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Midterm Notes.docx

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Western University
Biology 1201A
Richard Gardiner

Biology Midterm Notes Characteristics of Living things 1 Organisms tend to be complex and highly organized 2 Living organisms have the ability to take energy from the environment and change it form one for to another 3 Organism tend to be homeostatic they regulate their bodies and other internal structures to certain normal parameters 4 Living creatures respond to stimuli 5 Living things reproduce themselves by making copies of themselves 6 Organisms tend to grow and develop 7 Life adapts and evolves in step with external changes in the environment A Tour of the CellAnthony van Leeuwenhoek created a single lens microscope in 1673Robert Hooke first person to coin the word cell to describe the tiniest components of living systems 16351703 he saw the cells of plants from corkThe Electron Light Microscope resolution limit is about 02 microns size of a small bacterium 1 micron is 0001mm magnification limit of about 1000 times in 1950s the introductions of the electron microscope enabled us to see organelles viruses proteins etcThe Transmission Electron Microscope or TEMThe Scanning Electron Microscope or SEMCell Fractionation take cells apart to study their components centrifuge is used to fractionate cells and separate their major organelles machine that uses perpendicular force to separate denser from lighter ultracentrifuges are capable of speeds as fast as 150000 rpm applying forces over 1 million times the force of gravityThe Cell simplest collection of matter which has all the properties of life o Lowest hierarchical level which is alive o Cell is basic unit of life o Cell performs all functions necessary to live and reproduceVirus occur in virtually every kind of organism some wreck havoc others cause no disease or outward sign of their presence often highly specific to host can reproduce only when they enter a cellProkaryotic Cells pro before and karyote nucleus bacteria cyanobacteria mycoplasmas no nucleus genetic information in area called nucleoid visible components plasma membrane cell wall pili flagella mesosomes photosynthetic membranesBacteria range in size from approximately as small as the largest viruses to large enough for single cells to be visible by the naked eye that is from about 01 to about 600 micrometres over a single dimensionEukaryotic Cells Eu true and karyote nucleus found in four Kingdoms Protista Fungi Animalia Planta Visible components plasma membrane cytoplasm nucleus ribosomes organelles endomembrane system cytoskeleton cell wall cell matrix some organelles flagella True Nucleus surrounded with nuclear membrane contains DNA genetic library contains most of the genes in a eukaryotic cell averages about 5 microns in diameter separated from the cytoplasm by a double membrane these are separated by 2040nm where the double membranes are fused a pore allows large macromolecules and particles to pass throughThe nuclear side of the envelope is lined by the nuclear lamina a network of intermediate filaments that maintain the shape of the nucleus provides mechanical support as well as regulating important cellular events such as DNA replication and divisionWithin the nucleus the DNA and associated proteins are organized into fibrous material chromatin appear as diffuse mass however when the cell prepares to divide the chromatin fibers coil up to be seen as separate structures chromosomes each eukaryotic species has a characteristic number of chromosomesIn the nucleus is a region of densely stained fibers and granules adjoining chromatin the nucleolus in the nucleolus ribosomal RNA rRNA is synthesized and assembled with proteins from the cytoplasm to form ribosomal subunits the nucleus directs protein synthesis by synthesizing messenger RNA mRNACytoplasm material between the plasma membrane cell membrane and the nuclear envelope has a variable viscosity main chemical constituents are water 80 nucleic acids proteins lipids carbohydrates pigments etcRibosomes contain rRNA and protein a ribosome is composed of two subunits that combine to carry out protein synthesis free ribosomes are suspended in the cytosol and synthesize proteins that function within the cytosol bound ribosomes are attached to the outside of the endoplasmic reticulum ribosomes can shift between roles
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