Mendelian Genetics What is Inherited ? _____________ – sequence of DNA that codes for a protein, that determines a trait Genes are located on ___________________________________ Humans have 46, or 23 “_________________ ” pairs Genetics Genetics is the study of how ___________ (specific characteristics) are passed on from generation to generation Gregor Mendel “Father of Genetics” Monastery pea garden Application of Mathematics ____________ are determined by specific sequences of DNA called ___________. o Example: pea plants have a gene for flower color, pea plants have a gene for plant height, pea plants have a gene for seed shape. Alleles There are different possible forms of the same gene called alleles . o Example: pea plants can have a purple 1
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Mendelian GeneticsWhat is Inherited?
_____________ – sequence of DNA that codes for a protein, that determines a trait
Genes are located on ___________________________________ Humans have 46, or 23 “_________________” pairs
Genetics Genetics is the study of how ___________ (specific characteristics) are passed on from generation to generation
Gregor Mendel
“Father of Genetics” Monastery pea garden Application of Mathematics ____________ are determined by specific sequences of DNA called
___________.o Example: pea plants have a gene for flower color, pea plants
have a gene for plant height, pea plants have a gene for seed shape.
Alleles There are different possible forms of the same gene called alleles.o Example: pea plants can have a purple allele or a white allele for
flower color. _______________ – forms of a gene _______________ – an allele that always shows (B); needs only 1 copy
to show ________________ – an allele that only shows when no dominant
allele is present (b); needs 2 copies to show
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Plants Flowers reproduce ____________________. One flower contains sperm cells in its pollen and egg cells in its ovaries. Male and female sex cells must join in______________________________.
Found ________________________________________ – self-pollination produced offspring with _____________ identical to parents.
___________________________ – produced seeds with 2 different parents
______________________ -produced offspring with 2 different parents
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Genotype and Phenotype
____________________ – actual copies of a gene (letters) ____________________ – the visible characteristic ____________________ – shows gene combinations ____________________ – possess 2 identical alleles
o Ex. GG or gg ____________________ – possess 2 different alleles
o Ex. Gg
Genotype vs. Phenotype
Difference between how an organism “looks” & its genetics description of an ___________________________________________ description of an ___________________________________________ 2 organisms can have the same phenotype but have different
genotypes
3 Generation of Traits
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Mendel’s Law of Heredity #1
_____________________________________ o when gametes (eggs & sperm) are produced during meiosis,
homologous chromosomes separate from each othero each allele for a trait segregates (is packaged) into a separate
gamete
Simple Dominance
One allele is _________________ dominant over the other. Offspring will express the ___________________________
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Completing a Monohybrid (Single Trait) Cross
1. Write the parent genotypes
2. Separate alleles into gametes
3. Fill in the offspring genotypes (down AND across)
4. Check your worko All offspring
have the same number of alleles
o Dominant alleles are written first
Examples 1. A man with brown eyes (Bb) and a woman with blue eyes (bb) want to know what color eyes their children might have.
What is the probability an offspring will show the DOMINANT TRAIT ?
What is the probability an offspring will show the RECESSIVE TRAIT ?
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Possible OffspringGenotypePhenotype____________________________________________________________________________
2. A man with brown hair (BB) and a woman with blonde hair (bb) want to know what color hair their children might have.
What is the probability an offspring will show the DOMINANT TRAIT ?
What is the probability an offspring will show the RECESSIVE TRAIT ?
3. Mendel crosses a HYBRID purple plant (Pp) with a PURE white flower plant (pp). What are the possible offsprings?
What is the probability an offspring will show the DOMINANT TRAIT ?
What is the probability an offspring will show the RECESSIVE TRAIT ?
