Genetics

Human Genetics

Activity One  Background

Meet //**Gregor Mendel**//, who is known as the father of genetics. While Americans were fighting a bloody civil war on their own soil, Mendel was discovering the basis for [|genetic inheritance] in a humble monastery in Austria. Mendel was either inspired or lucky in his choice of organisms. He studied seven different traits, each of which has only two expressions. For example, a plant was either tall or short, had purple or white flowers, had round or wrinkled seeds and had either yellow or green pod color. The fact that there were only two expressions of each trait made it easy for Mendel to determine which trait was dominant and which trait was recessive. In crossing one plant with another, Mendel began with two [|true-breeding plants]; he called this his **parent generation**. The offspring of two parents are called the **F-1 generation**. If two true-breeding **(homozygous)** plants are crossed, all the F-1 offspring will look like the parents. For example, if two true-breeding white flowered plants are crossed, all the offspring will also have white flowers. This is because, in order to be true-breeding -- or homozygous -- both the genes for the trait are the same. In other words, the gene inherited from the father is identical to the gene inherited from the mother. Different versions of the same gene are called [|alleles]. Answer the following questions:
 * **What particular organism did Mendel use for his experiments?**
 * **Mendel soon discovered that, though each organism inherits a gene from each parent, only one gene is expressed. How did Mendel explain this?**
 * **What is Mendel's Law of Segregation?**
 * **What is his Law of Random Assortment?**
 * 1) Why did Mendel choose to experiment with garden peas?
 * 2) What is a "character?"
 * 3) How does a "trait" differ from a "character?"
 * 4) What is a "heritable trait?"
 * 5) Explain the term true-breeding and give an example.
 * 6) Explain the meaning of (a) the P generation, (b) the F1 generation, and (c) the F2 generation.
 * 7) What is a monohybrid cross?
 * 8) Explain the terms dominant and recessive.
 * 9) How do gametes relate to the daughter cells we studied in our meiosis unit?
 * 10) What is the relationship between genes and alleles?
 * 11) Explain the difference between homozygous and heterozygous alleles.
 * 12) What is the phenotype of an organism? Give an example.
 * 13) What is the genotype of an organism? Give an example.


 * What do you think happens if a purple flowering plant is crossed with a white-flowering plant?** **Why do you think this happens?**

**Activity Two**  Inheritance of traits takes place first through the process of meiosis. Work through the [|Mendel's Peas Lab]. **Activity Three** Generally speaking, we designate the dominant allele by naming it and giving it upper case status. For example, if tall is dominant, we would designate the dominant allele as **T** (tall is dominant so it is capitalized). If short is recessive, we would designate the recessive allele as **t** (tall is dominant, so we still use the letter t, but, because short is recessive, it is expressed in the lower case).

 **Read the following and determine which trait is dominant, which trait is recessive and what letters you would use to represent each.**
 * 1) A purebred tall plant is crossed with a purebred short plant to produce an offspring that is hybrid tall.
 * 2) A wrinkled purebred pea is crossed with a purebred smooth pea to produce an offspring that is hybrid smooth.
 * 3) A hybrid yellow pea is crossed with a purebred green pea to produce an offspring that is hybrid yellow.
 * 4) A purebred yellow flower crosses with a hybrid yellow flower to produce an offspring that is hybrid yellow.
 * 5) A hybrid sweet apple crosses with a hybrid sweet apple to produce offspring that are sour.
 * 6) A hybrid long tail cat crosses with a hybrid long tail cat to produce an offspring with a long tail.

Do This: Now that you are a Punnett square specialist, draw a Punnett square for each of the above six scenarios, showing the potential offspring. Circle the genotype of the offspring that is given in the scenario. Be sure you give the phenotypic and genotypic ratios.**
 * Need more practice? Try this link to show a [|monohybrid cross] using Punnett squares.

