BIOLOGY 111 1st Edition Lecture Outline of Last Lecture I Polypeptides II Proteins structure A Primary B Secondary C Tertiary D Quaternary III Nucleic Acids A Nucleotides B Polynucleotides C Chargaff s rule Outline of Current Lecture I Cell size II Prokaryotic Cell III Plasma membrane IV Eukaryotic cell A Animal B Plant V Endosymbiont Theory Current Lecture Cells Size sizes range from 1nm to 10m most plant and animal cells are between 10 100um in diameter and are only visible under microscope Why are cells this small Why don t cells grow in proportion with us In order to be most efficient cells remain small in size to maintain their surface area to volume ratio If cells were to grow in proportion with organisms their surface area increases As surface area increase the volume also increases BUT proportionally more than the surface area does Therefore there needs to be large enough surface area to These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute cover the volume Larger organisms do not have larger cells than smaller organisms they just have more cells why cells stop growing o internal region of cell served by part of cell surface o cells grow bigger volume enlarges and the cell membrane expands o at some point not enough surface is available to service all the interior o must stop growing and divide o the surface are to volume ratio gets smaller as the cell gets larger which is not ideal smaller cells have higher surface area to volume ratio Plasma membrane occurs as a double layer bilayer The hydrophobic parts tails are found inside the membrane The hydrophilic parts heads are found on the outside of the membrane This is so that they are in contact with aqueous solution and not the hydrophobic part the major difference between Prokaryotic and Eukaryotic cells is the location of their DNA Prokaryotic cell before the seed no nucleus nucleoid DNA floats freely in non enclosed membrane ribosomes make protein cell wall rigid structure outside the plasma membrane capsule jellylike outer coating plasma membrane membrane enclosing the cytoplasm fimbriae attachment structure on the surface flagella locomotion organelles on outside of cell wall at first it was Eukarya and Bacteria but then some organisms were found in extreme environments which gave Archaea differ from bacteria because of RNA sequence Animal Eukaryotic cell true nucleus has a nucleus o nuclear envelope double membrane enclosing the nucleus o nucleolus nonmembranous structure involved in ribosome production and located at the center of nucleus o chromatin material consisting of DNA and proteins plasma membrane membrane enclosing the cell o microvilli increase surface area and traps unwanted things Endoplasmic Reticulum ER active in membrane synthesis and other synthetic and metabolic processes and has rough and smooth regions o Rough ER have ribosomes o Smooth ER smooth b c doesn t have ribosomes detoxifies and stores calcium Golgi Apparatus active in synthesis modification sorting transporting of cell products Mitochondria cellular respiration occurs and most ATP is generated peroxisomes various specialized metabolic functions converts hydrogen into hydrogen peroxide as by product then converts it to water Lysosomes digestive enzymes where macromolecules are hydrolyzed Cytoskeleton gives shape to cell and is made up of proteins that differ based on diameter o Microfilaments actin filaments thinnest of the three o microtubules 13 columns hollow tubes made up of protein call tubulin alpha and beta thickest of the three types maintain cell shape cell motility motor protein ATP powered receptor for motor protein chromosome movements in cell division organelle movements o intermediate filament fibers medium of the three Centrosomes occur in triplets where cells microtubules are initiated contains o Centrioles nine sets of triplet microtubules arranged in a ring before a cell divides centrioles replicate they help to organize microtubule assembly in microtubules Flagellum locomotion only on some cells not all Cilia occur in doublets o motile move nonmotile fixed o 9 2 pattern nine doublets of microtubules are arranged in a ring at the center are two single microtubules o Dynein large motor proteins composed of several polypeptides responsible for bending movement of organelle o basal body structurally similar to a centriole with microtubule triplets in a 9 0 pattern anchors flagellum of cilium to the cell In animal cells BUT not in plant cells Lysosomes Centrosomes and centrioles Flagella although present in plant sperm In plant cells BUT not in animal cells cell wall outer layer that maintains cell shape and protects from mechanical damage made of cellulose other polysaccharides and protein central vacuole prominent in older plants function in storage breakdown of waste products hydrolysis of macromolecules enlargement of vacuole plant growth chloroplast photosynthetic organelle that converts energy of sunlight into chemical energy stored in sugar molecules plasmodesmata cytoplasmic channels through cell walls that connect the cytoplasms of adjacent cells Endosymbiosis theory mitochondria and plastids including chloroplasts originated as prokaryotic cells engulfed by an ancestral eukaryotic cell The engulfed cell and its host cell then evolved into a single organism endosymbiont a cell living within another cell