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316 Cards in this Set
- Front
- Back
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Which concept did Garrod come up with?
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Inborn Error Concept
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What causes alkaptonuria?
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failure of oxidation of homogentisic acid
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What are the 4 points of the one gene-one enzyme concept?
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1- all biochem processes under genetic control, 2- biochem processes are resolvable into series of indv stepwise rxns, 3- each biochem rxn is under control of a diff single gene, 4- mutation of single gene alters ability of cell to carry out a single primary chem rxn
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T/F. The Inborn errors of metabolism explains the one gene-one enzyme concept.
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F. inborn errors came first
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T/F. A single gene defect can affect multiple processes.
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T
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T/F. PKU results from an enzyme defect and can be corrected if caught early.
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T
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Who coined the term "chemical individuality?"
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Garrod
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What is diasthesis?
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predisposition to disease
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Which fairly recent realization explains the idea of chemical individuality? Provide an example.
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the gene for a given prot frequently exists in diff forms in diff indvs ex. diff forms of Apo gene
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Which ApoE genotypes are associated with higher LDL-C? With lower LDL-C?
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E4/4 & E4/3; E3/2 & E2/2
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High LDL is associated with which condition?
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atherosclerosis
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Which ApoE isoform is a risk factor for late-onset sporadic Alzheimers disease?
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E4 variant
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T/F. At all genetic loci, there is one standard allele that accounts for the vast majority of the alleles in the popn and the alternate alleles are rare.
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F. at some loci there is no single allele that is sufficiently common to be designated as standard or normal
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What is a polymorphic locus?
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nucleotide site where the most common allele has a frequency <0.99
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T/F. When a polymorphism exists at a genetic locus, at least 1 percent of the population must be heterozygous at that locus.
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F. 2%
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T/F. ~0.5-1% of bps in human genome is poymorphic.
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T
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T/F. Most DNA polymorphisms do not have phenotypic effects.
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T
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What is a mutation?
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a stable, heritable change in DNA
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Give an example of a type of unstable mutation.
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expanding triplet repeat mutations
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What is the most common cause of genetic disease?
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point mutations
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How might a base substitution in the coding region alter RNA splicing?
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creating a cryptic splice site or interfering with function of normal splice site
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Which type of mutation results in sickle-cell anemia?
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point mutation (missense)
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What is nonsense-mediated decay?
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proteins are left behind on mature mRNA at splice junctions, ribosome moves along and displaces proteins, if it hits a stop codon before removing all proteins, mRNA targeted for degradation
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What happens if there is a point mutation at the beginning of a juction marking the position of an intron?
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splicing disrupted, intron retained
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What happens if there is a point mutation in the middle of an intron?
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cryptic splice site activated, intron retained
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T/F. Common diseases later in life are often multifactorial.
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T
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T/F. Few genes result in monogenic disease when mutated.
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F. Significant fraction of total number of human genes
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T/F. Which class of genetic disorders is seen in higher frequency when there is parental consanguinity?
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autosomal recessive
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T/F. Cystic fibrosis is autosomal recessive.
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T
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Why might autosomal recessive disorders remain in the population?
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heterozygote advantage/ balanced polymorphism
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T/F. Sickle cell anaemia is autosomal dominant.
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F. autosomal recessive
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T/F. Sickle cell anaemia results from a frame-shift mutation in the gene encoding beta-globin.
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F. single-base mutation
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Why was it so difficult to discover the gene involved in CF?
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massive gene, of of the biggest proteins in the human genome (CFTR)
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Name 3 organs affected by sickle cell anaemia.
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heart, brain, liver
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T/F. Sickle cells have little or no multiplication of parasites.
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T
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Which disease has a high incidence among Ashkenazi Jews?
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Tay-Sachs
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Which type of mutation typically leads to Tay-Sachs?
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4 bp insertion
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Which enzyme is affected in Tay-Sachs disease? Which subunit(s)?
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hexosaminidase A; alpha
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What accumulates in patients with Tay-sachs and where?
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GM2; CNS
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T/F. The use of a mouse model was a powerful tool in figuring out the mechanisms of Tay-Sachs disease.
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F. mouse model is asymptomatic
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T/F. TSD is a lysosomal storage disorder.
