BIOB50-Chapter 1

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University of Toronto Scarborough
Biological Sciences
Rene Harrison

BIOB10 Chapter 1 Chapter 1 Introduction to the Study of Cell and Molecular Biology 1.1 The Discovery of Cells  Microscope: an instrument that provides a magnified image of a tiny object o Discovery unknown  Robert Hooke: English microscopist who discovered the cell while studying cork  Anton van Leeuwenhoek: Dutchman who earned a living selling clothes and buttons o Constructed microscopes of higher quality o Examined drop of pond water under microscope and called what he observed ‘animalcules’  These ‘animalcules’ darted back and forth o Described various forms of bacteria  Matthias Schleiden: German lawyer who became a botanist o Said that although variance in structure of various tissues, plants were made of cells and that the plant embryo arose from a single cell  Theodor Schwann: German zoologist published a report on cellular basis of animal life o Concluded that the cells of plants and animals are similar structures and proposed two components of cell theory  Cell theory: o All organisms are composed of one or more cells o The cell is the structural unit of life  Rudolf Virchow: German pathologist wrote third part of cell theory o Cells can arise only by division from a preexisting cell  FIGURE 1 - PAGE 2 1.2 Basic Properties of Cells  Life is the most basic property of cells, cells are the smallest unit to exhibit this property  FIGURE 2 – PAGE 3: HeLa cells were the first human cells to be kept in culture for long periods of time o These cells are cancerous and can be cultured indefinitely as long as conditions are favorable  Parts of a cell deteriorate, whole cells can be removed from organism and cultured in a lab where they can grow and reproduce for extended periods o May die if mistreated  Death is most basic property of life  Cells within body generally die by their own hand  victims of internal program that causes cells no longer needed or are dangerous to eliminate themselves  In vitro: grown in culture, outside the body Cells are Highly Complex and Organized  Complexity: refers to order and consistency  The more complex a structure is, the greater the number of parts that must be in their proper place o Less tolerance of errors in the nature and interactions of the parts o More regulation or control that must be exerted to maintain the system  Atoms  small – sized molecules  organization of diff. types of polymeric molecules into complexes  organized into subcellular organelles and finally into cells o At each level there is consistency and all the organelles have a particular shape and location o Each type of organelle has a consistent composition of macromolecules arranged in a predictable pattern BIOB10 Chapter 1  Species that seem different are actually very similar in the cells that make up their tissues and organelles that make up their cell  Many of the most basic processes (ex. Synthesis of proteins) are very similar in all living organisms Cells Possess a Genetic Program and the Means to Use It  Organisms are built according to info encoded in a collection of genes o All this info is packaged into chromosomes that occupy the space of a cell nucleus  Genes constitute blueprints for constructing cellular structures, directions for running cellular activities, program for making more of themselves  Molecular structure of genes allows for changes in genetic info (mutations) that lead to variation among individuals which forms basis of biological evolution Cells Are Capable of Producing More of Themselves  Cells reproduce by division o Mother cell’s contents are distributed into two daughter cells o Before division, genetic material is duplicated and each daughter cell receives an equal share of genetic info  Sometimes, the sharing is not equal and one of the cells will retain all the cytoplasm and only half the genetic material Cells Acquire and Utilize Energy  Every biological process requires input of energy  Most energy is from the sun in the form of electromagnetic radiation  Energy of light is trapped by light-absorbing pigments present in the membranes of photosynthetic cells  Light energy is converted by photosynthesis into chemical energy that is stored in energy- rich carbs (sucrose, starch)  Animals receive energy in the form of sugar glucose  Humans – glucose is released by liver into the blood where it circulates through body delivering chemical energy to all cells o Once in cell, glucose is disassembled and stored as ATP (usually) Cells Carry Out a Variety of Chemical Reactions  Many chemical transformations happen in the most simplest of cells  All chemical changes hat take place in cells require enzymes  Enzymes: molecules that greatly increase the rate at which a chemical reaction occurs  Metabolism: sum total of chemical reactions in a cell Cells Engage in Mechanical Activities  Materials are constantly transported from place to place, structures are assembled and then disassembled  The entire cell can sometimes move itself  Change in the shape of motor proteins usually initiate these mechanical changes Cells Are Able to Respond to Stimuli  Cells are covered with receptors that interact with substance in the environment  Receptors respond to hormones, growth factors, extracellular material  Receptors provide pathways through which external agents can evoke specific responses in target cells  Response to these receptors include: altering metabolic activities, moving, committing suicide Cells Are Capable of Self-Regulation BIOB10 Chapter 1  READ AGAIN – page 6 Cells Evolve  Organelles of complex cells show similarities to ancestral organism (plasma membrane, ribosome) 1.3 Two Fundamentally Different Classes of Ce
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