I have got some BIG issues! forgive the long post

Genetics as it applies to evolution, molecular biology, and medical aspects.

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saddy51
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I have got some BIG issues! forgive the long post

Post by saddy51 » Sun Jan 04, 2015 10:39 am

Hello everyone, I hope I am welcomes among you fellow scholars to ask questions.

I have been battling with a few topics in Biology that ware to well written in my Notes or Manual that are given by the professor and I have miserably failed to seek any kind of easy to understand references to comprehend the topics that I will mention. I hope some of you will help me to find or even be kind enough to explain a few things here that will make life a bit easier. All the overloaded use scientific jargons ( at least it seems to me :p) makes no sense haha.

Without further ado:
Here they are:

Indirect DNA testing: I know yo target the genes that are in severe proximity to our targeted gene and that you make use a fluorescent nucleotide or a tagged reporter molecule that will attach themselves to those genes and fluorescent in order to show presence of the bad genes :p. but a bit more knowledge might be useful, please help me out here :'( .

Blood Group Systems:

What the heck are MNSs?
I have a little understanding of Rh and how terrible it can be if mommys blood detect different antigen in Baby's blood however I don't get the genes Dd, Cc and Ee genes associated with it. Also tones of jargons! I will actually paste the whole note here for you convenience.

Please feel free to tell me something about the HLA systems

Here is the manual notes from my School babes!
BLOOD GROUP SYSTEMS
ABO
The ABO genes reside on the chromosome 9 (Bernstein’s theory). The blood groups A and B are further subdivided into subgroups, with A being in a form A1 or A2 (A1 is dominant to A2) and B in many forms of seemingly no clinical importance.
The ABH antigens are not primary gene products but instead the enzymatic reaction products catalyzed by the enzymes called glycosyltransferases. Immuno-dominant structures of A and B antigens are synthesized by a series of reactions; the A and B transferases encoded by the functional alleles (A and B alleles) of a single gene at the ABO locus, catalyze the last step of the synthesis, while the protein coded by the O allele is non-functional; therefore, the acceptor substrate, (H antigen) remains without a further modification.
GENETIC PATHWAY OF THE ABO SYSTEM
The term secretor, as used in blood banking, refers to secretion of ABH antigens in fluids such as saliva, sweat, tears, semen, and serum. If people are secretors, they will secrete antigens according to their blood groups. For example, group O people will secrete H antigen, group A people will secrete A and H antigens, etc. Soluble (secreted) antigens are called substances.
ABH secretion is controlled by two alleles, Se and se. Se is dominant and se is recessive (or amorphic). Approximately 80% of people are secretors (SeSe or Sese). The antibodies in the ABO system are mainly naturally occurring, i.e., they are non-red cell stimulated.
frequency.
Bombay phenotype is an extremely rare ABO group which derives the name "Bombay" because it was first discovered to exist among some people living in the region of Bombay, India. The Bombay group (Oh) results from the inheritance of two rare recessive h genes which occur at a locus other than the ABO gene locus. Because the h gene is very rare, Bombays often result from consanguineous matings in which parents are blood relatives (e.g., first cousins). Whenever inbreeding occurs, the proportion of rare homozygotes increases in
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Medical Biology and Genetics Winter term 2014/2015 MNSs
The antigens called M and N are glycophorins A and B (GPA and GPB), products of two tightly linked genes of the glycophorin gene family, each present in two different allelic forms. The antigens are very weak even though after repeated transfusions they may provoke a synthesis of the antibodies anti-M and anti-N. Due to their simple, codominant way of inheritance, their detection serves as one of the criteria during paternity trials.
The antigens S and s are linked to the M and N antigens. It is supposed that they occupy a single locus in a form of four different alleles (MS, Ms, Ns, and NS).
Rh
The human Rh system, with more than 40 antigens, is the most complex and together with the ABO system has profound clinical significance. Fisher-Race Theory, which explains its complex nature, is named after the two British workers who proposed it in the 1940's. Although too simplistic to explain this complex system, the theory is useful to explain routine inheritance of D, C, E, c, and e antigens. The main tenets of the theory are as follows:
1. Rh inheritance is controlled by 3 closely linked loci on each chromosome of a homologous pair.
2. Each locus has its own set of alleles which are Dd, Cc, and Ee. The D gene is dominant to the d gene, but Cc and Ee are co-dominant. Today we know that the d gene does not exist; when used it represents absence of the D gene.
3. The 3 loci are so closely linked that crossing-over does NOT occur, and the 3 genes on one chromosome are always inherited together.