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T
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A red cherry spot in the retina is a hallmark of which disease?
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TSD
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T/F. Patients with TSD are born with severe psychomotor deficits.
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F. born normal, progressively deteriorate
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Compare Sandhoff to TSD.
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both caused by defective hexosaminidase; beta and alpha subunits respectively; beta mutation produces defective hex A and B whereas when alpha subunit is mutated, hex B is still functional
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T/F. The mouse model of TSD catabolizes GM2 via GM3.
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F. GA2
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T/F. There is a mouse model for Sandhoff.
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T
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What is the human GM pathway?
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GM1 --> GM2 --> GM3 --> LacCer --> GluCer
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Which step results in sialidosis when disrupted?
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GM3 --> LacCer
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Which step results in GM1 gangliosidosis when disrupted?
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GM1 --> GM2
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Which step results in TSD when disrupted?
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GM2 --> GM3
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How was alpha1-antitrypsin deficiency treated?
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adenovirus to produce anti-trypsin enzyme
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How can haemochromatosis be treated?
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blood letting
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Name 4 autosomal dominant disorders.
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myotonic dystrophy, Huntingtons, spinocerebellar ataxia, Kennedy disease
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Which AD disease(s) result from large expansions of repeats outside the coding sequence?
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myotonic dystrophy 1 and 2
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T/F. HD results from expansions of repeats within coding sequences.
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T
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Why would UTR repeats and intron repeats cause disease?
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intron splicing attract translation components (splicing factors) and sequester them away from regions that require them
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T/F. MD may show anticipation.
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T
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Which disease is associated with a mask-like face?
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MD
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What does CAG code for?
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glutamine
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What age does HD affect people at?
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50+
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What are symptoms of HD?
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dementia, depression, chorea
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Which type of test can be used to identify expanded repeats (old way & new way)?
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Southern Blot; PCR with SNPs
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T/F. HD can be generated in mice, drosophila and nematodes.
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T
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Which chromosome & region is affected in people with HD?
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4p
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Cholesterol from the diet is sent to the __________, made into __________________, converted into _______________________ in the blood then travels around the body. Excess is carried to the ______________________ by ______________________.
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liver; VLDL; LDL; liver; HDL
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What happens when LDL is modified?
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inflammation, engulfed by macrophages which go to weak/damaged blood vessel sites under endothelium where they get trapped, secrete cytokines and recruit other cells narrowing the opening, atherosclerosis
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What is an example of an incomplete dominant disorder?
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familial hypercholesterolemia
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What is Xanthoma?
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fat deposits between fingers
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What is arcus lipoides?
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halo of fat deposits in pupil
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T/F. Increased expression of the LDL receptor results in an increase in cholesterol levels.
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F. LDL receptor helps get rid of cholesterol
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The LDL receptor is made in the _______, transported to the _______, then binds LDL and is contained in a(n) ______________, where the pH ____________________ allowing the receptor to dissociate and be recycled.
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ER; Golgi; endosome; decreases
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T/F. Restriction enzymes can be used to diagnose hypercholesterolemia.
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T
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What is a foam cell?
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macro that has engulfed acetylated cholesterol and is trapped, starts to die, cholesterol crystalizes, hard plaque
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When is atherosclerosis fatal?
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when there is a thrombotic event
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Where and how do LDL modifications happen?
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subepithelial layer, oxidants
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What type of disorder is Duchenne muscular dystrophy?
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X-linked recessive
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What type of disorder is Fragile-X?
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X-linked dominant
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In which type of disorder are females often more mildly and variably affected than males?
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X-linked dominant
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T/F. Fragile X syndrome results from a chromosomal defect.
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F. trinucleotide repeat expansion
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What are the 3 types of genetic heterogeneity?
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locus, allelic and clinical
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What is locus heterogeneity?
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heterogeneityàsame clinical phenotypes can
result from mutations at any one of several different loci |
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What is allelic heterogeneity?
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different mutations within a given gene can be seen in patients with a certain genetic
condition. |
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What is clinical heterogeneity?
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where mutations in the same
gene result in clinically diverse conditions |
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What is penetrance?
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frequency with which the disorder or
phenotype is manifested in an individual who has inherited the disease allele. |
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What is expressivity?
