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Bellwork Mon. Jan. 12, 2015
Epicanthus or Mongolian fold (M) is a dominant trait.
Over the “creased eyelid”(m) which most Europeans have.
1. What are the genotypic and phenotypic ratios of a
homoygous recessive “creased eyelided” (____) woman
having a child with a Mongolian fold if she marries the
skier heterozygous Mongolian eyelided (___) to the right?
Just do the cross and show the genotypic and phenotypic
ratios on your paper: ______ x ________
Genotypic Ratio:
Phenotypic Ratio:
Byggmark Schladming: Sweden
Bellwork: Wed. Dec. 2, 2015
cross: Tt x Tt
1. The different genotypes (“letters” or “genes”) of the above
cross are: ______, _____, and _____
2. The different phenotypes (what is their “Physical”
appearance?) of the above
cross?___________________________
3. % of tall plants:______________
4. % of short plants:_______________
More on Genetics
http://serendip.brynmawr.edu/sci_edu/waldron/pdf/GeneticsProtocol.pdf
Children tend to resemble their parents in
appearance like: similar eye color, hair texture,
height and other characteristics because children
inherit genes that control specific characteristics
from their parents.
 Where are genes found in our bodies?
 Researchers have shown that genes are parts
of DNA molecules, and DNA molecules are
packaged in chromosomes in the nucleus of
each cell in our body.
How does a baby inherit
genes from his or her
mother and father?
Caught Between Dark and Light
http://www.youtube.com/watch?v=OrX5HflxQQs
 genes inherited from one
generation to the next, show how
gene-carrying chromosomes
behave during meiosis and
fertilization.
 For example, think about how the
mother's and father's
chromosomes divide during
meiosis and fertilization.
 Each cell in a baby's body has two
copies of each gene, one copy
from his or her mother and one
copy from his or her father.
Inheritance of Albinism
A gene controls if a person can produce the
pigment melanin contributing to the color of skin,
eyes and hair.
Some people have the hereditary condition,
albinism and cannot produce melanin and have
little or no pigment in their skin and hair.
(Remember 2 different versions of the same gene
are called alleles. One allele of this gene codes for
melanin production and normally pigmented skin
and hair; it is symbolized by A. Another allele of
this gene codes for albinism; it is symbolized by a.)
Probability and Coin Flips
 You flip a coin one time. What is the probability that it lands
heads up? Tails up?
 # of outcomes = 2 (heads or tails)
 ½ or 50% for heads
 ½ or 50% for tails
The probability of flipping
heads is 50%. If you flip a
coin and it lands tails up,
does probability mean
that you are guaranteed
to flip heads on the next
flip?
NO!
LAB: Will you have an albino?
The way genes behave can be
simulated using a penny
A
a
Tails = recessive allele controlling pigment production (a).
Heads = dominant allele (A).
Say a parent is heterozygous (Aa) Tossing a coin & checking for tails
up vs. heads up represents 50-50 chance that an egg or sperm
produced by the parent will include an a allele or an A allele.
To simulate a mating between two heterozygous (Aa) parents, two
students will each toss a coin and the result of the pair of coin tosses will
indicate the pair of alleles contributed by an egg and a sperm to the baby
that results from that mating.
Probability and Coin Flips
 I flipped a coin 10 times while recording the number of times
it lands heads up and the number of times it lands tails up.
Heads
Tails
IIII
(4)
IIIIIII
(6)
Based on 10 flips, it would seem that the probability
of flipping a heads is 40% while the probability of
flipping tails is 60%.
Probability and Coin Flips
 I then flipped the coin 30 more times while still recording the
number of times it lands heads up and the number of times it
lands tails up.
Heads
Tails
IIIIIIIII
IIIIIIIIIIIII
(22)
IIIIIII
IIIIIIIIIII
(18)
Based on 40 flips, it would seem that the probability
of flipping a heads is 55% while the probability of
flipping tails is 45%. Closer but still not 0.5 and 0.5.