2.
Which statement regarding serum cross-matching and PRA is correct?
Correct Answer
A. The binding of anti-HLA antibodies to HLA antigens on donor cells leads to the activation of complement and the formation of the membrane attack complex
Explanation
This statement correctly describes the process of serum cross-matching and PRA. When anti-HLA antibodies bind to HLA antigens on donor cells, it triggers the activation of complement, a part of the immune system. This activation leads to the formation of the membrane attack complex, which can cause damage to the donor cells. This process is important in determining compatibility between a donor and recipient in organ transplantation.
3.
Below are the HLA-A, -B and -DR types of two individuals
Donor: A1, B8, B39, DR1, DR3
Recipient: A1, A24, B9, DR1, DR4
Please select all statements that apply:
Correct Answer(s)
A. The recipient is heterozygous for the HLA-DR allele
A. The donor is homozygous for the HLA-A allele
Explanation
Based on the given HLA types, the recipient has two different DR alleles (DR1 and DR4), indicating that they are heterozygous for the HLA-DR allele. On the other hand, the donor only has one A allele (A1) and no other A allele, indicating that they are homozygous for the HLA-A allele.
4.
Which of these statements most applies to familial matching?
Correct Answer
A. There is a 25% chance of a complete match between siblings
Explanation
Familial matching refers to the likelihood of a complete match between siblings. The correct answer states that there is a 25% chance of a complete match between siblings. This means that siblings share, on average, 25% of their HLA alleles, which are important for immune system compatibility. This percentage indicates the probability of a complete match between siblings in terms of these specific alleles.
5.
Which of these statements most applies to gel electrophoresis?
Correct Answer
A. Gel electrophoresis describes the movement of ions across an applied electrical field
Explanation
Gel electrophoresis is a technique used to separate molecules based on their electrical charge. In this process, an electrical field is applied to a gel matrix, causing charged molecules, such as DNA or proteins, to move through the gel. The movement of these ions is determined by their charge and size, allowing for the separation of different molecules based on their characteristics. Therefore, the statement "Gel electrophoresis describes the movement of ions across an applied electrical field" best applies to gel electrophoresis.
6.
Please identify the incorrect statements regarding agarose gel electrophoresis
Correct Answer(s)
A. A dye is used to track the migration of the DNA from the anode to the cathode
A. Smaller DNA fragments migrate faster towards the cathode
Explanation
The correct answer is that smaller DNA fragments migrate faster towards the cathode. This statement is incorrect because in agarose gel electrophoresis, DNA fragments migrate from the cathode (negative electrode) to the anode (positive electrode). The negatively charged DNA is attracted to the positive electrode and moves towards it. Therefore, smaller DNA fragments will migrate faster towards the anode.
7.
For kidney transplants, it is essential to match:
Correct Answer
A. HLA-A, HLA-B and HLA-DR antigens
Explanation
For kidney transplants, it is essential to match HLA-A, HLA-B, and HLA-DR antigens. These antigens are part of the human leukocyte antigen (HLA) system, which plays a crucial role in the immune response. Matching these antigens helps to minimize the risk of rejection by ensuring compatibility between the donor and recipient. HLA-A, HLA-B, and HLA-DR antigens are highly polymorphic, meaning they have many different variations. Matching these antigens increases the likelihood of a successful transplant and reduces the chances of graft rejection.
8.
Please select the correct statement. MHC molecules are:
Correct Answer
A. Glycoprotein complexes encoded for by genes found on chromosome 6
Explanation
MHC molecules are glycoprotein complexes, meaning they are proteins that have attached carbohydrate molecules. These complexes are encoded for by genes found on chromosome 6. This indicates that the genes responsible for producing MHC molecules are located on chromosome 6. Therefore, the correct statement is that MHC molecules are glycoprotein complexes encoded for by genes found on chromosome 6.
9.
Which of the following statements is incorrect?