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differences in the severity of a disorder in
individuals who have inherited the same disease alleles |
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What is mosaicism?
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It arises when not all cells in the body are genetically
identical through a mutation in early development result in either the germline or somatic cells being affected |
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What is a phenocopy?
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Environmental factor may result in a disorder with the same symptoms as an inherited disorder
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What is anticipation? Give 2 examples.
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The tendency of some variable dominant conditions to become more severe (or have earlier onset) in successive generations; MD and Fragile-X
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What is genomic imprinting?
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when the expression of an allele depends on the parent from which it was inherited
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Which disorder arises if the deletion is inherited from the father? From the mother?
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Prader-Willi; Angelman
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What are the 4 types of chromosomal disorders?
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aneuploidy, deletion, translocation, isochromosome formation
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What is a non-disjunction event? What may happen to the gametes?
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whole chromosome fails to segregate; trisomy or monosomy
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T/F. Paracentric inversion involves 2 breaks on same arm.
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T
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Which type of break may result in a ring chromosome?
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2 breaks in diff arms
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Which type of chromosomal disorder is turner's syndrome?
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monosomy X
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What can be achieved with a karyotype?
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count number of chromosomes, look for structural changes
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T/F. Karyotypes can detect CML
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T
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What is unique about people with Klinefelter's syndrome?
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XXY, infertile
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T/F. Turner syndrome affects only females
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T
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What is the traditional method for karyotyping? New method?
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G-banding; FISH/chromosome painting
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What causes PKU?
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phenylalanine hydroxylase deficiency
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Which disease can be corrected if caught early via screening infant urine?
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PKU
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T/F. There are 4 alleles for ApoE.
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F. 3
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T/F. Mutations are stable changes.
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T/F... mostly but expanding triplet repeat mutations can be unstable
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T/F. A triploidy mutation involves the entire genome.
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T
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T/F. Sickle-cell anaemia results from a frameshift mutation.
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F. point mutation
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T/F. Genes with premature stop codons produce predictable truncated proteins.
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F. due to NMD
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What is nonsense-mediated decay (NMD)?
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detects mRNAs with premature stop codons and degrades them
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T/F. Nonsense mutations typically result in truncated proteins.
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F. prevent any expression of the gene
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T/F. A point mutation in an exon can affect expression level.
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T
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What is the frequency of genetic diseases of live births?
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~5%
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Name 4 important databases of Human Genetic diseases.
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OMIM, genetic association database, genecards, genetests
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What are the pedigree symbols for the following: male, female, sex unknown?
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square, circle, diamond
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What is the pedigree symbol for twin sisters? For a miscarriage?
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2 circles connected by /\ ; little circle, filled in and crossed out
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T/F. TSD is autosomal dominant.
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F. autosomal recessive
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T/F. CF is an x-linked recessive disorder.
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F. autosomal recessive
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T/F. Thalassaemia heterozygotes are more resistant to malaria
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T
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Namee 3 haemoglobinopathies.
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sickle cell anaemia, alpha and beta thalassaemias, glucose-6-phospgate dehydrogenase deficiency
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_________ demonstrated that sickle cell anemia results from a point mutation affecting the gene encoding ____________
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Ingram; beta-globin
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T/F. Hemoglobin S is more soluble than Hemoglobin A.
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F. it is less soluble and crystallizes
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T/F. Sickle cell anemia patients usually live a full life thanks to blood transfusions.
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F. still usually fatal mid-life
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T/F. TSD is neurological disease.
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T
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T/F. TSD involves a mutation in an intron.
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F. exon
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T/F. GM2 is located on the cell surface.
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F. GM1
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T/F. PKU patients experience damage to the nervous system.
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T
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What is the function of antitrypsin?
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inhibits elastase
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What is the function of elastase?
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breaks down connective tissue
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What is the main problem with having expansions in a UTR?
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attracts splicing factors making them unavailable to sites that need them
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T/F. In Huntington's disease, splicing factors get sequestered in the nucleus.
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F. sequestering happens in MD.
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Name a disease which result in the production of a toxic protein.
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Huntington's
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Why do many expansions show anticipation?
