16: Viruses, Cancer, and the Immune System
- Page ID
- 16197
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)At this point, you should be fairly comfortable with the basic concepts of cell biology. The purpose of this chapter is to build on that basic knowledge and put it together into more complex systems. In addition, we will introduce some more advanced variations on some of the mechanisms and structures that were discussed in earlier chapters. The three topics, viruses, cancer, and immunity, are not only relevant as current news topics, but relate to one another through multiple pathways, which is why they are lumped together.
- 16.1: Viruses
- This page discusses the nature of viruses as non-living entities made of genetic material and proteins that require host cells for replication. It covers their genome types (RNA or DNA), structural forms (helical or icosahedral), and the presence of viral envelopes. Classification systems like ICTV and Baltimore are mentioned. Additionally, it introduces viroids, which are smaller RNA-only infectious agents that mainly affect plants.
- 16.2: Viral Life Cycles
- This page discusses the life cycles of viruses, highlighting the lytic cycle, which destroys host cells, and the lysogenic cycle, which allows for viral DNA integration into the host genome. It notes the differences between bacteriophages and eukaryotic viruses, like HIV, which also use integration.
- 16.3: Cancer
- This page explains that cancer is a genetic disease marked by uncontrolled cell growth due to mutations in somatic cells. It differentiates between benign and malignant tumors, noting that malignant tumors can spread, complicating treatment. Cancerous cells exhibit different organization and differentiation compared to normal cells. Understanding the mechanisms of cancer and specific mutations is essential for treatment, and early detection plays a critical role in improving survival rates.
- 16.4: Oncogenes
- This page discusses oncogenes, which result from dominant gain-of-function mutations in protooncogenes, leading to unchecked cell proliferation. Mechanisms of these mutations include coding region alterations, gene duplications, regulatory mutations, and translocations that form chimeric proteins. It also highlights that retroviral infections can enhance oncogene expression by integrating viral DNA near protooncogene promoters.
- 16.5: Tumor Suppressor Genes
- This page discusses the vital role of tumor suppressor genes in regulating the cell cycle and promoting DNA repair or apoptosis to prevent cancer. It highlights how mutations in BRCA1 and BRCA2 affect DNA repair, while the loss of p53 increases the risk of replicating damaged DNA. The loss of function in tumor suppressor genes is usually recessive, allowing one functional copy to prevent cancer, but typically, additional mutations are needed for cancer development.
- 16.6: Human Cancers
- This page explores the connection between specific mutated genes and various cancers, identifying distinct links for some oncogenes and tumor suppressor genes. It categorizes cancers by tissue origin, emphasizing carcinomas. Key relationships noted include retinoblastoma with the RB gene, breast cancer with BRCA mutations, and the prevalence of lung cancers associated with oncogenes and smoking. However, prostate cancer's genetic associations remain ambiguous.
- 16.7: Metastasis
- This page discusses the challenges of metastasis in cancer treatment, highlighting how it worsens prognosis and necessitates systemic therapy. Localized treatments target early tumors, while metastatic cells evade immune responses. Standard anti-cancer drugs can damage healthy tissues, prompting the development of innovative therapies like anti-angiogenesis drugs.
- 16.8: The Immune System
- This page provides an introduction to fundamental immunology concepts essential for cell biology students. It explains the immune system's adaptability through two responses: the innate response, which is nonspecific and common to all animals, and the adaptive response, specific to vertebrates. Key components include defensins, complement proteins, natural killer cells, antibodies produced by B cells, and T-cells.
- 16.9: DNA Rearrangement
- This page explains the processes that generate diversity in B cells and T cells, highlighting DNA rearrangement through V(D)J recombination, facilitated by RAG1 and RAG2, creating trillions of receptor combinations. Somatic hypermutation further enhances antibody variation.
Thumbnail: Ebola virus. (Public Domain; CDC).