Lesson 12: Single Gene Inheritance Before you
begin! Homework Name
o Your ideas: Be prepared to share with your peers
 What is a gene and how does that relate to a chromosome?
 In what fundamental way is meiosis different from mitosis (what is achieved)?
 In a Punnett square, what information goes on the outside?
 On the inside?
 What is 1/2 x 1/2 ?
 In humans, hair texture shows incomplete dominance. What kind(s) of kids can a curly haired man
have with a straight haired woman (three phenotypes – curly, wave, and straight)?
o Previously learned material
 What is the molecular basis of the word “allele”?

What are some genes important for us to study with regard to mood-altering drugs?
Required Reading: Introductory biology textbook or internet review is fine
Chapter(s) or section(s) on Meiosis (specific to sperm production in A&P text, pg. 643) and Punnett Squares
(watch Beginner’s Guide from Bozeman Science here https://www.youtube.com/watch?v=Y1PCwxUDTl8)
Chapter(s) section(s) on Mendel – single gene traits, dominant, recessive, incomplete dominance (some
information in A&P text, section 20-8 p. 634
Internet
 http://learn.genetics.utah.edu/content/begin/tour/ (introduction to heredity)
 http://anthro.palomar.edu/mendel/mendel_2.htm (introduction to Punnett squares)
 http://www.biology.arizona.edu/cell_bio/tutorials/meiosis/main.html (introduction to meiosis)
 https://www.youtube.com/watch?v=qCLmR9-YY7o Crash Course Biology on Meiosis (6 min.)
 https://www.youtube.com/watch?v=CBezq1fFUEA Crash Course: Heredity- good review
Supplemental Reading
 For anyone requiring a little back-to-basics on genes, heredity, chromosomes.
http://www.youtube.com/watch?v=eOvMNOMRRm8&feature=related
 For a reminder of what meiosis can do that mitosis cannot, visit
http://www.pbs.org/wgbh/nova/baby/divi_flash.html
Guiding Questions
1. How does DNA relate to genes and to chromosomes?
2. How are chromosomes divided during meiosis?
3. How are chromosomes reunited during fertilization?
4.
5.
6.
7.
What rules enable us to make predictions for specific matings?
What is dominance? What are some alternatives to dominance?
How are Punnett squares helpful for solving genetics problems?
How are Pedigrees helpful for solving genetics problems?
Key Terms
 Diploid
 Haploid
 Heterozygous
 Homozygous
 Dominant
 Recessive
 Chromosome
 Trisomy
 Sex Chromosome
 Autosome
 Incomplete dominance
Activity One: Web Site Review: Homework
Please review the Web sites below.
To consider heredity visit http://learn.genetics.utah.edu/content/begin/tour/ and select the tutorial called
“What is Heredity”. While there, also visit “What are Traits” which is very long. Repeatedly press “next” until
the thumb icon (hitchhikers thumb) is highlighted.





Give two examples of both a physical and a behavioral trait. One example should be NOT found in the
tutorial.
How do parents pass traits on to their children?
Of the parental chromosomes, what proportion of them are passed to children?
How does one define a dominant allele?
What are two ways that traits can be more complicated than ones like hitchhiker’s thumb?
To consider Punnett Squares http://anthro.palomar.edu/mendel/mendel_2.htm and/or
https://www.youtube.com/watch?v=Y1PCwxUDTl8





What do the single-letter symbols mean – “G” or “Y”?
How do you fill in the boxes of a Punnett Square?
How can the Punnett Square be used to predict probabilities of genetic outcomes?
How is cystic fibrosis inherited?
What is an example of a dominantly inherited trait?
In Lecture: Respond to discussion questions
Nucleotides, DNA, genes, chromosomes, and codons are all terms used to describe our genetic information.
Take each pair of terms and describe their relationship.
Nucleotides and genes
Genes and Chromosomes
DNA and codons
Chromosomes and DNA
Share your responses with your table partner
Where do your chromosomes come from?
How are they passed along?
What did Mendel figure out, even though he did not know about Genes or DNA?
Use white boards or paper for genetics problems
Need reinforcement of Punnett squares? Try these optional practice problems:
Activity Nine: Practice Problems
Genetics is an area of biology that some students find challenging because it is more problem solving than
memorization. To give yourself practice with this type of approach to studying, do as many practice problems as you
can. In the sites below, you will find an interactive quiz for genetics problems.
http://anthro.palomar.edu/mendel/quizzes/mendqui2.htmhttp://anthro.palomar.edu/mendel/mendel_3.htm