Domande Aperte Flashcards
(40 cards)
Main goals of the human genome project?
Sequence the entire human genome, create a database, understand relationship with some diseases
Define haploinsuffiency?
It occurs when one function allele is not enough to make up for the non functional one and leads to less functional proteins than needed. Leads to disease
First and second law of Mendel?
First law is the law of segregation which states that each organism has 2 alleles for each trait and they are separated during gamete formation.
Second law is the law of independent assortment which states that alleles of different genes are assorted independently from one another.
Define linkage disequilibrium?
It occurs when alleles are inherited together more often that you would expect by chance. If two genes are located very closely on the same chromosome they tend to be inherited together.
It is useful to understand how certain genes are linked to diseases.
Conditions of the hardy Weinberg equilibrium?
Large population, random mating, absence of new mutations, absence of natural selection and absence of migratory flux.
What are the possible causes behind an association between a SNP associated with a risk
factor and a disease?
The SNP might be the cause itself. The SNP and the disease can be in linkage disequilibrium, gene-environment interaction.
What type of mouse model would you do in case of a disease cause by either a nonsense or
frameshift mutation?
I would do a knock out mouse model bc since both nonsense and frameshift mutations lead to truncated protein a knock out mouse model will mimic the situation. If the mouse with the knocked out gene shows the same disease phenotype as the human patients that it suggest either of those type of mutations
We are interested in setting up a molecular diagnosis of a heterogenous genetic disease. What would be the most efficient strategy?
Using next generation sequencing as it is both efficient and cost effective.
Define the key features of a molecular marker?
A molecular marker is a specific DNA sequence that can be reliably detected and used to track the inheritance of diseases. Key features include : lots of polymorphisms, detectable.
Explain the concept of incomplete dominance?
It is a type of inheritance where one allele doesn’t overpower the other. It leads to a combine phenotype, a new blended phenotype.
Why was defining the genotype/phenotype relationships for the AB0 blood groups puzzling?
It was a quite puzzling due to : multiple alleles, biochemical complexity, unexpected phenotypes likely Bombay.
What does we mean by F1 generation and F2 generation? What are the respective expected genotypes?
F1 generation is the first filial generation, with expected genotype Aa.
F2 is the obtained by crossing the F1 generation, with expected genotypes AA,Aa,Aa,aa.
What are the mechanism through with a loss of function mutation can be dominant?
Haploinsufficiency : where one wt copy of the gene isn’t enough to produce enough product.
Dominant negative effect : where the altered gene product acts antagonistically towards the wt allele. ( osteogenesis imperfecta)
What is whole exome sequencing?
Technology is used to sequence only the exons of the genome with the aid of primers that identify exons via hybridization to them.
What is genomic imprinting?
It is a type of parental expression of genes. We only express the maternal or paternal copy .
What is loss of heterozygosity?
It is the loss of one allele at a specific locus due to a deletion mutation resulting in abnormal hemizigosity.
Is a splicing mutation always associated to a frameshift ?
Not always, but often occurs. It depend on how it alters the sequence.
What is the molecular cause of the Bombay phenotype ?
Homozygous recessive GH gene that impedes production of A/B proteins leading to AB blood types to test as 0.
Do X and Y recombine?how?
It occurs in small regions known as pseudoautsomal regions located at the tips of the chromosomes. In these regions the chromosomes are homologous allowing them to undergo crossing.
Definition of an allele?
Alleles are different version of the same gene.
When and where does recombination event happen?
Recombination occurs at discrete hotspots fixed position of. the chromosome and occurs when 2 molecules of DNA exchange pieces of their genetic material with each other.During the prophase 1 and 2.
What is a Barr body?
It is an inactivated X chromosome seen in the nucleus of females cells. It occurs in females since they have two X chromosomes to balance out gene expression.
What is SRY?
Sex reversal on Y chromosome. If this transcription factor is present the testes develop in the embryos.
What is pleiotropy? What is epistasis?
Pleiotropy is when one gene modulates the effect of many other genes.
Epistatis is when one gene modulates mask or modifies the effect of one gene.
