St. Michael’s School
Unit Plan
Unit Title: Human Genetics
Grade Level: 10th Grade
Subject/Topic Area(s): Biology
Designed By: Mónika Gómez
Time Frame: 3 weeks
Brief Summary of Unit: Students will use their knowledge of Mendelian inheritance to
understand the patterns of inheritance that govern human heredity. They will understand the way
genetic diseases can be passed on from one generation to the next. They will hopefully gain
some understanding on ways to prevent the spread of some genetic disorders.
STAGE 1 – DESIRED RESULTS
Content Standard(s) No. 2 Understand the genetic basis for the transfer of biological
characteristics from one generation to the next.
Benchmarks
2.3: Knows that new heritable characteristics can only result from new combinations of existing
genes or from mutations of genes in an organism’s sex cells; other changes in an organism
cannot be passed on.
2.5 Knows features of human genetics (most of the cells in a human contain two copies of each
of 22 chromosomes; in addition, one pair of chromosomes determines sex (XX or XY);
transmission of genetic information to offspring occurs through egg and sperm cells that contain
only one representative from each chromosome pair; dominant and recessive traits explain how
variation that are hidden in one generation can be expressed in the next.
Essential Question(s)
EVALUATION: laboratory practice, worksheets, pedigree analysis, internet research, quiz
and chapter test.
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STAGE 2 – LEARNING PLAN
1. Introduce the terms Karyotype. Have students construct their own karyotypes using cutouts from a sample human karyotype. Explain to students the difference between:
autosome and sex chromosomes. Explain to students that chromosomes in humans are
arranged in 23 pairs from biggest to smallest.
2. Introduce the term PEDIGREE. Explain how pedigrees are used to study inheritance of
traits in animals and humans. Give examples using several common human traits: tongue
rolling, attached earlobe, Hitchhikers thumb, widow’s peak. Allow students to build their
own family’s pedigree chart tracing the inheritance of one of the traits mentioned before..
Laboratory practice: Human Karyotyping
Distribute a review worksheet for the first section.
3. Discuss the inheritance pattern of the most common genetic disorders: autosomal and sex
linked; recessive and dominant.
Questionnaire, pedigree analysis activities and a crossword puzzle will be used to evaluate
the understanding of the concepts.
4. Students will present to each other the information they gathered from their research on
Genetic Disorders.
Quiz
Benchmark Questions
(Create three (3) questions for each benchmark in this unit.)
Multiple choice
__________ 1. Red-green color blindness is X-linked in humans. If a male is red-green color
blind, and both parents have normal color vision, which of the male's grandparents is most likely
to be red-green color blind?
A. maternal grandmother
B. maternal grandfather
C. paternal grandmother
D. paternal grandfather
E. either grandfather is equally likely
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________ 2. A couple has a female child with Tay Sachs disease, and three unaffected children.
Neither parent nor any of the four biological grandparents of the affected child has had this
disease. The most likely genetic explanation is that Tay Sachs disease is inherited as a(n)
______________ disease.
A. autosomal dominant
B. autosomal recessive
C. sex-linked recessive
D. sex-linked dominant
E. cannot make a reasonable guess from this information
________ 3. A human geneticist determined the pedigree shown in the diagram with filled
symbols showing the affected individuals. How is this pattern of inheritance described?
A. autosomal dominant
B. autosomal recessive
C. sex-linked recessive
D. sex-linked dominant
E. none of these
________ 4. A man who had purple ears came to the attention of a human geneticist. The human
geneticist did a pedigree analysis and made the following observations:
In this family, purple ears proved to be an inherited trait due to a single genetic locus. The man's
mother and one sister also had purple ears, but his father, his brother, and two other sisters had
normal ears. The man and his normal-eared wife had seven children, including four boys and
three girls. Two girls and two boys had purple ears.
The purple-ear trait is most probably:
A. autosomal, dominant
B. autosomal, recessive
C. sex-linked, dominant
D. sex-linked, recessive
E. cannot be determined from this information
First Message from a concerned grandmother:
I am wondering how to find out the blood type of my grandson...my daughter is A+…father is
in question...she is stressed to the max on the father of this baby boy.
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Answer to First Message by Professor Hallick:
Blood type analysis can occasionally rule out a potential father (i.e. if the mother is type A and
the child is type O, the father could not be type AB, but could be type A, B, or O), but is not a
method that can be used to establish paternity.
If the paternity of your grandson needs to be established for legal reasons, such as establishing
responsibility for child support, a DNA test would be the accepted method. There are
commercial laboratories that will do the test for a fee (several hundred dollars). Blood samples
would be required from the mother, child, and any alleged fathers.
Second Message from grandmother:
Thanks so much for your prompt reply. Here is the scenario....paternity isn't going to be
established...it is going to lay...for lack of a better expression. My daughter is type A, my
grandson is type B+, we do not know the types of the two gentlemen in question...my question is
what are the types that the fathers would have to be in order for him to be a B+?
_________5. What is the correct answer to the grandmother's question, "What are the types that
the fathers would have to be in order for him (grandson) to be a B+?"
A. B or O
B. A, B, AB or O
C. AB or B
D. A or B
E. A, B, or AB
Sentence Completion
1. _____________________________Chart that illustrates the relationship within a family
2. _____________________________Picture of chromosomes arranged in pairs
3. _____________________________Genetic disorder caused by the deletion of three
bases in the middle of the sequence for a protein, which causes abnormal production of
mucus in the digestive/respiratory systems.
4. _____________________________Genetic disorder which causes the inability to
distinguish certain colors
5. _____________________________Failure homologous chromosome separation during
Meiosis
6. _____________________________Chromosomal mutation where women only have one
X chromosome
7. _____________________________Genetic disorder of the blood caused by a
codominant allele, the disease affects hemoglobin in red blood cells.
8. ______________________________Syndrome present only in males due to sex
chromosome mutation caused by nondisjunction. Males have an extra copy of the X
chromosome
9. ______________________________A form of dwarfism caused by an autosomal
dominant allele
10. ______________________________Recessive allele related disorder that causes
abnormal blood clotting
11. ______________________________A buildup of phenylalanine caused by an autosomal
recessive allele
12. ___________________________________ 12. Genetic disorder involving the autosomal
nondisjunction in chromosome 21.
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