Lecture 3 Prokaryotic Cell Biology Bio119 3-1 I. CYTOPLASM A. The cytoplasm is thick! B. It contains nucleoid, ribosomes, macromolecules like proteins and RNA, small molecules like amino acids, some intracellular inclusions C. Nucleoid 1. DNA a. b. c. Table. Comparison of genome sizes of various organisms Organisms Genome Size (kbp) Predicted ORFs Circular or Linear, 1 or 2 molecules Mycoplasma genitalium 580 470 C, 1 Borrelia burgdorferi 910 853 L, 1 Helicobacter pylori 1700 1600 C, 1 E. coli 4600 4300 C, 1 Vibrio cholerae 4000 3890 C, 2 Mycobacterium tuberculosis 4400 3900 C, 1 Methanococcus jannaschii (archaea) 1700 1682 C, 1 (plasmids) Saccharomyces cerevisiae (eukaryote) 12,000 6000 L, 16 Human 3 million 30,000 L, 23 d. In an aggregate form called a nucleoidLecture 3 Prokaryotic Cell Biology Bio119 3-2 2. This structure may facilitate coupled: D. Ribosomes— 1. 2. Two subunits 3. E. Cytoplasmic Inclusion bodies 1. Two types 2. Some examples: a. Energy or metabolite granulesLecture 3 Prokaryotic Cell Biology Bio119 3-3 3. Magnetosomes 4. Gas, in Gas Vesicles II. CYTOPLASMIC MEMBRANE A. Also called inner membrane, plasma membrane B. As in every other membrane, composed of Phospholipids 1. 2. Hydrophilic part: 3. Hydrophobic part: 4. Connection between the hydrophilic head and hydrophobic tail is different in bacteria vs. archaeaLecture 3 Prokaryotic Cell Biology Bio119 3-4 5. The membranes of Archaea are unusual in other ways: C. Organisms add more rigid molecules to the membrane to give it strength 1. eukaryotes 2. most prokaryotes do not have sterols D. Proteins of two types: 1. Peripheral 2. Integral E. Functions of the cytoplasmic membrane 1. Mainly serves as a _____________________ barrier 2. An anchor for: ______________________ 3.Lecture 3 Prokaryotic Cell Biology Bio119 3-5 III. CELL WALL A. Needed to keep the prokaryotic cell from popping B. In bacteria: can be divided into two types based on thickness C. Cell wall Composition in Bacteria—Peptidoglycan: 1. Rigid layer 2. A polymer of two sugars: N-acetyl glucosamine and N-acetyl muramic acid in: 3. Multiple sugar chains are ___________________ by amino acids 4. Strength comes from the amino acid connection between the 2 or more sugar chainsLecture 3 Prokaryotic Cell Biology Bio119 3-6 D. Archaeal Cell Walls are made of different molecules 1. Pseudopeptidoglycan 2. In other archaea they are protein or polysaccharide. 3. Archaea can also stain gram- and gram+, but this is not based on the same underlying structures as in bacteria. a) Gram – archaea do not have an outer membrane They usually have surface layer of protein/glycopprotein b) Gram+ archaea have single thick layer for wall F. Because the cell wall is necessary for prokaryote survival, if you can compromise it, you can kill the bacteria 1. What happens if you remove the cell wall: 2. Because the wall is critical, it is the site of action of several antibacterial chemicals and antibiotics a. Lysozyme Enzyme that cuts:_______________________ Made by: _____________________________Lecture 3 Prokaryotic Cell Biology Bio119 3-7 b. Antibiotics such as Penicillins and Cephalosporins 1) Bind to the ___________________ enzyme 2) 3) Penicillins: 4) This is called __________________________________. 5) Result is that sugar chain is not crosslinked, therefore not as strong 6) w/o strong wall, 7) Death only occurs if the cells are ________________ Why? 8) Structure: β-lactam ring c. Resistance to penicillins can arise if the bacteria