Chapter 3 Vocabulary

Chapter 3

Heredity

NAME ______

Gregor Mendel______

______

Heredity______

______

Dominant trait______

______

Recessive trait______

______

Genes______

______

Alleles______

Genotype______

Phenotype______

Probability______

Sex Cells______

Sex Chromosomes______

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:

______
______
______
______

______– 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)

______– a model used to represent crosses between organisms

Steps to doing a Punnett Square:

1. identify the gametes of the parents

2. draw a square with 4 boxes

3. put the gametes from one parent on the top of the box and the gametes from the other parent on the side of the box

4. cross multiply to find the genotypes of the children

5. write the phenotypes of each child in the boxes

6. 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:

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?

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

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

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

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

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?)

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?

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?

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 each

genotype 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 of

Mr. 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 is

heterozygous for his round eye shape and marries a woman with oval eye shape, what type of eyes might the

kids have?

A. List the genotypes for each:

Heterozygous round eyes - ______Oval eyes - ______

B. Complete the Punnett square to show the possibilities that would

result 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? ____%

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 tall

head shape (T), which is dominant over a short head (t). If Patti is a short-headed woman, what type of

heads 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 Dragon

Name______

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.

Flip Trial # / Genotype (HH, Hh, hh)
Example: 1 / I flipped heads (H) and my partner flipped tails (h) so the genotype would be Hh
1
2
3
4
5
6
7
8
9
10

Trait Key:

Trait # / Dominant / Recessive
1. Body Color / Red / Green
2. Body Spots / Colored Body Spots / NO Body Spots
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
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 Reinforce

Mendel’s Work

Understanding Main Ideas

Study the figure. Then answer the following questions on a separate sheet of paper.

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 Vocabulary

Match 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