Genetics : the study of Inheritance
My boys ???
Who do you look like?
Who did you end up looking like?
Why is that then?
Lets have a look at our cells
about 1/20 mm
Ear enlargement (inside ear canal...what is DNA)
A couple of identical couples......
Would their kids all be identical ?
Here are the reasons for that answer (ie stuff about sex)
Now a history lesson......
Do you know who this fellow is?
what about this fellow?
Gregor Mendel (1822-1884)
A most important and clever scientist.
He is largely responsible for laying the scientific groundwork for the field of genetics.
Genetics is the branch of biology that deals with the principles of heredity and
variation, in other words how we and other organisms
Some words .
In bears, white ears are recessive to black
Mumma bear (white)
What is the genotype of Mumma Bear?
Poppa bear (black)
What genotypes could Poppa Bear have?
Poppa bear=________ or _______
In humans, blue eyes are recessive to brown
Mum (Brown eyes)
Nipper .Blue eyes
Is Mum homozygous for brown eyes?________
How do you know? (complete the punnet sq.)
In mice, albino is a recessive trait
Big Mumma mouse Poppa mouse
Complete the punnet sq. to show how Stuart
ended up an albino
If there were 8 babies in the litter, how many would
we expect to have normal colouring? _________
In Labs, black is the dominant trait
are all black
What is the genotype of the pups _____________
The pups grow up and 2 are mated
Here are their kids
Show how this came about?
(complete the punnet sq.)
What percentage would we expect to have golden colouring? ____________
Genetics crosses workskeet
These 2 produced the offspring shown.
Show the gamete types on the punnet sq.
Could these two produce a normal coloured offspring? ____
Explain with a punnet sq.
These 2 reproduce .
Sample Pedigree Chart
cardiomyopathy is inherited as an
III 5 ....moral & ethical issues!!
Chromosomal Sex Determination
Sex determination .(from)
What do we think of that naughty King Henry then?
What do you see here? DO NOT YELL OUT!!!
Genetic change (evolution) by selection
Approximately 800 bases of DNA sequence (approx. 1/4,000,000
An exercise: decoding DNA to make a protein
An EcoRI restriction enzyme.
another animation (more complex)
DNA fingerprinting is a laboratory procedure that requires six steps (see here):
An example of DNA fingerprints
The parents have:
one daughter and one son together .which ones? ______ &______
one daughter is from the mothers previous marriage which one? ______
and one son is adopted which one? ______
which superhero is Johnny's dad?
Was the defendant in
this case at the crime scene?
A way cool site with cloning animations and so on
Labrador retrievers, black fur is dominant to yellow.
Cystic fibrosis is regulated by a recessive allele, c.
pea plant with round seeds is crossed with a pea plant that has wrinkled
a) the genotype of each of the parents if the round seed plant is heterozygous.
b) the gametes produced by the parents
c) the genotypes and phenotypes of the F1 generation
d) the F2 generation if two round plants from the F1 generation were crossed
stems are dominant over short stems for pea plants.
pea plant with a tall phenotype is pollinated by a short plant, and the
seeds of the first
6. In a
certain species of plant, one purebred variety has hairy leaves and another
summer squash, white fruit color is dominant. Yellow is recessive.
a) the F1 generation
b) the F2
c) the offspring of a cross between an F1 individual and a homozygous white individual.
8. For Dalmatian dogs, the spotted condition is dominant to non-spotted.
a) Using a Punnett square, show the cross between two heterozygous parents.
spotted female Dalmatian dog is mated to an unknown male.
Mexican hairless dogs, the hairless condition is dominant to hairy.
horses, the trotter characteristic is dominant to the pacer characteristic.
Imagine for hair color that B gives brown hair and b gives blonde hair.
a) What are the chances of the offspring being homozygous brown haired?
b) What are the chances of the offspring having blonde hair?
c) What are the chances of the offspring being heterozygous brown haired?
d) What is the genotypic ratio?
e) What is the phenotypic ratio?
f) Is there a heterozygous blonde haired offspring? Why?
g) If curly hair is dominant to straight hair, what letters will we use to show these genes?
h) A heterozygous curly haired male marries a straight haired female. What are their genotypes?
i) What would be the gametes for the male parent?
j) What would be the gametes for the female parent?
k) What are the chances of the offspring being homozygous curly haired?
l) What are the chances of the offspring having straight hair?
m) What are the chances of the offspring being heterozygous curly haired?
n) What is the genotypic ratio?
o) What is the phenotypic ratio?
p) Is there a heterozygous straight haired offspring? Why?
