Prokaryotic vs Eukaryotic Cell Structure PDF

PROKARYOTIC VS EUKARYOTIC CELL LESSON 2 Learning Objectives: At the end of the lesson, you should be able to: 1. Classify the types of cells and describe each; 2. Describe the structures of the cell and their functions; 3. Identify some cell modifications that lead to adaptatio...

PROKARYOTIC VS EUKARYOTIC CELL LESSON 2 Learning Objectives: At the end of the lesson, you should be able to: 1. Classify the types of cells and describe each; 2. Describe the structures of the cell and their functions; 3. Identify some cell modifications that lead to adaptations; and 4. Explain the types of animal and plant tissues. Prokaryotic vs Eukaryotic Prokaryotic cells lack a nuclear envelope and membrane-bound organelles, an example of which is the bacterial cell. The bacterial cells are small but, about 0.2 to 5 μm, less complex, usually exists in unicellular forms, and have limited capabilities compared with eukaryotic cells. Eukaryotic cells are generally larger and have very distinct nuclei that are clearly surrounded by nuclear membranes. They also have numerous membrane-bound organelles found in the cytoplasm. Protists, plants, fungi, and animals have eukaryotic cells. for attachment for movement  PROKARYOTIC CELLS bisag asa makit an sa extreme environments makit an Organisms: Eubacteria and Archaebacteria Single celled absence of a membrane-bound nucleus lack membrane-bound organellesnot needing oxygen needs oxygen Metabolism: anaerobic and aerobic, diverse Almost all have cell wall (in most bacteria- main component of cell wall peptidoglycan) Cell division is usually binary fission: mostly budding  STRUCTURES OF PROKARYOTIC CELLS Capsule - a sticky outer layer that provides protection turgor pressure Cell wall - a structure that confers rigidity and shape to the cell Plasma membrane - a structure that serves as a permeability barrier used in vaccines Plasmid - a genetic material Nucleoid - a DNA-containing region within the cytoplasm Cytoplasm - the region where chromosomes (DNA), ribosomes, and various inclusions are found Ribosome - the site where protein is synthesized Flagellum - facilitates movement of bacteria  STRUCTURES OF PROKARYOTIC CELLS Pilus (plural, pili) and Fimbriae both are able to stick bacteria to surfaces, but pili are typically longer and fewer in number than fimbriae. found in virtually all Gram-negative bacteria but not in many Gram-positive bacteria. Short attachment pili - to colonize environmental surfaces or cells and resist flushing  Long conjugation pili, sex pili – longer but few in numbers EUKARYOTIC CELLS EUKARYOTES Organisms: Fungi, Plants and Animals Single celled (protists mostly) or multicellular (usually with tissues and organs) Cell wall – fungi; cellulose and plants; chitin Many organelles Mostly aerobic Cell division through mitosis and meiosis using a spindle; followed by cytokinesis  CELL PARTS AND FUNCTIONS CELL MEMBRANE aka “plasma membrane” separates the cell from its external environment outermost covering of animal cells (cell wall; plants) regulates the entrance and exit of substances provides shape and flexibility to the cell hydrophilic head (water-loving) - layer facing outward, toward the outside environment of the cell hydrophobic tail (water-fearing) - facing inward, away from the aqueous environment CYTOPLASM all the materials in the cell that surround the nucleus make up the cytoplasm organelles and cellular inclusions are found biggest part of the cell Cytoplasmic Organelles: 1. Endoplasmic Reticulum (Smooth ER and Rough ER) 2. Golgi apparatus 3. Mitochondrion 4. Lysosomes 5. Secretory granules 6. Lipid droplets  ENDOPLASMIC RETICULUM network of intercommunicating channels in the cytoplasm membrane-enclosed sacs and tubules types of endoplasmic reticulum are the rough endoplasmic reticulum (RER) and the smooth endoplasmic reticulum (SER) 1. RER, described as such due to the presence of ribosomes (the structure where protein is synthesized) - production of protein 2. SER is a more tubular and non-granular structure due to the absence of ribosomes - manufacture and metabolism of lipids checker courier GOLGI APPARATUS composed of sets of cisternae and numerous vesicles filled with fluid and suspended substances the processing, packaging, and sorting of secretory materials