**Activity Four**

Down in Bikini Bottoms, Sponge Bob and the gang are finally growing up and getting married. You know the rest of the story: the thought of a sweet bouncing baby sponge (or squid or sea star) is tugging at the corners of their minds. Read the scenarios given and [|determine the traits] of their offspring. And...just when you think you've finished, Mrs. Dennis throws [|another Bikini Bottoms worksheet] at you!  **Activity Five** ** Your teacher will distribute a packet of monohybrid cross scenarios which we will complete in class. **
 * [|More practice on simple Mendelian genetics.]**

**Activity Six** Sometimes inheritance patterns don't follow Mendel's rules. In fact, there is a spectrum of dominance that covers most inheritance patterns (where mutations do not occur):


 * [** __ incomplete dominance ..... complete dominance ..... co-dominance __ **]**

> > Try [|this activity] on your own. [|This activity] will give you an idea about how eye color is determined. Your teacher will give you a handout to use for this activity. **Activity Seven** <span style="background-color: #ff7000; font-family: 'Arial Black',Gadget,sans-serif; font-size: 120%;"> Now you are ready to solve:
 * in incomplete dominance, **neither** allele is dominant over the other.
 * in complete dominance, **one** allele is dominant and one is recessive.
 * In co-dominance, **both** alleles are dominant.
 * **Your teacher will distribute worksheets on incomplete dominance and co-dominance for completion in class.**
 * [|The Baffling Baby Mixup.] This is a webquest that should take only one class period.

<span style="background-color: #c0c0c0; color: #ff0000; display: block; font-size: 130%; text-align: center;">**Activity Eight** <span style="background-color: #fbff00; font-family: 'Arial Black',Gadget,sans-serif; font-size: 120%;">Do This: <span style="font-family: 'Arial Black',Gadget,sans-serif; font-size: 120%;"> See if you can create a family tree using [|this information]. Where will you start? How will you connect the family members? <span style="background-color: #c0c0c0; color: #ff0000; display: block; font-size: 130%; text-align: center;">**Activity Nine**

<span style="background-color: #ffec00; font-family: 'Arial Black',Gadget,sans-serif;">Do This: Now try this [|interactive lab] to put together your own precious little //<span style="font-family: 'Arial Black',Gadget,sans-serif;">alien **!**//

<span style="background-color: #f2f42f; font-family: 'Arial Black',Gadget,sans-serif;">Do This: Click on [|Dragon Genetics] to make sure you understand the relationship between genotype and phenotype.

Try this [|crossword puzzle] using what your know about genetics.

<span style="background-color: #f6f33c; font-family: 'Arial Black',Gadget,sans-serif;">Do This: You will be assigned to a group to play this [|genetic trait game].

[|Practice, Practice, Practice] by playing the concentration game!! <span style="background-color: #c0c0c0; color: #ff0000; display: block; font-size: 130%; text-align: center;">**Activity Ten** **Surely you didn't think you would escape without a project!** <span style="background-color: #e228d0; display: block; font-family: Tahoma,Geneva,sans-serif; font-size: 150%; text-align: center;">Project Information

Your teacher will provide a Guide Sheet for your project: Genetic Phenotypes of the Superheroes. Be sure to read the [|rubric] before handing in your project. **[|Rubric for PowerPoint.] Project due date: December 9, 2009**

<span style="background-color: #c0c0c0; color: #ff0000; display: block; font-size: 140%; text-align: center;">**Activity Eleven**
 * Review:**
 * 1) Describe the difference between heterozygous and homozygous.
 * 2) Explain the difference between phenotype and genotype.
 * 3) Explain the difference between dominant and recessive.
 * 4) What is a [|karyotype]? How is it used?
 * 5) How does co-dominance differ from incomplete dominance?
 * 6) Explain what is meant by the term sex-linked traits.
 * 7) What is polygenic inheritance?
 * 8) Explain the term multiple alleles as it applies to a population.
 * 9) How are Punnett squares set up differently when explaining sex-linked traits, incomplete dominance and co-dominance?
 * 10) What features Mendel's experiments contributed to his success?
 * 11) What organism did Mendel use in his experiments? Why was this important?
 * 12) What is genetic counseling? What is its purpose?
 * 13) Explain the law of segregation.
 * 14) Explain the law of independent assortment.
 * 15) What is meant by the term heredity?
 * 16) What is a gene? How are genes related to alleles?
 * 17) What is the difference between a monohybrid cross and a dihybrid cross?
 * 18) Eye color, hair color, and skin color are examples of what type of inheritance pattern?