Units of Instruction

Unit 1 - Review of Cell Biology

Unit 2 - Basic Biological Interactions of Radiation

Unit 3 - Cellular Response to Radiation

Unit 4 - Tissue Radiation Biology

Unit 5 - Modification of Cell and Tissue Responses to Radiation

Unit 6 - Radiation Pathology

Unit 7 - Total Body Radiation Response

Unit 8 - Late Effects of Radiation

Unit 9 - Clinical Radiobiology I - Diagnostic Radiology

Unit 1 Learning Objectives

At the completion of this unit, the student will be able to:

  1. List the basic unit of all living matter.
  2. List various cell characteristics.
  3. Define “protoplasm.”
  4. List the number of elements comprising protoplasm and be able to further list four of these elements considered to be especially important.
  5. List what is meant by the term “universal solvent.”
  6. Compare inorganic with inorganic compounds.
  7. Define what is meant by an “isotonic solution.”
  8. List the importance of proteins as related to cellular functioning.
  9. Recognize the importance of chromosomes and genes in protein synthesis.
  10. Define “amino acid” and “polymerization” and explain how they are related.
  11. List the functions of structural and enzymatic proteins.
  12. List the various characteristics/functions of carbohydrates.
  13. List the various characteristics/functions of lipids.
  14. List two types of nucleic acids and explain their importance.
  15. List the two purines and the two pyrimadines.
  16. Explain the process of DNA replication.
  17. Explain protein synthesis as related to RNA production.
  18. List the two major divisions of the cell.
  19. List various characteristics/functions of the following:
    • nuclear envelope
    • cell membrane
    • endoplasmic reticulum
    • ribosomes
    • mitochondria
    • lysosomes
    • Golgi Complex
    • nucleus
  20. Explain and diagrammatically recognize various phases of mitosis and meiosis.        
  21. Explain the various parts of the cell cycle.

Unit 1 - Review of Cell Biology

The Cell is divided into 2 major sections:   the nucleus and the cytoplasm

The nucleus is contained within the cytoplasm. 

The cytoplasm is the site of cell anabolism (building up of organic substances) and catabolism (breaking down of organic substances.

Nuclear Envelope:  separates the nucleus from the cytoplasm

structures within the cell are termed organelles

Cell Membrane:  semi-permeable membrane which monitors all exchanges of intracellular/ extracellular


                                - nonridgid

                                - composed of lipids and proteins

                                - can conduct electrical impulses


Endoplasmic Reticulum (ER):                       -a double membrane system

                                                                -irregular network branching throughout cytoplasm

                                                                -space between membranes thought to be continuous with the nuclear

                                                                 envelope (extension of the nuclear envelope)


                                                                -  2 types:  Granular ER (rough)  -  ribosomes on


                                                                                    Agranular ER (smooth)  -  no ribosomes


Ribosomes:           composed of protein and RNA in equal amounts

                           attached to ER or freely floating in cytoplasm

                            site of protein synthesis in cell


Mitochondria:            powerhouse of the cell

                                catabolizes nutrients through a process termed oxidation

                                elliptical in structure

                                  -  double membrane with inward folds termed cristae

                                location of enzymes for energy production

                                the number of mitochondria in a cell is determined by the amount of energy required by

                                the cell

Lysosomes:          contains enzymes which have the ability to digest proteins, DNA, some carbohydrates

                          and the cell itself

                                Early Theory:  radiation broke the lysosome membrane, thus releasing enzymes and

                                                         destroying cell

Golgi Complex:    a stacked set of double membrane structures with small vesicles (spheres)

                                acts as a packaging plant for the cell

                                cellular by-products are “packaged” and secreted from the cell

Nucleus:                contained within the cytoplasm, but physically separated from it (semi-permeable membrane)


Nucleolus:             contained within the nucleus

                                contains RNA

                                supervises what occurs in cell

                                contains DNA


Cell Division


Two cell  types:  somatic and germ (genetic)

  • each differ in the amount of genetic material they contain

somatic cells:  contain the diploid number of chromosomes

                                                                -  a constant number for a given species of plant or animal

                                                                                Humans  =  46

                                                                                Cats        =  38

                                                                                Dogs      =   78

                                                                                Gorillas  =  48

germ cells:  contain the haploid number of cells (1/2 the diploid  number)

                                humans  -  sperm cell = 23   egg cell  =  23

Mitosis:  process by which somatic cells reproduce

                1 parent cell divides and forms 2 daughter cells which are identical to the parent

                Reproduction Process  =     1.    Prophase

2. Metaphase

3. Anaphase

4. Telophase

Prophase:              three phases

                                Early  -                   genetic material (DNA) becomes granular and forms strands in the



                                Mid  -                     chromosomes form rodlike structures which become doubled and form

                                                                46 pairs of chromatids

                                                                                    -  separate except at a single point termed the centromere


                                Late  -                    nuclear envelope breaks down

                                                                centrosome  divides and migrates to opposite sides of the cell

                                                                spindle is formed

                                                                                - delicate fibers which extend from the cell’ poles

                                                                                  and between divided centrosome now termed centrioles


Metaphase:          nuclear membrane entirely breaks down

                                chromatids line up in the center of the cell forming the equatorial plate

                                2 chromatids attached to the spindle via the centromere

                                two chromatids begin to repel each other


Anaphase:            2 chromatids repel each other and travel to opposite sides of the cell via the spindle fibers


Telophase:            completion of cell division

                                46 chromosomes form a new nucleus close to the centrosome

                                spindle disappears

                                nuclear membrane forms around 46 chromosomes at end of the dividing cell

                                cytoplasm divides and the cell membrane pinches into two separate daughter cells

                                new cells are an exact duplicate of the parent cell


Interphase:           resting stage -  no mitotic process occurring

                                DNA is duplicated during this phase

                                a duplication of each chromosome is produced termed a chromatid


                                double helix unwinds  -  spare free, floating bases in nucleus are attracted to unmatched

                                                                   bases and therefore form exact copies of the original DNA



Cell Cycle:            the sequence of events in dividing cells in which an interphase period is divided into


                                                                G-1, S, G-2


                                G-1 and G-2 are time gaps between actual mitosis and S (DNA synthesis period)


                                G-O  -  theoretically suggested for cells which do not normally undergo division, but

                                            retain the ability to undergo division  (i.e liver cells)


Germ Cells:           reproduce via meiosis  -  the reduction division of the nucleus in sexual organisms which

                                                                           produces daughter nuclei having ½ of the number of

                                                                           chromosomes as the original nucleus,  process consists of

                                                                           two division processes in succession (chromosomes are

                                                                          duplicated only once, however)


Crossing-Over:     important event occurring meiosis

                                                - exchange of genes occurs between sister chromatids

  • allows for increased genetic variability within a species