Unit 3 PCAs Exam Questions With 100% Correct Answers 2024/2025

Unit 3 PCAs Exam Questions With 100% Correct Answers 2024/2025 Antibodies consist of - answertwo identical heavy chains and two identical light chains -antibodies are shaped like a Y Regions of TCRs and BCRs that are particularly variable in their amino acid sequences are known for - answerbinding to an antigen -What happens when amino acid sequences change in a protein? MHC molecules - answerare recognized by T cells -MHC molecules present foreign peptides. Based on your knowledge of MHC I and II, predict which cell type would be MOST likely not to express detectable MHC I. - answererythrocytes -MHC 1 is present on nucleated cells, and RBC have no nucleus Which of the following cell types would be LEAST likely to express MHC class II? - answerT cells -class 2 is expressed on antigen-presenting cells What defines an exogenous antigen? - answerIt is generated outside of the cell then taken into the cell by endocytosis. Which most accurately represents the general order of the steps to antigen presentation? - answerantigen acquisition, antigen breakdown into peptides, encounter of peptides with MHC molecules, binding of peptides to MHC molecules, and display of the peptide-loaded MHC molecules on the cell surface What defines an endogenous antigen? - answerIt is generated within the cell. The human MHC locus is one of the most polymorphic regions of the genome. What does this mean? - answerThere are many different alleles of these genes. -Polymorphisms are genetic variants that result in phenotypic differences. Peptide-binding diversity is increased by - answerboth multiple MHC alleles in the population and multiple homologous MHC genes in the genome. Committed lymphocyte progenitors originate in the - answerbone marrow -all blood cells originate in the bone marrow What term BEST describes a selection process against those cells whose T-cell receptors bind too strongly to self-peptide/MHC combinations? - answernegative selection -negative selection deletes autoreactive cells -"against" implies negative Which of the following molecules would double-negative T cells fail to express? - answerCD4 -Developing T cells have intact antigen processing machinery. Signaling through the pre-TCR occurs as a result of - answersuccessful assembly of the pre- TCR. -does not require ligand binding In negative selection, cells that receive _____ signal through their antigen receptors die. - answera strong -negative selection deletes autoreac