Drew E. Cressman

The Sara Yates Exley Chair in Teaching Excellence

on leave Fall 24

BA, Swarthmore College. PhD, University of Pennsylvania. Special interest in the molecular basis of gene regulation and the control of gene expression; specifically focused on the control of antigen-presenting genes of the immune system and the subcellular localization of the regulatory protein CIITA; author of papers on mammalian liver regeneration and CIITA activity; recipient of grants from the Irvington Institute for Biomedical Research and the National Science Foundation. SLC, 2000–

Undergraduate Courses 2024-2025

Biology

Advanced Cell Biology: Regulation of Cell Function

Advanced, Seminar—Spring

BIOL 4025

Prerequisite: Genetics, Cell Biology, or equivalent course

The wide variety of ways that different cells can respond to changes in their environment results from differences in the timing and level of expression of various gene and proteins, which collectively are responsible for modulating differences in cellular activity. Much of the regulation of gene function occurs at the level of DNA activity (transcription); and, indeed, it has been estimated that 10 percent of all human genes encode transcription factors responsible for this level of regulation. Because of the complexity of the cell and its critical need to maintain normal cellular function in a variety of environments, however, multiple mechanisms in addition to transcription-factor activity have evolved to modify and control cell activity. A fundamental goal in biology, therefore, is to understand this assortment of molecular mechanisms used by cells to regulate gene expression and subsequent cell function. In this course, we will focus on these various mechanisms, examining regulatory events at the level of transcription, translation, receptor activity and signal transduction, determination of cell fate, and the modification and localization of intracellular proteins. Once we understand how cells regulate their function, we can begin to imagine ways in which we may intervene to modify specific cell activities as well as how specific chemicals and compounds alter these regulatory mechanisms to the detriment of the cell. No textbooks are used in this course; instead, all topics and readings are drawn from recently published, peer-reviewed, scientific articles.

Faculty

Human Genetics

Open, Lecture—Spring

BIOL 2027

The formation of an individual’s life is dependent upon a complex mix of cultural experiences, social interactions, and personal health and physiology. At the center of this intricate web is the biological component unique to each of us, yet shared in some form by all life on earth—our genes. Genes contribute much to what makes each of us an individual, from hair color and body shape to intelligence and personality. In this course, we will attempt to gain an understanding of how genes and chromosomes provide the basic blueprint that leads to these unique physical and behavioral characteristics. In doing so, we will discuss the central concepts of human genetics, including: the mechanisms and patterns of inheritance, sex-linked traits, the genetics of behavior, how genes encode information in the form of DNA, the role of mutations in causing disease, human origins and evolution, and the application of various genetic technologies such as gene therapy and genetically modified organisms. Readings will be drawn from texts as well as current popular-press and peer-reviewed articles. No previous background in biology is required, other than a curiosity and desire to understand the genetic mechanisms that shape human existence and make us who we are.

Faculty

Previous Courses

Biology

Advanced Cell Biology

Advanced, Seminar—Spring

The different kinds of cells in an organism—and the different ways that any cell can respond to changes in its environment—result from differences in the timing and level of expression of various genes that are responsible for their different cellular activity. Therefore, a fundamental question in biology is to understand the mechanisms used by cells to regulate gene expression and subsequent cell function. Most regulation of gene function occurs at the level of DNA activity (transcription), and it has been estimated that 10% of all human genes encode the transcription factors responsible for this level of regulation. Because of the complexity of the cell and the critical need to maintain normal cell function in a variety of environments, however, multiple mechanisms have evolved to modify and control cell activity. In this course, we will focus on these various mechanisms, examining regulatory events at the level of transcription, translation, receptor activity and signal transduction, determination of cell fate, and the modification and localization of intracellular proteins. Once we understand how cells regulate their function, we can begin to imagine ways in which we may intervene to modify specific cell activities, as well as how specific chemicals and compounds alter those regulatory mechanisms to the detriment of the cell.

Faculty

Biology of Cancer

Intermediate, Seminar—Fall

Cancer is likely the most feared and notorious of human diseases, being devastating in both its scope and its prognosis. Cancer has been described as an alien invader inside one’s own body, characterized by its insidious spread and devious ability to resist countermeasures. Cancer’s legendary status is rightfully earned, accounting for 13% of all human deaths worldwide and killing an estimated eight million people annually. In 1971, President Richard Nixon declared a “war on cancer”; since then, more than $200 billion has been spent on cancer research. While clinical success has been modest, tremendous insights have been generated in understanding the cellular, molecular, and genetic mechanisms of this disease. In this course, we will explore the field of cancer biology, covering topics such as tumor viruses, cellular oncogenes and tumor suppressor genes, cell immortalization, multistep tumorigenesis, cancer development and metastasis, and the treatment of cancer. In addition, we will discuss new advances in cancer research and draw from recent articles in the published literature.

