A Curriculum Plan and Teaching Guide: Genes and Heredity
Introduction
This curriculum web is designed to introduce middle school students to the concepts of genes
and heredity. The topics listed below are designed to help teachers integrate the learning of basic
genetics into their classrooms.
Curriculum Standard(s)
S7L4. Students will recognize how biological traits are passed on to successive generations.
a. Explain the role of genes and chromosomes in the process of inheriting a specific trait.
Aim
This curriculum web aims to answer two basic questions: “Why do I look the way I do?” and
“How did this come to be?”
Rationale
Through this curriculum students will investigate the science of heredity and variation in living
organisms. The idea that traits are passed from parents has been used since prehistoric times to
improve crop plants and animals through selective breeding. Modern genetics began with Gregor
Mendel and seeks to understand the process of inheritance.
General Educational Goals
Students will examine many areas of genetics to help them learn about and better understand
how it relates to their lives.
Subject Matter Description
Relationship between traits and heredity
Experiments of Gregor Mendel
Dominant and Recessive Traits
Genes and alleles
Genotype and Phenotype
Punnett Squares
Probability
Learner Description
This curriculum web is designed for students in a 7th grade Life Science class. Students come
from a range of backgrounds and learning levels. This may include gifted, general education, and
special education students. Because learning styles vary among students, the activities will be
differentiated whenever possible.
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Prerequisites
Students need to be able to read at a 5th grade level or above. Students must have basic computer
skills such as keyboarding, accessing the internet, and surfing the web. It is helpful for students
to have a basic understanding of cells and in particular where DNA is held within the cell.
Learning Objectives
Many traits of an organism are inherited from its biological parents.
Genes and chromosomes determine the expressions of inherited traits.
Instructional Plan
Preparation:
Reserve computer lab or laptops for students for a minimum of ten days.
To minimize sound during videos, check out headphones or ask that students bring their own.
Save link to the Genes and Heredity website onto a classroom blog or write the link on the
board for students to locate site with ease.
Create Class genetic tree as a bulletin board or on a large piece of butcher paper.
Review activities and provide modifications as needed.
Modification ideas:
Partially filled in “Mendel’s Scientific Method” sheet.
Use heterogeneous groups for interactive games.
Allow students time to watch videos twice.
Provide Guided practice for the first question in each section of the Spongebob Genetics pages.
Introducing the curriculum web:
One to five Pre-Assessment: Ask the following questions to determine students’ prior
knowledge. Ask them to hold up a 1, 2, 3, 4, or 5 depending on how much they know about
each topic. One means “I have never heard of this.” Five means “I could explain this statement
to the class”. Ask any students holding up a 4 or 5 to share their knowledge with the class.
Many traits are inherited from parents and passed from parents to offspring through genes.
Gregor Mendel discovered the principles of heredity while studying pea plants.
When a dominant trait is present the recessive trait seems to fade into the background.
If I flip a coin the chances of getting heads is 50% or ½.
An organism’s appearance is known as its phenotype.
Begin a class discussion to get students thinking about how traits are passed from generation to
generation and the concepts of probability. The first question is for the day you begin “Mendel
and his Peas” and the second question is for “Traits and Inheritance”.
Why don’t you look like a giraffe?
Neither of your parents are a giraffe. They did not pass on the traits of a giraffe to you.
Display 3 pennies and a nickel, and ask students the following questions:
How many coins are there in all? (4)
What fraction of the coins are pennies? (3/4)
What fraction of the coins are nickels? (1/4)
What is the raio of pennies to nickels? (3 to 1)
Instructions/Activity pages:
Mendel and his Peas
Explain the relationship between traits and heredity.
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Genetics is the science of genes and heredity. Inside the nucleus of all your body cells are 23
pairs of chromosomes. Each chromosome carries hundreds to thousands of genes on it. Each
gene describes some of your traits. Your hair color, eye color, allergies, body shape, your
health, tastes, and on and on. These are all traits described by your genes. The genes describe
these traits with a kind of code - a genetic code. The genetic code is on your DNA which is
located inside the nucleus of your cells. Heredity is how we pass these coded traits on to our
children.
