PLEASE NOTE: If you missed class, go to Google Classroom. Go to classwork, then to the Fugate section and follow the instructions for getting signed up for CGS.
CGS #1 Takeaway
Traits are passed from one generation to the next in predictable patterns. In other words, there must be a something that controls the way in which traits are inherited.
CGS #1 Overview
After reviewing the background information on the Fugates, the majority of students are hypothesizing that their condition is inherited. Thus we will start our investigation by looking deeper into the science of genetics.
CGS #1
Organism: Arabidopsis plants
Focus area (what part of the plant are we studying): The buds that eventually produce flowers. The buds are technically called cotyledons.
Bud Types: The buds of this species of plants can have two shapes. They can either be rounded buds or pointed buds.
EXPERIMENTAL SET UP AND BACKGROUND INFORMATION
Because the majority of students thought that the evidence suggests that the Fugate's blue skin is a result of inheritance, we focused our efforts to understand the phenomena on a genetic explanation.
In the first activity that will support student understanding of the phenomena, we are using software called the Classic Genetics Simulator (CGS). This simulator models the trait outcomes that are observed in offspring when organisms reproduce. In this first lab, students are crossing Arabidopsis plants that have different bud leaves (cotyledons). Some Arabidopsis plants have pointed buds and some have rounded buds.
The crosses they were asked to do were the following:
Pointed x Pointed
Pointed x Rounded
Rounded x Rounded
OBSERVATIONS / DATA
Although we collected large amounts of data (students did five of each cross), the compiled data is what is shown below:
Pointed x pointed produced one outcome
All of the offspring were pointed
Pointed and rounded produced two outcomes
All offspring were rounded
or
Half the plants were rounded and half were pointed
Rounded and rounded also produced two outcomes
All plants were rounded
or
75% were rounded and 25% were pointed
CONCLUSIONS
Claim #1 : Some or all rounded plants must also have pointed genetic information
Evidence: When plants with rounded cotyledons were crossed with another plant with rounded cotyledons, some of the offspring produced had pointed cotyledons.
Reasoning: If both parent plans have a rounded appearance, they must have something that produces this appearance. However, if these parents sometimes produce offspring with pointed cotyledons and the characteristics that the offspring come from their parents, then at least one parent must have something that can produce pointed offspring even if the parents themselves are not pointed.
There are a fixed number of outcomes / the process by which genetic information is passed from one generation to the next is not random.
Evidence: There are limited number of outcomes all present in fourth's.
Pointed and pointed produced 4/4 pointed
Pointed and rounded produced either:
4/4 rounded or
2/4 rounded and 2/4 pointed
Rounded and rounded produced either
4/4 rounded or
3/4 rounded and 1/4 pointed
Reasoning: If the process by which traits were passed from one generation to the next were random, the would be far more outcomes than the ones observed. In addition, the fact that all of the outcomes appear to occur in fourths suggests that there is a specific process that limits the number of ways that traits can passed from one generation to the next. A process that could predict future outcomes, which would be impossible if it were random.