Embryology Biology 441 Spring 2008 Albert HarrisReview Questions for Period After Third Exam(and also for plant subjects)
Regarding plants: Which if the following also occur or can be created in plants, and not just in animals: tissue culture? Cell differentiation? Chimeras? Homeotic mutations?
(remember cauliflower?) Tumors? Invasive cancers? (no, but why not?) Primordial germ cells? (no, and why not?) Cell walls (not in animals); Model organisms (name at least two; One cell stage embryos that develop asymmetry based on external stimuli (yes, in Fucus, especially); dedifferentiation and redifferentiation into a different cell type?
Similarities and differences between the following pairs: eggs and seeds? What is auxin? What are several different effects of auxin? Approximately how did the bioassay work, by which the chemical structure of auxin was discovered? Please invent at least two other bioassays that could have been used instead (i.e. in order to discover the chemical structure of auxin), for example taking advantage of auxin's ability to stimulate root differentiation and elongation; or taking advantage of auxin's ability to inhibit the sprouting of new shoot meristems? What are auxin analogs, such as 2-4 D? Serotonin is to Prozac as what is to 2-4 D? How is 2-4 D analogous to diethylstilbestrol, and to Bisphenol A? What is indole acetic acid? Are any plant hormones gasses? What is the example which is a gas? Can you name at least five normal plant hormones? What are phototaxis and geotaxis? How does auxin play key roles in both of them? What parts of plants is auxin made in, mostly? What does auxin stimulate? What does auxin inhibit? Was auxin postulated to exist before it was discovered? (of course!) What phenomena caused scientists to postulate that a chemical with the effect(s) of auxin must exist? Was that how the chemical nature of a all the plant hormones were discovered. Have bioassays ever been used to confirm the existence of animal hormones, and to discover (or prove) their chemical structures? (hint: have any other methods except for bioassays ever been used to discover any of them?) What are floral meristems? What is "reaction wood" and what stimulates it to form? What is phyllotaxis? Sketch several different patterns of phyllotaxis. What combinations of symmetry exist in different patterns of phyllotaxis? What is photoperiodism? What is a "long day plant": Hint, it produces fruit in response to the day length becoming what? What would a short day plant be? For what purposes do plants use the substance called phytochrome?
Are there homologies between parts of flowers, petals, sepals, stamens, carpals? In addition to the formation of 2 or 4 separate embryos by separated cells of early echinoderm embryos (as Driesch discovered, but couldn't make sense of) what are at least two other examples in which splitting apart of parts of an embryo will result in formation of two or more entire organs? Balinsky produced what result in salamanders when he surgically implanted olfactory placodes under the skin of their embryos between the locations of the front and hind limb buds? What if he did the same experiment, implanting an otic placode? What is probably the reason he got this result? (Hint: In terms of secretion of fibroblast growth factor?)
Where and when are apical ectodermal ridges formed? Sketch the location of the apical ectodermal ridge on a bird embryo, including the shapes of the somatic ectodermal cells.
The anterior-posterior axis of development is controlled by tissues located where?
Make a sketch. What evidence supports this conclusion? What are 5 or 6 different examples of self-organizing structures of non-living matter? What were the major research accomplishments on the early German embryologist Karl Ernst von Baer in the early 1800s? In the later 1800s, what other German reinterpreted some of the same discoveries, in terms of a famous 3 word quote, of which the middle word was "recapitulates"? What was the major research accomplishment by which H. V. Wilson earned his appointment as Professor of Zoology at UNC? What is meant by a "cell lineage"? What happened when John Saunders cut off the end of a chicken wing bud and grafted it back with its anterior-posterior axis reversed? (Hint: It branched into three wings!) By what different experiment did he cause formation of chickens whose wings branched into four (hint: There are drawings and a photo at the end of the April 7th web page notes.) How many planes of reflection symmetry did the 4-branched wing have? I will be very favorably impressed if you can you suggest some logical reasons why the normal mechanisms that cause limb shape can cause branching into two, three, or sometimes four wings? As a hint, try to sketch the spatial patterns of transcription of hoxd-9, 10, 11, 12 & 13 in these branched limb buds, as compared with the spatial patterns where these hox genes are transcribed in normal limbs. A fly with two sets of autosomal chromosomes, And one X chromosome, but no Y chromosome Will develop into which sex? In other words... #1) AAX fly which sex? A sterile male Why? #2) An AAX human or other mammal would be what sex? No tiny answer this time. #3) What about AAX birds? What sex would they develop as? #4) A fly with AAXXY would develop as which sex? A sterile female But why? #5) What sex would you guess a AAAXX fly might develop into? #6) An AAXXXXXY human would develop as what sex? Why? What is the SRY gene in humans?. On which chromosome is it normally located? How is this gene related to sex determination? What would happen if the part of the gene containing the SRY gene were to break off from its normal location, and attach to some other chromosome, instead? (I mean, what would be the sex of people who inherited a copy of that other chromosome?) What about people who inherited a Y chromosome from which the SRY gene had been lost? Why