Genetics Problem (Chi-Square problem) Please help?
A research geneticist is trying to determine if the vestigial wing gene in fruit flies is inherited in a Mendelian fashion. The scientist breeds a true breeding normal winged fly with a true breeding vestigial winged fly. The scientist then lets the F1 generation freely breed offspring and counts the number of normal and vestigial winged offspring produced. The following numbers are recorded: 985 winged flies, 278 vestigial winged flies. Is this gene inherited in a Mendelian fashion? What are the? Degrees of freedom: Test statistic: Chi-square critical value: Is the gene inherited in a Mendelian fashion? Yes or No I dont understand this at all, please help?
I Need Genetics Help Please?!?
The original cross is CCpp x ccPP. All the F1 generation are CcPp, and they are crossed to produce the F2 generation. This is a dihybrid cross, and one expects a 9:3:3:1 ratio in the offspring. Make yourself a table with the genotypes across the side (cut/purple; cut/green; potato/purple and potato/green, and along the top label actual and expected. The actual values of the offspring are given in the problem. You have to calculate the expected. Do so by adding up all the offspring (189 + 67 + 50 + 14), for a total of 320. Divide by 16 (9 + 3 + 3 + 1), and the result is 20. Therefore, you expect 20 potato green, 60 (20 x 3) potato purple, 60 (20 x 3) cut green and 180 (20 x 9) cut purple. (Obviously, the total is the same. ) Then, you can calculate your chi squate value. Chi square = the sum of the ((actual - expected)2 / expected) terms. In this case, Chi square = ((189 - 180)2 / 180) + ((67 - 60)2 / 60) + ((50 - 60)2 / 60) + ((14 - 20)2 / 20). = 81/180 + 49/60 + 100/60 +36/20. = 0.45 + 0.82 + 1.67 + 1.8 =4.74. You then use the calculated chi square value (4.74) and the number of degrees of difference (3) and look them up on a probability table. The probability is greater than 10% (the usual cut-off point) that the differences from what were expected were due to chance, so your guess as to the crosses is confirmed.
Could someone please help me with this genetics problem involving the chi-square?
Let's back up a little from Chi squared for a minute. Professor Dropkin has been looking at people who are carriers (heterozygous) for a condition. This means they have different alleles (versions of a gene), one "W" and one "w". So when a couple who were carries had children, the cross would be Ww x Ww. This would produce an EXPECTED genotype ratio of 1:2:1 .......|..W..|..w..| ..W..| ..w...| So if there were 500 children born, how would this fit into that ratio? Divide 500 by 4, and you get 125. So the "expected" ratio for 500 children would be 125 WW : 250 Ww : 125 ww (so far, this answers 13-15). Obs...|.Exp.. 121....| 125 249....|.250 130....|.125 (obs-exp)2/exp ((-4) x (-4))/125 = 0.128 ((-1) x (-1))/250 = 0.004 ((5) x (5))/125 = 0.2 0.128 + 0.004 + 0.2 = 0.332 You have two degrees of freedom (df) because you have three different groups of genotypes (WW, Ww, ww) and df is # groups -1. When deciding if a hypothesis should be rejected or accepted, the level of 0.95 is generally the cutoff point. So in the row for df = 2, find where 0.332 would occur. If it's to the "left" (on your chart, on other charts, the order of the numbers are reversed) of the column for 0.95 (0.95 to 1.00), then the hypothesis should be accepted because the data was consistent with the expected values. If it's to the "right" (0.94 to 0.05) the hypothesis should be rejected.
Does your country have a spell like ”Chichin-puipui"?
I'm from the U.S.A. Typically people here do not employ magical spells or "cantrips" in everyday life (note, though, that people of some foreign cultural backgrounds do). It has to do with the U.S. being mostly a Christian nation (the use of magical spells is forbidden in Christianity). So: as John P says, in the situation you describe, in the U.S. the typical response of a parent is to use soothing words but **not words or phrases that are perceived to be in any way magical**. Note that this is not true in all situations, but is true in the particular situation you describe, the situation where a child is feeling pain. In some other situations, a superstitious act or phrase is often employed by some U.S. people in response to the situation. Example #1: "knocking on wood" https://en.wikipedia.org/wiki/Knocking_o... which is definitely regional (that is: in some U.S. locales it is common for people to practice it, while in other U.S. locales it is practically unknown). Example #2: "Heaven help us!" is an exclamation often used when something unpleasant has been announced. Notice that it is a sort of prayer (to the Christian God) and it is not perceived by Americans as a magical spell. It has become such a common phrase that often people do not consciously consider that they are calling upon God. That is: often people say it without thinking of it as a prayer.