FUNDAMENTALS OF GENETICS. USEFUL MATERIALS Video- Garden of Inheritance Guinea Pig Work sheet Text pages 159-176
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Video- Garden of Inheritance
Guinea Pig Work sheet
Text pages 159-176
Worksheet and word search
Why study peas?
Must begin with PURE BREEDING parents:
HYBRID offspring F1 First Filia Generation
P yellow X green tall X short wrinkled X round
F1 yellow tall round
these are TEST CROSSES to determine dominance and recessiveness
allowed to Self Pollination
F1 yellow X yellow Tall X Tall Round X Round
F2 3 yellow 1 green 3 tall 1 short 3 round 1 wrinkled
**Large sample sizes are needed to get an accurate picture of the frequency
P red X white
F1 red (self)
F2 705 red 224 white
Method for determining possible allele combination for the offspring
Chromosomes with alleles
Gene: tongue rolling
T- can roll
t – unable to roll
What is the probability of having an offspring with
heterozygous brown eyes?
4/4 or 100%
What are the genotype possibilities?
2/4 or 50% TT and 2/4 or 50% Tt
large sample side is needed to reduce the influence of chance and allow the true patterns to emerge.
Cross 2 pea plants that are both heterozygous purple flowered and heterozygous for smooth seeds.
P= purple p= white
N= non-wrinkled (smooth) n= wrinkled
Mendel was a patient and keen observer.
How are the members of this family the same?
How are they different?
Great! You probably noticed that the family members share facial features, hair color etc.
They are different because of their height
Some family members (including the parents) exhibit the characteristic short stature of Achondriplasia, a dominant genetic disorder that results in a form of dwarfism.
How is it possible for Matt and Amy (the parents) to have a child like Zach with Achondriplasia and three children who do not have the disease?
The key is understanding dominant and recessive genes and the concept of segregation
Zach and Jeremy are Fraternal Twins – what does that tell us about their genes?
Fraternal twins have genes that are different - genetically, they are no more similar than any other set of siblings.
If Zach and Jeremy were Identical Twins, how would this picture change?
Both boys would either display the short stature of Achondriplasia or be of normal height – Identical twins have identical genes!
What are the phenotypes for the following parents?
TtWw - _________________
TTww - _________________
What are the possible gametes formed by the parents listed above?
What is the result of a cross between a homozygous recessive parent and a heterozygous parent? Give phenotypic ratios and genotypic ratios.