Bio 118 1st Edition Lecture 6 Outline of Last Lecture a Lipids What is a Lipid b The Importance of Cell Membranes c Three Types of Lipids Found in Cells d Fats Oils Triglycerides e Sterols f Phospholipids g Phospholipids Water h Phospholipid Bilayers i Selective Permeability of Lipid Bilayers j Many Factors Affect Membrane Permeability k Bond Saturation and Membrane Permeability Outline of Current Lecture I Tour of the Cell a All Cells Have b Grouping Cells c Prokaryotic Cells Structural Overview d Prokaryotic Cells Genetic Information e Prokaryotic Cells Internal Structure f Prokaryotic Cells External Structure g An Introduction to Eukaryotes h Eukaryotic Cells i Eukaryotes and Prokaryotes Compared j The Nucleus k Rough Endoplasmic Reticulum l Smooth Endoplasmic Reticulum m Golgi Apparatus n Ribosomes o Peroxisomes p Lysosomes q How are materials delivered to lysosomes r Vacuoles s Mitochondria t Chloroplasts u The Cell Wall v Cytoskeleton 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 w Cell Systems 1 Nuclear Transport x Cell Systems 2 The Endomembrane System y The Signal Hypothesis z How are products shipped from the Golgi aa Cell Systems 3 The Dynamic Cytoskeleton bb Three Types of Cytoskeletal Elements Current Lecture All Cells Have Nucleic acids store and transmit information Proteins perform most of the cell s functions Carbohydrates chemical energy carbon support identity Plasma Membrane selectively permeable membrane barrier Grouping Cells According to morphology there are two broad groupings of life o Prokaryotes lack a membrane bound nucleus nucleoid o Eukaryotes Have a nucleus According to phylogeny or evolutionary history there are 3 domans o Bacteria o Archaea o Eukarya Prokaryotic Cells Structural Overview All prokaryotes lack a membrane bound nucleus Recent advances in microscopy reveal complexity in prokaryotic structure Archaeal cell structure is relatively poorly understood Bacterial cells vary greatly in size shape but most bacteria contain several similarities o Plasma membrane o A single chromosome o Ribosomes which synthesizes proteins o Stiff cell wall Prokaryotic Cells Genetic Information Most prokaryotic species have one supercoiled circular chromosomes found in the nucleoid region of the cell o The chromosome contains a long strand of DNA and a few supportive proteins o In addition to the large chromosome many bacteria contain plasmids o Small supercoiled circular DNA molecules o Plasmids usually contain genes that help the cell adapt to unusual environmental conditions Prokaryotic Cells Internal Structure In addition to the nucleoid chromosome and plasmids other structures are contained within cytoplasm o All prokaryotic cells contain ribosomes consisting of RNA molecules and protein for protein synthesis o Many prokaryotes have internal photosynthetic membranes o Some prokaryotes have membrane enclosed organelles o The inside of many prokaryotic cells is supported by a cytoskeleton of long thin protein filaments Prokaryotic Cells External Structure Some prokaryotes have tail like flagella on the cell surface that spin around to move the cell Most have a cell wall o Bacterial and archaeal cell walls are a tough fibrous layer that surrounds the plasma membrane Many species have an additional layer outside the cell wall composed of glycolipids An Introduction to Eukaryotes Eukaryotes range from microscopic algae to 100 meter tall redwood trees Many eukaryotes are multicellular others are unicellular Most eukaryotic cells are larger than most prokaryotic cells Eukaryotic Cells The relatively large size of the eukaryotic cell makes it difficult for molecules to diffuse across the entire cell o This problem is partially solved by breaking up the large cell volume into several smaller membrane bound organelles The compartmentalization of eukaryotic cells offer two primary advantages o Separation of incompatible chemical reactions o Increasing the efficiency of chemical reactions Eukaryotes and Prokaryotes Compared Four key differences between eukaryotic and prokaryotic cells have been identified o Eukaryotic chromosomes are found inside a membrane bound compartment called a nucleus o Eukaryotic cells are often much larger o Eukaryotic cells contain extensive amounts of internal membrane o Eukaryotic cells feature a diverse and dynamic cytoskeleton The Nucleus The Nucleus is large and highly organized STRUCTURE o The nucleus is surrounded by a double membrane nuclear envelope o The nucleus has a distinct region called the nucleolus FUNCTION o Information storage and processing Contains the cell s chromosomes o Ribosomal RNA synthesis in the nucleolus Rough Endoplasmic Reticulum STRUCTURE o The rough endoplasmic reticulum is a network of membrane bound tubes and sacs studded with ribosomes The interior is called the lumen o The rough ER is continuous with the nuclear envelope FUNCTION o Ribosomes associated with the Rough ER synthesize proteins o New proteins are folded and processed in the Rough ER lumen Smooth Endoplasmic STRUCTURE o The smooth endoplasmic reticulum lacks the ribosomes associated with the rough ER FUNCTION o Enzymes within the smooth ER may synthesize fatty acids and phospholipids or break down poisonous lipids o Reservoir for Ca 2 ions Golgi Apparatus STRUCTURE o The golgi apparatus is formed by a series of stacked flat membranous sacs called cisternae o Cis Closer to ER o Trans faces the cell membrane FUNCTION o Processes sorts and ships proteins synthesized in the Rough ER o Membranous vesicles carry materials to and from the organelle Ribosomes STRUCTURE o Non membranous not considered organelles o Have large and small subunits both containing RNA molecules and protein o Ribosomes can be attached to the rough ER or free in the cytosol the fluid part of the cytoplasm FUNCTION o Protein synthesis Peroxisomes STRUCTURE o Globular organelles bound by a single membrane FUNCTION o Center of oxidation reactions o Specialized peroxisomes in plants called glyoxysomes are packed with enzymes that oxidize fats to form a compound that can be used to store energy for the cell Lysosomes STRUCTURE o Lysosomes are single membrane bound structures containing approximately 40 different digestive enzymes o Lysosomes are found in animal cells FUNCTION o Lysosomes are used for digestion and waste processing How Are Materials Delivered to Lysosomes
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