Genetic's Flashcards
What is DNA composed of?
phosphate on C5
Deoxyribose -5 carbon Sugar
nitrogenous bases (purines and Pyrmidines) on C1
Purine bases are…
Adenine and Guanine
5 sided linked to 6 sided structure
Pyrimidine bases are…
Thymine and Cytosine
6 sided structure
Adenine binds to
Thymine (or Uracin in RNA) with 2 hydrogen bonds
Guanine binds to
Cytosine with 3 hydrogen bonds
What direction does coding strand run in PCR?
5’ to 3’
DNA vd RNA
RNA contains a ribose sugar
Uracil replaces thymine
RNA is single stranded
What is an exon?
coding region of DNA that is transcribed into mRNA
What is an intron?
intervening regions that do not code for a protein and are removed when mRNA is produced
What is mitosis?
Process of nuclear division
Occurs in somatic cells
results in diploid cells = 2 copies of each chromosome
What is meoisos?
Occurs in gametes
results in haploid cells = one copy of each chromosome
homologous chromosomes undergo recombination = genetic diversity
What is mRNA?
mRNA is transported to the cytoplasm for protein translation
What is tRNA?
transfer RNA - carries the amino acid to ribosome during protein translation
What is rRNA?
Ribosomal RNA - site of protein synthesis
What is transcription?
DNA is transcribed to mRNA
base pairing occurs with anti-sense strand
What is translation?
Occurs on ribosome. tRNA transfers amino acid to match a 3 nucleotide sequence, called a codon, to form a protein
What is a SNP?
a single nucleotide polymorphism
change of single nucleotide base that changes the codon
Synonymous SNP
Change results in same amino acid
Missense
Change results in an Amino acid change
Non sense
Change results in in a STOP codon
Hybrid
Crossing over of chromosome results in a new allele containing both portions of both original genes
RFLP
restriction fragment length polymorphism
PCR product is digested with restriction enzymes that cut DNA at specific sequences
DNA fragments are separated by electorphoresis
SS PCR
sequence specific PCR or allele specific
Primer is designed to only amplify one allele
a band is observed only if one allele is present
not ideal for high through put but useful for rarely found mutations such as Rh variants and Jk nulls
interpretation made by a technologist
Luminex xMAP
uses color coded microspheres and flow cytometry
microspheres bind to specific and signal is produced and measured by flow cytometry
Progenika BloodChip and BioArray Bead-Chip
DNA is extracted>multiplex PCR>Elongation on bead>Bead chip analysis
beads attached to slide and are color coded. probed attached to bead is specific for one allele and binds to nucleotide sequence of perfect match. A color photo is taken to ID location and specificity of each bead on the chip
Fyx
weak Fyb by serological testing
GATA
transcription factor turned off silences Fyb expression on RBC’s but not tissues
Doa/Dob
can have weak antibodies not detected in ABS but hgb not rising after transfusion
V/VS
identification of r’s varients which are VS+ and V- and have partial big C antigen . Serologically type C+ but make anti-C
Linkage disequilibrum
genes at closely linked loci tend to be inherited together. genes don’t sort independently and have a prevalence different than expected
Everytime Se gene so is Lu Lutheran.
Cross-over
Exchange of genetic material during meiosis = two new chromosomes. Occurs frequently in HLA system.
Recombination
observed new combination of traits different from those seen parents. Result of a cross-over
Lyonization
process by which all X is inactivated in females during the early stages of developement
XG gene
XG escapes inactivation and x-linked dominate
89% of females and 66% of males are Xga positive
XK gene
XK gene encodes for Kx antigen
lack of Kx antigen results in Mcleod phenotype
XK is subject to x activation.
X-linked recessive
Cis
alleles on the same chromosome
Trans
alleles on opposite chromosome
Position effect C/D
When Ce (r’) is in trans to D (R2, R0) the D antigen expression is reduced
Kell(mod)
When Kp(a) is expressed, other Kell antigens are reduced because of cis modifier effect = Kell(mod)
KLF1
KLF1 on Chromosome 19 encodes for Kruppel-like factor. Heterozygosity for 1 of several nucleic acid changes in KLF1 causes dominate Lu(a-b-) phenotype = In(Lu)
Lu(mod), P1, Inb, and AnWj.
GATA-1 gene
on X chromosome, changes are associated with X-linked type of Lu(mod) that initially presents as Lu(a-b-)
Regulator Rh null
RHAG on chromosome 6 is silenced. RHAG process RH associated glycoprotein that is required for Rh expression
Wr(b)
GPA is required for Wr(b) expression
Wr(b) is high prevalent antigen in Diego blood system
MNS null phenotype lacks Wrb.
Wrb is encoded be DI gene and carried on band 3
Rh null
Rh null RBC’s lack LW antigens., Fy5, and have reduced expression of U, S, s antigens
cM
the frequency of crossing over involving 2 genes on the same chromosome
the great the distance the better chance of crossing over
Genes on different chromosomes are never linked and cM distance is meaningless
the centimorgan is equal to 1% chance that a marker at one genetic locus will be seperated from a marker at a second locus due to crossing over
Direct exclusion
Child has antigen that should have been given by father
Indirect exclusion
Child lacks antigen that should have been given by father
Paternity Index
chance that the alleged father is the biological father compared to a random man
DNA methods used in paternity testing
Tandemly repeated sequences in the the non-coding region of the DNA is different in every person. Variable tandem repeats (VNTR) or short term repeats (STR) can be measured by electrophoresis. Using 12 STR loci is guaranteed to be unique in every individual. Also used for monitoring chimerism in bone marrow and graft vs host disease in solid organ transplant
