Genetics : the study of Inheritance

Traits & Mendel Monohybrid
crosses
Sex
determination
DNA Selection DNA
Technology

My boys ???

 

Who do you look like?

 

Hypothesis....?

 

Our traits.....

http://www.ncrtec.org/tl/camp/gene/gene6.htm#one

TABLE 1
Trait Chromosome for Gene Location Dominant Phenotype Possible Dominant Genotypes Recessive Phenotype Recessive Genotype
color of iris 2 not blue EE or Ee blue ee
widow's peak 4 peak PP or Pp no peak pp
cheek dimples  5 dimples DD or Dd not dimples dd
face freckles 9 freckles FF or Ff no freckles ff
mid-digital hair 10 hair HH or Hh no hair hh
Hitchhiker's thumb  17 straight TT or Tt curved tt
Hallux length (toes)  20 long 2nd toe BB or Bb long big toe or = to 2nd toe bb
ear lobes  21 free LL or Ll attached ll
tongue rolling  22 ability RR or Rr no ability rr
cleft chin  16 cleft YY or Yy no cleft yy

 

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)

http://gslc.genetics.utah.edu/units/basics/tour/

 

 

Cells.....(ultrastucture)

http://gslc.genetics.utah.edu/units/basics/cell/index.cfm

A couple of identical couples......

or

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  

 

 

 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
end up looking like we do.

 

Did you know?

   In 1850, Mendel took the examination for certification as a teacher, but failed. Ironically, some of his lowest marks were in biology. He was then sent by his abbot to the University of Vienna, where he studied physics, chemistry, mathematics, zoology, and botany from 1851 to 1853. Still, he never passed the examination for a teacher's license.

 

 

 

 

 

 

 

 

 

 

Mendel's work....

 

 

 

 

 

 


 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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Some words….

 

cross

 

F1 offspring

 

Gametes

 

Egg / ova

 

Sperm /pollen

 

pollination

 

fertilization

 

gene

 

allele

 

genotype

 

phenotype

 

dominant

 

recessive

 

 

 

CDA10_1.jpg

 

 

 

 

gamete

gamete

gamete

 

 

gamete

 

 

 

 

 

gamete

gamete

gamete

 

 

gamete

 

 

 

 

 

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BEARS

 

In bears, white ears are recessive to black

 Mumma bear (white)

What is the genotype of Mumma Bear?

Mumma bear=__________

 

 Poppa bear (black)

What genotypes could Poppa Bear have?

Poppa bear=________ or _______

 

 


 

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PEOPLE

 

In humans, blue eyes are recessive to brown

 

  X   

Dad (Blue eyes)                     Mum (Brown eyes)
"yum a MILF..."
[Mum I'd Like to Fertilise]

 

Nipper….Blue eyes

 

Is Mum homozygous for brown eyes?________

 

How do you know? (complete the punnet sq.)

 

 

gamete

gamete

gamete

 

 

gamete

 

 

 


 

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MICIES

 

In mice, albino is a recessive trait

 

   x

Big Mumma mouse            Poppa mouse

Stuart Little

 

Complete the punnet sq. to show how Stuart

ended up an albino

 

 

gamete

gamete

gamete

 

 

gamete

 

 

If there were 8 babies in the litter, how many would

we expect to have normal colouring? _________

 


 

 

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DOGGIES

 

In Labs, black is the dominant trait

 

   X    

 

 

The pups are all black
  

 

What is the genotype of the pups _____________

 

 

 

 

The pups grow up and 2 are mated

 

      X      

Here are their kids…

 

Show how this came about?

(complete the punnet sq.)

 

 

gamete

gamete

gamete

 

 

gamete

 

 

What percentage would we expect to have golden colouring? ____________

 

Genetics crosses workskeet

 

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FRUIT FLIES

 

 

http://www.exploratorium.edu/exhibits/mutant_flies/mutant_flies.html

 

Normal fruit fly              

Ebony colour (recessive)

Short wings (recessive)

Curly wing (dominant)

 

 

 

 

 

 

 

      x     

These 2 produced the offspring shown.

Show the gamete types on the punnet sq.

 

 

gamete

gamete

gamete

gamete

 

 

 

 

 

 

 

         X      

Could these two produce a normal coloured offspring? ____

Explain with a punnet sq.

 

 

gamete

gamete

gamete

 

 

gamete

 

 

 

 

 

 

 

 

These 2 reproduce….

    X    

 

 

And produce   

 

 

Explain

 

gamete

gamete

gamete

 

 

gamete

 

 

 


 

 

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Pedigree Charts

 

 

 

 

Sample Pedigree Chart

 

 Hypertrophic cardiomyopathy is inherited as an autosomal dominant
and like other autosomal dominant diseases does not skip generations
and in this case affects both sexes. As this trait is dominant, we know
that if a child has the the disease then at least one parent must also have
the gene.

Girl III 5 ....moral & ethical issues!!
(also dates??) I wonder...is she still alive

 

 

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Sex determination

 

 

Chromosomal Sex Determination

http://www.dushkin.com/connectext/psy/ch02/chrom.mhtml

 

 

 

 

 

Sex determination….(from)

http://www.tiscali.co.uk/reference/encyclopaedia/hutchinson/m0008111.html

 

 

 

What do we think of that naughty King Henry then? 

