Chapter 3Heredity

NAME _______________________

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Chapter 3 Vocabulary Gregor Mendel__________________________________________________________________________________________________Heredity_______________________________________________________________________________________________________Dominant trait____________________________________________________________________________________________________Recessive trait____________________________________________________________________________________________________Genes___________________________________________________________________________________________________________Alleles___________________________________________________________________________________________________________Genotype________________________________________________________________________________________________________Phenotype________________________________________________________________________________________________________Probability________________________________________________________________________________________________________Sex Cells___________________________________________________________________________________________________________Sex Chromosomes_____________________________________________________________________________________________________

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The father of genetics is _________________________. He lived from the year __________ to the year _____________. As a profession, he was a _________________ in the country _________________. He worked in the garden and studied _________ plants to show that the inheritance of traits follows particular laws._______________________ – a characteristic of an organism___________________ – the study of how traits are passed from parents to offspring

Why Mendel used pea plants:1. __________________________________________2. __________________________________________3. __________________________________________4. __________________________________________

__________________________________________– have offspring that always show the same form of the trait__________________________________________– a process in which one plant fertilizes the egg in a flower of a different plant__________________________ – tiny grains containing sperm; the male plant gamete

Mendel’s experiments:_______ generation – parental generation_______ generation – offspring in first cross – hybrids

__________________________ – the offspring of two different true breeding plants__________________________ – a cross between two plants that differ in only one trait_______ generation – the offspring that result when 2 hybrid plants are crossed

Mendel’s P cross (Parental cross) involved a true breeder short and a true breeder long. Resulted in _______________________ Mendel’s F1 cross = F1 x F1 = ________% of the offspring were long and ______% were short.

_____________________ – the factor that controls traits_________________ – the possibilities of a gene (e.g. A or a)__________________________ – one allele is dominant to a recessive allele

__________________________ – the allele that masks any other allele in a heterozygous situation (A in Aa) (symbolized by the first letter in the dominant trait’s name, always capital)

__________________________ – the allele that is masks by another allele in a heterozygous situation (a in Aa) (symbolized by the first letter in the dominant trait’s name, always lower case)

__________________________ – having two identical alleles for a trait (AA or aa) (Mendel called this “true-breeding”)_________________________________ ___________________ – having two dominant alleles for a trait (AA) (Mendel

called this “true breeding dominant”)__________________________ __________________________ – having two recessive alleles for a trait (aa) (Mendel

called this “true breeding recessive”)__________________________ – having two different alleles for a trait (Aa)__________________________ - the visible traits of an organism (long or short)__________________________ - the alleles that an organism carries (AA, Aa, or aa)

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__________________________ – a model used to represent crosses between organisms

Steps to doing a Punnett Square:1. identify the gametes of the parents2. draw a square with 4 boxes3. put the gametes from one parent on the top of the box and the gametes from the other parent on the side of the box4. cross multiply to find the genotypes of the children5. write the phenotypes of each child in the boxes6. calculate genotypic and phenotypic ratios

Try these Punnett Squares:1. GG (homozygous green plant) x gg (homozygous recessive yellow plant)

Phenotypic ratio:Green = _______%Yellow = _______%

Genotypic ratio:GG = _______%Gg = _______%gg = _______%

2. Gg (heterozygous green plant) x gg (homozygous recessive yellow plant)

Phenotypic ratio:Green = _______%

Yellow = _______%Genotypic ratio:

GG = _______%Gg = _______%

3. Gg (heterozygous green plant) x Gg (heterozygous green plant)Phenotypic ratio:

Green = _______%Yellow = _______%

Genotypic ratio:

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GG = _______%Gg = _______%

Practice Punnett Squares

NAME ______________________________________________________________

1. Widow’s peak is a dominant trait in humans. If a parent does not have a widow’s peak, what are the genes that the parent has?

2. If a parent does have a widow’s peak, what are the genes that the parent might have?

3. Long eyelashes are dominant in humans. What are the genes for a person who is a hybrid for long eyelashes?

4. The ability to roll your tongue is a dominant human trait. What are the genes for a person who is a pure dominant person?