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instability
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How many CTG repeats result in a MD premutaiton?
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35-50
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How many CTG repeats result in HD?
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~50+
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T/F. Diseases caused by expanding nucleotide repeats are often autosomal dominant.
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T
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T/F. Nucleotide repeat expansion do not occur on the sex chromosomes.
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F. Kennedy Disease is X-linked
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HD has similar symptoms as which disease?
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Parkinson's
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T/F. Neurons regenerate every few years.
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F. they do not regenerate
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T/F. Animal models can be used to study nuc repeat expansion diseases.
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T
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T/F. The immune system is involved in Familial Hypercholesterolemia
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T
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T/F. High plasma cholesterol is a sign of which disease?
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Familial Hypercholesterolemia
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What does the dystrophin protein do?
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helps keeps muscle intact
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What is the inheritence pattern for Duchenne muscular dystrophy?
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X-linked recessive
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T/F. Carriers of DMD usually exhibit no symptoms.
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T
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Which inheritence pattern affects more females than males?
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X-linked dominant
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What is the inheritance pattern for fragile X syndrome?
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X-linked dominant
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T/F. Fragile-X syndrome may result from a trinuc repeat expansion.
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T
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T/F. Fragile X syndrome is partially dominant.
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T. affects 1/3 female carriers mildly
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Which disease shows characteristic brain activation while patients do mental arithmetic?
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Fragile-X syndrome
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T/F. Fragile X may cause premutations
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T
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T/F. Fragile X shows incomplete penetrance.
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T
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What is the difference between a mosaic and a chimera?
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mosaic: 1 fertilized egg, genetic change following division; chimera: 2 fertilized eggs, divide, fusion or exchange of cells
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T/F. Some genetic defects result in phenocopies.
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F. phenocopies are caused by env and have symptoms as an inherited disorder
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What is an isochromosome?
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symmetric chromosome with two genetically identical arms
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What is the rate of spontaneous abortion in recognized conceptions and which percentage of that is due to chromosomal aberrations?
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20%; 50%
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What is a frequent cause of troploidy?
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dispermia
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Why is Turner's syndrome a problem even though XX females undergo X inactivation anyway?
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some gene transcribed early in development before inactivation
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Which chromosome never results in a trisomy?
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1
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What is another name for karyotyping?
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chromosome analysis
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Which samples can karyotyping be performed on?
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blood, bone marrow, amniotic fluid, placental tissue, amniocentesis
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What chromosomal abnormality is associated with CML?
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Philadelphia chromosome
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T/F. FISH allows for chromosomal differences to be detected by the human eye.
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F. detected by computer program
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Why are mitochondrial disorders not transmitted by fathers?
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sperm mitochondria degraded at conception
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Energy is generated in the mitochondria by ___________________________________ in a process known as _______________________.
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the respiratory chain; oxidative phosphorylation
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T/F. The mitochondral genome consists of circular ss DNA.
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F. ds
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The heavy strand of the mitochondrial genome is rich in with nuc? The light chain?
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guanine; cytosine
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T/F. In the mitochondrial genome, a short segment of the light strand is replicated a second time to give a triple strand structure known as 7S DNA.
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F. heavy chain
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What is the function of the 7S DNA?
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acts like a promoter
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T/F. Human cells contain single copies of mitochondrial DNA mols.
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F. thousands
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T/F. mt disorders typically affect many organs.
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T
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Which region is most commonly affected by mt disorders?
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basal ganglia in the brain
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What are ragged red fibres?
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muscle fibres with mitochondrial aggregates
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T/F. mt dysfunction can lead to diabetes.
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T
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What is mt myopathy?
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degeneration and loss of function of muscles associated with presence of ragged red fibres
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T/F. The mt genome in cells is typically homoplasmic.
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F. heteroplasmic
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Why does the heteroplasmic state occur?
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oogonia contain few mitochondria
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T/F. The heteroplasmic state is short-lived
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T
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T/F. Mt disorders do not show regular Mendelian patterns of inheritance.
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T
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T/F. Proportion of defective mt genomes remains constant over a lifetime.
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F. varies spatially and temporally
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Why are mt mutations affecting the ETC detrimental?
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create highly reactive free oxygen radicals which are highly mutagenic
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What causes LHON?
