Leboretory Manuai to Accompany Biology, 12th Edtios Figure 11.4 Two common patte
ID: 258840 • Letter: L
Question
Leboretory Manuai to Accompany Biology, 12th Edtios Figure 11.4 Two common patterns of autosomal inheritance in humans. a. Both parents are heterozygous. b. One parent is heterozygous and the for any trait that s dominant and the l you are working on. For example,C-normai, c- cystie fibross other s homozygeus recessive. The letter A stends is recessive. Subslitute the correct aliales for the problem r ? stands fo r afmy trait that Parents Aa Aa eggs DJ Recessva phenotype Aa Au Phanotypic Ratio Phanotypic Ratio 1. Neurofibromatosis (NF), sometimes called von Recklinghausen disease, is one of the most common genetic disorders. It affects roughly I in 3,000 people. It is seen equally in every racial and ethnic group throughout the world. At birth or later, the affected individual may have six or more large san spots on the skin. Such spots may increase in size and number and become darker. Small benign tumors (umps neurofibromas may occur under the skin or in the muscles. Neurofibromas are made up of nerve other cell types ) called Neurotibromatosis is a dominant disoerde r. If a heterozy sous woman reproduces with a bomozygous normal man, what are tbe chances a child will have I neurofibromatosis? g tissues. At first, tbe infant may have difficulty regaining 2. Cystic fibrosis is due to aboormal mucus-secretin the birth weight despite good appetite and vigor. A cough associated with a rapid respiratory rate but no fever indicates lung involvement. Larg secretions. Whereas children previously died in infancy due to infections, they now often survive because of antibiotic therapy e, frequent, and foul-smelling stools are due to abnormal pancreatic Cystic fibrosis is a recessive disorder. A carrier is an individual that appears to be normal but carries a recessive allele for a genetic disorder. A man and a woman are both carriersfor cystic fibrosis. What are the chances a child will have cystic fibrosis? the individual's nervous system that eventually leads to constant thrashing and writhing movements until insanity precedes death. Studies suggest that Huatington disease is due to a single faulty gene that has multiple effects, in which case there is now hope for a cure. 3. Huntington disease does not appear until the 30s or early 40s. There is a progressive deterioration of People with Huntington disease seem to be more fertile than others. It is amazing that more than 1,000 of the cases in the United States in the past century can be traced to one man born in 1831 Huntington disease is a dominant disorder. Drina is 25 years old and as yet has no signs of Huntington disease. Her mother does have Huntington disease but her father is free of the disorder. What are the chances that Drina will develop Huntington disease? Laboratory 11 Human Genetics 123 11-5Explanation / Answer
Figure 11.5: A
Mother
Aa
A
a
Father
Aa
A
AA
Dominant
Aa
Dominant
a
Aa
Dominant
aa
Recessive
Phenotype Ratio is 3 dominant: 1 recessive
B:
Mother
Aa
a
a
Father
Aa
A
Aa
Dominant
Aa
Dominant
a
aa
Recessive
aa
Recessive
Phenotype Ratio is 2 dominant: 2 recessive
Questions:
1. Neurofibromatosis is a autosomal genetic disorder wherein a single defective/mutant allele can cause the diseases (lumps/benign tumors on skin).
Consider the normal allele to be n and mutant allele to be N. Punnett Square for a cross between a heterozygous woman and a normal male is:
Mother
Nn
N
n
Father
nn
N
NN
Neurofibromatosis
Nn
Neurofibromatosis
n
nn
Normal
nn
Normal
Hence, chances of a child with neurofibromatosis is 2/4. Or 50%
Right option is 50%
2. Cystic fibrosis is a recessive disease. Hence both copies are required to cause the disease. Consider the normal allele to be C and mutant allele to be c.
A carrier will have genotype Cc as it has one copy of each allele. A man and woman both carriers for the disease will genotype Cc.
Mother
Cc
Cc
c
Father
Cc
C
CC
Normal
Cc
Carrier
c
Cc
Carrier
cc
Cystic fibrosis
The chances that the child has cystic fibrosis is 1/4 or 25%.
Right options are Cc; 25%.
3. Huntington disease is an autosomal dominant disease. Each person with Huntington’s disease will have one normal allele and one HD mutant allele. Hence, mother will be Hh (H= mutant HD; h= non-HD allele).
Mother
Hh
H
h
Father
hh
h
Hh
Huntington
hh
Normal
h
Hh Huntington
hh
Normal
Chances that Drina will have Huntingtons is 2/4 or 50%.
Right option is Hh (mother); 50%
Mother
Aa
A
a
Father
Aa
A
AA
Dominant
Aa
Dominant
a
Aa
Dominant
aa
Recessive
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