Use this PowerPoint to answer the questions on pages 4-7 in your guided notes packet on Mendel and Meiosis.

1. USE THIS POWERPOINT TO ANSWER QUESTIONS
ON PAGES 4-7 OF THE MENDELIAN GENETICS PACKET
GENE LOCI
P a B
P a b
GENOTYPE:
PHENOTYPE:

2. Autosomal Recessive Disorders
7. Connection: Many inherited disorders in humans are controlled by a single gene
Most such disorders are caused by
autosomal recessive alleles.
Examples include and cystic fibrosis and Tay-Sachs Disease
Watch a simple explanation of CF here

3. Autosomal Recessive Disorders
Tay Sachs
Cystic
Fibrosis

4. Practice Problem
 Practice Problem: A couple is planning on having
children and they would like to know what is the
chance that they will have a child that is deaf. The
ability to hear is dominant and deafness is
recessive. Both parents are heterozygous dominant.
Fill in the punnet square below and the genotypic
and phenotypic results.

5. Autosomal Dominant Disorders
Fraternal twins
http://images.buddytv.com/userquizimages/q-1/f143fd32-3547-40fb-9104-1197d29085b83.jpg

6. Autosomal Dominant Disorders
Neurofibromatosis
Huntington’s Disease

7. Practice Problem
 Practice Problem: A couple is planning on having
children and they would like to know what is the
chance that they will have a child that is deaf. The
ability to hear is dominant and deafness is
recessive. Both parents are heterozygous dominant.
Fill in the punnett square below and the genotypic
and phenotypic results.

8. #8: Connection
 8. Connection: Fetal testing can spot many inherited
disorders early in pregnancy
 Two types of tests are amniocentesis and chorionic villus
sampling

10. Chorionic villi sampling
Chorionic villus
sampling (CVS) is
the removal of a
small piece of tissue
(chorionic villi)
from the uterus
during early
pregnancy to
screen the baby for
genetic defects.

11. Interested in learning more about genetic disorders?
Check out the Utah Genetics Disorders Library here.

12. Variations on Mendel
9. The relationship of genotype to phenotype is rarely simple. Mendel’s principles
are valid for all sexually reproducing species. However, often the genotype does
not dictate the phenotype in the simple way his principles describe.

13. Practice Problem
 Incomplete dominance results in intermediate
phenotypes
 Practice Problem: A certain type of flower exhibits
incomplete dominance. Flowers that are
homozygous dominant are red, flowers that are
homozygous recessive are white and heterozygous
flowers are pink. Complete the punnet square
below for a cross between two heterozygous
flowers.

14. #10

15. 11. Codominance
 More than one dominant
trait is present and both
are expressed in their
original form.

16. #12 Pleiotropy
 The ability of a single
allele to have more than
one distinguishable
effect. For example the
allele responsible for
color pattern in Siamese
cats.

17. http://www.thecitychicken.com/mainpagemarch24-2011c.jpg
The Frizzle Effect:
an example of pleiotropy
In 1936, researchers Walter Landauer and
Elizabeth Upham observed that chickens that
expressed the dominant frizzle gene produced
feathers that curled outward rather than lying flat
against their bodies (Figure 2). However, this was
not the only phenotypic effect of this gene — along
with producing defective feathers, the frizzle gene
caused the fowl to have abnormal body
temperatures, higher metabolic and blood flow
rates, and greater digestive capacity.
Furthermore, chickens who had this allele also laid
fewer eggs than their wild-type
counterparts, further highlighting the pleiotropic
nature of the frizzle gene .
http://www.nature.com/scitable/resource
action=showFullImageForTopic&imgSrc=/scitable/content/37535/poncho_MID

18. Pleiotropy in Humans
Marfan Syndrome
 Marfan syndrome is a condition in
which your body's connective tissue is
abnormal. Connective tissue helps
support all parts of your body. It
also helps control how your body
grows and develops.
 Marfan syndrome most often affects
the connective tissue of the heart and
blood vessels, eyes, bones, lungs, and
covering of the spinal cord. Because
the condition affects many parts of http://www.marfan.net.au/images/human_body.jpg
the body, it can cause many
complications. Sometimes the
complications are life threatening.
 Interested? Read more here.

19. 13. A single characteristic may be influenced by many genes. This situation creates a
continuum of phenotypes, an example is height

20. Typical ‘Bell Curve’ for a polygenic trait
Some scientists suggest this accounts for behavioral traits
Not completely predetermined, but associated with genes

21. High blood pressure is a polygenic trait.
Food For Thought:
 What genes could
combine to contribute to
high blood pressure?

22. High blood pressure is a polygenic trait.
 The phenotype is an interaction between a person's
weight (one or more obesity genes), cholesterol
level (one or more genes controlling
metabolism), kidney function (salt transporter
genes), smoking (a tendency to addiction), and
probably lots of others too. Each of the contributing
genes can also have multiple alleles.

23. Environmental Effect on Phenotype
Food for Thought:
What do you think is happening in this picture? Why do you think some
phenotypes are effect by the environment? Can you think of other phenotypes
that are effected by the environment?

24. 14. Meiosis is a process by which…
Before watching the video or looking at your notes, see if you can answer the
questions on page 6 and 7 about meiosis.

25. STOP WHEN YOU GET TO:
THE CHROMOSOMAL BASIS
OF INHERITANCE ON PAGE 7