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Biology_1406_Chapter_4_Outline - General Biology 1406...

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General Biology – 1406Chapter 4I.Cell TheoryMrs. Daniel’s TheoryA.Every organism is composed of one or more cells1. All life is composed of one orB.Cell is smallest unit of organization with properties of lifemore cells– it has the capacity for metabolism,2. The cell is the basic unitresponses to the environment, growth, and reproductionshowing the properties of lifeC.Continuity of life arises directly from growth and(metabolism, responsiveness,division of single cellsgrowth, and reproduction)3. All cells come from pre-existing cellsII.CellsA.Cells differ in size, shape, and activitiesB.All cells have three similarities
1.Plasma Membranea.Thin outermost membrane that separates, but not isolates, each cell from its externalenvironmentb.Water and gases cross in and out freely, but other substances across the plasmamembrane is controlled2.Nucleus (nucleoid)a.In eukaryotic cells, DNA occupies a membrane-enclosed sac called the nucleusb.In prokaryotic cells, DNA occupies a region with no membrane (nucleoid)3.Cytoplasma.The cytoplasm includes everything between the plasma membrane and the region ofDNAb.Consists of a semifluid matrix and organelles. The organs of the cellsC.Cells Size1.Why are cells small?a.Surface-to-Volume Ratiob.Bigger cell, less surface area per unit volumec.Above a certain size, material cannot move in or out of cell fast enoughIII.MicroscopesA.Create detailed images of something that is too small to seeB.Light microscopes1.Simple – only one lens is used to magnify the image (magnifying glass)2.Compound – two lenses are used to magnify the image –We will be using compound light microscopes3.Limitations of Light Microscopya.Cells must be thin enough for light to pass through will be visible with light microscopyb.Structures are usually stainedc.Light microscopes can see details 200 nm in sizeC.Electron microscopes1.Transmission EM – focuses the electrons so that you end up with an image of theinternal cellular structure2.Scanning EM – focuses the electrons so that you end up with a 3D image of the sample(cell surface)3.Functionsa.Uses beams of electrons rather than lightb.Electrons are focused by magnets rather than glass lensesc.Can resolve structures down to 0.5 nmIV.Structure of Cell MembranesA.Fluid mosaic model – used to describe the organization of membranes1.Described as fluid because of the motions and interactions of its components2.Mixed composition (mosaic):
a.Phospholipid bilayer – made up of phospholipids oriented tail-to-tailb.Glycolipidsc.Sterolsd.Proteins – hydrogen bonds help proteins associate with the phospholipids1.Integral – proteins span the phospholipid bilayer2.Peripheral – proteins associate with the inner phospholipid layerB.Phospholipid1.Each phospholipid hasa.A hydrophilic head – likes to associate with water – loves waterb.Two hydrophobic tails – fatty acid chains that dislike associating with water –hates water, fearful of2.

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Term
Summer
Professor
NoProfessor
Tags
US History, cells, B Cell

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