Know the difference in resolution and magnification between light and electron microscopes Light microscope Electron microscopes o Visible light is passed through the specimen and then through glass lenses The lenses refract the light so that the image of the specimen is magnified as it is projected into the viewers eye o Up to 1 000x magnification and 0 2 m resolution Magnification Ratio of an object s image size to its real size Resolution Measure of the clarity of the image o Fully developed in the 1870s by German engineers o Focuses a beam of electrons through the specimen or onto its surface o Up to 1 000 000x magnification and about 1 nm resolution o Invented in 1930 mostly used in the 1950s o Two types of images Scanning electron microscopy SEM Shows surfaces in 3D Transmission electron microscope TEM Profiles a thin section of the internal structures of a specimen in 2D Understand the process of cell fractionation based on centrifugation and know what the purpose of cell fractionation is Cell Fractionation Takes cells apart and separates major organelles and other subcellular structures from one another o Process is carried out by a centrifuge which spins test tubes at increasing speeds o At each speed the resulting forces causes a subset of the cell components to settle to the bottom of the tube forming a pellet At lower speeds the pellet consists of larger components At higher speeds the pellet consists of smaller components o Allows researchers to prepare specific cell components in bulk and identify their functions which is usually not possible with intact cells Know what the differences in cell structure are between prokaryotic cells and eukaryotic cells Know that most eukaryotic cells are between 10 100 m in diameter whereas most prokaryotic cells are about 1 m in diameter Prokaryotic o Most prokaryotic cells are 1 5 m in diameter o DNA is concentrated in a region called the nucleoid not membrane enclosed o Do not have membrane bounded organelles o Bacteria and archea Eukaryotic membrane o Most of the DNA is found in the nucleus which is bounded by a double o Plasma membrane Functions as a selective barrier that allows passage of enough oxygen nutrients and wastes to service the entire cell Participate directly in the cell s metabolism because many enzymes are built into the membranes Each type of membrane has a unique composition of lipids and proteins suited to that membrane s specific functions o Larger than prokaryotic cells between 10 100 m Know the following terms plasma membrane cytoplasm nucleus cell wall ribosomes and chromosomes Be able to describe the structure of biological membranes lipid bilayers membrane proteins Nucleus contains most of the genes o Surrounded by nuclear envelope double membrane o Chromosomes Structures that carry the genetic information inside the nucleus Contains one long DNA molecule Chromatin The complex of DNA and proteins that makes up chromosomes Each human cell has 46 chromosomes in its nucleus o Nucleolus A mass of densely stained granules and fibers adjoining part of the chromatin ribosomes Nonmembranous structure involved in the production of RNA is synthesized ribosomes are produced Proteins imported from the cytoplasm are assembled with rRNA ribosomal RNA into large and small subunits of ribosomes Cell wall Outer layer that maintains cell s shape and protects cell from mechanical damage o Made of cellulose other polysaccharides and protein Ribosomes Complexes made of ribosomal RNA and protein o Carry out protein synthesis o Not membrane bounded and not considered organelles Made up of two subunits of ribosomal RNA and proteins o Free ribosomes Suspended in the cytoplasm o Bound ribosomes Attached to the outside of the endoplasmic reticulum or nuclear envelope Plasma membrane o Boundary that separates the living cell from its surroundings and controls traffic into and out of the cell it surrounds o Selectively permeable Allows some substances to cross it more easily than others o Most abundant lipids in most membranes are phospholipids Phospholipids are amphipathic has both a hydrophilic region and a hydrophobic region Molecular arrangement has the hydrophobic tails facing inwards and exposes the hydrophilic heads to water on the outside Most membrane proteins are also amphipathic These proteins reside in the phospholipid bilayer with the hydrophilic region on the outside Know the general structure and function are of the following cellular structures and organelles plasma membrane nucleus ribosomes ER Golgi lysosomes mitochondria and chloroplasts Understand that the pathway for the flow of materials to the cell surface is from ER to the Golgi to Golgi vesicles to the plasma membrane o Endoplasmic reticulum Consists of a network of membrane bounded tubules and sacs called cisternae Two distinct regions Smooth ER Outer surface lacks ribosomes o Function Synthesis of lipids including sex hormones Metabolism of carbohydrates detoxification of drugs and poisons especially in liver cells Storage of calcium ions Rough ER Studded with ribosomes on the outer surface of the membrane o Function Ribosomes on the rough ER aids in synthesis of secretory and other proteins from bound ribosomes Adds membrane proteins and phospholipids to its own membrane o Golgi apparatus Consists of flattened membranous sacs cisternae Function Modifies and stores proteins made in the ER then sends them to other destinations Vesicles are engaged in the transfer of material between parts of the golgi and other structures Transport vesicles move material from the ER to the Golgi apparatus After leaving the ER proteins inside the transport vesicles travel to the Golgi apparatus from the golgi in transport vesicles the proteins will eventually fuse with the plasma membrane o Lysosomes membranous sac of hydrolytic enzymes that many eukaryotic cells use to digest macromolecules Has a lipid bilayer Function Carry out intracellular digestion in a variety of circumstances Enzymes digest food or defective macromolecules to recycle their components by using phagocytosis Phagocytosis Eating by engulfing smaller organisms using a vacuole Lysosomes will merge with the food vacuoles and the enzymes digest the Lysosomes also use their enzymes to recycle the cell s own organic food material Autophagy A damaged organelle becomes surrounded by a double membrane and a lysosome fuses with the outer membrane of this vesicle o Vacuoles Large vesicles derived from the
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