 

What do you see here? DO NOT YELL OUT!!!

 

 

 

Genetic change (evolution) by selection

 


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DNA

 

 

      

 

 

 

 

 

 

 

 

 

 

drawing

Approximately 800 bases of DNA sequence (approx. 1/4,000,000
of the human genome), containing the first gene coding segment
of four in the human Ras gene. The coding portion of the gene is
located between bases 1624 and 1774. The remaining DNA around
this does not contain a genetic message and is often referred to as
“junk” DNA.

 

 

 

An exercise: decoding DNA to make a protein

 

 

 

 

 

........................................

 

 

 

 

Protein synthesis animation  

 

An EcoRI restriction enzyme.

 

 

 

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DNA Fingerprinting

 

library.thinkquest.org/ 12022/level6a.htm

 

 

 

 

another animation (more complex)

www.idigitalmotion.com/ portfolio.htm

 

 

 

 

 

From  http://www.biotech.iastate.edu/biotech_info_series/bio7.html

DNA fingerprinting is a laboratory procedure that requires six steps (see here):

 

An example of DNA fingerprints

 

 

 

 

 

 

 

Comparison of RFLP's within a family

 

The parents have:

 one daughter and one son together….which ones? ______  &______

 one daughter is from the mother’s previous marriage… which one? ______ 

 and one son is adopted… which one? ______ 

 

 

  which superhero is Johnny's dad?

 printing vesion of this

 

Was the defendant in this case at the crime scene?
(gone to the end of topic test!!!!)

 

 

 

 

 

 

 

 

 

 

 

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Recombinant DNA and Gene Cloning…..

A way cool site with cloning animations and so on

 

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Lots of questions

 

1. For Labrador retrievers, black fur is dominant to yellow.
Explain how two black dogs can have different genotypes.
Could a black dog have the same genotype as a yellow dog?

 

2. Cystic fibrosis is regulated by a recessive allele, c.
Explain how two normal parents can produce a child with this disorder.

 

3. A pea plant with round seeds is crossed with a pea plant that has wrinkled seeds.
For the cross, indicate each of the following:

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

 

4. Long stems are dominant over short stems for pea plants.
Determine the phenotypic and genotypic ratios of the F1 offspring from the cross pollination
of a heterozygous long stem plant with a short stem plant.

 

5. A pea plant with a tall phenotype is pollinated by a short plant, and the seeds of the first
generation hybrid produce 327 tall plants and 321 short plants.
Give the genotypes of all the plants. (parents, Tt and tt; all tall were Tt; dwarfs, tt)

 

6. In a certain species of plant, one purebred variety has hairy leaves and another pure variety
has smooth leaves. A cross of the 2 varieties produces offspring that all have smooth leaves.
Predict the ratio of phenotypes in the F2 generation.

 

7. In summer squash, white fruit color is dominant. Yellow is recessive.
A squash plant that is homozygous for white is crossed with a homozygous yellow one.
Predict the appearance of

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.

b) A spotted female Dalmatian dog is mated to an unknown male.
From the appearance of the pups, the owner concludes that the unknown male was a Dalmatian.
The owner notes that the female had six pups, three spotted and three non-spotted.
What are the genotype and phenotype of the unknown male?

 

9. For Mexican hairless dogs, the hairless condition is dominant to hairy.
A litter of eight pups is found; six are hairless and two are hairy.
What are the genotypes fo the parents?

 

10. In horses, the trotter characteristic is dominant to the pacer characteristic.
A male trotter mates with three different females, and each female produces a foal.
The first female, a pacer, gives birth to a foal that is a pacer.
The second female, also a pacer, gives birth to a foal that is a trotter.
The third female, a trotter, gives birth to a foal that is a pacer.
Determine the genotypes of the male, all three females, and the three foals sired.

 

11. Imagine for hair color that B gives brown hair and b gives blonde hair.
Use a Punnett square to determine the following in a cross of two heterozygous parents.

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?

 

12. Thalassemia is a serious human genetic disorder that causes severe anemia.
The homozygous condition (TmTm) leads to severe anemia. People with thalassemia die
before sexual maturity. The heterozygous condition (TmTn) causes a less serious form of anemia.
The genotype TnTn causes no symptoms of the disease.
Indicate the possible genotypes and phenotypes of the offspring if a male with the genotype
TmTn
marries a female of the same genotype.

 

 

 

 

13. T = Tall, t = short B = brown hair, b = blonde hair

Cross a homozygous tall, heterozygous brown haired male with a heterozygous tall, blonde haired female.
Use a Punnett square to show parents and gametes.

a) What is the phenotypic ratio?

b) How many offspring are homozygous for both characteristics?

c) How many offspring are heterozygous for both characteristics?

 

 

14. For human blood type, the alleles for types A and B are codominant, but both are dominant over the type O allele.
The Rh factor is separate from the ABO blood group and is located on a separate chromosome.
The Rh+ allele is dominant to Rh-.
Indicate the possible phenotypes from the mating of a woman, type,O, Rh-, with a man, type A, Rh+.

 

15. In a disputed paternity case, a woman with blood type B has a child with type O, and she claimed that
it had been fathered by a man with type A.
What can be proved from these facts?

 

 

 

 

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.

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