BIOL-L 312 Cell Biology
BIOL-L 312 Cell Biology
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Date Created: 01/18/15
113 Notes LECTURE ONE WELCOME TO CELL BIOLOGY What is a cell 0 Lowest level of structure that can perform activities required for life 0 Activities homeostasis capacity to reproduce and grow responding to stimuli 0 Common biochemistry all cells use the same basic building blocks DNA RNA amino acids lipids carbohydrates 0 Common macromolecules and supramolecular structures and physiology lipid bilayers ribosomes use ATP as energy 0 All cells have a delimiting membrane to separate inside from out 0 Capacity for reproduction Why Study Cells 0 Form generally fits function 0 By studying a biological structure you determine what it does and how it works 0 Life emerges from interactions of structures 0 Combinations of structures components provide organization called a system What does a cell need to do 0 To live or die 0 If live then how does it produce and store energy 0 If die can it do so in a controlled way apoptosis 0 Communicate o How does information flow within the cell the environment and to neighboring cells 0 Proliferate o How does a cell divide o How does it move 0 How does a cell determine its polarity Cellular Diversity 0 Two major classes of cells based on complexity of intracellular organization 0 Prokaryotes no nucleus or nuclear envelope 0 Eukaryotes nucleus Bacteria vs Yeast o What is the difference 0 Bacteria is smaller 0 Bacteria DNA is less organized Structure of a Eukaryotic Cell 0 It is complex with many organelles discrete units of the cell necessary to carry out specific functions What does the nuclear envelope enclose 0 Nuclear envelope encloses the nucleus which contains nucleolus and DNA 0 Nucleolus production of ribosome with ribosomal RNA present The Mitochondria o It has two bilayer membranes 0 The folds inside the mitochondria is one bilayer membrane 0 It has its own genome o Remnant of evolution how a prokaryotes became a eukaryote The Chloroplasts o Thylakoids stacks of chlorophyll containing membranes 0 Has its own genome The Endoplasmic Reticulum 0 Site of lipid and protein biosynthesis o Extends from nuclear envelope 0 On the rough ER there are ribosomes where protein biosynthesis occurs 0 Smooth ER without ribosomes is where lipid biosynthesis occurs 0 Lipid biosynthesis can occur in both rough and smooth 0 Only protein synthesis occurs ONLY in the rough ER The Golgi Apparatus 0 Site of protein modification 0 Structure is a stack of membranes with vesicles 0 Sugars for modification and proteins to be modified are packaged into vesicles to enter the Golgi and leave the Golgi for exocytosis or cytoplasm from the Golgi 0 Transport center of the cell The Lysosome o Digestion with digestive enzymes to breakdown old cells and malfunctioning parts of the cell 0 Parts are recycled from lysosome for reuse in the cell 0 Microorganisms are degraded in lysosomes The Peroxisome o This has enzymes important for oxidative reactions 0 Produce and degrade H202 o Breaks down fatty acids cholesterol and bile Model Organisms o What is a model organism 0 Simple to study organisms that are used to understand different processes 0 Why do we use model organisms to study cell biology 0 They are easy to manipulate 0 Their genesprocesses are conserved across species The information gathered can be applied to higher order organisms 0 They reproduce quickly reducing the time span of the experiment Which are the main ones 0 1 Escherichia coli bacterium o 2 Saccharomyces cerevisiae yeast 0 3 Arabidopsis thaliana weed o 4 Drosophila melanogaster fruit fly 0 5 Mus musculus mouse 0 6 Homo sapiens human Yeast A minimal model eukaryote 0 There are two types of yeast Saccharomyces cerevisiae budding yeast and schizosaccharomyces pombe fission yeast beer yeast 0 Has a very rapid life cycle 0 Generation time is 90 minutes ls easily cultured in large amounts Has a simple genome 0 Its genome is entirely sequenced Has a simplified endomembrane system Is genetically amenable Has many conserved processes Can survive freezing Yeast used to find key regulators of the cell cycle Lee Hartwell and Paul Nurse used yeast to find key regulators of the cell cycle These key regulators are highly conserved amongst the species so much so that yeast regulators can be used in humans when theirs are deficient Yeast can also be used to study 0 Control of cell cycle protein secretion membrane biogenesis gene regulation chromosome structure and aging Roundworm Caenorhabditis elegans Rapid generation time days Whole organisms can be frozen Transparent body wall 0 Useful for visualizing fluorescence Simple basic multicellular organism Defined cell lineage and number 929 cells per C elegans 0 Can track each cell and determine what it becomes 0 Can also study the formation of the nervous system and apoptosis Was the first multicellular organism whose genome was completely sequenced Fruit fly Drosophila melanogaster Rapid generation time days Complex multicellular organism Genetically amenable Good developmental biology model IUDrosophila stock center The Eyeless gene is conserved during evolution and encodes the master transcriptional control protein that initiates eye formation in both flies and man The genetic control of early embryonic development Edward Lewis Christiane NussleinVolhard Eric Wieschus Mouse Mus Musculus Complex multicellular Biologically and genetically similar to humans Cell lines can be established Knockout animals possible Human disease models possible Comparison of the Human and Mouse Genomes Both genomes contain 25000300000 protein coding genes 0 Mouse genome 25 x 109 bp 0 Human genome of 29 x 109 bp 0 Over 908 of mouse and human genomes can be partitioned into regions of conserved synteny A Model Plant Arabdopsis thaliana 0 Small fast growing 0 Genome small and sequenced 0 Seeds can be frozen The Human Genome 0 Of the 25000 genes in the human genome 236 have unknown functions 135 control activity within the nucleus 123 allow communication inside of or between cells 102 are enzymes 50 relate to the cytoskeleton 48 are transporters for small molecules 33 are involved in cellcell adhesion 29 are tumor suppressors OOOOOOOO 09 are involved in immune functions