Faculty

Cell Biology

Intermediate, Seminar—Spring

Cells are the most basic unit of life on the planet. All life forms are simply conglomerations of cells, ranging from the individual bacterial cells to the higher order plants and animals. Humans, themselves, are made up of trillions of cells. So what exactly is a cell? What is it made of? How does it function? In a complex organism, how do cells communicate with one another and coordinate their activities? How do they regulate their growth? What role do genes play in controlling cellular function? This course will address these questions and introduce the basic biology of cells while keeping in mind their larger role in tissues and organs. If we can understand the structures and functions of the individual cells that serve as the subunits of larger organisms, we can begin to understand the biological nature of humans and other complex life forms.

Faculty

First-Year Studies: Conflicts in Biology

Open, FYS—Year

As the frontiers of science are pushed forward, conflicts naturally emerge between new hypotheses and established ideas. Biology is no exception to this rule. Since the time of the ancient Greeks, new proposals examining the biological nature of humans and the living world have initially met with resistance and even ridicule before becoming established as modern paradigms. What appears obvious now was once regarded as revolutionary, while it is conceivable that current ideas one day will be regarded as bordering on the absurd. Oftentimes, these conflicts arise not only due to the convergence of scientific principles but also result from personality clashes of the individuals involved in the research area. Paradigm shifts have occurred in a variety of biological fields, ranging from early ideas on heredity, sex determination, and evolution to more recent advances in prion and mad cow diseases, animal model usage, genetic engineering, cutting-edge cancer therapies, and the interplay between genes and environment. Using these and other examples, we will examine the progress of biological thought and the persistence of the scientific method in changing our understanding of life. During the fall semester, students will meet weekly with the instructor for individual conferences. In the spring, we will meet weekly or every other week, depending on students’ needs and the progress of their conference projects.

Faculty

Forensic Biology

Open, Seminar—Spring

From hit television shows such as CSI, Bones, and Forensic Files to newspaper headlines that breathlessly relate the discovery of a murder victim’s remains...and to Casey Anthony, JonBenet Ramsey, and other real-life cases, it is clear that the world of forensic science has captured the public imagination. Forensic science describes the application of scientific knowledge to legal problems and encompasses an impressively wide variety of subdisciplines and areas of expertise, ranging from forensic anthropology to wildlife forensics. In this course, we will specifically focus on the realm of forensic biology—the generation and use of legally relevant information gleaned from the field of biology. In an effort to move beyond sensationalism and the way forensic biology is portrayed in the public media, we will explore the actual science and techniques that form the basis of forensic biology and seek to understand the use and limitations of such information in the legal sphere. Beginning with the historical development of forensic biology, selected topics will likely include death and stages of decomposition; determination of postmortem intervals; the role of microorganisms in decomposition; vertebrate and invertebrate scavenging; wound patterning; urban mummification; biological material collection and storage; victim and ancestral identification by genetic analysis; the use of DNA databases such as CODIS; and the biological basis of other criminalistics procedures, including fingerprinting and blood type analysis. Finally, we will consider DNA privacy and US Supreme Court rulings, including the 2013 decision Maryland v. King, which established the right of law enforcement to take DNA samples from individuals arrested for a crime. In all of these areas, the techniques and concepts employed are derived from some of the most fundamental principles and structure/function relationships that underlie the entire field of biology. No background in biology is required; indeed, a primary objective of this course is to use our exploration within the framework of forensic biology as a means to develop a broader and more thorough understanding of the science of biology.

Faculty

General Biology Series: Genes, Cells, and Evolution

Open, Lecture—Fall

Biology, the study of life on Earth, encompasses structures and forms ranging from the very minute to the very large. In order to grasp the complexities of life, we begin this study with the cellular and molecular forms and mechanisms that serve as the foundation for all living organisms. The initial part of the semester will introduce the fundamental molecules critical to the biochemistry of life processes. From there, we branch out to investigate the major ideas, structures, and concepts central to the biology of cells, genetics, and the chromosomal basis of inheritance. Finally, we conclude the semester by examining how those principles relate to the mechanisms of evolution. Throughout the semester, we will discuss the individuals responsible for major discoveries, as well as the experimental techniques and process by which such advances in biological understanding are made. Classes will be supplemented with weekly laboratory work.

Faculty

General Biology: Genes, Cells, and Evolution

Open, Small Lecture—Fall

Biology, the study of life on Earth, encompasses structures and forms ranging from the very minute to the very large. In order to grasp the complexities of life, we begin this study with the cellular and molecular forms and mechanisms that serve as the foundation for all living organisms. The initial part of the semester will introduce the fundamental molecules critical to the biochemistry of life processes. From there, we branch out to investigate the major ideas, structures, and concepts central to the biology of cells, genetics, and the chromosomal basis of inheritance. Finally, we conclude the semester by examining how those principles relate to the mechanisms of evolution. Throughout the semester, we will discuss the individuals responsible for major discoveries, as well as the experimental techniques and process by which such advances in biological understanding are made. Classes will be supplemented with weekly laboratory work. This course serves as the gateway course into the biology department curriculum.

