Welcome to the Biology program. Faculty and laboratories in BBE and affiliated programs at Caltech provide outstanding opportunities to carry out creative and innovative work in fundamental, translational, and applied research across a broad spectrum of life sciences. The Biology graduate program provides each student with the opportunity to pioneer cutting-edge research and to take advanced major and cross-disciplinary course work, providing well-rounded and integrated training in biology, along with specialized instruction in areas of particular interest. Explore the menu for details about the program, faculty interests, specializations and admissions.
Laboratories in this research area are broadly interested in molecular mechanisms underlying DNA replication, DNA repair, gene expression, regulation of cell division, protein trafficking, protein degradation, cell-cell interaction, and synapse formation. The approaches used include structural, biochemical, and single-molecule approaches to understand the function and regulation of individual protein and RNA molecules, molecular pathways and circuits.
Biophysics is an interdisciplinary science involving the application of the methods and ideas of physics to the study of biological systems. It spans biological scales from quantum-mechanical descriptions of enzyme catalysis to musculoskeletal models of kinesiology to global environmental analyses. Building on Caltech's rich history and deep present expertise in both physics and biology, the Biophysics track offers students rigorous education in the fundamentals as well as world-class research opportunities. Strong investments in instrumentation have given Caltech faculty and students access to the dedicated Caltech/Stanford X-ray beamline at SLAC, state-of-the-art cryoelectron microscopes, and a suite of MRI systems, among other systems. Faculty from multiple Divisions offer a broad range of research opportunities to interested students.
Cell biology involves study of the structure and function of cells, the minimal self-sustaining units of life. To understand living systems, one must illuminate the principles that underlie the structure, function, and propagation of individual cells. For example, how do cells grow and divide, how do new cells assemble their components, and how do assembled cells renew their components throughout the life of an organism? Other questions include the issues of how cells communicate through signaling mechanisms and how these signals influence the function and behavior of cells. Studies of human diseases typically involve, at least in part, a characterization of how biological processes have gone awry at the cellular level. The environment at Caltech offers a rich opportunity for research into the current pressing questions of modern cell biology.
The antedisciplinary science of computational biology transcends traditional domains in the physical, mathematical and biological sciences to tackle fundamental questions about biological systems and the interpretation of biological data. Within the division of Biology and Biological Engineering at Caltech, computational biology questions that form the focus of current research efforts include how to model and understand the role of protein structures, how to interpret and analyze genomics data, and what are the best ways to perturb and control biological systems to reveal their form and function. The computational biology faculty have expertise in physics, statistics, mathematics, and computer science, and both students and faculty interface regularly with other departments and divisions across campus, resulting in a fertile research environment.
Developmental biology focuses on how organisms arise from single cells. The process starts with the fertilized egg, which has the ability to generate all cell types in the body, and continues with the formation of complex structures like the nervous system, limbs, and heart. Studies in developmental biology utilize a broad toolkit that combines classical experimental embryology with modern approaches, including transcriptomics, epigenomics, proteomics and high resolution imaging, to tackle fascinating questions of how multicellular organisms develop and evolve. By spanning model systems from invertebrates to vertebrates and plants, work at Caltech not only provides deep basic science insights for understanding development and evolution, but also is directly relevant to stem cell biology, congenital birth defects and many diseases.
Evolution is the unifying thread that runs through all of biology. All heritable features of biological entities - the sequences of genes or the properties of proteins, viruses, cell types, body plans or organismal societies - are subject to descent with modification. Evolutionary biology is the study of patterns of variation among these entities and the processes that generate their rich diversity. At Caltech, many labs pursue mechanistic studies of evolution at different levels of biological organization. These include studies of gene regulation across species, comparative genomics and transcriptomics, structural evolution of proteins, macromolecular complexes and viruses, the emergence of new body plans, and the neural basis of behavioral evolution. Evolution is also studied in biomedical contexts, such as bacterial resistance to antibiotics, and is harnessed for bioengineering purposes via the directed evolution of enzymes with useful properties.
Genetics underlies all of biology and much biological inquiry. We build on the rich history of Caltech geneticists such as Morgan, Beadle, Delbruck, Benzer, Wood, Lewis and Hood, who laid the foundations of our understanding of genes, genetic pathways and genome sequences, to modern developmental and behavioral genetics using flies, worms, mice, yeast, plants and zebrafish. This work is essential to elucidate the genetic control of development, physiology and behavior. In addition to these model organisms, modern genomics and genome editing methods make almost any organism amenable to genetic analysis. The goal of Genetics education at Caltech is to train students to understand and apply a range of genetic concepts, from genome informatics to pathway and network analysis. We use genetics to study development, cell biology, organismal physiology, behavior and ecosystems.