5. Draw a Punnett square for a cross between a person who is WW and a person who is Ww for widow’s peak.

6. Draw a Punnett square for a cross between two people who are both Rr for the ability to roll their tongues.

7. In the Punnett square you drew in number 6, were the parents able to roll their tongues?

8. In the Punnett square you drew in number 6, how many of the 4 children were able to roll their tongues?

9. In the Punnett square you drew in number 6, how many of the 4 children has the same genes as their parents?

10. In the Punnett square you drew in number 6, how many of the 4 children are pure recessive?

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1. Pink hair is dominant over blue hair in smurfs. Cross a homozygous dominant hair smurf with a homozygous recessive hair smurf.

2. Orange skin is dominant over blue skin in oranges. Cross a heterozygous skin orange with a homozygous dominant skin orange.

3. Black hair is dominant over red hair in Labrador retrievers. Cross a homozygous dominant hair retriever with a heterozygous hair retriever.

4. Green pods are dominant over yellow pods in string beans. Cross 2 heterozygous pod string beans.

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5. Curly hair is dominant over straight hair in poodles. Cross a purebred dominant with a true breed recessive poodle.

Punnett Square Practice

NAME __________________________________ CLASS ___ DATE _______

Please circle your final answer.

1. A pea plant which is heterozygous for long (Long is dominant, short is recessive) is crossed with a pea plant which is homozygous recessive. What are the genotypic and phenotypic ratios of the offspring?

2. A person who is heterozygous for widow’s peak (Widow’s peak is dominant, no peak is recessive) has children with another heterozygote. What are the genotypic and phenotypic ratios of the offspring?

3. A guinea pig which is homozygous dominant (black is dominant, white is recessive) is crossed with another guinea pig which is heterozygous. What are the genotypic and phenotypic ratios of the offspring?

4. A person who does not have the ability to roll his tongue (rolling is dominant, not rolling is recessive) has children with a person who is heterozygous for tongue rolling. What are the genotypic and phenotypic ratios of the offspring? (Hint: if you can’t roll your tongue, and rolling is dominant, what must the genotype of a non-roller be?)

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5. Two organisms, which are heterozygous for long eyelashes, have children. (Having long eyelashes is dominant, short eyelashes is recessive). What are the genotypic and phenotypic ratio of the offspring?

6. Two pea plants are crossed. One is homozygous recessive for long (Long is dominant and short is recessive) and the other is heterozygous. If 100 pea plant offspring are produced, how many of them will be long?

7. A person without freckles (Freckles is dominant, no freckles is recessive) has children with a person who is homozygous dominant for freckles. How many of their children will have freckles if they have 4 children?

8. In pea plants, green pods are dominant over yellow. If yellow plant (known to be homozygous recessive) is crossed with a green plant (could be homozygous dominant or could be heterozygous), and the offspring are all green, what was the genotype of the green parent?

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9. A person with a widow’s peak could be homozygous dominant or could be heterozygous. If that person is crossed with a person without a widow’s peak, and 50% of their children do not have widow’s peaks, what was the genotype of the parent with the widow’s peak?

10. Non-red hair is dominant over red hair. A person with red hair is crossed with a person with non-red hair. All of the offspring have non-red hair. What was the genotype of the non-red haired parent?

11. If a pea plant which is heterozygous long is crossed with another heterozygous long pea plant, and they produce 200 offspring, how many of those offspring will be short?

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12. Make up your own word problem involving free and attached ear lobes (free ear lobes are dominant over attached). Solve the word problem.

SpongeBob Genetics Quiz Name ____________________________

1. For each genotype below, indicate whether it is a heterozygous (He) OR homozygous (Ho).

TT _____ Pp _____ dd _____ Ff _____ Tt _____ FF _____

Which of the genotypes listed above would be considered purebred? _____________________

2. In Squidward’s family, a blue body color (B) is dominant to green (b). Determine the phenotype for eachgenotype below based on this information.

BB _________________ Bb _________________ bb _________________

3. If tall eyeballs (T) are dominant to short eyeballs(t), give the genotypes that are possible for members ofMr. Krabbs’ family.

Tall eyeballs = ___________________ Short eyeballs = ______________________

4. SpongeBob is known for his big round eyes (R), which is dominant over an oval eye shape (r). If he isheterozygous for his round eye shape and marries a woman with oval eye shape, what type of eyes might thekids have?