Faculty

Genetics

Sophomore and Above, Seminar—Spring

Prerequisite: completion of AP Biology or an equivalent course

At the biological core of all life on Earth is the gene. The unique combination of genes in each individual ultimately forms the basis for that person’s physical appearance, metabolic capacity, thought processes, and behavior; therefore, in order to understand how life develops and functions, it is critical to understand what genes are, how they work, and how they are passed on from parents to offspring. In this course, we will begin by investigating the theories of inheritance first put forth by Mendel and then progress to our current concepts of how genes are transmitted through individuals, families, and whole populations. We will also examine chromosome structure and the molecular functions of genes and DNA— and how mutations in DNA can lead to physical abnormalities and diseases such as Trisomy 21, hemophilia, or others. Finally, we will discuss the role of genetics in influencing such complex phenotypes as behavior or traits such as intelligence. Classes will be supplemented with weekly laboratory work.

Faculty

Human Genetics

Open, Lecture—Fall

The formation of an individual’s life is dependent upon a complex mixture of cultural experiences, social interactions, and personal health and physiology. At the center of this intricate web lies the biological components unique to each of us, yet shared in some form by all life on Earth—our genes. Genes contribute much to what makes each of us an individual, from hair color and body shape to intelligence and personality. Such genes and traits are inherited from our parents, yet environmental factors can profoundly influence their function in different individuals. Stunning advancements in the field of genetics are reported every day, from the identification of new genes for particular traits to the development of gene-based tests for human diseases. But what exactly are genes, and how do they work in humans? In this course, we will explore how genes and chromosomes provide the basic blueprint that leads to our unique physical and behavioral characteristics. In doing so, we will discuss the central concepts of human genetics, including: the mechanisms and patterns of inheritance, sex-linked traits, the genetics of behavior, DNA and proteins, the role of mutations in causing disease, human origins and evolution, and the application of various technologies such as gene therapy and genetic engineering. Readings will be drawn from texts, as well as from current popular-press and peer-reviewed articles. No previous background in biology is required other than a curiosity and desire to understand the genetic mechanisms that shape human existence and make us who we are.

Faculty

Virology

Advanced, Seminar—Spring

Prerequisite: completion of college-level course work in biology and/or chemistry

Viruses are some of the smallest biological entities found in nature—yet, at the same time, perhaps the most notorious. Having no independent metabolic activity of their own, they function as intracellular parasites depending entirely on infecting and interacting with the cells of a host organism to produce new copies of themselves. The effects on the host organism can be catastrophic, leading to disease and death. HIV has killed more than 18-million people since its identification and infected twice that number. Ebola, West Nile, herpes, and pox viruses are all well-known yet shrouded in fear and mystery. During the course of this semester, we will examine the biology of viruses by discussing: their physical and genetic properties; their interaction with host cells; their ability to commandeer the cellular machinery for their own reproductive needs; the effects of viral infection on host cells; and, finally, how viruses and other subviral entities may have originated and evolved. In addition, we will examine how viruses have been discussed in the primary research literature and other media, with readings drawn from Laurie Garrett’s The Coming Plague and others.

Faculty

Viruses and Pandemics

Open, Seminar—Fall

Ebola, smallpox, influenza, rabies...these and other viruses are the smallest lifeforms on Earth, yet they are one of the most powerful and devastating biological forces ever unleashed. Throughout human history, virally-caused pandemics have periodically ravaged human populations—altering the social fabric, confounding political and medical responses, and revealing the fragility of the human species. Examples range from the Antonine Plague, which killed five-million people during the time of the Roman empire, to the 15-million deaths during the Cocoliztli epidemic of the 1600s in Mexico and Central America, to the Spanish flu pandemic of the early 20th century that claimed an estimated 50- to 100-million victims. The current COVID-19 pandemic has reminded the world of the dominance of viruses and exposed the challenges of confronting these microscopic pathogens on a global scale. This course will examine the biology and behavior of viruses, the role of such pathogens in inducing different pandemics throughout the course of history, and the means by which they can rapidly spread through a population. We will explore how vaccines, quarantines, and other medical, social and political responses work to mitigate and eventually overcome viral outbreaks, as well as how we track down and study pathogenic viruses. During the course, we will consider the representation of viruses through readings drawn from texts such as Richard Preston’s The Hot Zone, John Barry’s The Great Influenza, and C. J. Peters’ Virus Hunter.

Faculty