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point mutations affecting NADH dehydrogenase
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What is another name for Frenchman disease?
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LHON
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T/F. LHON is a mitochondrial disorder.
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T
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T/F. MELAS is an X-linked recessive disorder.
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F. mitochondrial
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Mutations to ATP synthase result in which two mt disorders? Which one is more severe and why?
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Leigh's syndrome and NARP; Leigh's; proportion and tissue distribution of mutant mtDNAs
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Name 3 disorders associated with tRNA gene mutations.
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MELAS, diabetes, Alzheimer's
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T/F. More children than adults suffer from CPEO and Kearns-Sayre Syndrome.
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F.
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T/F. The effect of a deletion in mtDNA is different in adults and children.
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T
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T/F. Pearson's syndrome is a severe disorder resulting from a mtDNA deletion which affects children more than adults.
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T
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T/F. Kearns-Sayre syndrome results in severe anaemia and diabetes.
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F. Pearson's syndrome
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T/F. Somatic mutations in mtDNA accumulate with age.
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T
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Why is genetic predisposition to type II diabetes often maternally inherited?
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mtDNA
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T/F. Charcters important in evolution are not amenable to Mendelian analysis
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T
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What are 2 other terms for characters likely important in evolution?
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continuous/quantitative characters
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T/F. Multifactorial or complex disorders are common.
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T
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What is the polygenic theory of quantitative traits?
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a variable character that depends on the additive action of a large number of independent causes will show normal distribution in the population
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2T/F. Qualitative traits have a distribution similar to a Gaussian Curve.
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F. quantitative
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T/F. Height shows a normal distribution in the population.
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T
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T/F. Distribution looks more like a Gaussian curve as the number of loci increases.
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T
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T/F. Some diseases run in families but do not show Mendelian pedigree patterns.
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T
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Who developed the polygenic theory of discontinuous characters?
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Douglas Falconer
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What were Falconers postulates?
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1: an underlying continuously variable suceptibility is polygenic and follows Gaussian distribution. 2: there is a threshold where indvs whose suceptibility exceeds a critical threshold value develop the disease
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According to Falconer, the distribution of liability in the sibs of affected people is shifted in which direction compared to the distribution of liability in the general population?
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to the right
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T/F. Counseling in non-Mendelian conditions uses empiric risks.
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T
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T/F. Few factors are purely mendelian, purely Polygenic or purely environmental.
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T
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T/F. MS is a congenital disease.
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F. it occurs later in life
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T/F. Mental retardation is a congenital disorder.
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T
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T/F. Alzheimer's disease is a psychiatric disorder
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T
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What are the 5 hallmarks for multifactorial inheritance?
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1. most affected children have normal parents. 2. recurrence risk increases with the number of children affected in a family. 3. recurrence risk increases with severity of the defect 4. consanguinity slightly increases the risk for an affected child 5. risk of affected relatives falls off very quickly with degree of relationship
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T/F. Prior sequence info is required for PCR.
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T
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What are the ingredients needed for PCR?
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primers, target sequence, Taq polymerase, dNTPs
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What is hot-start PCR and why is it used?
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leave out enzyme or primers until first denaturation to lower background resulting from non-spcfc binding of primers
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What is touch-down PCR and why is it used?
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incrementally lower annealing temp to discrourage formation of nonspecific products
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Why are nested primers sometimes used in PCR?
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reduce non-specific binding of primers
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What are the advantages of PCR as a cloning method?
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fast, easy, sensitive, robust amplification
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What are the disadvantages of PCR as a cloning method?
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need target DNA seq info, short size and limiting amounts of PCR products, infidelity of DNA replication
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T/F. PCR is sensitive enough to identify single nucleotide differences between sequences.
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T
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Why is inverse PCR used?
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to access DNA that is immediately adjacent to a known sequence
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Which type of PCR circularizes DNA with DNA ligase?
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inverse PCR
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Which type of PCR is used to distinguish between 2 alleles that may differ by only a single nucleotides?
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allele-specific PCR
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What does allele-specific PCR depend on?
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perfect base pairing of the 3' end nucleotide of primers
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Describe the primers used in allele-specific PCR.