Thalassemia is a serious human genetic disorder
that causes severe anemia.
13. T = Tall, t = short B = brown hair, b = blonde hair
homozygous tall, heterozygous brown haired male with a heterozygous tall,
blonde haired female.
a) What is the phenotypic ratio?
b) How many offspring are homozygous for both characteristics?
c) How many offspring are heterozygous for both characteristics?
human blood type, the alleles for types A and B are
codominant, but both are dominant over the type O allele.
a disputed paternity case, a woman with blood type B has a child with type
O, and she claimed that
a) Indicate the genotypes and phenotypes of the F1 generation from the mating of a heterozygous Himalayan coat rabbit with an albino coat rabbit.
b) The mating of a full color rabbit with a light gray rabbit produces two full color offspring, one light gray offspring, and one albino offspring. Indicate the genotypes of the parents.
c) A chinchilla color rabbit is mated with a light gray rabbit. The breeder knows that the light grey rabbit had an albino mother. Indicate the genotypes and phenotypes of the F1 generation from this mating.
d) A test cross is performed with light gray rabbit, and the following offspring are noted: five Himalayan color rabbits and five light gray rabbits. Indicate the genotype of the light-gray rabbit.
25. A geneticist notes that crossing a round shaped radish with a long shaped radish produces oval shape radishes. If oval radishes are crossed with oval radishes, the following phenotypes are noted in the F1 generation: 100 long, 200 oval, and 100 round radishes. Use symbols explain the results obtained for the F1 and F2 generations.
26. Palomino horses are known to be caused by the interaction of two different genes. The allele Cr in the homozygous condition produces a chestnut, or reddish color, horse. The allele Cm produces a very pale cream color, called cremello, in the homozygous condition. The palomino color is caused by the interaction of both the chestnut and cremello alleles. Indicate the expected ratios in the F1 generation from mating a palomino with a cremello.
27 In mice, the gene C causes pigment to be produced, while the recessive gene c makes it impossible to produce pigment. Individuals without pigment are albino. Another gene, B, located on a different chromosome, causes a chemical reaction with the pigment and produces a black coat color. The recessive gene, b, causes an incomplete breakdown of the pigment, and a tan, or light-brown, color is produced. The genes that produce black or tan coat color rely on the gene C, which produces pigment, but are independent of it. Indicate the phenotypes of the parents and provide the genotypic and phenotypic ratios of the F1 generation from the following crosses:
a) CCBB x Ccbb (b) ccBB x CcBb (c) CcBb x ccbb (d) CcBb x CcBb
28. The mating of a tan mouse and a black mouse produces many different offspring. The geneticist notices that one of the offspring is albino. Indicate the genotype of the tan parent. How would you determine the genotype of the black parent?
29. The gene R produces a rose comb in chickens. An independent gene, P, which is located on a different chromosome, produces a pea comb. The absence of the dominant rose comb gene and pea comb allele (rrpp) produces birds with single combs. However, when the rose and pea comb alleles are present together, they interact to produce a walnut comb (R_P_).
Indicate the phenotypes of the parents and give the genotypic and phenotypic ratios of the F1 generation from the following crosses:
a) rrPP x RRpp (b) RrPp x RRPP (c) RrPP x rrPP (d) RrPp x RrPp
30. For shorthorn cattle, the mating of a red bull and a white cow produces a calf that is described as roan. Roan results from intermingled red and white hair. Many matings between roan bulls and roan cows produce cattle in the following ratio: 1 red, 2 roan, 1 white. Is this a problem of codominance or multiple alleles? Explain your answer.
31. For ABO blood groups, the A and B genes are codominant but both A and B are dominant over type O. Indicate the blood types possible from the mating of a male who is blood type O with a female of blood type AB. Could a female with blood type AB ever produce a child with blood type AB? Could she ever have a child with blood type O?
32. For mice, the allele C produces color. The allele c is an albino. Another allele, B, causes the activation of the pigment and produces black color. The recessive allele, b, causes the incomplete activation of pigment and produces brown color. The alleles C and B are located on separate chromosomes and segregate independently. Determine the F1 generation from the cross CcBb x CcBb.
33. Baldness (HB) is dominant in males but recessive in females. The normal gene (Hn) is dominant in females, but recessive in males. Explain how a bald offspring can he produced from the mating of a normal female with a normal male. Could these parents ever produce a bald girl? Explain your answer.
34. Use the phenotype chart (pedigree) at the right to answer the following questions.
a) How many children do the parents A and B have?
b) Indicate the genotypes of the parents.
c) Give the genotypes of M and N.