J. A. CAMPBELL Harvey Mudd College
Claremont, California 9171 1
Questions
6 1 9 8 . Triglycerides (esters of glycerine with t h r e e f a t t y acids, which m a y all be different) a r e found both in t h e intestine a n d in t h e neighboring mucosal cells. Suggest a n experiment which would give some evidence a s t o whether t h e y diffused through t h e cell wall unchanged o r a s f a t t y acids, monoglycerides, a n d glycerine. Q199. I n Atacosa County, T e x a s a series of water wells were drilled (roughly along a line t o t h e S E ) into t h e Carrizo s a n d s formation into which water enters from a n o u t crop o n t h e northern e n d . T h e resulting wells a n d t h e i r water varied a s shown. Wells 4, 5, a n d 6 smelled "gassy." Well Miles from outcrop Depth ( f t ) Odor Organic m a t t e r (%/I) % CH4 in dissolved gas
1 0.5 215
2 3 4 5 6 10 14 22 31 32 1137 1800 3200 4100 4200 g a s s y
28.7
2.9
2.6
...
. ..
.
15.0 62
8.3
18
tion of t h e first cleft at cell division one; of t h e second a t cell division two. Draw pictures of t h e likely 2 cell a n d 4 cell symmetries. W h a t forces lead t o these symmetries? Repeat for t h e 8 cell and 1 6 cell stages. W h e n does it a p p e a r most likely t h a t cell differentiation begins? W h a t i s t h e latest stage a t which differentiation "must" begin? When could left a n d righthandedness a p p e a r ? W h e n is it most likely t o appear? 6 2 0 1 . S a l a m a n d e r newts d o n o t develop suckers as d o frog tadpoles. However, grafting frog ectoderm o n a newt i n a position equivalent t o where a frog would develop a sucker leads t o sucker development o n t h e newt. Interpret. ( S p e m m a n a n d Schotte, Naturwiss, 20,463 (1932)) Q202. African e l e p h a n t s c a n n o t he trained to work for m a n even a few hours each d a y h u t t h e smaller I n d i a n ele p h a n t s c a n work a 4-5 hour d a y . W h y t h e difference?
11.5
16
W h a t would vou d o next if vou h a d discovered these facts? 8 2 0 0 . Consider t h e division of a fertilized single cell as a problem in s y m m e t l y . Predict t h e probable orienta-
This column consists of questions (plus possible, but certainly not uniquely satisiaetory, answers) requiring no more than a concurrent first-year, college level course, a data handbook, and a willingness to apply fundamental chemical ideas to the systems which surround us (or even are inside us). Contributions for possible inclusion are solicited. Initiated in the January 1912 issue of thi.~Journnl.
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Answers A19R. Feed a mixture of two or more pure triglycerides each of which contains only one fatty acid [GI (FA1)~and GI (FAz)J]. Then see whether the glyceride content of the mucosal cells and the intestine both contain only these two triglycerides. If so, diffusion without hydrolysis occurs. If triglycerGI[FA&[FA21 are found (plus free ides such as GI[FAx][FA~]~, fatty acids and mono and diglycerides), hydrolysis and subsequent resynthesis have occurred. If these are found only in the mucosal eells, not the intestine, diffusion occurs first; if also in the intestine. the seauenee. hvdrolvsis. . . . diffusion.. resvnthesis . occurs. A199. Take option, on land around 22 miles south of the outcrop. Note that the percent of organic matter in the water and the percent CH+ in the dissolved gas is a maximum here, dropping off as the water moves further south. Drill to 3000 or more feet and you should hit gas (almost certainly) and oil (probably). There may well be another pocket 32 miles south. so give this a try as well since the indicators increase somewhat between 31 and 32 miles. Before drilling do some geological tests to determine the most likely spots. Hut get those options first. A200. First diuision; probably vertical in gravitational field to give 2 (nearly) identical eells side by side r - ' . Second diuision; orobablv vertical aeain but 4 eells then rearrange into tetrahedron of (nearly) identical eellsi; Third diui.sion: probably vertical again but 8 cells move into ~
520 / Journal of Chemical Education
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Archimedean antiprism (cube with top layer rotated in its plane 45' with respect to bottom layer)@ to give 8 (nearly) identical cells. Fourth diuision: probably vertical again but 16 (nearly) identical cells formed cannot now arrange so each remains identical to others. Thus the next division (number 5) will almost certainly begin to produce differentiated cells since they start in different surroundings. Vertical division follows from presence of vertical gravitational fields. Symmetrical distributions from tendency to adhere and to minimize exposed (nonshared). cell interfacial area. Handedness could aooear at division 1 but may (probably does) appear much later when collection "folds" an itself. A201. The future of a given cell is determined both by its nuclear DNA content and by its environment. For a given individual all nuclei contain the same DNA so it is local environment that determines which DNA is active and which inactive. However, there must be a compatible match with the environment if the cell is to survive. Clearly frog ectoderm cells are compatible with newt ectodermal positions. But the frog cell makes suckers whereas the newt cellsmnnot. A202. Elephants are the largest land animals and require a ereat deal of food to keep them going and time to eat it. The Asian elephant is smaller than the African elephant, needs less eating time so can do work part of the time. The larger African elephant cannot consistently go without food for long enough periods to do useful work. ~~
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