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Questions:
1. Mental retardation
2. Dihydropteridine reductase
3. Autosomal recessive
4. Incidence: 1 in 10,000
Allele Frequency: 1 in 100
Normal allele
Group # 1:
Intron
Exon
PKU allele # 1
DNA
Deletion of Exon
results in loss of
52 amino acids
mRNA
protein
protein would be
smaller than normal
and take on a different
shape because the
charges of the amino
acid and alter the way
they bind together
The amino acids that signal the enzyme to cut the DNA could be lost in the deletion resulting in the DNA not
being cut as it normally would. This deletion could also cause a frame shift that could change the amino
acids that occur after the mutation. This could lead to the base sequence that the enzyme cuts to appear more
or less frequently than normal, causing the DNA to be cut differently. This would affect the size, shape, and
function of the protein created, causing a deficiency of phenylalanine hydroxylase resulting in PKU.
Phenylketonuria
Normal allele
PKU allele # 4
gaa
aaa
DNA
gaa
aaa
Intron
Exon
mRNA
Glu280
Lys280
protein
•The codon for Glutamate (gaa) was mutated to a codon for Lysine (aaa).
•This would cause the loss of a negatively charged amino acid which is then replaced
with a positively charged amino acid.
Questions
1.
Group # 22
Light pigmentation, epilepsy,
“moosy” odor
PAH
Autosomal recessive
1 per 10,000; 1/100
2.
3.
4.
Normal allele
CGA
DNA
PKU allele # _11__
TGA
PAH
mRNA
protein
Intron
Exon
CGA
UGA
ARG
STOP
CODON
1.
Mental Retardation, mousy odor,
light pigmentation, peculiarities of
gait, stance, and sitting posture,
eczema, and epilepsy.
Phenylalanine hydroxylase enzyme.
Autosomal recessive
Incidence is 1 per 10,000
allele frequency = 0.01 or 1/100
2.
3.
4.
Group # 25
Normal allele
DNA
PKU allele # 23
TCC
mRNA
protein
Intron
Exon
TTC
UCC
SER
273
UUC
PHE
273
Serine is an uncharged polar amino acid, which is replaced with phenylalanine an uncharged
nonpolar amino acid. Changing from polar to nonpolar would be crucial to the enzyme
phenylalanine hydroxylase, which normally converts phenylalanine to the amino acid, tyrosine.
Questions
1. Symptoms of PKU
Group #28
a. Untreated: mental retardation, “mousy” odor, light pigmentation, peculiarities of gait,
stance, and sitting posture, eczema, and epilepsy
b. Treated: mildly depressed IQ
2. PKU results from a mutation in the structural gene for phenylalanine hydroxylase.
3. The mode of inheritance is autosomol recessive.
4. The incidence of PKU in Europeans at birth is 1 per 10,000.
a. The predicted allele frequency of the PKU allele is 1/100
b. The predicted carrier frequency is 198 per 10,000 or .0198.
Normal allele
DNA
PKU allele # 46
DNA
In-frame deletion
occurs to exon 11
mRNA
mRNA
protein
protein
Exon 11
Intron
Exon
Protein has section missing due to
deletion of exon 11, there for it is
lacking 5 amino acids
Questions
1.
Mental retardation, light pigmentation,
eczema, and epilepsy
Phenylalanine hydroxylase
Autosomal recessive
2.
3.
4.
Group #
Names
32
PKU in Europeans is 1 in 10,000.
Predicted allele frequency is 1 in 100.
Normal allele
PKU allele # __61_
DNA
mRNA
protein
The deletions of the bases in codon 376 and 377 caused a
Intron
Exon
stop codon to be created at 399, making a premature
termination in the protein.