biol+4+inheritance+SAC

This SAC is based on the Drosophila activities and **your excursion to CSIRO education centre**. You will have the double lesson on Thursday 21st August.

You should answer all the relevant questions on the Dosophila activity sheets and the **CSIRO corn activity**. These hand outs are NOT being assessed. You will be provided with a range of questions to answer in Thursday's lesson.

You will be allowed to bring the Dosophila sheets and the **handout from the CSIRO excursion**. Make sure you also have a calculator and ruler.

Inheritance is a large area and I will expect you to show an understanding of the following:
 * single gene inheritance-dominant/recessive/codominant/incomplete dominance
 * single gene with more than two alleles, eg blood grouping
 * two gene inheritance-linked and non-linked
 * effect of crossing over
 * indpendent assortment
 * use of test crosses
 * analysis of pedigrees
 * experimental procedures associated with doing crosses

It is imperative that you are familiar with all the relevant terminology associated with inheritance. The SAC will contain questions that
 * relate to the experiment procedure, either directly to the excursion or other contexts
 * involve application of theory in a variety of contexts
 * require understanding of terminology
 * involve analysis of pedigrees

You can post any questions relating to the SAC below.


 * Should we know about reciprocal crosses for the sac? Would it be at all useful?**

//A. This is a term that I have not mentioned and I would not be directly assessing you on this in the SAC. Is it worthwhile in general to know about, well the broader you knowledge and understanding in an area the better, but this would not be any where near being the most important idea to concern yourself with at this stage. VM //

__**Phenotypic ratios in the F2 and testcross offspring of an initial cross between two pure-breeding strains**__
 * In the textbook, theres a table like this:**
 * //F2// || //Testcross// || //Genetic explanation// ||
 * 3:1 || 1:1 || One phenotype is dominant, the other recessive. The trait is inherited by segregation of alleles of a single autosomal gene. ||
 * 1:2:1 || 1:1 || The heterozygote is of distinct phenotype because incomplete dominance of codominance applies. The trait is inherited by segregation of alleles of a single autosomal gene. ||
 * 9:3:3:1 || 1:1:1:1 || For each of the two traits there is a dominant and recessive phenotype. Each trait is determined by a single autosomal gene. The alleles of each gene assort independently. ||
 * The genetic explanation for the middle section is very confusing. What do they mean by "incomplete dominance of codominance applies"?**

//A. I would think that it is a typo and should read incomplete **or** codominance applies. VM //

Oooooooooooooooh. That makes so much more sense now. thanks.