Biology 30

Unit 3 Genetics

Unit Overview

This unit introduces the application of probability theory to Mendelian genetics. Consideration of Mendel's laws of heredity and the concept of the gene as a discrete carrier of hereditary information leads to the discussion of chromosomes, genes, and DNA . Both the technical and ethical aspects of genetic engineering and biotechnology are discussed, as is the study of population genetics.

Conceptual Development

The Conceptual Development section will be updated to reflect changes to K-10 Science curricula.
See Figure 12.

Note: A pre-assessment to determine the entry level of the students may be appropriate.

Key Concepts

Chromosomes, ethics and morality, gene pool, heredity, probability, DNA, chromosome mapping.

Webbing Highlights

• Relate DNA and genes to chemical structures (Unit 30-1) and to where they are found in cells (30-2).
• Relate genetic information to the diversity of life forms (20-3).

Science-Technology-Society-Environment (S T S E) Focus

• "creation" of new species
• genetic disease technologies
• human genome project

Factors of Scientific Literacy Which Should be Emphasized

• A1 ...... public/private
• A2 ...... historic
• A6 ...... probabilistic
• A8 ...... tentative
• A9 ...... human/culture related
• B16 ..... system
• B18 ..... population
• B19 ..... probability
• B20 ..... theory
• B26 ..... evolution
• B32 ..... validation
• C8 ....... hypothesizing
• C9 ....... inferring
• C10 ..... predicting
• C12 ..... interpreting data
• C14 ..... problem solving
• C17 ..... using mathematics
• C18 ..... using time-space relationships
• D2 ....... scientists and technologists are human
• D3 ....... impact of science and technology
• D6 ....... resources for science and technology
• D9 ....... social influence on science and technology
• D10 ..... technology controlled by society
• D11 ..... science, technology, and other realms
• E13 ...... using quantitative relationships
• F2 ....... questioning
• F5 ....... respect for logic
• F6 ....... consideration of consequence
• F7 ....... demand for verification
• G3 ....... continuous learner
• G7 ....... vocation
• G9 ....... valuing contributors

Common Essential Learnings Foundational Objectives

1. Explain the significance of Mendel's experiments and observations, and the laws derived from them.
   

   1.1 Explain the concept of independent events.
   1.2 Understand that the probability of an independent event is not altered by the outcomes of previous events.
   1.3 Describe Mendel's experiments and observations.
   1.4 Describe the relationship between genotype and phenotype.
   1.5 Use the concept of the gene to explain Mendel's laws.
   1.6 Describe the ideas of dominant and recessive traits with examples.
   1.7 Consider the value of the punnett square by creating examples of mono and dihybrid crosses.
   1.8 Explain the law of segregation.

2. Discuss the relationships among chromosomes, genes, and DNA.
   

   2.1 Describe how the genetic code is carried on the DNA.
   2.2 Outline the process of replication.
   2.3 Compare mitosis and meiosis.
   2.4 Describe the process of transcription.
   2.5 Describe the functions of mRNA, tRNA, amino acids, and ribosomes in protein synthesis.
   2.6 Describe the causes and effects of both chromosome and gene mutations.
   2.7 Consider the purposes and techniques of gene mapping.
   2.8 Examine incomplete dominance, alleles, sex determination, and sex-linked traits in the context of human genetics.
   2.9 Discuss several human genetic disorders such as hemophilia, sickle-cell anemia, Down's syndrome, and Tay-Sach's disease.
   2.10 Discuss the similarities and differences between sex chromosomes and somatic chromosomes.
   2.11 Using examples from living organisms discuss the importance of asexual and sexual reproduction to their growth and survival.

3. Delineate the impact of biotechnology on our society.
   

   3.1 Describe the basic processes involved in the production of recombinant DNA.
   3.2 Discuss examples of current uses of recombinant DNA technology in the agricultural and pharmaceutical industries.
   3.3 Discuss the techniques of genetic screening.
   3.4 Consider the implications of genetic screening of adults, children, and fetuses .

4. Discuss the application of population genetics to the study of evolution.
   

   4.1 Describe the concepts of the deme and the gene pool.
   4.2 Consider the Hardy-Weinberg principle.
   4.3 Describe the factors which influence genetic drift.
   4.4 Consider the relevance of the gene pool and the idea of mutations to the concept of evolution which will be studied later in unit 5.