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2 allele specific primers with different 3' end nucleotides (one for each allele) + 1 conserved primer which can bind to both alleles
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Which technique uses a known nucleic acid population to interrogate an imperfectly understood nucleic acid population?
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nucleic acid hybridization
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What is a heteroduplex? Which technique uses this?
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probe and target sequences with complementary or partially complementary sequence anneal; nucleic acid hybridization
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T/F. In nucleic acid hybridization, only DNA hybridizes with the probe.
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F. RNA can hybridize also
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T/F. Homoduplexes are the goal of nucleic acid hybridization.
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F. heteroduplexes
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What are the 2 general ways that DNA and RNA can be labeled?
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in vitro synthesis; end-labeling
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What is the function of DNase I?
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introduces ss nicls by cleaving phosphodiester bonds
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T/F. Nick-translation can be used to label DNA
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T
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What is a klenow fragment?
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subunit of polymerase which adds nucleotides
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Which labeling technique uses hexanucleotides?
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random primed DNA labeling
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Which labeling method uses a kinase and labeled ATP?
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end-labeling
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How can your rapidly screen to see if someone carries the sickle cell allele?
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dot-blot hybridization
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T/F. The target for a southern blot is RNA.
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F. DNA
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T/F. The target for a northern blot is RNA.
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T
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T/F. In northern blot hybridization, the RNA is digested using restriction enzymes or sonication.
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F. RNA is not broken up
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RE mapping and RFLP depend on which technique?
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Southern blot hybridization
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T/F. PCR cannot detect large deletions therefore southern blot hybridization is used instead.
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T
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T/F. Tissue in situ hybridization can be used to look at level of transcription of a gene in the tissue.
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T
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Why do you look at mismatch signals for microarrays?
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to see if binding was non-specific
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Name 5 vector systems.
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plasmids, cosmid vectors, BACs, PACs, YACs.
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Which modifications make plasmids good vectors?
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multiple cloning site + reporter gene +Ab resistance gene
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What is Sp6 and what is it used for?
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promoter which makes RNA; plasmids for making riboprobes (used in tissue in situ hybridization)
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What do cos sequences do?
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slow down replication, bacteria loses its fidelity
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T/F. Large inserts are unstable in BACs with higher copy number.
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T
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What is needed to make a YAC?
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2 telomeres, 1 centromere, 1 ARS
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What are the most important cloning vectors?
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YACs
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T/F. Coding but not non-coding regions are well conserved among species.
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T
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T/F. About half our genes are associated with CpG islands.
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T
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T/F. Exon trapping identifies expresed sequences.
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T
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Which gene identification method uses biotin-labeling of cloned DNA and streptavidin-magnetic beads?
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cDNA selection/capture
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Which type of PCR do you use if you have the 5' end but want the 3' end?
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3' RACE-PCR
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T/F. Every RNA has an oligo poly A tail.
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T
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Which technique uses an anchor primer and an internal sense primer?
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3' Race PCR
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Which technique uses an internal antisense primer, terminal transferase and dATP?
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5' Race PCR
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What are nuclease S1 protection assays and primer extension assays used for?
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mapping the TSS
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T/F. ~10% of the human genome is coding.
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F. 1.5%
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T/F. Most of the mitochondrial genome is coding.
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T
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What is the structure and function of 7S DNA?
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shorty segment of H of mitochondrial DNA replicated a 2nd time to give a triple strand structure; mitochondrial promoter
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How many genes does the mt genome have?
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37
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T/F. The mt depends on the nuclear genes for rRNA and tRNA.
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F. it encodes these but depends on nuclear genes for other components.
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T/F. The mt tRNA can recognize 64 codons.
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F. only 60 (remaining 4 serve as stop codons)
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Which part of the mt genome is non coding?
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D loop (triple stranded)
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T/F. Replication of mitochondrial H and L proceeds in opposite directions.
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T
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T/F. 1/2 of the mt H strand must be synthesized before the L strand can be synthesized.
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F. 2/3
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T/F. Most mt genes overlap.
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F. just one case
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T/F. Intermediate repeated DNA is ~45% of the human genome.
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T
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What is the mean size of genes?
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27 kb
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T/F. Exon content of genes varies greatly.
