Chapter 3. 진정세균과고세균 (Bacteria and Archaea)

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1 Chapter 3 진정세균과고세균 (Bacteria and Archaea)

2 원핵세포 (Prokaryotes ) Prokaryotes differ from eukaryotes in size and simplicity Most lack internal membrane systems Prokaryotes are divided into two taxa 진정세균 (bacteria) and 고세균 (archaea)

3 Shape and Arrangement 구균 (Cocci, coccus) spheres 쌍구균 (Diplococci, pairs) 연쇄상구균 (Streptococci, chains) 포도상구균 (Staphylococci, grape like clusters) 사분체 (Tetrads, 4 cocci in a square) 간균 (Bacilli, bacillus) rods

4 세포막 (Plasma Membrane) Absolute requirement for all living organisms Encompasses the cytoplasm Selectively permeable barrier Interacts with external environment Receptors for detection of and response to chemicals in surroundings Transport systems Metabolic processes

5 Fluid Mosaic Model of Membrane Structure Lipid bilayers with floating proteins 표재성단백질 (peripheral protein) 내재성단백질 (integral protein)

6 Asymmetry of Most Membrane Lipids 양친매성지질 (Amphipathic lipids) Polar ends hydrophilic interact with water Non polar tails hydrophobic insoluble in water

7 세포벽 (Bacterial Cell Wall) Peptidoglycan (Peptide + Sugar) Rigid structure that lies just outside the cell membrane Two types based on Gram stain Gram positive stain purple; thick peptidoglycan Gram negative stain pink; thin peptidoglycan and outer membrane

8 Peptidoglycan Structure Meshlike polymer of identical subunits forming long strands Two alternating sugars N acetylglucosamine (NAG) N acetylmuramic acid (NAM) Alternating D and L amino acids

9 Peptidoglycan Structure Helical shape Crosslinked by peptides for strength This cross linking step is inhibited by penicillin

10 Cell Wall Functions Maintains shape of the bacteriu Helps protect cell from osmotic lysis Helps protect from toxic materials May contribute to pathogenicity

11 Mechanism of Gram Stain Reaction Gram stain reaction due to nature of cell wall Shrinkage of the pores of peptidoglycan layer of gram positive cells Thinner peptidoglycan layer and larger pores of gram negative bacteria does not prevent loss of crystal violet

12 Osmotic Protection by Cell Wall Antibacterial Mechanism of Penicillin 저장액 등장액 고장액 Lysis Plasmolysis

13 Ribosomes Consisting of protein and RNA Svedburg unit, sedimentation coefficient Total (70S) = small subunit (30S)+ large subunit (50S) RNA 16S in small subunit 23S and 5S in large subunit

14 Plasmids Extrachromosomal DNA Small, closed circular DNA molecules Exist and replicate independently of chromosome Episomes May integrate into chromosome Confer selective advantage to host (e.g., drug resistance)

15 Motility Chemotaxis ( 주화성 ) Chemoreceptor ( 화학수용체 ) Move toward chemical attractants such as nutrients, away from harmful substances Move in response to temperature, light, oxygen, osmotic pressure, and gravity Fimbriae ( 핌브리아 ), pili ( 선모 ) Flagella ( 편모 )

16 Chapter 4 진핵세포의구조와기능 (Eukaryotic Cell Structure and Function)

17 Common Features of Eukaryotic Cells Membrane delimited nuclei Membrane bound organelles that perform specific functions Intra cytoplasmic membrane complex serves as transport system More structurally complex and generally larger than bacterial or archaeal cells

18 세포골격 (Cytoskeleton) Vast network of interconnected filaments within the cytoplasmic matrix 미세섬유 (microfilaments, actin) 미세소관 (microtubules) 중간섬유 (intermediate filaments) Plays role in both cell shape and cell movement

19 Secretory Endocytic Pathway Intricate complex of membranous organelles and vesicles that move materials into the cell from outside, from inside to outside, and within the cell Endoplasmic reticulum (ER) Golgi apparatus Lysosomes

20 Endoplasmic Reticulum (ER) Irregular network of branching and fusing membranous tubules and flattened sacs Rough ER Smooth ER

21 Endoplasmic Reticulum (ER) Rough ER Ribosomes attached Synthesis of secreted proteins by ER associated ribosomes Smooth ER Devoid of ribosomes Synthesis of lipids by ER associated enzymes Transports proteins, lipids, and other materials within cell Major site of cell membrane synthesis

22 Golgi Apparatus Membranous organelle made of cisternae stacked on each other Cis and trans faces Involved in modification, packaging, and secretion of materials

