complete dominance huntington's disease - a dominant disorder · huntington's disease - a...
TRANSCRIPT
Chapter 10/11
Genetics 1
Inheritance Patterns
Complete dominance
The dominant alleleis expressed over the recessive allele
Huntington's disease - a dominant disorder
Causes the deterioration of the nervous system
Incomplete dominance One allele is not
completely dominant over the recessive allele
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Genetics 2
Inheritance Patterns
CodominanceBoth alleles for a gene are expressed
Sickle cell anemia- A codominant disorder
Defective hemoglobincauses the cells to have a sickle shape.
Heterozygous genotypessuffer some effects of thedisease and are resistant toMalaria
Homozygous genotypessuffer the full effects of the disease
Polygenic inheritance - theeffect of two or more genes on a single phenotype
Example: Skin color is controlled by three separate genes.
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Genetics 3
Blood Types There are multiple allelesfor blood types
Antigens - carbohydrates on the cell surface that determine the blood type
Antibodies - Proteins which attack foreign cells
Agglutination - antibodies cause the blood to clump up when the wrong blood types are mixed together
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Genetics 4
Blood Types Universal donor
Universal recipient
Punnett square
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Genetics 5
Linked Genes Walter Sutton (1902)
Chromosome theory of inheritance
Thomas Morgan
Discovered linked genes
Used fruit flies for his research
Genes located on thesame chromosome and can be inherited together
Linked genes do notassort independently during meiosis
Crossing over canunlink genes
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Genetics 6
Linked Genes
Sex linked genes
Genes located on the sex chromosome
XY = maleXX = female
The sperm cell determines the sex of a child since the egg cell always carries an X chromosome
There are no alleles on the Y chromosome
Hemophilia (blood clotting disorder) andColor blindness are recessivesex linked disorders
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Genetics 7
Mutagens - chemicals or radiationthat alter an organism's DNA
Mutation - a change in the organism's DNA
Mutations
A change to a single base pair
Base pair substitution
Base pair insertion and base pair deletion
replacement of one nucleotide pair with another
Addition or loss of a nucleotide pait
Chromosome mutation
Change in the numberof chromosomes
nondisjunction-a pair or sister chromatids or tetrads do not separate properly
Leads to gametes withtoo many or too few chromosomes
Aneuploidy - a fertilized eggwith too many or too few chromosomes
Trisomy - an extra chromosomeMonosomy - A chromosome is missingPolyploidy - an entire extra set of chromosomes
Can lead to a protein which does not function properly
Change in the structure of a chromosome
Point mutation
Karyotype - used in order to determine the chromosomes arenormal in number and appearance