is the human sex ratio expected to be 50% males and 50% females? Is that the ratio of Y-carrying sperm to X carrying sperm? What will happen if Y carrying sperm swim somewhat faster, or otherwise are more successful in fertilizing oocytes? What is androgen insensitivity syndrome? What sex do people with this syndrome appear to be? Do they have testes or ovaries? Do they have vas deferens or fallopian tubes? What effect on mammal sexual development can be predicted from the use of millions of tons of artificial estrogen analogs to make plastic water bottles and make the lining of soft drink cans? [Water kept in baby bottles absorbs enough of one of these substances to cause male tadpoles to develop into female frogs.] What is the mechanism of sex determination in birds, as compared with mammals? Sex determination in alligators and most species of turtles is controlled by what variable (at what time)? If box turtle eggs develop at lower than average temperatures, what will the sex ratio become? How is sex determined in fish? Do many species of fish start life as one sex, but then change to the other sex? How is sex controlled in wasps, bees, ants and other Hymeoptera. How is this believed to be related to the repeated independent evolution of "social insects" (With "colonies", "queens", etc.) [Thought question, what would have evolved if unfertilized, haploid eggs developed into males instead of into females?] What part of which germ layer do the genital ridges develop from? What special cell type then migrate to these ridges from other parts of the embryo? Do oocytes and sperm cells develop from the genital ridges, or from the cells that migrate to them? In adult mammal males and females, compare the locations of their gonads. Is the difference a result of developing from different tissues, or what? Which kind of gonad has the histological structure of spaghetti, and which has a histology more like plum pudding. Which kind of gonad has a strong organ capsule made of collagen fibers tightly wrapped around it? Which kind of gamete is released through small temporary blister-like breaks in the tissue of the gonad? How do gametes leave the gonads of the other sex? Where do Sertoli cells develop, and what two important functions do they serve? Where do primordial germ cells first form, in mammals, birds, flies and nematodes? What are pole cells? [Thought question: what kind of evidence would be sufficient to prove that primordial germ cells use some form of chemotaxis to find their way to the gonads? What are some examples of asexual reproduction? Do some examples of asexual development occur from oocytes, cleavage, gastrulation etc.? What are some examples of asexual development via completely different sequences of intermediates? What is Wolffian lens regeneration? How does the germ layer subdivision origin of the original lens differ from the origin of the regenerated lens? If an organ or tissue can regenerate when removed, what is a possible mechanism for preventing extra organs or tissues from developing at other times, when regeneration is not needed? Who invented the concept of contact inhibition? On the basis of what three statistical measurements and comparisons? Were they referring to inhibition of cell crawling or cell division? * Difficult thought question: Please invent three equivalent sets of measurements of rates of cell growth and counts of mitoses by which someone could have tried to test whether there also is a phenomenon of contact inhibition of cell growth? Explain how either or both forms of contact inhibition could provide an explanation why tissues and organs don't regenerate until they need to. *Suggest possible causal relation between cancer, regeneration, and such inhibitory control mechanisms (as contact inhibition). Draw a typical cancer cell, including its nucleus; draw an equivalent non-cancerous cell. How are each of the following related to cancer: Protein growth factors; Growth factor receptors; G-proteins (such as ras); protein kinases. What are the meanings of the following terms: sarcoma, carcinoma, adenoma, leukemia, lymphoma, neuroblastoma, teratoma, oncogene, nitrogen mustard, spindle poisons, fusion protein, GTPase, apoptosis? Why do we need an immune system? What two differentiated cell types do the attacking? Do they ever attack anything other than germs? 2 examples. An "antigen" is any molecule that is selectively bound to by (what parts of?) proteins called what? Which are made and secreted by what differentiated cells? Virus-infected cells are induced to do what? This is accomplished by what other differentiated cell type? The "Generator of Diversity" accomplishes what? What is unusual about the genes for antibody binding sites? Which is more surprising? That people EVER make anti-self binding sites, or that this doesn't happen much more frequently? What are the differences between T-lymphocytes as compared with B-Lymphocytes? Antigens are bound to by what? What is very unusual about the genes that code for the binding sites of antibody proteins? What is the similarity between an allergy and an autoimmune disease? Do vaccines make you become immune to diseases or allergic to some of the antigens of the germs that cause that disease? (Hint: Both) What causes Lupus and Multiple Sclerosis? What would be necessary to produce actual cures of these diseases? Why hasnŐt anybody found such cures? And what factors prevent most scientists and physicians from even looking for cures? What are adjuvants? What are believed to be the possible mechanisms of immune self-tolerance? What happens if these mechanisms fail? What is meant by variolation? How is it similar to vaccination? What usually happens when a virus from one species of animal somehow becomes able to infect members of some other species? THIS COMPLETES THE LIST OF REVIEW QUESTIONS.
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