Antigens of the Rh blood group system are thus products of RHD and RHCE
(collectively referred to as RH30), the two tightly linked and highly homologous genes occupying the short arm of the chromosome 1.
RhD carries the D antigen as the most potent blood group immunogen, but it is absent from a relatively large segment of the population (i.e. Rh-negative phenotype), mainly as the result of RHD gene deletion. RHCE exists in four allelic forms and each allele determines the expression of two antigens in Ce, ce, cE or CE combination (RHCE is the collective name of the four alleles). RHD and RHCE genes, each, contain 10 exons and span ~75 kb DNA sequence. Complex formation with the product of another single copy gene RHAG (also referred to as RH50) is essential for the presentation of the Rh antigenic activity. RH50 is similarily organized into 10 exons and shares 36% sequence identity with RH30 but is located at a separate locus.
While the RH50 locus is almost invariant, the RH30 locus harbors a large repertoire of allelic diversity at the level of populations.
Because crossing over cannot occur, the genotype Cde/cde is impossible in a child from this mating. Even though the father has C, d, and e genes, the Cde and cde on each chromosome are always transmitted to offspring together.
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Medical Biology and Genetics Winter term 2014/2015
HLA system
The human HLA system referred to as MHC (major histocompatibility complex) is located on the chromosome 6 and contains over 100 genes. The MHC genes are divided into class I, II and III regions. The class I genes encode the chain of the antigen-presenting HLA-A, B and C molecules. The centromeric class II genes, previously known as immune-response genes, encode antigen presenting HLA-DR, DP and DQ molecules, but also proteasome (LMP) and peptide-transporter (TAP) genes. The MHC class III region contains many genes with varying functions. It has been proposed that the MHC region is an immunologic gene cluster, as many of the gene products are involved in the generation of the immune response. This could be due to for instance facilitated co-evolution of genes, co-regulation of gene expression, or gene conversion by having the genes together in the MHC.
One of the most conspicuous properties of MHC is that that some alleles occur more frequently together than expected by chance. The non-random pairing of alleles in the MHC is called gametic or linkage disequilibrium (LD) and it is influenced by the low recombination rate in the MHC region. The LD could extend over the whole MHC and for instance the alleles A1, B8, TNFa2, DR3, DQ2, TAP2*0101 and DPB1*0101, which confer an increased risk for development of many autoimmune diseases, are known to often be inherited together in an extended haplotype O. The extended haplotypes could be evolutionary conserved and are often refereed to as ancestral haplotypes.
The allelic diversity of MHC genes is, in contrast to diversity in TCR and Ig genes, not manifest within, but among, persons in a population. The MHC polymorphism in the population might be formed by different mechanisms.
The antigen-presenting MHC class II molecules are very polymorphic and there exist several alleles of the genes in the population. It is this feature which makes them interesting for donor-recipient matching in transplantations. Some alleles have also been shown to be associated with, mostly autoimmune, diseases.
MHC class II molecules are integral membrane glycoproteins consisting of a heavy chain with a molecular weight of approximately 34000 and a lighter chain with a molecular weight of approximately 29000. They consits of two domains (1 and 1) forming the peptide- binding region (PBR) and two other immunoglobulin like domains (2 and 2) forming the membrane proximal region. The class II proteins appear to form (super) dimers at the cell surface.
FINGERPRINTING AND DNA PROFILING
Like the fingerprints that came into use by detectives and police labs during the 1930s, each person has a unique DNA fingerprint. The term DNA fingerprinting was coined by British researcher Alex Jeffreys in 1984 to allude to the traditional use of fingerprints as the most unique means of human identification.
Classical DNA fingerprinting where minisatellite polymorphisms have been detected is being replaced by so called DNA profiling using microsatellites.
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Medical Biology and Genetics Winter term 2014/2015
USES OF DNA FINGERPRINTS
Apart of classical medical applications, DNA fingerprints are useful in the justice system.
1. FBI and its CODIS database
2. Paternity in custody and child support litigation 3. Personal identification

Please kindly respect copy right. If you wish to use this information do so by seeking permission. I will let you know which name you need to use.

Thnk you very much you beautiful people.

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Athira
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Post by Athira » Thu Jan 15, 2015 5:11 pm

Well,I don't know much about these stuff :-(- but I promise-I'll try to read about these as soon as possible and will get back to you soon..Till then please wait! :-)

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