Immunology covers the macromolecules that define the boundary between an organism's "self", its commensals, and its environment; the developmental programming of cells that detect and respond to danger; and the impact of these cells and molecules on an organism's health. This field is often considered a discrete specialty in biomedical research, but at Caltech, immunology is treated as a complex biological system in which the roles of crucial components can be dissected and revealed by the system's performance under dynamic challenge. Caltech immunologists focus on areas where immunology is most illuminated by being viewed in a broader biological context, with strong synergy with research in developmental biology, structural biology, neurobiology and microbiology. This gives Caltech immunologists unusually strong access to new perspectives, technologies and approaches outside of the conventional boundaries of immunology.
Caltech's version of microbiology is unique. Faculty from several divisions seek to understand microbial systems at various spatial and temporal scales: from the molecular to the global, and from the present to the past. We recognize and celebrate that microbes have profoundly shaped every aspect of the biosphere and geosphere. We work with model microbes to explore diverse subjects, ranging from basic biology and biochemistry, to the understanding of physical principles governing biological systems, to emerging questions of robustness, stability, and design in complex networks. We also seek to understand how microbes behave within populations and communities, as well as how microbial communities impact their environments. Our research includes studies of pathogenic and non-pathogenic viruses, and use the tools of molecular biology, cell biology, physiology, and systems biology to understand how viruses enter cells, make copies of themselves, and emerge from cells to infect more hosts, all while evading the host immune response. Finally, Caltech microbiologists seek to leverage the metabolic versatility of microbes as engineering components to solve societal problems.
The field of molecular biology explores how the molecules of life contribute to biological processes. These molecules include DNA, RNA, and proteins, as well as lipids and carbohydrates. Representative areas of study at Caltech include signal transduction, protein degradation, DNA replication, transcriptional regulation, small RNAs, genomic stability, protein folding, immunological recognition, cytoskeletal structure, mitochondrial dynamics, protein trafficking, and organelle assembly. Experimental systems range from the simplest bacteria to the most complex vertebrate cells. Caltech laboratories mostly address the basic mechanisms underlying these processes, but these studies often have profound implications for human health and disease. The strength of Caltech in chemistry, physics, engineering, and computer science provides a fertile environment for interdisciplinary approaches to molecular biology.
Neurobiologists at Caltech pursue fundamental questions in neuroscience, from molecules that mediate the development and function of individual cells in the nervous system, to mechanisms that underlie various sensory modalities, to neural circuits that regulate behavioral and organismal states. Neurobiological research at Caltech includes basic research to uncover key principles that underlie neuronal function and behavior, development of technologies that enable novel experimental approaches, and exploration of mechanisms that cause disorders of the nervous system. This research is pursued using many animal models, including jellyfish, nematodes, fruit flies, leaches, beetles, lamprey, zebrafish, birds, rodents, and humans. The diverse and interdisciplinary nature of neurobiology research at Caltech provides an outstanding environment for students to develop a broad understanding of the nervous system and also expertise in the most exciting and important questions in the field.
Stem Cell Biology
Stem cells are crucial in the development and maintenance of multicellular organisms as they have the potential to develop into a wide range of differentiated cell types. Embryonic stem cells (ESCs) have the potential to develop into all parts of the body and at Caltech they are cultured alongside extra-embryonic stem cells to generate synthetic embryo-like structures. ESCs can also be grown under a variety of conditions to enable them to develop into pure populations of almost any cell type, a strategy with huge potential in regenerative medicine. We also study adult stem cells with more restricted developmental potential and so able, for example, to develop into all types of blood cells, or into all of the cell types of the liver, pancreas or gut. These cells can be cultured independently or as tissue organoids, which are invaluable to study functions of the organs they represent.
Structural biology is the study of how biological molecules are built. Understanding a molecule's three-dimensional shape can provide enormous insight to its function. But determining a molecular structure is only just the beginning; structural biology is at its core really about interpreting structures. To do this requires an interdisciplinary strategy that relies on imaging, chemistry, and biophysics to understand how complexes work at a molecular level. With increasingly powerful structural prediction algorithms combined with technical advances in cryoelectron microscopy and cryoelectron tomography, we are entering a new and exciting era of structural biology. The resources, expertise, and collaborative environment of Caltech position it at the forefront of the structural biology field.
At the start of the 21st century, after the sequencing of the human genome, we found ourselves with a new problem: biological systems are far more complex than we had previously reckoned. Even the smallest microbe has almost 200 genes. In the face of such staggering complexity, how can we understand how to build a cell, an animal, or an ecosystem? This is the grand challenge of Systems Biology, to use what we have learned about the parts—genes, proteins, or cells—toward understanding how these parts self-organize to produce functions, behaviors, and adaptations that underlie the resilience of living systems. To tackle such complexity, the Systems Biology program at Caltech aims to train the next generation of biologists to integrate biological approaches with tools and concepts from fields that have traditionally dealt with complex systems, including engineering, computer science, mathematics, chemistry, and physics.