A. List the genotypes for each:

Heterozygous round eyes - _______ Oval eyes - _______

B. Complete the Punnett square to show the possibilities that wouldresult if SpongeBob had children with an oval-eyed woman.

C. List the possible genotypes and phenotypes for their children.

D. What are the chances of a child with a round eye shape? ____%

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E. What are the chances of a child with an oval eye shape? ____%

5. Patrick recently married Patti, a cute girl he met at a local dance. He is considered a purebred for his tallhead shape (T), which is dominant over a short head (t). If Patti is a short-headed woman, what type ofheads would their children have?

A. List the genotypes for each: Patrick - ______ Patti - _______

B. Complete the Punnett square to show the possible offspring.

C. Which type of head is most likely: tall or short? Explain.

D. Would the children be considered purebreds? Explain.

Worksheet created by T. Trimpe 2003 http://sciencespot.net/

Design a DragonName__________________________________________

In this lab you and a partner will flip a penny 10 times each and record the number of the heads and tails combinations for each flip. A “heads” flip represents a dominant allele (H) and a “tails” flip represents a recessive allele (h). When you are done, look at the Trait Key telling you which traits are dominant and recessive for dragons. Then, you will draw a dragon according to the alleles that you flipped for. For example, if a red body color is dominant and you flip a heads and your partner flips tails, you will color your dragon red because the genotype would be Hh. You will still color it red if your partner flips a heads, because red body color is dominant making an HH genotype. If a green body color is recessive, you AND your partner will have to flip tails to have your dragon express the green body color trait to make the genotype hh. Make sure to hand in your flip chart and the picture of your genetically designed dragon.

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Trait Key:

Trait # Dominant Recessive

1. Body Color Red Green

2. Body Spots Colored Body Spots NO Body Spots

Flip Trial # Genotype (HH, Hh, hh)

Example: 1 I flipped heads (H) and my partner flipped tails (h) so the genotype would be Hh

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2

3

4

5

6

7

8

9

10

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3. Fire Breather Breathes Fire Does not Breathe Fire

4. Tail Spikes No Tail Spikes Present Spikes Present on Tail

5. Teeth Pointy Teeth Square Teeth

6. Ear Shape Round Ears Pointy Ears

7. Claw Length Short Claws Long Claws

8. Tongue Length Long Short

9. Wing Color Black Blue

10. Stomach Color Yellow Orange

Name ______________________________________________________________

Punnett Squares –

Crosses Involving One Trait

In a certain species of animal, black fur (B) is dominant over brown fur (b). Using the following Punnett square, predict the genotypes and phenotypes of the offspring whose parents are both Bb or have heterozygous black fur.

B b

B

Genotypes:

_____% homozygous black fur (BB)

_____% heterozygous black fur (Bb)

_____% homozygous brown fur (bb)

Phenotypes:

_____% black fur

_____% brown fur

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b

Now do the same when one parent is homozygous black ()BB) and the other is homozygous brown (bb).

Repeat this process again when one parent is heterozygous (Bb) black and the other is homozygous brown (bb).

Section 3-1 Review and ReinforceMendel’s WorkUnderstanding Main IdeasStudy the figure. Then answer the following questions on a separate sheet of paper.

Genotypes:

_____% homozygous black fur (BB)

_____% heterozygous black fur (Bb)

_____% homozygous brown fur (bb)

Phenotypes:

_____% black fur

_____% brown fur

Genotypes:

_____% homozygous black fur (BB)

_____% heterozygous black fur (Bb)

_____% homozygous brown fur (bb)

Phenotypes:

_____% black fur

_____% brown fur

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1. What trait in pea plants is being studied in the cross above?2. What are the two alleles of this trait?3. Which allele is the dominant allele? Explain how you know.4. Which allele is the recessive allele? Explain.5. What alleles do the F1 offspring have? Explain which allele was inherited from which

parent.