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T
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T/F. The Class III region of the HLA complex is highly gene rich.
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T.
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T/F. Gene families arose by gene duplication and led to pseudogenes.
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T
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T/F. Pseudogenes do not undergo processing.
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F. some do
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Which RNAs can function as antisense regulators of genes to inhibit translation?
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micro RNAs
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Why might pseudogenes be retained aka why might they be useful?
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Counteract miRNA effects... distracts the miRNA from attacking real transcripts
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What is the function of RNA pol I?
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transcribes RNA
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What is the function of RNA pol II?
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transcribes nuclear genes
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What is the function of RNA pol III?
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transcribes tRNAs
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Where is the promoter region in relation to the TSS?
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~200 bp upstream
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Where is the TATA box in relation to the TSS?
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at position -30 (upstream)
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What does the TATA box bind?
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general transcription factors (TFIIX)
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Which protein mediates TF binding during pol II transcription?
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TATA-binding protein (TBP)
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What do GC boxes bind?
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TF Sp1
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What does the CAAT box bind?
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TFs CTF and NF1
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What does the Oct box bind?
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TFs Oct-1 and Oct-2
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How can enhancers be distinguished from promoters?
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further away from TSS, upstream or downstream, action is not dependent on orientation
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T/F. If you invert an enhancer, it loses its function.
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F. orientation independent
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T/F. Enhancers and silencers facilitate DNA looping.
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T
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What do response elements do?
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induce genes in response to signals
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Give 3 examples of response elements.
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CRE, SRE, HRE
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T/F. Housekeeping genes are expressed in most tissues most of the time.
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T
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Which type of pathway leads to activation of target genes containing CRE?
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G protein pathway (hormone, G prot, ATP --> cAMP, PKA to nuc)
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What does the following sequence signal: AAUAAA?
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end of transcription is soon
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T/F. AAUAAA is cut off and not retained in the mRNA.
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F. it is retained, poly A tail added
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What is added to mRNA to form a cap?
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7-methyl-guanosine
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T/F. The mRNA cap is essential for the initiation of transcription.
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F. translation
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T/F. TS stops when an exonuclease meets the polymerase.
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T
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What is RNA editing?
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substitution by deamination from very selected cytosine or adenine residues
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T/F. RNA editing can be used to make a large version of a protein in one tissue and a smaller version in another tissue.
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T
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What does CpG occur less frequently in the genome?
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accidental deamination of C produces U (gets exised) whereas deamination of methylated cytosine produces T (inefficient repair)
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T/F. Restriction enzymes do not cut methylated sites.
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F. some do ie Hpa II
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T/F. About half our genes are associated with CpG islands.
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T
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T/F. Adults have constant levels of methylation.
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T
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What are the steps of ChIP?
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crosslink proteins to DNA, lyse cells, isolate chromatin, fragment, add protein-specific Ab, precipitate, reverse cross-linking, degrade protein, purify DNA
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If the # of cM is 1, what is the recombination frequency and how many gametes out of 100 will be recombinant?
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0.01; 1
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How much DNA is = to 1 cM?
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0.7-1 Mb
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Which type of meiosis is used to measure recombination frequency?
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informative meoisis (able to distinguish between parental and recombinant chrmsms)
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T/F. The higher the recombination fraction, the more meioses are needed to obtain evidence that 2 loci are linked.
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T
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Why is a haplotype?
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set of closely linked alleles that tend to be inherited together at meiosis due to their close proximity
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T/F. When 2 loci are close together, recombination is rare.
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T
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T/F. Linkage relates to specific alleles
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F. relates to gene loci
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What is an association?
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alleles at different gene loci that are inherited together
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What is linkage disequilibrium?
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recombination that occurs more or less frequently than expected
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Which type of crossover leads to 4 recombinant chromatids?
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4-strand double crossover
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Which type of crossover leads to 2 recombinant chromatids?
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single & 3 strand double crossover
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Which type of crossover leads to no recombinant chromatids?
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2-strand double cross over
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What are the 3 characteristics of genetic markers used for the mapping of human disease genes?
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show clean pattern of mendelian inheritance, can be scored easily, highly polymorphic
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What is the highest possible frequency of recombination?
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50%; 0.50
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