Correct Answer
A. MCH class II molecules are encoded for by HLA-A-, HLA-B and HLA-DR genes
Explanation
The correct answer is that MCH class II molecules are encoded for by HLA-A-, HLA-B and HLA-DR genes. This statement is incorrect because MHC class II molecules are actually encoded for by HLA-DR, HLA-DP, and HLA-DQ genes. The HLA-A and HLA-B genes encode for MHC class I molecules, while the HLA-C genes also encode for MHC class I molecules. MHC class III molecules, on the other hand, encode various components of complement.
10.
Which of these statements is correct?
Correct Answer
A. SSP-PCR requires the used of specific DNA primers
Explanation
SSP-PCR stands for Sequence-Specific Primer Polymerase Chain Reaction. It is a molecular method used to detect specific DNA sequences. In SSP-PCR, specific DNA primers are used to target and amplify the desired DNA sequence. This method is commonly used in HLA typing, where it is used to assign a specific HLA tissue type. Therefore, the statement that SSP-PCR requires the use of specific DNA primers is correct.
11.
Which of these statements regarding SSP-PCR is incorrect?
Correct Answer
A. The PCR process is used as an amplification step followed by a post-amplification step to detect specific alleles
Explanation
SSP-PCR is a technique used for genotyping specific alleles. It involves a single cycle consisting of three stages: denaturation, annealing, and extension. The PCR process is used to amplify the DNA, and then a post-amplification step is performed to detect the specific alleles. If no amplification product is observed, it can be assumed that the individual does not express the specific allele being tested. Therefore, the statement "in the absence of an amplification product, it can be assumed that the individual does not express a specific allele" is correct.
12.
The human leukocyte antigens are otherwise known as ________ molecules.
Correct Answer
MHC, major histocompatibility complex
Explanation
The human leukocyte antigens are also referred to as MHC, which stands for major histocompatibility complex. MHC molecules are proteins found on the surface of cells that play a crucial role in the immune system by presenting antigens to T cells. These antigens are recognized by T cells, which then initiate an immune response against foreign substances or infected cells. Therefore, MHC molecules are essential for immune recognition and response.
13.
In total, there are ________ different classes of HLA molecule.
Correct Answer
three, 3
Explanation
There are three different classes of HLA molecule. HLA molecules are proteins found on the surface of cells that play a crucial role in the immune system. These molecules are responsible for presenting antigens to immune cells, which helps in the recognition of foreign substances and initiation of an immune response. The three classes of HLA molecules are HLA class I, HLA class II, and HLA class III. Each class has a distinct function and is involved in different aspects of the immune response.
14.
HLA antigens are encoded for by genes found on chromosome ________
Correct Answer
six, 6
Explanation
HLA antigens are encoded for by genes found on chromosome six. The HLA system, also known as the human leukocyte antigen system, is a group of genes that play a crucial role in the immune system. These genes are located on chromosome six, which is one of the 23 pairs of chromosomes found in humans. The HLA antigens are important for immune recognition and the ability to distinguish between self and non-self cells. By being encoded on chromosome six, these genes ensure that the HLA antigens are properly expressed and function effectively in the immune response.
15.
Individuals that are antigenically similar are said to be ________ .
Correct Answer
histocompatible, compatible
Explanation
Individuals that are antigenically similar are said to be histocompatible or compatible. Histocompatibility refers to the ability of cells or tissues to be accepted without an immune response. When individuals are histocompatible, it means that their antigens are similar enough that they can tolerate each other's cells or tissues without triggering an immune response. This is important in organ transplantation, where histocompatibility is crucial to prevent rejection of the transplanted organ. Compatibility, on the other hand, refers to the ability of two individuals to coexist or work well together. In the context of the question, both terms can be used interchangeably to describe the antigenic similarity between individuals.
16.
HLA-A, -B and -C antigens are encoded for by class _______ genes.
Correct Answer
one, 1, i, I
Explanation
HLA-A, -B, and -C antigens are encoded for by class I genes.
17.
HLA-DR, -DP and -DQ antigens are encoded for by class ________ genes.