for use within and outside the cell a membranous pouch, that buds off from the smooth ER, then migrates and fuses with the plasma membrane  escorts the waste proteins outside the cell escorts the cell to the golgi body Fig. 6-16-1 Nucleus Rough ER Smooth ER Plasma membrane Fig. 6-16-2 Nucleus Rough ER Smooth ER cis Golgi Plasma trans Golgi membrane Fig. 6-16-3 Nucleus Rough ER Smooth ER cis Golgi Plasma trans Golgi membrane LYSOSOMES small, spherical, membrane-bound organelles which contain a number of enzymes helps digest food, disease-causing bacteria engulfed by white blood cells, and worn-out and broken parts of the cell  A lysosome is a membranous sac of hydrolytic packed with HCL enzymes that can digest macromolecules Lysosomal enzymes can hydrolyze proteins, fats, polysaccharides, and nucleic acids Some types of cell can engulf another cell by phagocytosis; this forms a food vacuole A lysosome fuses with the food vacuole and digests the molecules Lysosomes also use enzymes to recycle the cell’s own organelles and macromolecules, a process called autophagy Fig. 6-14 Nucleus 1 µm Vesicle containing 1 µm two damaged organelles Mitochondrion fragment Peroxisome fragment Lysosome Digestive enzymes Lysosome Lysosome Plasma Peroxisome membrane Digestion Food vacuole Digestion Mitochondrion Vesicle (a) Phagocytosis (b) Autophagy Fig. 6-14a Nucleus 1 µm Lysosome Digestive enzymes Lysosome Plasma membrane Digestion Food vacuole (a) Phagocytosis Fig. 6-14b Vesicle containing 1 µm two damaged organelles Mitochondrion fragment Peroxisome fragment Lysosome Peroxisome Mitochondrion Digestion Vesicle (b) Autophagy VACUOLES A plant cell or fungal cell may have one or several vacuoles Food vacuoles are formed by phagocytosis Contractile vacuoles, found in many freshwater protists, pump excess water out of cells Central vacuoles, found in many mature plant cells, hold organic compounds and water Fig. 6-15 Central vacuole Cytosol Nucleus Central vacuole Cell wall Chloroplast 5 µm MITOCHONDRIA: Chemical Energy Conversion Mitochondria are in nearly all eukaryotic cells They have a smooth outer membrane and an inner membrane folded into cristae The inner membrane creates two compartments: intermembrane space and mitochondrial matrix Some metabolic steps of cellular respiration are catalyzed in the mitochondrial matrix Cristae present a large surface area for enzymes that synthesize ATP CHLOROPLASTS: Capture of Light Energy The chloroplast is a member of a family of organelles called plastids Chloroplasts contain the green pigment chlorophyll, as well as enzymes and other molecules that function in photosynthesis Chloroplasts are found in leaves and other green organs of plants and in algae  Chloroplast structure includes: Thylakoids, membranous sacs, stacked to form a granum Stroma, the internal fluid Fig. 6-18 Ribosomes Stroma Inner and outer membranes Granum 1 µm Thylakoid  SECRETORY GRANULES large dense granules with membranes fuse with the cell membrane to secrete substances such as enzymes, proteins, and signaling molecules out of the cell LIPID DROPLETS store fatty acids and sterols take up much space and volume in adipocytes (fat cells) appear as black spherical bodies of varying sizes when stained with osmium tetroxide  CYTOPLASMIC INCLUSIONS non-membranous substances and structures suspended in the cytoplasm with varying functions presence or absence Cytoplasmic Inclusions: depends on the cell type 1. Ribosomes 2. Centriole (although ribosomes are 3. Cytoskeleton present in all cells) 4. Glycogen granules 5. Pigments RIBOSOMES the most numerous of all cytoplasmic structures spherical in structure and measure about 15 to 20 nanometers (nm) in diameter sites where proteins are made Proteins that are needed by the cell itself are produced by those ribosomes that float freely in the cytoplasm proteins that will be exported outside of the cell are produced by those attached to the ER Small ribosomal subunit – programs protein synthesis – binds mRNA and mediates the interaction between mRNA codon and tRNA anticodon Large ribosomal subunit – plays an important role in production – it contains the peptidyl transferase site, the site at which peptide bonds are formed CENTROSOMES AND CENTRIOLES In many cells, microtubules grow out from a centrosome near the nucleus The centrosome