Download Principle of Dominance

Bio book Chapter 11, pgs. 262-269
Vocabulary You Should Know:
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Dominant
Recessive
Homozygous
Heterozygous
Genotype
Phenotype
Mono/Dihybrid Cross (punnett squares)
Laws of Genetics
Bio book Chapter 11, pgs. 265-271
• Principle of Segregation – Genes (1 from each
parent) are separated from each other when
gametes form (meiosis).
• Principle of Independent Assortment - Alleles
for different genes separate independently of
one another when gametes form (meiosis).
• Principle of Dominance – Some alleles are
dominant & others are recessive.
These laws account for the variations in
inherited characteristics.
Mendelian Genetics Review
• Gregor Mendel studied biological inheritance
pea plants.
with ____
Genes determine traits.
• ______
• Different forms of a gene: ______
alleles
• The Principle of Dominance states that some
alleles are dominant
_________& others are ________.
recessive
• The Principle of Segregation states that during
gamete formation, ______
alleles segregate from each
other so that each gamete carries only a ______
single
copy of each gene
____.
...There are Exceptions to Every Rule!
• Genetics is not as simple as just dominant or
recessive
• Some alleles are neither dominant nor recessive
• Majority of genes have more than 2 alleles
• Many traits are controlled by more than 1 gene
Incomplete Dominance
• 2 traits combine to make a 3rd trait.
Where 1 allele is not completely dominant over another
• Ex: some flowers. Red + White = Pink
Bio book pg. 196
Codominance
Bio book pg. 197
• Both traits appear at the same time. Both alleles
of a gene are equally expressed in the phenotype
• Ex: Speckled black & white chickens, roan
colored horses, AB blood type
Multiple Alleles
• 3 or more alleles of the same gene
• Most human genes have 2+ alleles
• Ex: blood type, eye color, hair color
Bio book pg. 273
Polygenic Traits
• Trait controlled by 2 or more genes
• Ex: Skin color
Bio book pg. 198
Epistasis
• Affects polygenic inheritance
• At the phenotypic level, examples include the
gene causing albinism hiding the gene
controlling the color of a person's hair. In
another example, a gene coding for a widow's
peak would be hidden by a gene causing
baldness.
Epistasis
• Several gene products affect the coat color of
a Labrador retriever.
Blood Type
• Multiple Alleles: A, B, O
• Codominance: AB
Bio book pg. 197
Sex-linked Genes
• Color blindness
•
http://colorvisiontesting.com/online%20test.htm#demonstrationcard
• Hemophilia
Bio book pg. 206-208
Genetics & the Environment
Bio book pg. 199
• Characteristics of any organism are
determined not only by their inherited genes.
• Characteristics are determined by the
interaction between the genes & the
environment
• Genes provide a plan for development, but
how that plan unfolds also depends on the
environment
Drug Use
Medicines
Bio book pg. 206
Pedigree Chart
Bio book pg. 209
Marks locations of genes on chromosomes with fluorescent tags
Chromosome Painting
Allows: visualization of individual chromosomes; comparison of
various species’ genomes, location of abnormalities
Chromosome Painting
Gel Electrophoresis
Electrical current is used to separate a mixture of DNA fragments
from each other
DNA Fingerprint
Representation of parts of an individual’s DNA that can be used to
identify a person at a molecular level.
DNA Fingerprint
Genetic Engineering
• Individual organs and entire organisms can be
cloned
• New genes can be added to an organism’s
DNA
• Produces organisms with new traits
YouTube Videos
• https://www.youtube.com/playlist?list=PLhUN
qW4x0Dfp12EgBYMSouUcZiIUOx1nV