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74 Cards in this Set
- Front
- Back
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If two monozygotic twins demonstrate 100% concordance what type of genetic inheritance is this?
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completely genetic
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If two dizygotic twins demonstrate 50% concordance, what type of genetic inheritance is this
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completely genetic
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If concordance is greater among monozygotic twins than dizygotic twins, what does this say about whether or not this is a genetic trait?
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there is a component of genetics with the trait
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If the concordance for MZ=DZ what type of genetic inheritance is this?
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totally environmental
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If pyloric stenosis shows concordance for MZ=22% and DZ=2%, is there a significant genetic component?
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yes
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Which of the following has a genetic component? Cleft lip & palate, pyloric stenosis, schizophrenia, insulin dependent diabetes melitus
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all
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What do multiple miscarriages and retardation suggest?
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chromosomal abnormalitites
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What do earlier age of onset and increasing severity with generation suggest? (anticipation… males)
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trinucleotide repeat disease
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What is a compound heterozygote?
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2 different mutant alleles at the same loci, from mom and dad
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If affected individuals are seen in every generation, what does this suggest?
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Dominant inheritance
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What is the probability of the child of an affected heterozygous parent having an effected child?
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50%
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What term does the following define? The range of phenotypic expression seen among family members carrying the same mutation.
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Variable expressivity
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What term does the following define? Individuals carry the disease gene but don not show clinical symptoms (all or none)
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Reduced penetrance
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What type of inheritance is demonstrated with Marfans?
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autosomal dominant with reduced penetrance
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What type of inheritance does Huntington's disease demonstrate?
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Autosomal dominance with age dependent penetrance
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If no male to male transmission occurs, what type of inheritance is suggested and the disease is rarely expressed in females? Why is there no male to male inheritance?
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X-linked recessive… because males get their X from their mothers… and females get two Xs
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What is the chance that the daughter of an affected male of an X-recessive inheritance will be a carrier?
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100%
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What are the odds that carrier females of an X-linked recessive disease will transmit an allele to their… a) son… b) daughter
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both are 50%
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If there is an affected in each generation, both males and females are affected, but there are no male to male transmissions and all of the daughters of an affected male are affected, what type of inheritance is suspected?
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X-linked dominance
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In X-linked dominant, who are more likely to be affected, males or females, why?
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Females are 2X as likely to be affected, because they receive an X from mom and an X from dad
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In X-linked dominant disorders, what is the probability that an affected male will have an affected… a) son… b) daughter
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a) son - zero… b) daughter 100%
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In X-linked dominance inheritance, which gender is more likely to be mildly affected, why?
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females, because they have X-inactivation (mosaic), while males can't switch to another X because they have only one X
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What is anticiaption and which gender is likely to produce this phenomenon?
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a)progressively earlier onset and increasing severity with sucessive generations… b) males
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For Huntington's what are the respective penetrance following CAG repeats? <27 CAG… 27-35 CAG… 36-39 CAG… > 39 CAG
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<27 CAG: Normal… 27-35 CAG: premutation… 36-39 CAG: reduced penetrance… > 39 CAG: complete penetrance
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What is a polymorphism as compared to a mutant allele?
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Polymorphism is an allele that exhibits many forms (at least two different types in the population), while a mutant differs from both wild-type and polymorphic alleles (can be used to indicate diseased gene)
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What does hemizygous mean?
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males having an X and a Y
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What is incomplete dominance?
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when an intermediate for a trait exists between homozygous and heterozygous phenotypes
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What is codomince?
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When the phenotype for both alleles is expressed
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In sickle cell anemia for a heterozyous individual, what type of inheritance is seen with respect to each allele?
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the normal allele is incompletely dominant… the abnormal allele is incompletely recessive… it manifests as a recessive trait
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With resect to inheritance, what is it called when half of the normal protein causes disese?
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haploinsufficient
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What is it called when the abnormal allele interferes with the function of the normal allele?
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Dominant negative effect
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What is it called when the mutant allele is enhanced in one or more of its normal properties? Give two examples.
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simple gain of function… Huntington's and dwarfing condition achondroplasia (dwarfism)
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Contrast the following 1) Allelic heterogeneity, 2) locus heterogeneity and, 3) genetic heterogeneity
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1) Allelic Heterogeneity is a different mutation at the same loci, 2) locus heterogeneity are mutations at different loci, 3) Genetic Allelic encompasses both heterogeneity and locus heterogeneity
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Give two examples of locus heterogeneity.
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1) Retinitis pigmentosa (x-linked, autosomal recessive and autosomal dominant forms… and sometimes with retardation) 2) Ehlers-Danlos syndrome [connective tissue collagen being fragile or too elastic] ( x-linked, autosomal recessive and autosomal dominant forms)
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T/F Allelic heterogeneity is a form of genetic expression in which different mutant alleles at the same locus lead to the same disease phenotype.
