Transcript Genotypes to Phenotypes

Heredity Group
National Academies NorthStar Summer Institute
for Undergraduate Science Education
Summer 2012
 Note
that the photos and diagrams in this
presentation were acquired from various
sources and there may be copyright
issues with them.
 Participants
• Bernd Fritzsch, University of Iowa
• Erin Irish, University of Iowa
• Bao Vang, University of Minnesota
• Steven Ralph, University of North Dakota
• Kathy Sukalski, University of North Dakota
• Jim Tucker, Wayne State University
 Facilitators
• Brad Williamson, University of Kansas
• Brett Goodwin, University of North Dakota

This unit is part of an undergraduate
introductory biology course for majors
 Background
information students are
expected to know:
• DNA is the material of heredity; Central Dogma
• The following concepts: gene; allele; simple
dominant and recessive relationships
• How to use a Punnett square
Goal # 1: Be able to distinguish
between genotypes and phenotypes
Goal # 2: Explain and predict how
genotypes and the environment interact
to produce phenotypes




1-1 Be able to differentiate among recessive,
dominant, and semi-dominant traits (BT=2)
1-2 Be able to demonstrate and analyze how
alleles interact to produce phenotypes (Punnett
Square) (BT=3 & 4)
1-3 Be able to explain, interpret, and predict the
biochemical mechanisms by which cells express
their genotypes to produce phenotypes (BT=5)
1-4 Be able to evaluate and predict the impact of
epistatic gene interactions on phenotypes (BT=6)
 Red
cells are covered with surface
markers (antigens that happen to be
sugars). The sugars are added
sequentially to the cells by enzymes.
 Very important to know before doing a
blood transfusion.
H gene
product
O
A allele
A & B alleles
B allele
A
AB
B
Ruth, blood type A, has a child, Mark, with
O blood type. She suspects that Paul is
the father. Blood tests reveal that Paul is
AB. Can he be absolved of parental
responsibilities with that result?
A. Yes
B. No
C. Insufficient information
Objectives 1.1 and 1.2
Paul AB
A
B
A
Ruth
A
A
or
O
AA
AA
or
AO
AB
AB
or
BO
Horace might be Mark’s (AB) father.
His blood type is B. Can he be ruled
out? (Ruth, the mom, is A)
A. Yes
B. No
C. Insufficient information
Objectives 1.1 and 1.2
Which of the following must be true in
order to explain the ABO
phenomenon? (Hint: More than one
must be true!)
A is dominant to O
A is dominant to B
B is dominant to O
B is dominant to A
O is dominant to A
O is dominant to B
Which of the following must be true in
order to explain the ABO
phenomenon? (Hint: More than one
must be true!)
A is dominant to O
A is dominant to B
B is dominant to O
B is dominant to A
O is dominant to A
O is dominant to B
 Design
a Punnett square for William and
Lilith’s family
 On
your own – 1 minute
 With a partner -2 minutes
 Propose a mechanism to explain the case
Objectives 1.3 and 1.4
H gene
product
Epistasis
O
A allele
A & B alleles
B allele
A
AB
B
Goal # 1: Be able to distinguish between
genotypes and phenotypes
Goal # 2: Explain and predict how
genotypes and the environment
interact to produce phenotypes
 (2-1)
Be able to identify traits that are under
the control of multiple alleles (BT=2)
 (2-2)
Be able to illustrate and interpret how
environments and genotypes interact to
produce phenotypes (BT= 3)
 (2-3)
Be able to examine data and articulate
how a single genotype can influence
multiple phenotypes (BT=4)
 Melanin
is a pigment produced by an
enzyme called tyrosinase out of the tyrosine
L-Tyrosine
Tyrosinase
L-DOPA
Tyrosinase
Dopaquinone
Melanin
L-Tyrosine
Tyrosinase
Melanin
L-Tyrosine
Tyrosinase
Melanin
Skin Cancer
On the previous slide, which of the following
environmental factors is the most likely
cause for skin cancer?
A.) diet
B.) sunlight exposure
C.) temperature
D.) cigarette smoking
 Write
a one minute summary of the
relationship between skin cancer,
melanin density and UV exposure.
 Generate
a graph that illustrates this
relationship
 Tyrosinase produces melanin
• tyrosinase comes in multiple alleles

Tyrosinase is influenced by
• environmental factors such as UV
• Other genes (were not discussed)
 Genotype results in multiple phenotypes
• Cancer
• Vitamin deficiencies (were not discussed)
Summary of Genotypes to Phenotypes
Flower color Red
Blood types
A
Pink
B
AB
White
O
Skin color
Discrete distributions
of traits;
1 gene, 2 - 3 alleles
Continuous distribution;
multiple genes/alleles
• Genes produce specific products including enzymes
• Enzymes produce phenotypes
• Genes can interact via epistasis to modify
phenotypes
• Environment acts on genotype to influence