• Use Student Evaluation: A Teacher Handbook.
• Consult key resource supports.
• Review pages in this guide

Suggested Activities and Inquiries

Note: Many activities have been identified in the key resources Information Bulletin.

1. Student checked traits.

   This activity can be used to introduce the ideas expressed in objectives 1.1, 1.2, 1.4, 1.5 and 1.6. This also provides students an opportunity to practice observation and recording techniques while working in a small group environment. Additional traits can be studied.

   Objectives: 1.1, 1.4, 1.6, 1.7, CCT, COM, PSVS
   Factors: C9, C10, C12, C17, E13, F6, F7
   Assessment: WA - Laboratory Report; Short-Answer Quiz/Test

   Teacher Chart

   Trait	Dominant Factor	Recessive Factor	Identification
   Tongue Rolling	roll tongue (genotype) (Rr or RR)	rr	Tongue can be bent into a U shape
   Attachment of the ear lobe	attached (FF or Ff)	ff	Free ear lobe part of ear hangs below attached part
   Cheek indentations	DD or Dd	dd	Dimples or depressions in the cheeks
   Second toe length	SS or Ss	ss	Second toe longer

   Instructional Strategies

   Student Procedure

   a) Tell the students how to recognize the traits but do not tell them if it is dominant or recessive.
   b) Set up a chart with the students for recording the information.
   c) Have the students work in pairs where one will record while the other observes.
   

   • Do at least half the class.
     
   • The teams should add to the above total at least 10 more individuals from the school.
     
   • Finally, ask the students in each group to do their family members and add this to their total.
   d) At the next class period discuss dominance and recessive traits and have the students, in their groups set up a chart (dominant and recessive) and decide which traits are dominant and which are recessive. Do not assess the information ye t.
   e) Introduce the ideas of genotype and phenotype. Have students in their teams set up a chart and record the genotype and phenotype for each of the traits.
   f) Discuss the punnett square and then have the student pairs draw out punnett squares for at least 2 of the traits.
   g) It is possible to discuss population sampling and the kinds of information that the class obtained as small groups, as a large class group and how this relates to the percentages in a punnett square of each of the traits.

   Evaluation Strategy

   Have student teams turn in charts d, e, and f and allocate 8 marks for each activity.

2. You could bring in an animal breeder and/or have students collect pedigrees from cattle, horse, sheep or dog breeders. There are also other possibilities. How has their work affected the balance of the traits present in various kinds of animals?

3. Trace a family tree for a number of traits. (Be sensitive to cultural or ethnic concerns regarding diseases or extended family adoptions, etc.)

4. Collect immigration and emigration information of various ethnic groups from the Provincial Government to see how various genes in the gene pool may be changing.
5. Contact pharmacists, extension agrologists, etc. to discover if there are new developments like genetically engineered drugs or crops.
6. Have students perform some of the classic investigations dealing with:
   • probability
   • mitosis and meiosis
   • aspects of DNA
   • human pedigrees
7. How might the field of genetics be applied to improving the economy of your local community and the Province of Saskatchewan. It is important that you discuss the specific genetics you would apply and what kind of jobs that this would generate.
8. When large extinctions occur on the earth, such as with the loss of the dinosaurs, what is the genetic impact?
9. Try Activity 11 page 100 for this unit.
10. Investigate the ancestry of bread wheats (or other crops) developed on the prairies. Check with Agriculture Saskatchewan or Canada.
11. Use the "DNA Investigations" simulation from the December, 1991 issue of the Science Teacher.
12. Cross red-eyed female fruit flies with white-eyed Males. Cross F₁ x F₁. Analyze the results. (Reflect on the CEL and DSL connections.)
13. Much of this unit could be done using Mapping Our Genes: The Human Genome Project. Use cooperative learning methods to analyze 10 case studies of human genetic disorders. Many genetic concepts and principles will be covered. Use outreach: invite disabled people in to speak or have students visit clinics.
14. In the traditional Haida culture there were two large family groups (phratries) called the Ravens and the Eagles. Members of the same phratry were forbidden to marry. Why do you think this practice was established? How? What genetic advantages and disadvantages does this have?
15. How did the introduction of pathogens to New World Aboriginal peoples shift the genetic composition of populations?
16. Have student do research on new species of organisms that are created in a lab and used either in medicine or agriculture.
17. How has genetics changed our current ecosystems? How will they change in the future?