MS - LS3.B (A) - Genetic Variation - FINAL (WND 2/25/2014)

Module: Genetic Variation

DCI: LS3.B (A) In sexually reproducing organisms, each parent contributes half of the genes acquired (at random) by the offspring. Individuals have to of each chromosomes and hence two alleles of each gene, one acquired from each parent. These versions may be identical or may differ from each other.

PE: MS-LS3-2 Develop and use a model to describe why asexual reproduction results in offspring with identical genetic information and sexual reproduction results in offspring with genetic variation.

[Clarification Statement: Emphasis is on using models such as Punnett squares, diagrams, and simulations to describe the cause and effect relationship of gene transmission from parent(s) to offspring and resulting genetic variation.]

- During sexual reproduction, each parent contributes half of the genes to the offspring.  

- Individuals inherit two of each chromosome, and then have two alleles for each gene (one copy from each parent). 

- The versions of alleles may be identical to each other or they may be different. 

So, this batch and the last one (inheritance) are the only two aligned to this PE (with no real mention of asexual reproduction in the content standards.  That's a little confusing.  As long as students know that organisms which reproduce sexually have more genetic variation, that's probably really all that matters.  No explicit knowledge of asexual reproduction is required. 

This batch will focus on the mechanics of getting unique copies of chromosomes into the cells of daughter organisms.  We can use Punnett squares for this one, and can use them to point to the idea that one half of the genetic information comes from each parent, and that the combination of genetic information from each parent results in offspring with unique characteristics. 

Possible Question Starters: 

"Sexually reproducing organisms can be distinguished from asexually reproducing organisms by studying which of the following?"
correct answer - the extent of variety in the genetic information between parents and offspring