Biochemistry Of Cell Pdf

[Mario Roby]

Ourprogram builds a strong foundation in modern biochemistry and cell biology, while developing critical thought and independence to ensure competitive preparation for a future research career. Formal course work is developed through consultation between the student and an advisory committee of faculty members.Faculty have research expertise in diverse areas including biochemistry, biophysics and structural biology, cancer biology, cell and developmental biology, computational biology, genetics, microbiology, neurobiology, plant biology, signal transduction, and synthetic and systems biology. Entering students conduct three research rotations before selecting a thesis advisor in the second semester.

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Offers research opportunities in structural, functional, and physical studies of macromolecules and macromolecular complexes. The interdisciplinary nature of macromolecular science provides opportunities for collaborations with other departments at the university, including biochemistry and physics.

Offers research opportunities that explore the structure, function, and dynamics of living cells. Using a range of modern cell biological techniques, a strong focus is pulled on both in vitro and in vivo models to understand better cells' structure and function in their natural contexts.

Offers research opportunities that investigate the mechanisms and molecules involved in the embryogenesis of various model organisms. Research in this program focuses on understanding how cells communicate with each other to form tissues, organs, and, eventually, an entire organism.

Offers research opportunities to advance understanding of the mechanisms that control biological function. The program uses biophysical techniques, computational modeling, and other experimental methods to determine how biomolecules are regulated at the highest levels of resolution.

Our faculty members are some of the most distinguished scholars in their fields and work closely with undergraduate students on research projects, independent study courses, or senior thesis projects.

You have probably studied the cell many times, either in high school, or in college biology classes. There are many websites available that review both prokaryotic (bacterial and archeal cell types) and eukaryotic cells (protist, fungi, plant, and animal cell types). All cells have some similar structural components, including genetic material in the form of chromosomes, a membrane bound lipid bilayer that separates the inside of the cell from the outside of the cell, and ribosomes that are responsible for protein synthesis. This tutorial is designed specifically from the viewpoint of chemistry. It explores four classes of biomolecules that are also present in all cell types (lipids, proteins, nucleic acids and carbohydrates) and describes in a simplified pictorial manner where they are found, made, and degraded in a typical eukaryotic, animal cell (i.e. their history). This cell review focuses on the organelle structures common in eukaryotic cells. Subsequent chapters will concentrate on the structure and function of specific biomolecules.

The building and breaking down of life-sustaining chemicals within an organism is known as Metabolism. Overall, the three main purposes of metabolism are: (1) the conversion of food to energy to run cellular processes; (2) the conversion of food/fuel to building blocks for the production of primary metabolites, such as proteins, lipids, nucleic acids, and other secondary metabolites; and (3) the elimination of waste products. These enzyme-catalyzed reactions allow organisms to grow and reproduce, maintain their structures, and respond to their environments.

Figure 1.1 Catabolic and Anabolic Reactions. Catabolic reactions involve the breakdown of molecules into smaller components, whereas anabolic reactions build larger molecules from smaller molecules. Catabolic reactions usually release energy whereas anabolic processes usually require energy.

Figure 1.2 Mechanisms of Enzyme-Substrate Binding. (A) In the Lock and Key Model, substrates fit into the active site of the enzyme with no further modifications to the enzyme shape required. (B) In the Induced Fit Model, substrate interaction with the enzyme causes the shape of the enzyme to change to better fit the substrate and mediate the chemical reaction.

Metabolism is a feature of all cellular life, from the very simplistic prokaryotic cells (Archae and Bacterial cells) to the more complex eukaryotic cells (Fungi, Animal and Plant cells) (Fig. 1.3). Prokaryotic cells and eukaryotic cells are defined by major differences in size and structural features. Prokaryotic cells are simplistic cells that are approximately 1,000 times smaller than their eukaryotic counterparts. All prokaryotes have a single, circular chromosome located in a nucleoid region of the cell, as well as ribosomes that produce proteins that perform cellular metabolic functions. Prokaryotic cells also contain a plasma membrane and external cell wall structure. Some prokaryotes also have cilia or flagella that aid in locomotion.

Figure 1.3 Structure of Prokaryotic and Eukaryotic Cell Types. Depiction of the relative size of a prokaryotic cell (A) which is approximately 1,000 times smaller that a eukaryotic cell (B). All prokaryotic cells contain a chromosomal DNA that is concentrated in a nucleoid, ribosomes, and a cell membrane-cell wall system. Some prokaryotic cells may also possess flagella, pili, fimbriae, and capsules. Eukaryotic cells are much larger than procaryotic cells and require the additional compartmentalization of structures into membrane-bound organelles to mediate metabolic functions.

The design for a cell mostly resides in the blueprint for the cell, the genetic code, which is comprised of deoxyribonucleic acid (DNA) housed in the cell nucleus and a small amount in the mitochondria (Figure 1.5). Of course, the DNA blueprint must be read out or transcribed into ribonucleic acid (RNA) and then translated to proteins by ribozome structures, which themselves were encoded by the DNA and contain a combination of RNA and protein subunits. The genetic code has the master plan that determines the sequence of all cellular proteins, which then perform almost all other activities in the cell, including enzymatic functions, motility, architectural structure, transport, etc. In contrast to DNA, RNA and protein polymers, the formation of the other two major macromolecules (carbohydrates and lipids) are not driven by such a template but rather by the enzymes that catalyzes the synthesis.

Figure 1.5 The Blueprint for Life is Housed in Deoxyribonucleic Acid (DNA). Within eukaryotic cells DNA is localized to two major places within the cell. The first is the nuclear DNA that forms linear chromosome structures (shown on the right). The second is the circular DNA housed in the mitochondria (shown on the left). The mitochonrdial structures replicate independently of the cell and are thought to have originated as prokaryotic symbionts during the early evolution of the eukaryotic cell type.

Many of the chemical constituents of the cell arise not from direct synthesis but from import of both small and large molecules. The imported molecules must pass through the nonpolar lipid bilayer that forms the cell membrane, and in some cases through additional membranes if they need to reside inside membrane-bound organelles. Molecules can move into the cell by two major processes, diffusionor active transport. The process of diffusion moves molecules down their concentration gradient from an area of high concentration to an area of low concentration and does not require an input of energy. Active transport, on the other hand, requires energy to move molecules against their concentration gradient from an area of low concentration to an area of high concentration. Diffusion across the plasma membrane can either be passive or facilitated. In passive diffusion, small, nonpolar molecules (such as CO2 and O2) move across the membrane directly across the membrane (Fig 1.6A). Larger and/or polar molecules move by facilitated diffusion, which requires a channel or carrier protein (Fig 1.6B). Computer simulations of the facilitated diffusion of lactose or water across the membrane are shown at the following links: Animation of lactose diffusion through the LacY protein and Animation of water diffusion through the aquaporin channel, (These animations were created by the Theoretical and Computational Biophysics group at the Beckman Institute, University of Illinois at Urbana-Champaign. These molecular dynamic simulations were made with VMD/NAMD/BioCoRE/JMV/other software support developed by the Group with NIH support.)

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