Chapter 2
 Molecules, Cells, and Theories - Notes (Changes and Suggestions in blue and green - 3/6/06)
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1. Explain the importance of chemistry and chemical reactions.
     - make up all body substances
     - perform all body activities
     - provide energy for all body activities

2. Explain the importance of cells, proper cell structure and functioning.

     - cells and substances they produce make up all body parts and perform all body functions
     - abnormal or unfavorable conditions for cells result in abnormal or unfavorable body structure and functioning

3. Describe the hierarchy of structure and functioning in the body.

     - cells are grouped with similar cells to form tissues, which are combined to form organs, which are combined to form systems, which are combined to form the individuals person

4. Name important body chemicals and list their main functions

     - water - solvent, lubricant, cushion, temperature regulation, cell shrinking and swelling (osmosis), acid/base balance
     - carbohydrates = single sugars or chains of sugars - energy, building materials, cell receptors
     - nucleic acids = single nucleotides or chains of nucleotides (e.g., ATP, DNA, RNA) - individual nucleotides carry energy, chains provide information that directs cells activities (i.e., genes, protein synthesis for structure and regulating enzymatic reactions)
     - proteins = chains of amino acids - building materials, receptors, hormones, enzymes, antibodies
     - lipids = diverse types of molecules (e.g., glycerides, phospholipids, steroids) - energy, building materials, hormones
     - molecular complexes = glycoproteins, mucopolysaccharides, lipoproteins - building materials, communication, transport of materials
     - free radicals = atoms or molecules with an unpaired electron - regulating body functions, defense activities

5. Describe methods of formation of, harmful effects from, and body defense mechanisms against free radicals.

     - formed during normal body reactions (e.g., signaling, energy production, lipid chain reactions) and when a free radical damages a molecule
     - cause oxidation = damage to nucleic acids, protein, and lipids -> damage to cells and secretions from cells -> damage to body structure and functioning
     - body defense mechanisms reduce free radical production, remove free radicals, and repair oxidative damage from free radicals

6. Describe methods of formation of and harmful effects from glycation.

     - glycation = binding of glucose or other sugar molecules to amino acids and to proteins - > advanced glycation end-products
     - cause distortion of proteins, promotion of free radical formation and oxidative damage, reduction in defense mechanisms against free radicals, promotion of age-related abnormalities and diseases (e.g., high blood pressure, atherosclerosis, Alzheimer's disease, diabetes mellitus)

7. List main parts of cells and their functions.

     - cell membrane - hold cell together, regulate entry and exit of materials, receive messages
     - cytoplasm - supports parts, produces and stored substances, provides energy
     - endoplasmic reticulum - compartmentalizes cells, manufactures lipids and proteins
     - Golgi apparatus - collects, packages, and exports materials produced by a cell
     - vacuoles - stores substances including enzymes for defense and digestion within the cell
     - mitochondria - interconverts substances, produces energy, main source of free radicals
     - microtubules and microfilaments - provide cell with support, transport of materials, and movement
     - nucleus - houses genetic information as DNA in chromosomes to control cell activities

8. Explain how genes control cell structure and function and body structure and function.

     - 46 chromosomes, each containing many genes
     - gene = segment of DNA with a message (e.g., instruction to make a protein)
     - copy of DNA in form of mRNA carries instruction from gene to cytoplasm
     - ribosomes "read" mRNA to make protein
     - proteins make up body structure, regulate production of other body structural molecules (e.g., carbohydrates, lipids), and regulate body activities (i.e., as enzymes)
     - telomere = end region of a chromosome

9. Describe the main steps in cell reproduction by mitosis.

     - cell duplicates DNA in each chromosome
          - only part of the telomere is duplicated, using the enzyme telomerase
     - chromosomes are lined up in a row, copies are separated with one of each moving to opposite ends of the cell
     - cell pinches into two portions, each with one set of chromosomes

10. List reasons why mitosis is important.

     - body growth, repair of damaged parts, replacement of damaged or dead cells

11. Describe the Hayflick limit and its possible importance to aging and disease..

     - in experimental settings, many types of human body cells can undergo a limited number of mitoses and then cannot divide again. This number = Hayflick limit = replicative senescence
     - the Hayflick limit decreases as the age of the person from whom the cells are taken increases
     - since the Hayflick limit seems to mimic or demonstrate aging processes in cells, understanding the Hayflick limit or controlling it may lead to understanding or control of aging or of certain diseases (e.g., cancer)

12. Describe neoplasia and its two main forms (i.e., benign neoplasia,, cancer).

     - neoplasia = uncontrolled continuous cell reproduction
          - benign neoplasia = neoplasia that does not spread
          - cancer = malignant neoplasia = neoplasia that spreads
     - aging -> increased incidence of neoplasia
          - increases in the number and proportion of elders -> increased incidence and importance of neoplasia
     (See also pp. 66-67 and neoplasias in other body systems)

