Structure of Prokaryotic and Eukaryotic Cell PDF

 Two Basic Types of Cells Prokaryotes Single-celled. Reproduce by binary fission (another copy by dividing). No cell nucleus or any other membrane- bound organelles. DNA travels openly around the cell. All bacteria are prokaryotes. Eukaryotes Most organisms th...

 Two Basic Types of Cells Prokaryotes Single-celled. Reproduce by binary fission (another copy by dividing). No cell nucleus or any other membrane- bound organelles. DNA travels openly around the cell. All bacteria are prokaryotes. Eukaryotes Most organisms that we can see, such as trees, grass, worms, flies, mice, humans, mushrooms and yeast are eukaryotes. Can either be single-celled or multi-celled. Can reproduce in one of several ways (Ex. meiosis, mitosis). Have cell nucleus within containing its DNA. Nucleus most evident distinction between these cell types.  1). Prokaryotic and eukaryotic cells differ in size and complexity Similarities All cells are surrounded by a plasma membrane. The semi-fluid substance within the cell is called “cytosol”, containing the cell organelles. All cells contain chromosomes which have genes in the form of DNA. All cells have tiny organelles called “Ribosomes” that make proteins.  1). Prokaryotic and eukaryotic cells differ in size and complexity Differences A major difference between prokaryotic and eukaryotic cells is the location of chromosomes. – In an eukaryotic cell, chromosomes are contained in a true nucleus ). – In a prokaryotic cell, the DNA is concentrated in the nucleoid) without a membrane separating it from the rest of the cell. – In prokaryotic cell, DNA is a single strand or double strand DNA. But in eukaryotic cell, DNA is double strand.  Prokaryotic and eukaryotic cells differ in size and complexity All cells are surrounded by a plasma membrane. The semifluid substance within the membrane is the cytosol, containing the organelles. All cells contain chromosomes which have genes in the form of DNA. All cells also have ribosomes, tiny organelles that make proteins using the instructions contained in genes.  A major difference between prokaryotic and eukaryotic cells is the location of chromosomes. In an eukaryotic cell, chromosomes are contained in a membrane-enclosed organelle, the nucleus. In a prokaryotic cell, the DNA is concentrated in the nucleoid without a membrane separating it from the rest of the cell. Structure of Prokaryotes  Types of Prokaryotes Prokaryotes Bacteria Archaea - Exist in most - Exist in extreme environments (hot environments and salty) They are differing in some other structural, biochemical and physiological characteristics Bacteria come in two flavors: Gram positive vs Gram-negative prokaryotes  Bacterial Structures  Flagella  Pili  Capsule  Plasma Membrane  Cytoplasm  Cell Wall  Lipopolysaccharides  Teichoic Acids  Inclusions  Spores  Prokaryotes Ribosomes: Small electron dense particles Involved in prt.synthesis 70 S(30 S + 50S) Different from host cell ribosomes in SR. Streptomycin interferes with bacterial metabolism sparing the host cell ribosomes. 3 types of RNAs: Ribosomal, transfer , mRNA Found within cytoplasm or attached to plasma membrane.  Prokaryotes Cytoplasm: Also known as proto-plasm. Gel-like matrix of water, enzymes, nutrients, wastes, (organic n inorganic solutes) and gases and contains cell structures like numerous ribosomes and polysomes. No ER n memb.bound organelles. Shows signs of internal mobility like cytoplasmic streaming , amoeboid movement and formation and disappearance of vacoules. Location of growth, metabolism, and replication. Granules or inclusions:  Bacteria’s way of storing nutrients.  Staining of some granules aids in identification.  Plasma Membrane  Separates the cell from its environment.  Limits the protoplast  Thin n elastic , can be only seen with electron microscope  With the exception of mycoplasma , bacterial cytoplasmic memb.lacks sterol.  Phospholipid molecules oriented so that hydrophilic,water-loving heads directed outward and hydrophobic ,water-hating tails directed inward.  