is a “microtubule-organizing center” In animal cells, the centrosome has a pair of centrioles, each with nine triplets of microtubules arranged in a ring Fig. 6-22 Centrosome Microtubule Centrioles 0.25 µm Longitudinal section of Microtubules Cross section one centriole of the other centriole Cilia and Flagella Microtubules control the beating of cilia and flagella, locomotor appendages of some cells Cilia and flagella differ in their beating patterns Video: Chlamydomonas Video: Paramecium Cilia Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 6-23 Direction of swimming (a) Motion of flagella 5 µm Direction of organism’s movement Power stroke Recovery stroke (b) Motion of cilia 15 µm  Cilia and flagella share a common ultrastructure: A core of microtubules sheathed by the plasma membrane A basal body that anchors the cilium or flagellum A motor protein called dynein, which drives the bending movements of a cilium or flagellum Animation: Cilia and Flagella Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 6-24 Outer microtubule 0.1 µm Plasma doublet membrane Dynein proteins Central microtubule Radial spoke Protein cross- Microtubules linking outer doublets (b) Cross section of Plasma cilium membrane Basal body 0.5 µm (a) Longitudinal section 0.1 µm of cilium Triplet (c) Cross section of basal body  How dynein “walking” moves flagella and cilia: −Dynein arms alternately grab, move, and release the outer microtubules Protein cross-links limit sliding Forces exerted by dynein arms cause doublets to curve, bending the cilium or flagellum Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings Fig. 6-25 Microtubule doublets ATP Dynein protein (a) Effect of unrestrained dynein movement ATP Cross-linking proteins inside outer doublets Anchorage in cell (b) Effect of cross-linking proteins 1 3 2 (c) Wavelike motion Fig. 6-25a Microtubule doublets ATP Dynein protein (a) Effect of unrestrained dynein movement Fig. 6-25b ATP Cross-linking proteins inside outer doublets Anchorage in cell (b) Effect of cross-linking proteins 1 3 2 (c) Wavelike motion CYTOSKELETON is a cellular "scaffolding" or "skeleton" that crisscrosses the cytoplasm eukaryotic cells and prokaryotic cells have a cytoskeleton helps to maintain cell shape it holds organelles in place, and for some cells, it enables cell movement plays important roles in both the intracellular movement of substances and in cell division Table 6-1a 10 µm Column of tubulin dimers 25 nm   Tubulin dimer Table 6-1b 10 µm Actin subunit 7 nm Table 6-1c 5 µm Keratin proteins Fibrous subunit (keratins coiled together) 8–12 nm GLYCOGEN GRANULES found in the form of granules in the cytosol/cytoplasm in many cell types plays an important role in the glucose cycle Glycogen forms an energy reserve that can be quickly mobilized to meet a sudden need for glucose Glycogen granules are abundant in liver cells  PIGMENTS Pigments are substances that do not require staining by dyes because they already possess their own color. These are especially abundant in plant cells.  NUCLEUS is found in most eukaryotic cells the site where nucleic acids are synthesized and, therefore, directs all the activities of the cell site for the storage of hereditary factors source of ribonucleic acid (RNA), a molecule responsible for various cellular functions such as genetic coding and expression Chromatin - found inside the nucleus - made up of DNA and proteins, and forms chromosomes during cell division.  NUCLEOLUS Brain of the nucleus takes part in the production of subunits that unites to form ribosomes plays an important role in the synthesis of proteins and in the production of ribosomes in eukaryotic cells It is rich in RNA NUCLEAR MEMBRANE is the two-layered outer limit of the nucleus separating it from the cytoplasm It contains ribosomes on its outer membrane Nuclear pores can be seen in the nuclear envelope - act as selective channels between the cytoplasm and the inside of the nucleus, selectively allowing molecules which contain the correct location signals to pass in and out Fig. 6-UN1 Cell Component Structure Function Concept 6.3 Nucleus Surrounded by nuclear Houses chromosomes, made of The eukaryotic cell’s genetic envelope (double membrane) chromatin (DNA, the genetic instructions are housed in perforated by nuclear pores. material, and