Watch Tour the Basics: What is Heredity? Be sure to click on the question along the top that
says “What is Heredity?” http://learn.genetics.utah.edu/content/begin/tour/
Complete 3-2-1 Exit Ticket on your own paper. You are welcome to re-watch the video to help
you with this.
Describe the experiments of Gregor Mendel.
Gregor Mendel was an Austrian monk. He experimented with pea plants in the mid-1800's. He
kept track of a number of traits over several generations, including: color of the seeds, plant
height, whether the pod was smooth or wrinkled, and the shape of seeds. Over time, he
noticed that certain plants produced new plants that were similar to the parents. For example,
short "parent" plants produced more short plants, and tall "parent" plants have tall offspring.
When he bred plants with different traits, he found patterns in the appearance of the new
plants. He concluded that some genes are dominant and other ones are recessive. Dominant
genes hide other genes that are present, and the trait corresponding to that gene will appear.
Traits represented by recessive genes will only appear when the dominant gene is not present.
Use these websites to learn more about Gregor Mendel and his pea plants.
Exploring Nature Education: Gregor Mendel’s Genetics Discoveries with Peas
http://www.exploringnature.org/db/detail.php?dbID=22&detID=54
Wikipedia: Gregor Mendel http://en.wikipedia.org/wiki/Gregor_Mendel
Gregor Mendel (1822-1884) http://www.accessexcellence.org/RC/AB/BC/Gregor_Mendel.php
Your textbook (Holt: Life Science) is also a good resource of information on Gregor Mendel
starting on page 114.
Complete Mendel’s Scientific Method. You may work on this with a partner.
Explain the difference between dominant and recessive traits.
Genes contain information about a specific characteristic or trait and can either be dominant or
recessive. Genes are found on chromosomes, but not all copies of a gene are identical. The
different form of a gene is called an allele. Allele’s are represented using capital letters
(dominant) and lower case letters (recessive). When the alleles are identical, the individual is
homozygous for that trait. If the pair is made of two different alleles, the individual is
heterozygous. A homozygous pair of can be either dominant (AA, BB) or recessive (aa, bb).
Heterozygous pairs are made up of one dominant and one recessive allele (Aa, Bb). In
heterozygous individuals only the dominant allele is expressed, while the other allele, the
recessive, is hidden but still present. Capital letters represent dominant genes and lower case
letters, recessive genes. What does all this mean? Let’s look at an example: In bunny rabbits,
brown fur color is dominant over white fur color. We would represent a brown allele with an
uppercase “B”. We would represent a white allele with a lowercase “b”. If a baby bunny rabbit
inherited two dominant alleles “BB”, his fur color would be brown. If the baby bunny rabbit
inherited one dominant and one recessive allele “Bb”, his fur color would still be brown. This is
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because the dominant allele would cover up or hide the recessive allele. Finally, if the baby
bunny rabbit inherited two recessive alleles “bb” he would have white fur. White fur would only
be possible if no dominant allele was present.
Watch Tour the Basics: What is a trait? http://learn.genetics.utah.edu/content/begin/tour/
Follow the link and watch the image slideshow called “OBSERVABLE TRAITS”. Be sure to identify
which trait you express. You may need to ask a shoulder partner for assistance.
http://learn.genetics.utah.edu/content/begin/traits/
A Tree of Genetic Traits: Your teacher will give you a genetic “leaf” to fill out. When you are
finished place it on the correct branch of the class genetic tree.
Discussion Questions:
Some traits are more common in a population than others. What is the most common
combination of traits in the group? What is the least common combination of traits in the
group?
Culminating Activity: Create one of the following describing the experiments of Gregor Mendel:
How-to-Manual, Imaginary Diary, Documentary, Song, or Resume. You may produce your
project using Power Point, Moviemaker, or Word. Be sure to review the rubric before you
begin, so you know how you will be assessed.
Traits and Inheritance
Explain how genes and alleles are related to genotype and phenotype.
Genes affect the traits of offspring. An organism’s appearance is known as its phenotype. In
bunny rabbits, possible phenotypes for the characteristic of fur color include brown, white, and
black. Both inherited alleles together form an organism’s genotype. Our baby bunny rabbits
with brown fur could have a genotype of either “BB” or “Bb”. Another of our baby bunny
rabbits may have a white fur and their genotype would be expressed “bb”. Phenotype refers to
the appearance or expression of the trait, and Genotype refers to the genetic make-up of the
gene. Remember: If you are asked for a phenotype, you should give a characteristic (brown or
white). If you are asked for a genotype, you should give an allele combination “bb” or “Bb” or
“BB”.
