Analyzing Human Inheritance Pedigrees are graphic representations of an individuals family tree Used to predict the chances of an offspring receiving a trait Used to determine the inheritance pattern of a particular trait How Can We Study
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Presentation Transcript
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Analyzing Human Inheritance<br>
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Pedigrees are graphic representations of an individual’s family tree
Used to predict the chances of an offspring receiving a trait
Used to determine the inheritance pattern of a particular trait How Can We Study Human Inheritance?<br>
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Pedigrees<br>
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Normal Male Normal Female
Affected Male Affected Female
Mating Siblings
Known Carriers Pedigree Symbols<br>
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Cystic Fibrosis (CF)
Caused by a recessive allele
A missing membrane protein causes mucous build up in places like the lungs
Most common among Caucasions Inherited Genetic Disorders<br>
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Sickle-cell Anemia
Caused by a codominant allele
An altered hemoglobin protein changes the shape of the red blood cells
Most common among African-Americans Inherited Genetic Disorders<br>
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Tay-Sachs
Caused by a recessive allele
A missing enzyme causes lipid build up in the brain (death by age 4)
Most common among eastern European Jews Inherited Genetic Disorders<br>
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Huntington’s
Caused by a dominant allele
Late-onset of symptoms (age 40) result in the deterioration of the nervous system Inherited Genetic Disorders<br>
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Phenylketonuria (PKU)
Caused by a recessive allele
A missing enzyme prevents the break down of phenylalanine (the build up can cause brain damage)
If caught early, an altered diet can prevent damage Inherited Genetic Disorders<br>
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Analyzing Chromosomes<br>
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A karyotype is an ordered display of an individual’s chromosomes
Scientists take a picture of the chromosomes during metaphase Analyzing Chromosomes<br>
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Each chromosome is paired with its homologue
The display is used to detect chromosomal abnormalities Analyzing Chromosomes<br>
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During (meiosis) cell division, sometimes chromosomes fail to separate correctly
Nondisjunction
This produces gametes with incorrect numbers of chromosomes How Do Chromosomal Abnormalities Occur?<br>
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Meiotic Nondisjunction<br>
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Two types of zygotes can result from nondisjunction:
Trisomy
Zygote has 3 copies of a chromosome
Monosomy
Zygote only has 1 copy of a chromosome Results of Nondisjunction<br>
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Down Syndrome
Caused by a trisomy 21
Most common serious birth defect in the U.S. Chromosomal Abnormalities<br>
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Klinefelter Syndrome
Caused by an extra X chromosome in males (ex. XXY) Chromosomal Abnormalities<br>
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Jacobs or Extra Y
Caused by an extra Y chromosome in males (ex. XYY) Chromosomal Abnormalities<br>
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Metafemale or Triple X
Caused by an extra X chromosome in females (ex. XXX)
Turner Syndrome
Caused when females only get one X chromosome (XO)
This is the only viable human
monosomy Chromosomal Abnormalities<br>
