Using Rules of Probability to Solve Genetics Problems

I'm totally lost in this subject especially when i have to solve problems using probability for trihybrid. I have of not knowing when to use the Rule of Addition and when to us the rule om Multiplication. I will try to show you what i know and maybe you can help me impron on what i already know. R r R(RR)(Rr) r(rR)(rr) In this examble I know that when Rr x Rr mates, half the gamets will recieve the "R" allele and the other 1/2 the "r" allele. So for the probabilty of "RR" to occur it would be 1/4 by rules of Multiplication. 1/2 x 1/2. that's about how much i understand so far i need help in problems using addition rule problems for trihybrids and beyond if you c... click for more

Finding a simple method in using probability to solve a hybrid cross

The genotype of F1 individuals in a tetrahybrid cross is AaBbCcDd. Assuming independent assortment of these four genes, what are the probabilities that F2 offspring will have the following genotypes? a)aabbccdd b)AaBbCcDd c)AABBCCDD d)AaBBCcDd e)AaBBCCdd Now that i'm given this information, the first thing i normally do is make a list of all the possibe alleles (this is not a punnet square which is really time consuming, but the method i'm going to use is also time consuming. If you know of any other method please let me know?) Possible Alleles ABCD aBCD AbCD abCD ABcD aBcD AbcD abcD ABCd aBCd AbCd aBCd ABcd aBcd Abcd abcd Now from what i understand the ... click for more

Genetics

1. a. The ability to taste the chemical phenylthiocarbamide is an autosomal dominant phenotype, and the inability to taste it is recessive. If a taster woman with a nontaster father marries a taster man who in a previous marriage had a nontaster daughter, what is the probability that their first child will be (1) A nontaster girl (2) A taster girl (3) A taster boy b. What is the probability that their first two children will be tasters of either sex? 2. Duchenne muscular dystrophy is sex-linked and usually affects only males. Victims of the disease become progressively weaker, starting early in life. a. What is the probability that a woman whose brother has Duchenn... click for more

Genetics

For the problems attached please show the symbols used in human pedigree analysis and/or Punnett Square if needed. Please also explain answers. Thank you! --- 1. A sex-linked recessive allele c produces a red-green colorblindness in humans. A normal woman whose father was colorblind carries a colorblind man. a. What genotypes are possible for the mother of the colorblind man? b. What are the chances that the first child from this marriage will be a colorblind boy? c. Of the girls produced by these parents, what proportion can be expected to be colorblind? d. Of all the children (sex unspecified) of these parents, what proportion can be expected to have normal color vi... click for more

Genetics/Meiosis questions

How many types of telophase II products can be formed if a homozygote (AA or aa) is under study? How many types of telophase II products can be formed if a heterozygote (Aa) is under study? How many kinds of gametes can be formed if the genotype is AABB? Make a drawing of this type of cell in Prophase I. Label the chromosomes. How many kinds of gametes can be formed if the genotype is AaBb? Make a drawing of this type of cell in Prophase I (zygotene). Label the chromosomes. How does each one of the Telophase II products (one of the 4 cells in the tetrad) compare with the Prophase I cell with regard to chromosome number? (See attached file for full problem description)