Class Notes (1,036,460)
US (406,916)
UCSD (7,455)
BICD (131)
BICD 100 (109)
Lecture 2

# BICD 100 Lecture Notes - Lecture 2: Chi-Squared Distribution, Mendelian Inheritance, Punnett SquarePremium

2 pages109 viewsWinter 2019

Department
Biol/Genetics,Cellular & Develop
Course Code
BICD 100
Professor
Deborah Yelon
Lecture
2

This preview shows half of the first page. to view the full 2 pages of the document.
Following two traits at once.
-
Crossed yellow and round peas with green and wrinkled peas
-
F1 is all round and yellow peas
-
Now we can get new combinations like yellow and wrinkled and green and round
F2 self-fertilized generation gets 9/16 y/r, 2/16 y/w, 3/16 g/r, and 1/16 g/w.
-
Each postulate has its exceptions so is not necessarily always true
Independent assortment
Mendel's 4th postulate
-
O
GW
Gw
gW
gw
GW
GGWW
GGWw
GgWW
GgWw
Gw
GGWw
GGww
GgWW
Ggww
gW
GgWW
GgWw
ggWW
ggWw
gw
GgWw
Ggww
ggWw
Ggww
Now we can see the 9:3:3:1 ratio present with a heterozygous dihybrid cross
Draw a Punnett square of a GgWw xGgWw dihybrid cross
-
The above ratio is phenotypic but the genotypic ratio is more complicated
-
When two independent events occur simultaneously, the combined probability of the 2
outcomes is equal to the product of their individual probabilities. p(A and B) = p(A)*p(B)
Product law of probabilities
-
Dihybrid cross:
Taking real-life data and deciding if it fits your genetic hypothesis
-
Chi-square analysis evaluates the influence of chance on data
-
Are they significantly different
X^2= sigma(O-E)^2/E
Statistical test to check your experimental results against expected ratios
-
Null hypothesis: any differences between expected values and observed values are likely to be due
to chance
-
Alternate hypothesis: the differences between expected and observed values are significant and
unlikely
-
Chi-square analysis
State the null hypothesis
-
Calculate expected numbers of progeny
-
Use formula to calculate chi-square value
-
Use table to translate chi-square into p value
-
Draw conclusion about hypothesis
-
Five steps of chi
Low p value means that the difference between your observe3d results and the expected
results is unlikely to be due to chance
P value less than 0.05 means you can reject the null hypothesis
Probability that your results are due to chance
-
Meaning of a p value
(2) More on Mendelian Genetics
Thursday, January 10, 2019
2:00 PM
week 1 Page 1
###### You're Reading a Preview

Unlock to view full version

Subscribers Only

#### Loved by over 2.2 million students

Over 90% improved by at least one letter grade.