proteins); contains the nucleus and carried out The nuclear envelope is nucleoli, where ribosomal by the ribosomes continuous with the subunits are made. Pores endoplasmic reticulum (ER). regulate entry and exit of materials. (ER) Ribosome Two subunits made of ribo- Protein synthesis somal RNA and proteins; can be free in cytosol or bound to ER Concept 6.4 Endoplasmic reticulum Extensive network of Smooth ER: synthesis of The endomembrane system membrane-bound tubules and lipids, metabolism of carbohy- regulates protein traffic and (Nuclear sacs; membrane separates drates, Ca2+ storage, detoxifica-tion performs metabolic functions envelope) lumen from cytosol; of drugs and poisons in the cell continuous with the nuclear envelope. Rough ER: Aids in synthesis of secretory and other proteins from bound ribosomes; adds carbohydrates to glycoproteins; produces new membrane Golgi apparatus Stacks of flattened Modification of proteins, carbo- membranous hydrates on proteins, and phos- sacs; has polarity pholipids; synthesis of many (cis and trans polysaccharides; sorting of Golgi faces) products, which are then released in vesicles. Lysosome Membranous sac of hydrolytic Breakdown of ingested substances, enzymes (in animal cells) cell macromolecules, and damaged organelles for recycling Vacuole Large membrane-bounded Digestion, storage, waste vesicle in plants disposal, water balance, cell growth, and protection Concept 6.5 Mitochondrion Bounded by double Cellular respiration Mitochondria and chloro- membrane; plasts change energy from inner membrane has one form to another infoldings (cristae) Chloroplast Typically two membranes Photosynthesis around fluid stroma, which contains membranous thylakoids stacked into grana (in plants) Peroxisome Specialized metabolic Contains enzymes that transfer compartment bounded by a hydrogen to water, producing single membrane hydrogen peroxide (H2O2) as a by-product, which is converted to water by other enzymes in the peroxisome Fig. 6-UN1a Cell Component Structure Function Concept 6.3 Nucleus Surrounded by nuclear Houses chromosomes, made of The eukaryotic cell’s genetic envelope (double membrane) chromatin (DNA, the genetic instructions are housed in perforated by nuclear pores. material, and proteins); contains the nucleus and carried out The nuclear envelope is nucleoli, where ribosomal by the ribosomes continuous with the subunits are made. Pores endoplasmic reticulum (ER). regulate entry and exit os materials. (ER) Ribosome Two subunits made of ribo- Protein synthesis somal RNA and proteins; can be free in cytosol or bound to ER Fig. 6-UN1b Cell Component Structure Function Concept 6.4 Endoplasmic reticulum Extensive network of Smooth ER: synthesis of The endomembrane system membrane-bound tubules and lipids, metabolism of carbohy- (Nuclear sacs; membrane separates drates, Ca2+ storage, detoxifica- regulates protein traffic and envelope) performs metabolic functions lumen from cytosol; tion of drugs and poisons in the cell continuous with the nuclear envelope. Rough ER: Aids in sythesis of secretory and other proteins from bound ribosomes; adds carbohydrates to glycoproteins; produces new membrane Golgi apparatus Stacks of flattened Modification of proteins, carbo- membranous hydrates on proteins, and phos- sacs; has polarity pholipids; synthesis of many (cis and trans polysaccharides; sorting of faces) Golgi products, which are then released in vesicles. Breakdown of ingested sub- Lysosome Membranous sac of hydrolytic stances cell macromolecules, and enzymes (in animal cells) damaged organelles for recycling Vacuole Large membrane-bounded Digestion, storage, waste vesicle in plants disposal, water balance, cell growth, and protection Fig. 6-UN1c Cell Component Structure Function Concept 6.5 Mitochondrion Bounded by double Cellular respiration Mitochondria and chloro- membrane; plasts change energy from inner membrane has one form to another infoldings (cristae) Chloroplast Typically two membranes Photosynthesis around fluid stroma, which contains membranous thylakoids stacked into grana (in plants) Peroxisome Specialized metabolic Contains enzymes that transfer compartment bounded by a hydrogen to water, producing single membrane hydrogen peroxide (H2O2) as a by-product, which is converted to water by other enzymes in the peroxisome