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True
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Give an example of allelic heterogeneity.
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Some mutations in the RET gene can cause Hirschsprung disease (colonic motility/severe constipation) or multiple endocrine neoplasia (dominantly inherited cancer) or both
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Lecture 9
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Which cell type can proliferate (self-renewal) and differentiate into various lineages?
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Stem cell
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a)Which comes first, the progenitor or a determined cell?… b) what is the difference?
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Progenitor --> determined… b) the progenitor has information for identity, but is not stable… the determined cell is now restricted to a cell type but does not yet express the phenotype
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Does a determined cell express its phenotype?
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no
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As cell lineages develop, when will it usually express terminal markers (phenotype)?
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as it differentiate to express terminal markers it will usually coordinate with withdrawl from the cell cycle… which restrict its fate (limit its potential)
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What is believed finally happens in differentiation?
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a one way street (terminal process) that ends in cell death.
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What is special about germ cells?
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they completely differentiate, but they retain some potency
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What mechanism explains stem cell potency?
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repression of differentiation
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What is a fate map?
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Brings understanding to embryology by tracing cell lineages of daughter cells from a progenitor
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What experiment do researchers to to understand the state of commitment of cell (survive, divide, differentiate or die)?
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experimental Transformation, which reveals the processes of determination and induction
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What is induction?
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cell-to-cell communication (The first critical step in initiating differentiation) that directs cells to new developmental pathways
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What is differentiation?
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The process of commitment of cells to particular fates
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What is a master gene?
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the gene that regulates transcription factors expression and drive entire tissue and organ programs in development
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Are these master genes well conserved in animals?
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yes, thus we can look at worms, flies and frogs
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What are the two major mechanisms by which cell identity is established (determination)?
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1. Asymmetric Division: Inheritance of cytoplasmic determinant, thus sister cells are born different 2. Symmetric division: sister cells become different due to influences acting on them
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Cells are primarily differentiated by which process?
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induction
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Why are inductive mechanism important?
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they are important because they ensure that cells and tissues deveop in the proper spatial arrangement, e.g., axis, limbs, etc.
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what is a morphogen
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A protein present in embryonic tissues in a concentration gradient that induces a developmental process over a distance… (e.g., the transplantation of a posterior limb bud can induce the new surrounding cells to differentiate with a new game plan)
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What is sonic hedgehog?
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a diffusible peptide morphogen
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How is the morphogen concentration relevant to development?
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different cell populations will respond differently with differential gene expression based on this gradient
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Do morphogens usually work via passive diffusion?
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No, inhibitor of the morphogen help shape the pattern
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What are/were hegehog, notch, TGFß, and Wnts considered?
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They're now considered inducing reagents… they were once considered peptide growth factors,,, or affectors of the signaling pathways that are regulated by growth factors
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what are the 2 types of stem cells?
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embryonic and adult
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Early in development, which cells layer retains potency and forms the embryo proper and adult tissues, the outer layer (trophecdtoderm) or inner layer (Inner cell mass… ICM) ?
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ICM
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Which cells are totipotent?
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ICM
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What are totipotent (ICM) cells?
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Totipotent cells differentiate into embryonic stem cells, which can be used to generate different lineages
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Where do embryonic stem cells come from?
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ICM
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How can knock-out or knock-in mouse be made using Embryonic stem cells
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inject ES into the ICM of host blastocyte
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What is a chimeric mouse?
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a mouse that has both the characteristics of its own DNA and the DNA from the contributed embryonic stem cell
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Characterize adult stem cells (progentor cell, e.g., myloid).
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They are stem cells associated with a particular tissue, like hematopoietic or neural cells
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Are adult stem cells identified morphologically?
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No, they are identified with cell marker using FACS, where a flourescent marker is added to surface receptor
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What is FACS?
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flourescence activated cell sorter
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What device would you purify a cell population to have only adult stem cells ?
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look for cell markers using FACS
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How are animal clones made… and why does this confound our understanding of differentiated cell lines?
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clones are made with adult differentiated cell nuclei… its confounding only in the sense that in vivo cell don't de-differentiate, but this is offset by the fact that these cells still have their entire genome
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What is somatic cell nuclear transfer (SCNT) aka, therapeutic cloning?
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an approached used to generate embryonic stem cells to be used to regenerate tissue
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How is SCNT accomplished
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by taking an embryo and emptying its DNA and replacing it with an adult nucleus --> leading to a nuclear transfer blastocyte… could be used for neuro-degenerative, hamatopoietic and heart disease
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T/F: it will not be possible to grow stem cells from adult tissues.
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False, it may be possible one day
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What is combinatorial control
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the use of a discrete number of transcription factor to control a greater number of gene expression
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