exp 4 Flashcards
where can small scale mutations occur
coding sequences
noncoding portions
in regions between genes
When base substitutions occur within the coding regions, what are the three possible effects
silent mutations- no amino acid change
missense mutations- amino acid change
nonsense mutations- stop codons
what can insertions or deletions do within a coding sequence?
they can either cause the gain or loss of a codon
or cause a frameshift mutation
if a mutation does not occur within the coding sequence of a gene, will it still affect the expression of the gene?
it can, if it occurs at the promoter, at a regulatory element, an untranslated region, or a splice site
what is a SNP?
it is a base substituion within the genoe
what do SNPS serve as?
they serve as molecular markers and are used to index the variation that exists between inidviduals
why are SNPs important?
they can be genetically linked to a gene directly involve in a disease
do SNPS cause diseases
no, they but they may exist nearby a gene that is involved in the disease and can be used as a predictor
what is the goal of a GWAS
it is used to identify SNPS that may be predictors of disease
how do GWAS work
it is used to determine whether a particular SNP is statistically found more often in individuals with the disease
what is a haplotype?
it is a set of closely linked genetic markers or DNA variations on a chromosome that tend to be inherited together
what is newborn screening
it is a heel prick test that is used within 24-48 hours after birth to analyze for disorders
what is fetal DNA screening
it is analysis of fetal DNA prior to birth
what is preimplantation genetic diagnosis
it is genetic profiling of embryos where cells from early cleavage stage embryos can be removed and analyzed
embryos without disorders can be selected for implantation
how do microarray chip methods work
immobilzed known DNA is fixed to the array
patient and control DNA are fluorescently labeled and they will hybridize with the array
the pattern of fluorescence will be used to detect abnormalities
what is predictive testing
it is testing for individuals who are presymptomatic and may be tested for the risk of developing a condition, but these tests carry a degree of uncertainty
what are the drawbacks of DTC
they are not the most secure for privacy and the companies do not test for all variants, they only test the most common so they cannot be entirely predictive
what is the purpose of cytogenetics
it is the study of chromosomal organization and allows us to determine large scale chromosomal mutations
how will organisms that are closely related be visualized chromosomally?
they will share similar chromosome makeups in number, size, shape, and bands
how are karyotypes prepared
cells are induced to enter mitosis by adding a mitogenic agent and then will be arrested in metaphase
what is the purpose of colchicine in karyotype preparation
it is added to the culture and binds to microtubule-forming proteins that will prevent formation of the spindle apparatus, this arrests metaphase
why do we arrest metaphase
chromosomes are maximally condensed and easily seen at this point
what is the purpose of karytotyping fetal cells when the mother is older
we can use this to detect mutations in fetal cells and it is important in older mothers as there is a higher risk for nondisjunction event mutations
what are the 4 variations of centromere position
metacentric, submetacentric, acrocentric, and telocentric
what is the purpose of G-banding
it is a technique used for producing light/ dark banding patterns in chromosomes
when G banding, what is the purpose of treating chromosomes with trypsin
it digests the proteins which will help expose the DNA for staining
what do dark bands correspond to
dark bands are regions rich in adenine and thymine, they are less transcriptionally active and are more condensed
what do light bands correspond to
they are regions rich in guanine and cytosine and are more transcriptionally active and less condensed
what is FISH
it is a better method of visualizing karyotypes as it has a better resolution
how does FISH work
condensed chromosomes are treated to denature the DNA and the DNA is exposed to single stranded fluorescently labeled DNA proves that will recognize/bind to specific regions of the chromosomes and can be visualized
What are genome mutations
changes in the number of chromosome
what are chromosomal mutations
change in chromosome structure
what is polyploid
mutations that results in one or more of every kind of chromosome in the set
if there 3 copies of every chromosome in a genome what type of mutation is it
polyploid
what is aneuploid
mutations in the genome that have one or two extra/missing chromosomes, but not of the whole set
what type of mutation is a trisomic
it is an aneuploid mutation where there are 3 of one type of chromosome and 2 of the rest
what type of mutation is monosimic
it is an aneuploid mutation where it has 1 of 1 type of chromosome and 2 of the rest
what type of mutation is down syndrome
it is a trisomy mutation where there are three copies of chromosome 21
what type of mutation is kleinfelter syndrome
it is a trisomy mutation where a male has an extra X chromosome
what is turner syndrome
it is a monosomy mutation in females where there is only one X chromosome and two copies of all autosomes
what causes Aneuoploids?
nondisjunction events where chromosomes fail to segregate in Meiosis I or when sister chromatids fail to segregate during Meiosis II
what are chromosomal mutations
they are mutations where size, shape, and/or the arrangements of genes on a chromosomes is altered
what are duplications?
they are chromosomal mutations where a chromosomal segment is present in multiple copies
what are deletions
they are chromosomal mutations where chromosomal segments are missing
what are inversions
they are chromosomal mutations where a segment is flipped around in orientation in the same chromosome
what are translocations
they are chromosomal mutations where a segment will move to another chromosome or a different location on the same chromosome
the segments may also swap
what generally causes chromosome mutations
chromosomal breaks that are repaired incorrectly
how are chromosome mutations identified
the mutations often include many genes in the altered segment and are detectable as changes in the banding of FISH hybridization pattern
