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43 Cards in this Set

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Mendelian Traits:
Autosomal Dominant Inheritance
Heterozygotes express the trait
Vertical pattern of transmission from one generation to the next
Transmitted by both sexes
Offspring are at 50% risk
Structural genes are often involved
New mutations are common ( point mut more common in sperm).
Incomplete penetrance
a trait that is not expressed in the phenotype of a gene carrier
Complete penetrance
genetic trait that is expressed in the phenotype
Variable expression
a genetic mutation associated with more than oe phenotype
Phenotypic variablity.
Give an example of variable expression (phenotypic).
The expression of Van der Woude syndrome varies within a family: some have cleft lip, some cleft palate, others lip pits
Interfamilial variation may be due to the effect of different mutations within the same gene.
Mendelian Traits: Autosomal Recessive Inheritance
Homozygotes express the trait
Horizontal pattern of transmission within a sibship.
Transmitted by both sexes
Offspring of carrier parents are at 25% risk
Functional genes are often involved
Ex. Sickle cell disease
Consanguinity is more common
Incomplete penetrance
a trait that is not expressed in the phenotype of a gene carrier
Complete penetrance
genetic trait that is expressed in the phenotype
Variable expression
a genetic mutation associated with more than oe phenotype
Phenotypic variablity.
Give an example of variable expression (phenotypic).
The expression of Van der Woude syndrome varies within a family: some have cleft lip, some cleft palate, others lip pits
Interfamilial variation may be due to the effect of different mutations within the same gene.
Mendelian Traits: Autosomal Recessive Inheritance
Homozygotes express the trait
Horizontal pattern of transmission within a sibship.
Transmitted by both sexes
Offspring of carrier parents are at 25% risk
Functional genes are often involved
Ex. Sickle cell disease
Consanguinity is more common
X-linked recessive inheritance: When is it lethal?
When transmitted by fmeales only- example Duchenne Muscular Dystrophy.
X-linked recessive inheritance: When is it not lethal?
WHen transmitted by both sexes- example color blindness
Anticipation
The phenotype becomes more severe or evident at a younger age of onset with each successive generation
Example: The triple repeat (The repeat number correlates to the severity of the disease, at meiosis can’t line up correctly).
Give an example of anticipation be specific
The premutation for Fragile X in a normal transmitting male expands during female meiosis in his unaffected daughter to a full mutation in her affected son.
Parent of Origin Effect
Parent of Origin effect - The phenotype varies depending on which parent transmits the abnormal allele
How does Methylation affect gene products (parent of origin effect)?
Methylation patterns differ in male and female meiosis: some genes are active only when inherited from one parent (imprinting)
Ex. Only the maternal copy of the Angelman syndrome gene is active; the paternal gene is inactive.
Polygenic traits
many genes each make a small contribution to the phenotype
Ex. Intelligence, height
Multifactorial traits
Few genes make a major contribution to the phenotype in a permissive environment
Ex. Spina Bifida, MTHFR and folate deficiency
Mosaicism
A mutation affects only some cells in the body with a variable phenotype
osteogenesis imperfecta Type II (lethal autosomal dominate trait)
Specific Example of Chromosomal translation
Down Syndrom due to familial translocation
Specific example of maternal inheritance
Mitochondrial genome is cytoplasmic so mitochondrial defects are passed down in the egg cytoplasm from the mother to all of her children
Carrier Frequency
Prevalence of an altered diease gene
Founder Effect
higher fequency of a specific gene mutation in a populaiton founded by a small ancestral group
What percent of sibilings will be a carrier of CF of an affected brother/sister?
66P of siblings will be a carrier of CF of an affected brother/sister.
What do you use genome scanning techniques for?
To search for chromosome aberrations (differences).
What is CGH? (genetic testing)
Comparative Genomic Hybridiation (CGH). Used to determine deletion or insertion.
Start Codon
AUG
Why are splice site important?
They tell the the intron will be cleaved out, if there is a mutation on an intron will get the wrong exons put to other aka wrong mRNA.
Define: Polymorphism
DNA changes that do NOT alter the protein function.
Define: Mutation
Change in normal base pair and ALTERS protein function.
Missense Mutation
Changes to a codon cause a another AA to be added.
Nonsense
Change AA codon to a STOP codon
Frameshift
insertion/deletion of base pairs cause a STOP codon downstream
What part of blood do you use for DNA testing?
WBC
Linkage Analysis
Looks for DNA markers near gene of interest. Need multiple family members DNA aalysis.
ASO Hybridization
Allele Specific Oligonucleotide Hybridization.
1) Amplify DNA
2) Add radiolabeled normal probes and known mutant DNA
3) Observe that the mutant matches up with one ( on paper dot mutatnt will match up with known)
PCR
Polymerase Chain Reaction (PCR). Use 2 primers amplify
Single Strand Conformational Polymorphism (SSCP)
Denature
Put in Gel
Look for difference in movement compaired to normal.
Checking shape!
Heteroduplex Analysis (CSGE)
Amplify
Denature
Single Strand
Cold
Re-nature (can see the extra nucleotides, due to genetic problem).
See that some bands are different on gel.
DNA Sequencing
Read Left to right and then top to bottom
Protein Truncation Assay
DNA --> RNA
RNA --> Protein
Protein put on gel.
See different mobility on getl for the truncated one!
What is the major cause of morbidity and mortality in infants?
Congenital anomalies