2 BIOL0011 Lecture Cell organelles.pdf

9/9/2016 BIOL0011 Lecture 2...

9/9/2016 BIOL0011 Lecture 2 Cell organelle Outline Cellular Basis of Life: Cell membrane structure (phospholipid bilayer, Eukaryotic cholesterol, proteins, carbohydrates) and function (transport, protection, communication) Cell Organelles Eukaryotic (plant and animal) organelle structure and function Nucleus, Endoplasmic reticulum, Golgi, Mitochondria, Chloroplast Endosymbiont theory 9/9/2016 BIOL0011 2016‐17 1 9/9/2016 BIOL0011 2016‐17 2 Objectives – On successful learning of this topic Organelle Structures you will be able to: A look inside a cell 1. Describe in words & labelled diagrams the structure of organelles found in eukaryotic cells 2. State the functions of each organelle 3. Describe in words and labelled diagram (with correct symbols) the Fluid Mosaic model of cell membrane structure 4. State the functions of cell membranes. 9/9/2016 BIOL0011 2016‐17 3 9/9/2016 BIOL0011 2016‐17 4 Cell Structure – Cell Membrane Cell Membrane Components 1. Phospholipids (glycerol+ 2 fatty acids + phosphate) Hydrophillic 2. Glycosphingolipids (sphingostine +fatty acid+ colysaccharide) 3. Glycoproteins (protein+ polysaccharide) 4. Transmembrane proteins 5. Partially embedded proteins Hydrophobic 6. Peripheral proteins Phospholipid bilayer 7. Cholesterol 8. Microtubule cytoskeleton  Fluid Mosaic model 1972, Singer & Nicolson Plasma membrane has a fluid, phospholipid bilayer with protein & lipid molecules floating in it like a mosaic. 9/9/2016 BIOL0011 2016‐17 5 9/9/2016 BIOL0011 2016‐17 6 http://www.people.virginia.edu/~rjh9u/cellmemb.html 1  9/9/2016 Cell Membrane Constituents – phospholipid bilayer Cell Membrane Constituents ‐ cholesterol The lipids and proteins are fluid ‐ Water soluble. Water insoluble Water soluble. can change places or move laterally; Phosphate groups Phosphate groups Fatty acids essential for processes like osmosis, Non-polar endocytosis. Intracellular Extracellular region region Cholesterol in animal cell membranes decreases the Phospholipid bilayer forms the main structure… fluidity making membrane less http://www.cytochemistry.net/Cell-biology/membrane_intro.htm  barrier between aqueous environments; permeable to water soluble molecules by reducing fatty  selectively allows substances to pass through acid chain shifting.  moves to form transient hydrocarbon pores. 9/9/2016 BIOL0011 2016‐17 7 9/9/2016 BIOL0011 2016‐17 8 Cell Membrane Constituents ‐ proteins Cell Membrane Function Proteins held in membrane  Protective barrier around all cells hydrophobic regions interacting with hydrophobic fatty acid tails.  Transport – diffusion, osmosis, endocytosis, attaching to cytoskeleton. exocytosis, facilitated diffusion, active transport Proteins function in catalysis, transport, communication.  Osmoregulation ‐ maintain internal enzymes, receptor proteins, environment of cell by selectively regulating Conjugated proteins – recognition proteins, carrier & exchange of material. lipoproteins, glycoproteins channel proteins, protein pumps  Receive signals; detect hormones In tissues, cell membranes are connected by junctions:  Communicate with other cells Adhering (held by glue), Tight (encircled by multiprotein complexes) or Gap (interlocked by membrane proteins) 9/9/2016 BIOL0011 2016‐17 9 9/9/2016 BIOL0011 2016‐17 10 Eukaryotic Cell Organelles ‐ Nucleus Eukaryotic Cell organelles ‐ Nucleus Pores of double membrane Allows entry: e.g. nucleotides for DNA replication. Most conspicuous Allows exit: e.g. mRNA and ribosomes. structure Double membrane/ DNA coupled with proteins (histones) form chromatin envelope perforated by (becomes compact chromosomes before nuclear division). pores Has the genes, ‘instructions’ for making proteins that determines the organisms traits (including Semi‐fluid nucleoplasm enzymes that control metabolic activities). with chromatin, proteins, granules, fibres, nucleoli Nucleolus (≥1) Manufacture ribosomes (RNA + protein). 9/9/2016 BIOL0011 2016‐17 11 9/9/2016 BIOL0011 2016‐17 12 2  9/9/2016 Eukaryotic Cell Organelles ‐ Endoplasmic reticulum Eukaryotic Cell Organelles ‐ Endoplasmic reticulum creates system of passageways Elaborate system of channel materials to different locations within cell folded, stacked and may have ribosomes attached to the cisternae tubular membranes Smooth ER (ER) called cisternae. Rough ER (RER)  Site of lipid synthesis e.g., Occurs throughout  Site of protein steroid hormones. the cytoplasm synthesis and  Destruction of toxic Is continuous with transport. materials in liver outer membrane of  Regulation of calcium ion the nuclear envelope concentration (e.g., during muscle contraction). 