Possible gametes ____ ____ ____ ____ ____ ____ ____ ____
How many out of 16 will be
_______ TALL & ROUND
_______ TALL & WRINKLED
_______ SHORT & ROUND
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_______ SHORT & WRINKLED
Other Patterns of Inheritance
1. ________________________________ – one allele is not dominant over the other
o Heterozygote is blendedo Ex. four o’clocks
RR – Red WW – White RW - Pink
If the dragons in Harry Potter have fire‐power alleles F (strong fire) and F’ (no fire) that follow incomplete dominance, what are the phenotypes for the following dragon‐fire genotypes?
o FFo F’Fo F’F’
2. ______________________ – both alleles contribute to the phenotype Heterozygote shows both
If merpeople have tail color alleles B (blue) and G (green) that follow the codominance inheritance rule, what are possible genotypes and phenotypes?
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Genotypes Phenotypes
Sample Problems
1. In horses, alleles for red (R) and white (W) hairs are codominant, and the heterozygous condition is called roan. Show a cross and ratios between two roan horses.
2. In Four O’Clock plants red flowers (R) are incompletely dominant over white (r) flowers. Heterozygous plants show a blended phenotype of pink flowers. Make a cross with a red Four O’Clock plant and a white Four O’Clock plant.
3. The Four O'clock plant has two alleles for flower color: Red (R) and white (r). These show incomplete dominance. Show the expected offspring of a cross between two pink-flowered plants. Include genotypes, phenotypes and ratios.
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4. In cats, black fur (B) and tan fur (T) are co-dominant. Hybrid cats show a tabby pattern that includes black and tan hairs. Cross a TABBY female cat and a TAN male cat.
5. IF the red allele in Four-o’clocks was completely DOMINANT over the white allele, what would the phenotype be for a plant with a Rr genotype?
Blood Typing Ex. Human Blood Groupso A, B are codominanto O is recessive
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2 alleles affect the phenotype in separate, distinguishable wayso ABO blood groupso Both the IA, IB, are dominant to the i alleleo IA & IB alleles are codominant to each other
Determines presence of oligosaccharides on the surface of red blood cells
Blood Typing Problems
1. A man has type A blood and his wife has type B blood. A physician types the blood of their four children and is surprised to find one of each of the four blood types among them. He is not familiar with genetics and asks how such a thing could happen. How would you
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explain this to him? (include a diagram).
2. A couple preparing for marriage have their blood types determined, along with their required blood test for syphilis. Both individuals are type AB. They ask what types of blood their children may have. What would you tell them and how would you explain your answer? (include a diagram in your explanation).
3. A wealthy, elderly couple die together in an accident. Soon afterwards a man shows up to claim their fortune contending that he is their only son who ran away from home as a boy. Other relatives dispute this claim. Hospital records show that the deceased couple are blood type O and AB. The claimant (son?) to the fortune was type O. Do you think that the claimant was an imposter, or not? Explain, with use of diagram.
4. Veronica has a baby, and accuses Frank as being the father. Frank says "No, I'm not the father. I think her friend Hank is the father of her baby." The court orders blood types of all four of these people: Veronica's blood type is B, her baby's type is A, Frank is type AB,
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and Hank is type O. From this evidence alone, what would the court's conclusion be about each man (as to being the father of the child)? Explain the conclusion using diagrams.
3. ______________________________ – special inheritance pattern for genes on the X or Y chromosome.
Males only have 1 X chromosome, so ALL alleles from it are expressed, even if they are recessive.
Ex. Colorblindness – 1/10 US males have red/green
Sample Problems
1. In humans colorblindness (b) is an example of a sex-linked recessive trait. In this problem, a male withcolorblindness marries a female who is not colorblind but carries the (b) allele.Using a Punnett square, describe the phenotypes of their potential offspring.
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2. In fruit flies red eye color (R) is dominant to white eyes (r). In a cross between two flies, 50% of the male and50% of the female offspring had red eyes. The other half of the males and females had white eyes. What are the phenotype, and all possible genotypes, of the offspring?
3. Hemophilia is a rare heredity human disease of the blood. The blood of individuals with this condition does not clot properly. Without the capacity for blood clotting, even a small cut can be lethal. In a marriage of two nonhemophiliac parents, a bleeder son is born. What are the probabilities of these parents giving birth to sons being bleeders, and to daughters being bleeders?