Building VocabularyMatch each term with its definition by writing the letter of the correct definition on the line beside the term._____ 6. Genetics a. the passing of traits from parents to offspring_____ 7. Alleles b. an organism with two different alleles for a trait_____ 8. Traits c. factors that control traits_____ 9. Recessive allele d. physical characteristics of organisms_____10. Genes e. an allele whose trait always shows up in the organism_____11. Hybrid f. the different forms of a gene_____12. Heredity g. the scientific study of heredity_____13. Dominant allele h. an allele whose trait is masked in the presence of a

dominant allele

Incomplete Dominance Punnett SquaresUnlike simple Mendelian dominance and recessiveness, SOME traits are inherited by INCOMPLETE dominance.In some flowers, red (RR), white (WW), and pink (RW) colors can exist. RED and WHITE are incompletely dominant. In some animals, fur can be black (BB), white (WW), or gray (BW). Try these:

pink flowers X white flowers Black fur x white fur Gray fur x gray fur

P generation F1 Generation

F1 Generation F2 Generation

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Multiple Alleles Punnett Squares

Some people have proteins on the outside of their blood cells, while other people do not. Blood type Proteins on blood cells:A AB BAB A and BO none

Blood type is inherited by multiple alleles. A and B are co-dominant, which means that they are equally dominant if they are both found in the same person. There is one recessive allele, O. A person can have any two of those three alleles. Genotypes and phenotypes are summarized in the table:

Try these:

blood type AO X blood type BO blood type AA X blood type BO blood type BB X blood type AO

Genotype PhenotypeAA AAO ABO BBB BAB BOO O

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1. Fur color in huskies in INCOMPLETELY DOMINANT. Cross a brown with a white husky.

B=brown

W= white

What % of the offspring are white?_____brown?_________tan?___________

2. Cross 2 tan huskies

What percent % of the of the offspring are brown?____________white_________tan___________

3. HARRY AND HARRIET GOT MARRIED. HARRY HAS BLOOD TYPE O AND HARRIET HAS BLOOD TYPE AB. THEIR BABY HAS BLOOD TYPE 0 AND IT DOES NOT LOOK LIKE EITHER ONE OF THEM. IS LITTLE MARVIN THEIRS?

Use a punnet square to prove your answer

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Hospital Mix-up!The local hospital has reported a power outage. Unfortunately, three babies were born during this power outage and they got mixed up!

See if you can determine which baby belongs to which set of parents based on their blood type.

The three babies that were born are:

Baby 1 – Blood type O

Baby 2 – Blood type A

Baby 3 – Blood type AB

Couple Mother’s blood type

Father’s blood type

Which Baby?

Fred and Wilma Flintstone

A O

Lucy and Ricky Ricardo

B A

George and Jane Jetson

O B

Punnett Square Practice

Name: ________________________________ Date: _________ Period: _______

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1. Let’s say that in seals, the gene for the length of the whiskers has two alleles. The dominant allele (W) codes long whiskers and the recessive allele (w) codes for short whiskers.

a. What percentage of offspring would be expected to have short whiskers from the cross of two long-whiskered seals, on that is homozygous dominant and one that is heterozygous?

b. If one parent seal is pure long-whiskered and the other is short-whiskered, what percent of offspring would have short whiskers?

2. In purple people eaters, one-horn is dominant and no horns is recessive. Draw a Punnett square showing the cross of a purple people eater that is hybrid for horns with a purple people eater that does not have horns. Summarize the genotypes and phenotypes of the possible offspring.

3. In dogs, there is an hereditary deafness caused by a recessive gene, “d.” A kennel owner has a male dog that she wants to use for breeding purposes if possible. The dog can hear, so the owner knows his genotype is either DD or Dd. If the dog’s genotype is Dd,

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the owner does not wish to use him for breeding so that the deafness gene will not be passed on. This can be tested by breeding the dog to a deaf female (dd). Draw the Punnett squares to illustrate these two possible crosses. In each case, what percentage/how many of the offspring would be expected to be hearing? Deaf? How could you tell the genotype of this male dog? Also, using Punnett square(s), show how two hearing dogs could produce deaf offspring.

4. In humans, brown eyes (B) are dominant over blue (b). A brown eyed man marries a blue eyed woman and they have three children, two of whom are brown eyed and one of whom is blue eyed. Draw the Punnett square that illustrates this marriage. What is the man’s genotype? What are the genotypes of his children?