GENETICS Flashcards
What is the function of Primase?
During DNA replication, it makes RNA Primer for NDA polymrase III to initiate replication
What different role does DNA polymerase I & III do?
DNA Polymerase I is responsible for Degrading RNA Primer, replacing with DNA.
DNA Polymerase III is responsible for Elongating leading strand by adding Deoxyneucleotides to the 3’ end.
There are difference between DNA polymerase I and III with exoneuclease function. What is it?
I: 3’ - 5’ proofreading exoneuclease
5’ - 3’ exoneuclease for RNA primer replacing
III: 3’ - 5’ proofreading exoneuclease
What consists of neucleosome core?
DNA
H2A H2B
H3
H4
There is one histone outside neucleosome core. What is it, and what are their function?
H1 histone
- packaging of chromatin to more thicker more compact one(heterochromatin) which limit DNA Transcription.
What are functions of Small neuclear riboneucleoprotein?
Slice out introns from pre-mRNA forming mature mRNA.
What is the definition of linkage disequilibrium?
Tendency of certain alleles to occur more often together. This can be because they are inherited with same chromosome.
Ex) HLA gene, CFTR gene
DQ1 probability on population is 0.3
DQ2 probability is 0.2
In this case, probability of people both having those are 0.06
But its actually 0.2 becasue of linkage disequilibrium.
What is the definition of heteroplasmy?
Presence of both normal and mutated mtRNA.l in one cell. Proportion of Abnormal mitochondria decides severity of mitochondrial inherited disease.
What is the definition of pleiotropy?
Multiple phenotypic manifestation due to one genetic mutation.
What can occur to defect of neucleotide excision repair?
Xeroderma pigmentosum
- unable to repair DNA pyrimidne dimers by UV exposure during G1 phase
- normal at birth by after a year, photosensitivity and hypo- hyperligmentation of skin, and malignancy of skin.
What can occur due to defect of Mismatch repair?
Lynch syndrome(hereditory nonpolyposis colorectal cancer)
- mismatched segment is not replaced during S phase
- greater incidence of colorectal, endometrial, ovarial cancer.
What is the function of p53 protein, and what disease can occur due to this protein’s malfunction?
Regulatory protein that halts cell cycle when DNA is damaged.
Its mutation is found in many cancers. And inheritary mutation of this gene cause Li-Fraumeni disease responsible for multiple malignancy on younger age.
What is nondisjunction of gene?
Failure to properly devide two chromosome during meiosis.
Most Down syndrome case are due to meiosis type I/II?
Meiosis type I
What is Px, Sx of achondroplasia?
Px) sporadic(85%) and Autosomal dominant(15%) disease, by mutation of FGFR3 gene. Homogygus is lethal so heterogygus is the only survival chance, leading to 50% of preaentation of offspring.
Sx) short stature, big head, prominant forehead.
What can cause nonhomologous end joining? And dysfuction of NHEJ can cause what?
Ionizing radiation(xray, gamma ray)
Its dyafunction can cause ataxia telangiectasia
What is the important repair function for spontaneuous and toxic deamination and hoe does it work?
Base excision repair
- Glycosylase removes altered base and creates AP sites and endonuclease and ligase repairs it.
What are probability of HLA gene to be perfectly match with siblings? And why is it important?
1/4
The human leukocyte antigen (HLA) genes encode major histocompatibility complex (MHC) molecules that are key to activation of the immune system in response to foreign (non-self) antigens. All the HLA genes are clustered together, meaning that there is a low rate of crossover and that offspring essentially inherit 2 HLA haplotypes, one from each parent. Therefore, the probability that a sibling would be an identical HLA match is 1/4.
Molecular typing of HLA antigens is performed prior to transplants (eg, allogeneic stem cell transplant) to evaluate potential donors for mismatch in HLA alleles (eg, HLA-DR8 versus HLA-DR3), which is associated with higher rates of posttransplant complications (eg, graft versus host disease, graft failure). An HLA-identical sibling donor would drastically reduce the likelihood of serious complications and increase the likelihood of a successful transplant
What is the definition of dominant negative mutation?
Dominant negative mutations occur when an abnormal gene negatively affects the product of the wild-type gene in the same cell. For example, certain oncogene p53 mutations can lead to translation of a protein product that prevents wild-type p53 from binding to the promoter of its target genes.
What is the definition of genetic linkage?
Genetic linkage describes the tendency of alleles located near one another on the same chromosome to be inherited jointly.
What is the definition of incomplete penetrition?
Penetrance refers to the proportion of individuals with a given genotype that express the associated phenotype. In incomplete penetrance, less than 100% of individuals with a given genotype express its associated phenotype.
What is the dwfinition of locus heterogeniety?
Locus heterogeneity refers to the ability of one disease or trait to be caused by mutations in multiple different genes. An example is familial hypercholesteremia, which can be caused by different mutations affecting cholesterol metabolism genes (eg, LDL receptor, apo B-100).
What is polyploidy?
Polyploidy occurs when more than 2 complete sets of homologous chromosomes exist within an organism or cell.
What is difference between Gene sequencing and FISH, Microarray?
Gene sequencing can detect genes without probes but others need labeled probes to find certain genes
