Biology 441, Spring 2013: Review for First Hour Exam


How to get ready for next Monday's hour exam.

I advise you to concentrate a lot of study on that diagram I drew, titled, "Comparison of Gastrulation in Different Organisms" [linked here].  You can get very many points on the exam by memorizing this diagram and knowing the basic anatomy of each kind of organism, how (and why?) development differs (and/or is similar) in each kind of embryo.

Also, the exam might contain individual drawings from that big diagram, such as a gastrulating sea urchin, or a gastrulating bird embryo, or the formation of the two kinds of extra embryonic membranes by a teleost embryo, and you will earn ten points, or more or less, by correctly identifying "That is an embryo of such and such kind of animal, and it is at the so and so stage of development, and this part here is called the something organ, the function of which is to do whatever, and every variation of those sorts of questions.

The exam might also ask you to make your own drawings (for example of a gastrulating teleost embryo).

Other drawings and photographs that were posted on the web pages for lectures in this course this semester will also be used to create exam questions."This diagram shows what?" Please draw your own diagram of the relative locations of the chorion, allantois, etc. in a bird embryo" "Or compare them in mammal versus bird embryos..."etc. "Or what would happen if this structure failed to develop". You can earn lots of exam points by correct answers to just these kinds of questions.

You need to know the meaning and significance of each of the following words and phenomena, and that means more than just a definition:

1] Oocyte
2] Trans-membrane potential (or voltage)
3] The fast block to polyspermy
4] The slow block to polyspermy
5] Cortical vesicles (of oocytes).
6] Sperm adhesion to oocytes. (Including what destroys the adhesion molecules).
7] The role of potassium ions, and permeability to potassium ions, in allowing fertilization.
8] The role of sodium ions, and changes in permeability to sodium ions, in blocking fertilization.
9] The similarities of nerve and muscle cell resting potentials, and action potentials, to the transmembrane
    voltage of oocytes before and after fertilization.
10] The fertilization membrane (of echinoderm eggs).
11] What would happen if the blocks to polyspermy failed to occur.

Explain (in general terms) how new kinds of contraceptives could be developed...

12] Based on premature activation of either the fast or slow block to polyspermy, or both?
13] Based on preventing activation of either the fast or slow block to polyspermy, or both?
14] Based on inhibiting permeability of oocytes to sodium ions.
15] Inhibiting permeability of oocytes to potassium ions.
16] Preventing increases in the concentration of calcium ions in oocytes.
17] Preventing secretion of cytoplasmic granules.
18] Preventing fusion of the oocyte's plasma membrane to sperm plasma membranes
19] Preventing fusion of cortical granule membranes to oocyte plasma membranes
20] Prematurely inactivating the sperm-oocyte adhesion proteins.
21] Preventing inactivation of these proteins, themselves.
22] A drug that selectively inactivates the enzymes that destroy these proteins.
23] A drug that inactivates the enzymes, that sperm secrete to digest their way through the zona pellucida.
24] A drug that somehow strengthens the zona pellucida, so those sperm-secreted enzymes can't penetrate.
25) A drug that prevents meiotic divisions.

Invent at least one more kind of molecular strategy for achieving birth control (comparable, but different than # 12 through #25.)

Please forgive this over-emphasis on contraception; my goals are (first) to test your understanding of the many molecular and cellular events and mechanisms that are needed for successful fertilization; and second, to illustrate the potential medical usefulness of inhibiting or stimulating each such process; and third, for you also to recognize that cures for different kinds of human infertility could be developed for each of these processes.

And fourthly! Please keep alert through this entire course that every phenomenon you learn about is a medical opportunity (and/or a potential disease). For every process and structure, they are not just something to memorize and get/lose points for on exams; Many of them prevent, or can cause, diseases, birth defects, infertility, and other serious matters of life, death and future medical breakthroughs.

It is so easy to forget the importance of embryological phenomenon: The reason to learn them is not just to take up space in your brain, or even just to get points on Med. School Admission Exams! But that is easy to forget, right? Therefore, any time I can invent an exam question that tests whether you understand the medical relevance, or potential medical use to help people, of any process or fact that you learn in this course, then I will ask that question on the examinations.

Here comes more vocabulary, which isn't just to take up brain space.

26] Animal pole
27] Vegetal pole
28] Polar bodies
29] Difference between first and second polar bodies.
30] Haploid
31] Diploid
32] Tetraploid (and could you figure out what pentaploid means? What about octoploid?)
33] Holoblastic cleavage (and early embryos of which kinds of animals undergo holoblastic cleavage?)

not too much more to come...


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