BIOL233 Immune Systems Unit 6 Quiz

Podcast Beta

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary factor that determines whether a lymphocyte becomes a B or T lymphocyte?

Genetic mutations

Cellular energy levels

Anatomical site of development and gene expression (correct)

Environmental factors

Where do B lymphocytes primarily develop?

Bone marrow (correct)

Lymph nodes

Spleen

Thymus gland

Which of the following chains compose the T-cell receptor (TCR)?

Kappa chain and lambda chain

Alpha chain and beta chain (correct)

Beta chain and delta chain

Alpha chain and gamma chain

What is V(D)J recombination primarily associated with?

Generating diversity in Ig and TCR genes Signup and view all the answers

Which of the following is NOT a factor that determines lymphocyte differentiation?

B cell receptor activation Signup and view all the answers

What type of T cells express the α/β T-cell receptor?

CD4 and CD8 T cells Signup and view all the answers

In which stage of lymphocyte development do cell functions begin to change?

During differentiation based on gene expression Signup and view all the answers

Which term describes immature cells capable of giving rise to various cell types in lymphocyte production?

Pluripotent stem cells Signup and view all the answers

What type of receptors do γ/δ T cells express?

T cell receptors Signup and view all the answers

Which of the following statements is true about the structure of T cell receptors (TCRs)?

They are composed of an α-chain and a β-chain. Signup and view all the answers

What is the primary mechanism through which lymphocytes generate a diverse repertoire of receptors?

V(D)J recombination Signup and view all the answers

Which of the following loci is NOT involved in the encoding of immunoglobulin heavy chains?

Ig delta locus Signup and view all the answers

How many gene segments roughly encode T cell receptors and immunoglobulins?

300 different gene segments Signup and view all the answers

What segments are required for the construction of the Ig k-light chain?

Ck, Vk, and Jk gene segments Signup and view all the answers

Which characteristic distinguishes the receptors on B cells from those on T cells?

B cells express immunoglobulins. Signup and view all the answers

Which of the following statements regarding receptor diversity in lymphocytes is accurate?

B and T cells generate receptors for different antigens. Signup and view all the answers

What is excised during the process of forming the k-chain in B cells?

Looped DNA Signup and view all the answers

Which regions of the antibody variable region are responsible for antigen-binding specificity?

Complementarity Determining Regions Signup and view all the answers

What segment contributes to the formation of CDR3 in immunoglobulin heavy chains?

Parts of V, D, and J segments Signup and view all the answers

What type of light chain contains 30 functional genes and produces structurally identical proteins?

Ig λ-light chain Signup and view all the answers

How many constant region genes are present for the heavy chain in humans?

9 Signup and view all the answers

What is the basic organizational similarity between TCR genes and immunoglobulin genes?

Both use V, D, and J gene segments Signup and view all the answers

In TCR α genes, which regions are primarily coded for by the V genes?

CDR1 and CDR2 Signup and view all the answers

What defines the distinguishing feature of the TCR β chain variable region?

Involves multiple segments including V, D, and J Signup and view all the answers

Study Notes

Lymphocyte Development and Production

Lymphocytes are white blood cells divided into B lymphocytes and T lymphocytes.
Formation occurs from pluripotent stem cells in the bone marrow, guided by lymphoid progenitor cells.
Lymphocyte identity as B or T cells is determined by anatomical site (bone marrow for B cells, thymus for T cells) and gene expression changes during differentiation.

B and T Lymphocyte Development Stages

B lymphocyte development occurs entirely in the bone marrow, while T lymphocyte development involves migration to the thymus.
Three types of T cells exist: CD4 T cells and CD8 T cells (both expressing the α/β TCR) and γ/δ T cells (expressing the γ/δ TCR).

Lymphocyte Receptor Genes

B cells generate immunoglobulins (Igs), and T cells produce T cell receptors (TCRs) to recognize diverse antigens.
Each receptor must exhibit unique antigen specificities, aggregating a vast repertoire.

Gene Segment Composition

Igs consist of 2 heavy chains and 2 light chains, while TCRs comprise an α-chain and β-chain.
Approximately 300 different gene segments code for the receptors, allowing for the production of 10^9 to 10^14 unique surface receptors.

V(D)J Recombination

This genetic mechanism enables lymphocytes to rearrange gene segments, enhancing receptor diversity.
Each precursor cell undergoes rearrangement resulting in specific immunoglobulin or TCR gene assembly.

B-Lymphocyte Receptor Genes Structure

Igs contain variable (V) and constant (C) regions, encoded by three loci: heavy locus (chromosome 14), kappa locus (chromosome 2), and lambda locus (chromosome 22).
K-light chain is structured with a single constant region and a variable region formed by numerous gene segments, enabling diverse antigen binding.

K-Light Chain Rearrangement

DNA segments fold and join via excision, leading to rearrangement and formation of the primary mRNA transcript, ultimately translated into a protein.

Antigen Binding Specificity

Igs possess three Complementarity Determining Regions (CDRs) critical for binding specific antigens, particularly CDR3 influenced by V and J segments.
λ-light chains, while structurally similar to k-light chains, have different numbers of functional genes and segments.

Heavy Chain Gene Rearrangement

Variable regions of heavy chains are encoded by segments similar in organization to the k-light chain, including additional D segments.
Two rearrangements occur: joining one D segment to one J segment, then one V segment to one D segment, influencing antibody class.

T-Lymphocyte Receptor Genes Overview

TCR genes, encoding for α and β chains, exhibit a cloning structure akin to Ig genes, enabling similar V(D)J rearrangements.
TCR α gene includes one C region and numerous V and J gene segments, whereas TCR β gene consists of V, D, and J segments, with corresponding constant region genes.

Diversity of Antigen Specificity

The extensive genetic diversity in both B and T lymphocyte receptor genes ensures the immune system can recognize and respond to an ordinary spectrum of pathogens.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Test your understanding of lymphocyte development, gene organization, and expression as covered in BIOL233. This quiz focuses on lymphocyte production, receptor genes, and the diversity of immunoglobulins and T-cell receptors. Prepare to delve into regulatory mechanisms and gene rearrangement in this essential topic of immune systems.