Proteins embedded in two layers of lipids (lipid bilayayer) FUNCTIONS: Semipermeable membrane  Housing enzymes for cell wall, outer membrane synthesis, assembly n secretion of extractoplasmic n extracellular substances  Generation of ATP  Cell motility  Mediation of chromosomal segragation during replication  Cell Wall Peptido-glycan Polymer (amino acids + sugars) Unique to bacteria Sugars; NAG & NAM – N-acetylglucosamine – N-acetymuramic acid D form of Amino acids used not L form – Hard to break down D form Amino acids cross link NAG & NAM Prokaryotes – Cell Wall  Peptidoglycan is a huge polymer of interlocking chains of identical peptidoglycan monomers.  Provides rigid support while freely permeable to solutes.  Backbone of peptidoglycan molecule composed of two derivatives of glucose: - N-acetylglucosamine (NAG) - N-acetlymuramic acid (NAM)  NAG / NAM strands are connected by inter- peptide bridges.  Prokaryotes - Cell Wall From the peptidoglycan inwards all bacteria are very similar. Going further out, the bacterial world divides into two major classes (plus a couple of odd types). These are: Gram Positive Gram Negative  Cytoplasm 80% Water {20% Salts-Proteins) – Osmotic Shock important DNA is circular, Haploid – Advantages of 1N DNA over 2N DNA – More efficient; grows quicker – Mutations allow adaptation to environment quicker Plasmids; extra circular DNA – Antibiotic Resistance No organelles (Mitochondria, Golgi, etc.)  Prokaryotes - Glycocalyx Some bacteria have an additional layer outside of the cell wall called the glycocalyx. This additional layer can come in one of two forms: 1- Glycoproteins loosely associated with the cell wall. - Slime layer causes bacteria to adhere to solid surfaces and helps prevent the cell from drying out. - Streptococcus The slime layer of Gram+ Streptococcus mutans allows it to accumulate on tooth enamel (yuck mouth and one of the causes of cavities). Other bacteria in the mouth become trapped in the slime and form a biofilm & eventually a buildup of plaque.  Prokaryotes - Glycocalyx 2.Polysaccharides firmly attached to the cell wall.  Capsules adhere to solid surfaces and to nutrients in the environment.  Adhesive power of capsules is a major factor in the initiation of some bacterial diseases.  Capsule also protect bacteria from being phagocitized by cells of the hosts immune system.  Prokaryotes – Surface Appendages  Some prokaryotes have distinct appendages that allow them to move about or adhere to solid surfaces.  Consist of delicate strands of proteins.  Flagella: Long, thin extensions that allow some bacteria to move about freely in aqueous environments.  Endoflagella: Wind around bacteria, causing movement in waves.  Flagella Motility - movement Swarming occurs with some bacteria – Spread across Petri Dish – Proteus species most evident Arrangement basis for classification – Monotrichous; 1 flagella – Lophotrichous; tuft at one end – Amphitrichous; both ends – Peritrichous; all around bacteria  Pili Short protein appendages – smaller than flagella Adhere bacteria to surfaces – E. coli has numerous types K88, K99, F41, etc. – Antibodies to it will block adherence. F-pilus; used in conjugation – Exchange of genetic information  Endospores Resistant structure – Heat, irradiation, cold – Boiling >1 hr still viable – Takes time and energy to destroy spores Location important in classification – Central, Subterminal, Terminal Bacillus stearothermophilus -spores – Used for quality control of heat sterilization equipment Bacillus anthracis - spores – Used in biological warfare  Eukaryotic cell Cytoplasm = cytosol + organelles  Genes that control the eukaryotic cells The nucleus Nuclear envelope is a double membrane, each membrane is lipid bilayer with proteins perforation by pores chromatin – DNA, histons, non-histon protein cell division – chromatin condensate to chromosomes the nucleolus – synthesis of ribosomes components  The nucleus control protein synthesis by sending molecular messengers in the form RNA – mRNA - messenger - TRANSCRIPTION is synthesized in nucleus according the DNA in ribosomes is genetic information translate into the primary structure of a specific protein - TRANSLATION free ribosomes – suspended in the cytosol, function of protein in cytosol bound ribosomes are attached to outside membrane network called the endoplazmatic reticulum; make proteins destined into membrane and for export from the cell (secretion) Ribosomes  The endomembrane system Nuclear envelope, endoplasmic reticulum, Golgi apparatus, lysosoms, various kinds of vacuoles and plasma membrane ER consist of a network of membranous tubules and sacs called cisternae ER is continuous with nuclear envelope Smooth ER - cytoplasmatic surface lacks ribosomes Rough ER – ribosomes are attached to the cytoplasmatic side Function of smooth ER – synthesis of lipids (phospholipids, steroids), metabolism of carbohydrates (glycogen) and detoxification of drugs (barbiturates) and poisons Function of rough ER – secretion of proteins, glycoproteins formation of transport vesicules to other components of endomembrane system Golgi apparatus – sorting cell products, they are modified and stored (removes sugar monomers and product diverse oligosaccharides) two poles are reffered to as the cis face ad trans face Exocytosis and Endocytosis is transport of large molecules Cell secretes macromolecules by a fusion of vesicles with plasma membrane = Exocytosis - budded from the Golgi – products Endocytosis – cell takes in macromolecules a particulate matter by forming new vesicles from plasma membrane three types : Phagocytosis – cell engulf a particle Pinocytosis – cell gulf droplets of extracellular fluid Receptor-mediated endocytosis is very specific – receptor and ligand Lysosomes are digestive compartments membrane bounded sac of hydrolytic enzymes enzymes hydrolyze in acidic environment (pH 5) proteins, polysaccharides, fats and nucleic acids function is intracellular digestion of food particles, smaller organisms and organic components engulfing by phagocytosis and own organic old material by autophagy Vacuoles, vesicles membrane–bounded sacs vacuoles have various functions: food vacuoles contractile vacuoles tonoplast Mitochondria and chloroplasts Convert energy (ATP) that cells use for work Mitochondria are the sites of cellular respiration Chloroplasts are sites of photosynthesis Semiautonomic organelles, that grow and reproduce within the cell contain own DNA (prokaryotic origin)  Mitochondria in all eukaryotic cells hundreds or thousands two membrane, each is phospholipid bilayer with a unique collection of embedded proteins The outer membrane is smooth, the inner membrane is convoluted with infolding called cristae Intermembrane space Mitochondrial matrix Chloroplast A member of plant organelles family called plastids: leukoplast chromoplasts chloroplasts thylakoids Inner membranous system, outside of it is stroma photosynthesis  the dynamic networks of The cytoskelet protein fibers extending 1 throughout the cytoplasm Support, motility, 2 regulation microfilaments (2) 3 intermediate filaments (3) microtubules (1) 3. cell-shape, mechanical support, provides anchorage for many organelles and cytosolic enzymes 2. the thinnest filaments, twisted double chain of actin subunits, cell-shape, cell organization, pull a forces, function in muscle, amoeboid movement – pseudopodia 1. compression-resisting function, dynamic behavior, binding GTP for polymerization, intracellular transport (associated with dyneins and kinesins, they transport organelles like mitochondria or vesicles, the axoneme of cilia and flagella, the mitotic spindle Centrosomes and Centriolas 9 set of triplets microtubules tubulin α, β => microtubules grow out from a centrosome, within of animal cells are a pair of centriolas cell shape, cell motility, cell division, organelle movements Flagella and Cilia Unicellular eukaryotic organisms, sperm of animals, algae and some plants Cilia occur in large numbers on the cell surface. Cilia work like oars:  Flagellum Flagella are longer and are usually limited to just one or few the motor molecule called dynein basal body identical to centriole 9 doublets of outer microtubules one doublet of inner microtubule  Microfilaments - Actin filaments Molecules of actin – a globular protein G => F fibrilar protein Is a twisted double chain of actin subunits function is bear tension (pulling forces) ameboid movement – extend and contraction of pseudopodia maintenance of shape, changes of shape  Cellulose of plant cell walls helps to plant cells Plant Cells: to allow high pressure to build inside of it, without bursting. A plant cell has to be able to have chloroplast accept large amounts of liquid through use photosynthesis osmosis, without being destroyed. An animal have cell wall cell does not have this cell wall. If you start to one large vacuole fill the animal cell with too much distilled water are rectangular or other fluid, it will eventually pop. Animal Cells: don't have chloroplast no cell wall one or more small vacuole either circular or have irregular shape