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BIOC19H3 Study Guide - Midterm Guide: Plecoptera, Blood Transfusion, Zonule Of Zinn

Biological Sciences
Course Code
Ian Brown
Study Guide

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1. Developmental Biology (definitions?
levels? historical advances?)
- Definitions:
1) The study of the developing animal from the fertilized egg right through to the adult
2) The study of development of specific tissues
- Levels:
1) Morphological level
2) Molecular Level
- Historical advances: a total of 5 phases, currently at phase 4 & 5
2. Course Central Theme (example?) Regulation of gene expression underlies morphological changes seen in development
- Example:
1) HMGA2: a key gene regulating height in human by increasing cell production
3. Historical Advances in Developmental
- Phase 1 - Descriptive studies:
1) Visual observation: look at species with very large eggs with naked eye (e.g. chicken
eggs, frog eggs) or via detailed anatomical drawings
2) Microscopic observation: with single lens magnifiers (16th century), compound
microscope (18th century), confocal microscope and/or EM
- Phase 2 - Comparative studies: compare the embryological sequence of morphological
changes in different species
1) Recapitulation theory: ontogeny recapitulates phylogeny
- Phase 3 - Experimental embryological developmental studies: modify normal
development in order to study its underlying mechanisms
1) Vital staining
2) Selective cell surgery: kill one cell at the two cell stage and observe the effects, or
separate the two cells at the two cell stage and observe the effects
- Phase 4 - Molecular biology studies: study the molecular basis for the sequence of the
morphological changes
- Phase 5 - Transgenic plants and animals: the use of recombinant DNA technology to
make useful new plants and animals with novel genetic features
1) Micro-injection: put foreign genes into nucleus of fertilized egg
4. Invention of the Compound Microscope
(depends on? advances made?)
- Depends on:
1) Advances in glass making techniques
2) Proper specimen preparation
- Advanced made:
1) All organisms are composed of cells
2) Number of cells increases with development (single-cell fertilized egg -> adult
3) Structure of individual cells increases in complexity with development
4) Cells organize into tissue and organs
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5. Tissue Preparation for Microscopes (their purpose?
methods? materials used? cautions?)
- Fixation:
1) Purpose: preserve tissue, prevent autolysis and make tissue hardy
2) Methods: physical (heat/cold) or chemical
3) Materials used: 4% formaldehyde for compound microscope;
glutaraldehyde for EM
4) Caution: artifact
- Embedding:
1) Purpose: provide additional structural rigidity to tissue
2) Materials used: wax for compound microscope; plastic for EM
- Sectioning:
1) Purpose: cut thin slices of tissue in order pass light/electrons
through it
2) Methods: microtomes, vibratomes, cryostats
3) Materials used: Xylene to dissolve the wax; alcohol and water to
wash off the chemicals
- Staining:
1) Purpose: increase the contrast of tissue
2) Methods: chemical staining or antibody staining
6. Artifact (examples?) A structure not naturally present in the sample being observed that
arises during tissue preparation.
- Examples:
1) Lacunae spaces in hyaline cartilage: created during the preparation
for compound microscope
2) Bacterial mesosomes: created during the preparation for electron
7. Electron microscopy (advances made?) - Advances made:
1) Cells are composed of organelles
2) Complexity and number of organelles within a cell increase during
8. Ontogeny recapitulation phylogeny (ontogeny?
phylogeny? aka? proposed by? acceptance?)
All embryos are similar early in development reflecting their common
- Ontogeny: the development of an organism
- Phylogeny: the evolutionary history of its species
- Aka: Biogenetic law
- Proposed by: Ernst Haekel, 1866
- Acceptance: no longer accepted because it's overemphasized
similarities between embryos of related species
9. Early embryogenesis (steps? followed by?) - Steps:
1) Zygote: fertilized egg (1 cell)
2) Eight-cell stage: with 8 blastomeres (8 cells)
3) Morula: spherical, solid embryonic mass of blastomeres formed
before the blastula (8-16 cells)
4) Blastula: hollow ball with a fluid-filled blastocoel ( ~128 cells)
5) Gastrula: endoderm, mesoderm, ectoderm
- Followed by: organogenesis
10. Three germ layer - Ectoderm: gives rise to nervous system, epidermis of skin, hair, nails,
sweat glands, teeth, lens of eyes
- Endoderm: gives rise to linings of stomach, intestines, pancreas, liver,
lungs, urinary bladder
- Mesoderm: muscle, blood, bone, connective tissue, dermis of skin

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11. Vital staining (toxicity? examples?
Stain that is taken in by live cells in vivo
- Toxicity: non-toxic initially, but often leads to eventual death of the cell
- Examples:
1) Lysotracker: detects lysosomes
- Function: to determine the fate map
12. Fate map (first? animal pole? vegetal pole?) Diagram of an early embryo showing which tissue the cells in each region will give rise
- First: done on frog eggs by Vogt in 1929
- Animal pole: part of the zygote that contains rapidly dividing cells - future
ectoderm and mesoderm
- Vegetal pole: part of the zygote that contains slowly dividing cells - future
13. Basic laws of the molecular biology of
development (model?)
All cells of an organism have the same genetic information; different cell types arise
because different sets of genes are turned on
- Model:
1) Housekeeping gene: codes a protein needed by all cells, regardless of type
2) Cell-specific gene: even though present in all cells, they are only activated in certain
cell types
14. Transgenic plants and animals (examples?) - Examples:
1) Giant mouse: injected human growth gene with functional promoter into a mouse
2) Charlotte's goat: injected spider webbing gene (silk coating gene) with functional
promotor (milking producing) into a goat
3) ANDi: a rhesus monkey with a jellyfish gene for GFP
15. Differentiation (levels? dedifferentiation?
default state of differentiated cells?)
Process whereby genetically identical cells develop into different specialized cells
- Levels:
1) Morphological differentiation
2) Molecular differentiation
- Dedifferentiation: loss of the differentiated state when differentiated cells are
removed from its normal environment (with normal supporting factors)
- Default state of differentiated cells: cell death
16. Regeneration (steps? examples?) Reformation of lost body parts/tissues
- Steps:
1) Local dedifferentiation
2) Rapid cell division
3) Stop dividing and re-differentiation
- Examples:
1) Amphibians, lizards
2) Human liver (partially)
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