26 2 expected observed results

26:2 Expected Results and Observed Results
Objectives:
Discuss the purpose of the Punnett square
Compare expected results and observed results
Explain the importance of Gregor Mendel’s work

The Punnett square
The Punnett square is a way to show which genes can combine when a sperm and egg joins.
Letters are used in place of genes
A capital letter is used for the dominant gene
A lower case letter is used for the recessive gene

Pure recessive color
Lower case letters
Capital letters are dominant and the trait will show
Heterozygous color
One capital letter, one lower case letter

Expected Results
Using the Punnett square you are able to predict traits in offspring.
The ratio is 1:4 that a dominate trait will show.

Observed Results
You can not always see the expected results using a Punnett square.
One parent can have a heterozygous trait while the other parent has a pure recessive trait .

If that occurs then there is a 50% chance that the trait will show.
http://www.google.com/imgres?q=punnett+square+examples&hl=en&biw=1270&bih=683&gbv=2&tbm=isch&tbnid=6eR6nC9th1Q6QM:&imgrefurl=http://www.exploringnature.org/db/detail.php%3FdbID%3D22%26detID%3D2290&docid=4iunWTrHoOHeVM&imgurl=http://www.exploringnature.org/graphics/anatomy/Punnetts_square.jpg&w=538&h=720&ei=HCEvT4KOFJHpggfMs8TUDw&zoom=1&iact=hc&vpx=184&vpy=125&dur=3414&hovh=260&hovw=194&tx=87&ty=159&sig=110912335990059377268&page=1&tbnh=157&tbnw=122&start=0&ndsp=18&ved=1t:429,r:0,s:0

Mendel’s work
Gregor Mendel was an Australian monk in 1805.
He notices certain traits in garden pea plants
Using the scientific method he experimented to find out which traits were recessive and which were dominant in pea plants.

One trait he noticed was height .
He observed that when a tall plant was mated with a short plant all of the offspring was always tall.
He then took the tall offspring and mated them and found that 3/4 of the plants produced were tall and 1/4 were short .

Mendel concluded that some traits were present in the tall plants, but were not seen
His experiments explained the basic law of genetics

26 2 expected observed results

by jaguilar on Feb 14, 2012

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26 2 expected observed results — Presentation Transcript