13. Describe apoptosis and its relevance in aging.

     - apoptosis = deliberate programmed cell death
     - important during early development, may mimic certain age changes, unknown relevance in aging

14. Explain relationships between studying aging and studying genetics.

     - genes influence or determine XL and ML, interactions between lifestyle and age-related changes, age-related diseases (e.g., Alzheimer's diseases, progeroid syndromes, Werner's disease)
     - understanding the relationships between genetics and diseases that mimic aging may lead to better understanding of normal aging

15. Describe the structure and functions of intercellular materials.

     - amorphous materials = fluids, gels, and hard substances
     - fibers include collagen (strong, flexible) and elastin (weak, elastic)
     - intercellular materials influence transport of materials, support, cushioning, binding, body movements, and other physical properties of the body

16. Distinguish between evolutionary theories of aging and physiological theories of aging.

     - evolutionary theories deal with how and why aging came into existence in living things over eons of time
     - physiological theories deal with how an why aging occurs in present day organisms

17. Distinguish between programmed theories of aging and stochastic theories of aging.

     - programmed theories assume that aging is a planned process with specific causes
     - stochastic theories assume that aging occurs because of chance events

18. List evolutionary theories of aging.

     - disposable body theory, antagonistic pleiotropy theory, accumulation of late-acting error theory

19. Describe, compare and contrast the disposable body theory, the antagonistic pleiotropy theory, and the accumulation of late-acting error theory of aging.

     - disposable body theory - aging occurs because the body allocates only enough resources to prevent it to ensure adequate reproduction. Lack of additional resource allocation allows deterioration of the body = aging. A stochastic theory.
     - antagonistic pleiotropy theory - genes that promote activities that are helpful in early life promote activities that are harmful in later life. These harmful effects = aging. A programmed theory
     - accumulation of late-acting error theory = harmful genes that are not allowed to act until later in life have not been eliminated by natural selection. Over eons, these harmful genes have accumulated through mutations. The result of their activities = aging. A programmed theory.

20. List and briefly describe physiological theories of aging (genetic, rate of living, free radical, mitochondrial, mitochondrial DNA, clinker, cross-linkage, hormone, calcium, immune system, wear and tear, network) and their relevance to aging.

          genetic timers
           - genetic biography = genes used in sequence, and 1st part of story = aging
           - antagonistic pleiotropy theory = genes that promote activities that are helpful in early life promote activities that are harmful in later life. These harmful effects = aging
           - genetic clock = certain genes monitor age and signal aging to begin
           - death gene = certain gene(s) signal aging in order to produce death
           - telomere theory = loss of telomeres disrupts normal gene activities -> aging

      limited gene usage
           - somatic mutation = usage damages genes -> faulty information -> aging
           - faulty repair = decline in DNA repair -> genetic errors -> faulty information -> aging
           - error catastrophe = damage in genetic transcription to RNA or translation to protein -> cascade of errors -> aging

     rate of living theory - normal metabolism causes progressive damage (e.g., free radical damage) = aging. Faster metabolism -> faster aging -> shorter XL and ML.

      free radical = free radicals produced by environmental or cell metabolic processes -> damage to cell components (i.e., DNA, proteins, lipids) -> aging

     mitochondrial theory = mitochondria produce free radicals and regulate signaling substances. Damaged mitochondria produce more free radicals and do not regulate signaling substances well -> detrimental effects = aging

     mitochondrial DNA theory = mitochondrial DNA sustains more damage from free radicals and other causes that does DNA in nuclear chromosomes. Mitochondria with damaged DNA produce less energy and most free radicals -> detrimental effects = aging

    clinker = accumulation of harmful chemicals (e.g., lipofuscin, amyloid, glucose) -> damaged functioning = aging

    cross-linkage = linking of molecules (e.g., collagen, glucose) -> improper structure and functioning = aging
      - glycation theory = most harmful cross-links result from glycation from glucose

    hormone theories
          - hormone imbalance = decreased regulation of and by the endocrine system (e.g., insulin, growth hormone, glucocorticoids, reproductive system hormones) -> disruption of coordination of body functions -> detrimental effects = aging

   calcium theory
      - declining regulation of calcium concentrations and movements -> declining regulation of body activities = aging

    immune system
      - autoimmunity = immune system damages and destroys normal body components -> aging
      - immune deficiency = inadequate immune functioning ->   protection ->   damage -> aging
      - immune dysregulation = combination of autoimmune activities plus immune deficiencies plus imbalance of signals from the immune system to other systems -> detrimental effects = aging

   wear and tear
       - random accumulation of injuries -> aging

   network theories
      - combinations and interactions among two or more of the other theories

21. Explain why forming and testing theories of aging are important.

     - forming testable hypotheses and theories -> further research -> increased understanding of aging
     - once confirmed -> modulation or control of aging; ability to distinguish aging from environmental, abnormal and disease factors

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© Copyright 1999 - Augustine G. DiGiovanna - All rights reserved.
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