Correct Answer
two, 2, II, ii
Explanation
HLA-DR, -DP and -DQ antigens are encoded for by class II genes. These genes are part of the major histocompatibility complex (MHC) in humans. Class II genes are responsible for encoding proteins that play a crucial role in the immune system, specifically in presenting antigens to T cells. The HLA-DR, -DP, and -DQ antigens are important for immune recognition and response, and their encoding genes are classified as class II genes.
18.
HLA genes are very close together. As such they are inherited en bloc. We each inherit two _________, one from each parent.
Correct Answer
haplotypes
Explanation
HLA genes, also known as human leukocyte antigen genes, are located very close together on the chromosome. This means that they are inherited as a group, or en bloc. Each individual inherits two sets of these genes, one from each parent. These sets of genes are called haplotypes.
19.
HLA alleles are expressed in a ________ fashion.
Correct Answer
co-dominant, codominant
Explanation
HLA alleles are expressed in a co-dominant fashion, meaning that both alleles in a heterozygous individual are fully expressed and contribute to the phenotype. This is in contrast to a dominant-recessive relationship, where one allele is dominant and masks the expression of the recessive allele. In co-dominance, both alleles are equally expressed, resulting in a combined phenotype that shows characteristics of both alleles. Therefore, the terms "co-dominant" and "codominant" can be used interchangeably to describe the expression pattern of HLA alleles.
20.
HLA typing can be done using ________ and molecular methods.
Correct Answer
serological
Explanation
HLA typing can be done using serological and molecular methods. Serological methods involve testing for the presence of specific HLA antigens using antibodies, while molecular methods involve identifying specific HLA genes or alleles using techniques such as PCR or DNA sequencing. Both methods are used in HLA typing to determine an individual's HLA profile, which is important in various medical applications such as organ transplantation and disease susceptibility.
21.
Pre-transplant tests include ABO blood typing, HLA typing, ________ cross-matching and the PRA.
Correct Answer
serum, serological
Explanation
Pre-transplant tests include ABO blood typing, HLA typing, serum cross-matching, and the PRA. These tests are performed to assess compatibility between the donor and recipient before a transplant procedure. ABO blood typing determines the blood group of the individuals involved. HLA typing identifies the human leukocyte antigen compatibility, which is crucial for successful transplantation. Serum cross-matching detects the presence of antibodies in the recipient's serum that may react with the donor's cells. The PRA (Panel Reactive Antibody) test measures the level of antibodies in the recipient's blood against a panel of potential donors. Therefore, the inclusion of "serum" and "serological" in the answer is appropriate as they refer to the tests and procedures involved in pre-transplant evaluation.
22.
The PRA is an abbreviation for the ________ ________ ________ test . It estimates the percentage of the population that are likely to be unsuitable donors.
Correct Answer
panel reactive antibody, percent reactive antibody, percentage reactive antibody, panel reactive antibodies, percent reactive antibodies, percentage reactive antibodies
Explanation
The correct answer is "panel reactive antibody". The PRA test estimates the percentage of the population that are likely to be unsuitable donors.
23.
How many mismatches are there for the HLA-A locus?
Correct Answer
0, zero, none
Explanation
There are no mismatches for the HLA-A locus. This means that there is a perfect match between the alleles at this specific location.
24.
How many mismatches are there for the HLA-B locus?
Correct Answer
two, 2
Explanation
The HLA-B locus refers to a specific region of the human leukocyte antigen (HLA) gene complex. Mismatches in this locus occur when there are differences between the alleles present in two individuals. The answer states that there are two mismatches for the HLA-B locus, indicating that there are two instances where the alleles between two individuals differ at this specific gene region.
25.
How many mismatches are there for the HLA-DR locus?
Correct Answer
one, 1
Explanation
The HLA-DR locus has one mismatch. This means that there is a difference or variation in one specific region or allele of the HLA-DR gene. This mismatch could be due to a genetic mutation or variation in the DNA sequence of the HLA-DR gene. It is important to note that mismatches in the HLA-DR locus can have implications for organ transplantation and immune responses.