9/9/2016 BIOL0011 2016‐17 13 9/9/2016 BIOL0011 2016‐17 14 Eukaryotic Cell Organelles ‐ Ribosomes Eukaryotic Cell Organelles ‐ Golgi apparatus/ complex/ body Large numbers found throughout cells Golgi apparatus (thousands, millions). Stack of membranes (cisternae) Proteins & several long RNAs bound formed from fusion of vesicles derived from RER. No membrane. Produced by nucleoli  Function to chemically modify Exist free in cytoplasm, or bound to ER. 80s proteins destined for export Disassembles into 2 subunits when not from the cell e.g., glycoproteins. actively synthesizing protein  Involved in lysosome formation  Site of protein synthesis, where RNA is  Involved in formation of translated into protein. complex polysaccharides of plant cell walls. 9/9/2016 BIOL0011 2016‐17 15 9/9/2016 BIOL0011 2016‐17 16 Eukaryotic Cell Organelles ‐ Lysosomes & Perioxomes Eukaryotic Cell Organelles ‐ Mitochondria Sausage‐shaped with double Lysosomes Peroxisome membrane Produced by Golgi Produced by RER Outer membrane with porins Bound by single Bound by single membrane to (channel protein pores) membrane to protect protect cell from its Crista – folded inner membrane cell from its contents. contents. Site of ETC for ATP synthesis in Storage vesicles with  Contain hydrolytic aerobic cellular respiration hydrolytic enzymes. oxidase enzymes Semi – fluid matrix.  Function to break down that act against has DNA old organelles, ingested toxins e.g., catalase. Site of oxidative decarboxylation & bacteria, and digest Kreb’s cycle (FADH & NAHD synthesis) macromolecules. in aerobic cellular respiration 9/9/2016 BIOL0011 2016‐17 17 9/9/2016 BIOL0011 2016‐17 18 3  9/9/2016 Eukaryotic Cell Organelles ‐ Chloroplast Endosymbiont theory In photosynthetic cells Bound by double membrane Postulates that chloroplasts and mitochondria with porins in cells are the result of years of evolution Thylakoids ‐ system of initiated by the endocytosis of bacteria and flattened membrane sacs cyanobacteria which were not digested but  site of ATP, NADPH instead became symbiotic. production (light dependent stage). Mitochondria & chloroplast have Stroma membranes, aqueous cytoplasm, ribosomes  site of glucose and genetic material….. production/ Calvin cycle suggesting the may have been cells. (light independent stage) 9/9/2016 BIOL0011 2016‐17 19 9/9/2016 BIOL0011 2016‐17 20 Eukaryotic Cell Organelles ‐ Vacuole Cell Structure ‐ Microtubules/filaments Plant cell vacuoles Animal cell vacuole Microtubules Large central vacuole Temporary vacuoles hollow, cylindrical structures  Forms the cell’s cytoskeleton. e.g., food vacuole composed of tubulin (protein) subunits Bound by a tonoplast.  Forms the internal framework of the cell Contains cell sap Contractile vacuoles Microfilaments (solution of salts, formed from solid, thinner, more flexible structures.  Providing machinery sugars, pigment, acids for movement of cells endocytosis. composed of actin (contractile protein). and organelles in and enzymes). excrete excess water animals & protists.  Involved in storage & and waste Intermediate filaments (forms cilia & flagella in a (9+2 arrangement) osmotic regulation. tough, rope‐like composed of a variety of proteins. 9/9/2016 BIOL0011 2016‐17 21 9/9/2016 BIOL0011 2016‐17 22 Cell Structure ‐ Cilia & flagella Cell Structure – Cell Wall Cilia Present in bacteria,  Rigid, protective, Short, hair‐like, fungi and plants. support numerous structures Plant cell walls  Slow dehydration; Flagella  Prevents cell bursting that project from the Cellulose microfibrils surface of cell. Longer than cilia and  Allows transport of fewer in number. bundled together & substances in/out Involved in movement embedded in  Apoplast pathway for of entire cell or Has beating motion polysaccharide matrix. which propels the cell movement for water movement of materials Secondary wall (as opposed to symplast pathway by the cell e.g., the through the medium via plasmodesmata) impregnated with lignin lining of the respiratory e.g., tail of the sperm. Cilia Flagella to form wood tract. In tissues, the link to other cells are formed by plasmodesmata – gaps in cell wall through which ER run 9/9/2016 BIOL0011 2016‐17 23 9/9/2016 24 BIOL0011 2016‐17 4  9/9/2016 Identify the components Cells are the basic units of life Title: Fluid Mosaic Model of Cell Membrane Which cell organelle performs the following A. phospholipid bilayer B. polysaccharide C. glycoprotein life processes in eukaryotic cells. D. glycolipid E. peripheral protein F. hydrophilic phosphate head feed G. hydrophobic fatty acid tail H. transmembrane channel protein I. partially embedded protein respire J. cholesterol excrete What major component is metabolize missing from this osmoregulate illustration? communicate reproduce 9/9/2016 BIOL0011 2016‐17 25 9/9/2016 BIOL0011 2016‐17 26 5