plasticity manifest? (2)
    • structural genes/products are directly affected by the external env OR
    • regulatory genes are affected by the enc and in turn affect the expression of structural genes
  35. Reaction norm describes?
    how a genotype reacts to the env to produce a range of phenotypes
  36. How may the env affect development?
    • no plasticity
    • developmental plasticity scenario (most common)
    • high variable plasticity, strong genotype-env interactions
  37. Draw how the env may affect development
  38. In what stages is adaptive phenotype plasticity seen in vision science?
    • embryological
    • postnatal
    • adulthood and ageing
  39. Examples of types of ageing (3)
    • biological ageing
    • chronological/calendar ageing
    • cosmetic ageing
  40. What is biological ageing?
    ageing in the physical structures and functioning in the body
  41. What is chronological/calendar ageing?
    the passage of time since birth
  42. What is cosmetic ageing?
    changes in outward appearance with advancing age
  43. Define age
    roughly the number of years a person has lived
  44. Define ageing
    the temporal process of growing old
  45. What types of definitions are there for senescence?
    • individual
    • population-wide
  46. What is the individual definition of senescence?
    the accumulation of harmful events that create a noticeable change in appearance or function in the course of ageing
  47. What is the population-wide definition of senescence?
    a progressive increase in the age-specific death rate even when the population is maintained under conditions that are ideal for survival underlined by a generalised deterioration ina  broad spectrum of physiological and metabolic functions
  48. Define senility
    the accumulation of the most severe senescent events
  49. When are we mature?
    • subjective
    • sexual maturity
    • peak physical performance
    • past peak performance
  50. When does biological ageing begin? (6)
    • Subjective
    • has too many illnesses
    • social role transition into grandparent
    • ability to recognise faces
    • computer gaming ability deteriorates
    • ability to run quickly
  51. When does ageing begin? (3)
    • when homeostasis fails
    • loss of physiological aptitude after an organisms reached max repro capabilities
    • gradual decline in organ functional reserves --> reduces ability to maintain homeostasis under stress
  52. Ageing is not ___________ but may ____________
    • pathological
    • predispose a person to disease in the presence of precipitating factors
  53. When does senescence appear?
    When cells, tissues and organs are not maintained
  54. What does senescence do to an organism?
    • deteriorate
    • die
  55. There is often a ____ in the appearance of _____ and the ______
    • delay
    • age changes
    • commencement of failures in homeostasis
  56. Why is there a delay in the appearance of age changes and the commencement in the failure of homeostasis?
    The body has a large reserve capacity e.g. deterioration in accommodation
  57. What is mitotic homeostasis?
    • when cells degenerate, they are regenerated 
    • process to preserve functional integrity of tissues and organs 
    • a balanced process in younger people
  58. Why is degeneration not balanced by regeneration on older people?
    telomere shortening and apoptosis
  59. What are telomeres?
    the ends of chromosomes
  60. Chromosomes are involved in?
    the replication and stability of DNA molecules
  61. Why is there a failure in mitotic homeostasis?
    shortened telomeres --> damaged DNA --> ceased function/damaged products
  62. When do telomeres shorten and at what rate?
    • During DNA replication in somatic cells
    • 100 base pairs per cell division
  63. What are telomeres synthesised from?
    the enzyme telomerase
  64. Presence and rate of biological changes vary _____
  65. Chronological/calendar age is only one contributing factor to ______
    biological ageing
  66. Why do we age or undergo senescence? (3)
    • unknown but reasons lie in 2 observations
    • force of natural selection is weaker at later stages i.e. after repro age, natural selection has less effect on genes
    • acquisition of longer longevity involves cost
  67. Theories of senescence (7)
    • genetic basis
    • free radical theory
    • accumulated waste theory
    • cross-linking of collagen and other proteins
    • hormonal theories
    • autoimmune theory
    • catastrophe theory
  68. What theories are associated with the genetic basis of senescence?
    • anatagonsistic pleiotrophy hypothesis
    • developmental theory of ageing
    • genetic clock
  69. What is the antagonistic pleiotrophy hypothesis? (2)
    • ageing is consequence of declining force of natural selection
    • traits that benefit young organisms can have detrimental effects on ageing phenotypes - escapes natural selection but leads to ageing
  70. What is the developmental theory of ageing?
    • ageing process is the result of a developmental program that is active for the organisms entire lifespan
    • modification of gene expression from environmental influence can influence risk for disease, morbidity and mortality
  71. What is the genetic clock?
    • cells can only divide by a number of times
    • locus of clock are the telomeres
  72. What is the limited gene usage theory?
    • instructions in genes can only be read about 50x
    • errors accumulate and weakens body
  73. What is the error catastrophe theory?
    • damage is not to genes but to RNA and protein molecules that read genes and carry out instructions
    • damaged molecules spread mistakes --> weakens body
  74. What is the free-radical theory?
    • damage to DNA/protein/enzymes/body
    • from molecules with odd number of electrons which chemically reacts to other atoms to obtain complete electron pairs
    • build-up damage results in cell-death
  75. What is the evidence against free-radical theory?
    • lack of correlation with species with longevity
    • antioxidants can be harmful rather than beneficial
    • long-lived mutants can have high levels of oxidative damage
  76. What is the accumulated waste theory?
    • waste products accumulated from a loss of homeostasis --> obstructs normal cell activity 
    • e.g. lipofuscin
  77. What is the the cross-linking of collagen and other proteins theory?
    free radicals, glucose and light increases cross-linking --> inhibits normal cell function
  78. What are the hormonal theories?
    • hormones are chemical messengers
    • hormone mediates ageing
  79. What is the autoimmune theory?
    • ability of body to distinguish normal from foreign weakens
    • immune cells destroy own bodily components
  80. What is the life history theory?
    • life span and reproduction cannot be max simultaneously through natural selection
    • resources are limited - fitness maximised by trading e.g. reproduction > homeostasis
    • ageing observed when loss of homeostasis > repair
    • e.g. oxidation
  81. Why do we die?
    physiological decrements associated with senescence results in increased vulnerability to intrinsic and extrinsic factors and may cause death
  82. Define ageing (5)
    • cumulative
    • universal
    • progressive
    • inherent
    • deleterious
  83. What is mortality
    • death
    • it is random
  84. Mortality rate is not specific to the ___ but to the ____
    • individual
    • population
  85. Randomness in ageing must derive from randomness at 3 time points
    • beginning
    • middle
    • end of life
  86. At the beginning of life there is
    inherent variability in the quality of the organism
  87. At the middle of life there are
    natural shocks that occur during life
  88. At the end of life there is (4)
    • illness
    • old age
    • predator
    • accident