Use these websites to learn more about phenotype, genotype and Punnett squares.
Probability of Inheritance: http://anthro.palomar.edu/mendel/mendel_2.htm
Thinkquest: http://library.thinkquest.org/20830/Textbook/Genetics.htm
Complete #1-3 for homework: Sponge Bob Genetics 1
Complete #1-3 for homework: Sponge Bob Genetics 2
Use the information in a Punnett Square.
The Punnett square is a diagram that is used to predict an outcome of a particular cross or
breeding experiment. It is named after Reginald C. Punnett, who devised the approach, and is
used by biologists to determine the probability of an offspring having a particular genotype or
phenotype. The Punnett square is a summary of every possible combination of one maternal
(mother) allele with one paternal (father) allele for each gene being studied in the cross.
Play “Pass the Genes, please”. Play until you can create the whole “baby melon” without any
mistakes: http://nature.ca/genome/04/041/0414_e.cfm
Complete the following online lab to learn more about Punnett squares:
http://www.mhhe.com/biosci/genbio/virtual_labs/BL_05/BL_05.html
Finish both Sponge Bob Genetics 1 and 2 for homework.
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Explain how probability can be used to predict possible genotypes in offspring.
The mathematical chance that something will happen is known as probability. Probability is
usually written as a percentage or a fraction. When you toss a coin, there is a 50% chance of
getting heads. In a parent with two different alleles, such as Pp, there is a 50% chance of
offspring getting P and a 50% chance of getting p. Picture:
http://1.bp.blogspot.com/_hW5DgGNOtTw/R69n1CJbHCI/AAAAAAAAABk/7HEv1XCSjI4/s320/p
unnet+square.jpg In this example, the Dad Rabbit is homozygous for grey fur and the mother
is homozygous for brown fur. Because grey is dominant, their offspring will all be heterozygous
for grey fur. If we were asked for the genotype probability or ratio, we would express it as 100%
Bb. If we were asked for the phenotype probability or ratio, we would express it as 100% Grey.
On your own paper, create a cross between to bunnies using the same principles stated above
but the father’s genotype is Bb and the mother’s genotype is Bb. Figure out the probability of
their genotypes and their phenotypes. Check your answers.
Play Hoop Shoot and predict possible outcomes of a genetic cross. You may need a scratch
sheet. http://www.sciencereviewgames.com/srg/games/hs.php?id=136
Take the Google Doc Quiz:
Culminating Activity: Create one of the following to explain how to complete and analyze a
Punnett square: Wiki page, PowerPoint, Movie, Bulletin Board.. Be sure to review the rubric
before you begin, so you know how you will be assessed.
Grouping Strategy Suggestions:
Individual assessments- 321 exit ticket, Spongebob Genetics 1, Spongebob Genetics 2, Google
Doc quiz, and Summative assessment.
Paired optionsBy product or topic interest: Culminating activities (Teachers may allow students to chose one
of the culminating activities instead of completing both.)
Heterogeneous: Both interactive games (Pass the Genes Please and Dragon Genetics), Mendel’s
Scientific Method
Scheduling Time:
Allow for at least two 50 minute periods for each of the two main topic pages: Mendel and his
Peas and Traits and Inheritance. Different learners will progress at various speeds. Allow for at
least one additional day with access to computers. Spongebob activities may be done for
homework. If not, allow one day of class time (without computers) for both pages. If
completing both culminating activities give students 3 days with the computers for each
project. It may also be beneficial to have students pick one of the culminating activities to
complete.
Extensions- The following links provide activities to reinforce concepts in genetics:
http://www.teach-nology.com/teachers/lesson_plans/science/biology/genetics/
Website includes several lesson plans to reinforce and extend the learning of genetics.
http://serendip.brynmawr.edu/sci_edu/waldron/
Website offers several biology activities including cell division and genetics.
http://www.kn.att.com/wired/fil/pages/websciencejk.html
This webquest should be used for extension only. Students investigate genetically modified
organisms, cloning, medicine and genetics or DNA identification.
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