Highlighted content wk 1 Flashcards
1) Define aneuploid.
2) When is this term usually used?
1) Wrong number of copies
2) In relation to one chromosome in an individual
1) Define autosomes
2) Define sex chromosomes
1) Non-sex chromosomes
2) X and Y
mRNA is transported from the nucleus to the cytoplasm where the encoded information is translated into the amino acid sequence of a protein. Does this occur before or after processing?
After
What requires the interaction of mRNA, ribosomes (rRNA), tRNA molecules, amino acids, enzymes, and energy sources?
Translation
Methylation is an example of what?
Genetic imprinting (the parental “tagging” of alleles that prevent transcription)
Are mitochondrial genes are inherited exclusively maternally, paternally, or from both?
Exclusively maternally
What type of genetic disorder’s defect is due to an excess or a deficiency of the genes contained in whole chromosomes or chromosome segments?
Chromosome disorders
What causes single-gene disorders?
Mutations in individual genes
“disease is the result of multiple different genes acting together, often in concert with environmental factors” describes what kind of genetic disorder?
Multifactorial inheritance
The primary oocyte undergoes ______________________ and then waits until puberty
prophase I
What occurs during prophase I?
Homologues are condensed and separated
Mutations in individual genes can result in what kind of disorder?
Single-gene disorders
Define polymorphism
Two or more versions of an allele, with each comprising at least 1% of the population
What does locus relate to?
location
Alternative versions of a locus on the DNA code are called what?
Alleles
1) Define genotype
2) Define phenotype
1) The genetic material in a person – in a specific locus the two alleles occupying that locus on two homologues
2) The expressed physical traits of the genotype
The alterations that wind up on the _________ strand are the mutations we are talking about
protein
True or false: SNPs only involve a single location
True
Frameshift mutations: When the insertion / deletion number of nucleotides is not a multiple of three, what happens?
Everything downstream is messed up
Dynamic mutation:
Often the wild type allele is polymorphic with varying number of tandem repeats, however, the _____________ expands as it is passed down in some families, causing abnormalities of gene expression
number
How do you track the rate of disease-causing gene mutations: what 3 things make the frequency traceable?
1) You have to look at incidence of new cases not present in mom or dad
2) Disease has to be caused by single mutation
3) Has to be evident in baby
Achondroplasia:
1) FGFR3 binds to _______________________ factors
2) What is the cause of achondroplasia?
1) fibroblast growth factors
2) Proliferation of chondrocytes at growth plate is inappropriately inhibited due to constitutive activation of FGFR3
Delayed motor involvement, dental crowding, OSA, otitis media, hydrocephalus, and foramen magnum stenosis are all potential complications of what genetic condition?
Achondroplasia
1) Define homozygous
2) Define heterozygous
3) Define compound heterozygous
4) Define hemizygous and give an example
1) Having a pair of identical alleles
2) Having two different alleles – one mutant and one wild type
3) Having two mutant alleles
4) Only one allele (MC a male with the mutant allele on single X chromosome)
List the 3 typical patterns single gene disorders tend to follow
Autosomal recessive
Autosomal dominant
X-linked
Define Penetrance
probability that mutant allele or alleles will have any phenotypic expression at all
When frequency of expression is less than 100% - in other words, when at least someone with the genotype completely fails to demonstrate disease – it is said to show what kind of penetrance?
“reduced” or “incomplete”
True or false: the baby’s sex doesn’t matter for autosomal genes mendelian inheritance
True
A disease demonstrates “incomplete dominance” when ________________ dominant individuals suffer more severely from autosomal dominant disease than their _______________ counterparts
homozygous; heterozygous
True or false: most diseases are incomplete dominant
True
65 highlight edit this card to simplify
1) Hemochromatosis is a disease of iron overload resulting in mutation of the ____________ gene.
2) What is its penetrance and expressivity?
3) What inheritance pattern does it have?
1) HFE
2) Incomplete penetrance; variable expressivity
3) Autosomal recessive
1) What absorbs iron in the body?
2) What two things determine iron stores in the body?
1) Enterocytes in small intestine
2) Dietary absorption and release of iron from macrophages that phagocytize RBC’s
1) Does hepcidin block or enable further iron absorption?
2) How is hepcidin affected by a mutant HFE gene?
1) Block
2) Hepcidin signaling is inhibited, allowing the release of iron
What are the two types of hereditary hemochromatosis?
Homozygous and compound heterozygous
True or false: with hereditary hemochromatosis, homozygosity does not always lead to dz
True (b/c penetrance varies)
____________________, as an example, is incompletely dominant, because it is usually fatal when homozygous
Achondroplasia
Male-limited precocious puberty:
1) What type of genetic disorder is this an example of?
2) What is mutated?
3) What does this mutation do?
4) What are the physical Sx?
5) Do heterozygous women get this?
1) Sex-linked autosomal dominant
2) LCGR gene which encodes receptor for luteinizing hormone
3) Mutations constitutively activate receptors signaling luteinizing hormone even in the absence of hormone
4) Affected boys develop secondary sex characteristics with growth spurt at 4 years of age; epiphyseal fusion occurs early and adults have short stature
5) No
Give an example of a factor deficient in hemophilia A
Factor VIII (8)
Who can hemophilia A be inherited from?
Either mom or dad
With X-linked dominant conditions, affected females are roughly twice as common as affected males, but they typically have milder expression of the phenotype
Why?
Incomplete dominance
Why are Mitochondrial DNA disease so rare?
Because energy production is so fundamental and ubiquitous to all cellular function
Achondroplasia:
1) What do is the risk of inheritance in subsequent children of unaffected parents?
2) How about offspring of affected individual?
1) Same odds you started with (small) since you’re not a carrier
2) 50%
Pedigrees:
1) What do empty squares and circles mean?
2) What do fully filled in squares and circles mean?
3) What do squares and circles with dots in the middle mean?
1) Unaffected male (square) and female (circle)
2) Affected male and female
3) They carry the disease but don’t show it (“obligate carrier”)
Autosomal recessive disorder are typically seen in siblings and potential offspring of the proband – not in parents, offspring, or other relatives. Why?
Autosomal recessive patterns manifest by skipping generations as the affected are usually children of unaffected carriers. (answer is from google)
Autosomal Dominant Inheritance:
1) In what generations does the phenotype usually appear?
2) True or false: Each affected person has an affected parent. Explain your answer and list any exceptions.
3) Any child of affected heterozygous parent has ____% chance of having disease
4) Who are equally likely to give it to children of either sex: males, females, or both?
1) In every generation
2) True; exceptions are due to incomplete penetrance, variable expressivity, and new mutations
3) 50%
4) Males and females equally likely to give it to children of either sex
Sex-limited Autosomal Dominant Disease: Male-limited precocious puberty
1) What gene is mutated?
2) What does this mutation do?
3) What are the physical Sx?
1) LCGR gene which encodes receptor for luteinizing hormone
2) Constitutively activate receptors signaling luteinizing hormone even in its absence
3) Affected boys develop secondary sex characteristics with growth spurt at 4 years of age; epiphyseal fusion occurs early and adults have short stature
True or false: Women heterozygous for male-limited precocious puberty do not get it
True