23 Lysosomes Membrane bound vesicles found in most eukaryotes Involved in intracellular digestion Hydrolases Function best under slightly acidic conditions Maintain an acidic environment by pumping protons into their interior

24 세포내흡입 (Endocytosis) All eukaryotic cells Used to bring materials into the cell Solutes or particles taken up and enclosed in vesicles pinched from plasma membrane In most cases materials are then delivered to lysosome and destroyed

25 Types of Endocytosis Phagocytosis Use of cell surface protrusions to surround and engulf particles Fuse with lysosomes and resulting vesicles called phagosomes Pinocytosis Uptake of liquid materials Clathrin dependent endocytosis Caveolin dependent endocytosis

26 Clathrin dependent endocytosis Entry of LDL (low density lipoprotein) Involves membrane regions coated on cytoplasmic side with the protein clathrin (coated pits) Coated pits have external receptors that specifically bind macromolecules Pinching off of coated pits forms coated vesicles

27 자가소화 (autophage) 대자가소화 (macroautophage) 자가파고솜 (autophagosome) 라이소솜과융합

28 Nucleus Membrane bound spherical structure that houses genetic material of eukaryotic cell Nucleolus for ribosome synthesis Nuclear pore for material transport

29 Chromatin, nucleosome and chromosome Chromatin Dense fibrous material Complex of DNA, histones, and other proteins Five types of histones form nucleosomes H1, H2A, H2B, H3, and H4 Nucleosomes Chromosomes Condensation of chromatin during cell division

30 Eukaryotic Ribosomes Larger than the 70S bacterial and archaeal ribosomes Total (80S) = large SU (60S) + small SU (40S) Attached to ER or free in cytoplasmic matrix

31 Mitochondria The power houses of the cell Site of tricarboxylic acid (TCA) cycle activity ATP is generated by electron transport and oxidative phosphorylation Have own ribosomes and mitochodrial DNA

32 Chloroplast ( 엽록체 ) Site of photosynthetic reactions Thylakoids site of light reactions (trapping of light energy to generate ATP, NADPH, and oxygen) Stroma site of dark reactions (formation of carbohydrates from water and carbon dioxide)

33 Chapter 5 바이러스와비세포성감염인자 (Viruses and Other Acellular Infectious Agents)

34 Importance of Viruses Major cause of disease Important as a new source of therapy Important in evolution Transfer genes between bacteria, others Important model systems in molecular biology

35 General Properties of Viruses Virion Complete virus particle Consists of 1 molecule of DNA or RNA enclosed in coat of protein Cannot reproduce independent of living cells nor carry out cell division

36 Virions Infect All Cell Types (Bacterio)Phage Bacterial viruses Most are eukaryotic viruses Classified into families based on Genome structure, life cycle, morphology, and genetic relatedness

37 Structure of Viruses Virion size nm in diameter Nucleo capsid Nucleic acid (DNA or RNA) + protein coat (capsid) Envelopes ( 외피 ) Presence of membrane Enveloped viruses Non enveloped viruses

38 Capsids Large macromolecular structures which serve as protein coat of virus Protect viral genetic material and aids in its transfer between host cells Made of protein subunits called protomers Helical, icosahedral ( 정이십면체 ), or complex

39 Helical and icosahedral Capsids Helical Tabacco mosaic virus Icosahedral Most of viruses

40 외피 (Viral Envelopes) An outer, flexible, membranous layer Arise from host cell plasma or nuclear membranes Envelope proteins, which are viral encoded, may project from the envelope surface as spikes Involved in viral attachment to host cell Used for identification of virus

41 Viral Genome Diverse nature of genomes Single or double stranded DNA or RNA The size of the nucleic acid also varies from virus to virus Segmented or circular

42 Attachment, Entry, and Uncoating Specific receptor attachment Receptor determines host preference Specific tissue (tropism) Enveloped virus Fusing with plasma membrane Endocytosis Non enveloped virus Endocytosis

43 Synthesis of Viral Protein and Genome Genome dictates the events DNA viruses replicate DNA genome RNA viruses replicate RNA genome Early or late viral proteins Structural or nonstructural viral proteins

44 Virion Release Non enveloped viruses lyse the host cell Enveloped viruses use budding Viral proteins are first incorporated into host membrane Nucleocapsid binds to viral proteins Envelop derived from host cell membrane

45 Quantification of Virus Direct counting count viral particles Indirect counting by an observable of the virus Plaque assays Dilutions of virus preparation made and plated on lawn of host cells Number of plaques counted Results expressed as plaque forming units (PFU) PFU/ml = number of plaques/sample dilution

46 Prions Proteinaceous Infectious Particle Cause variety of degenerative diseases in humans and animals Scrapie in sheep Bovine spongiform encephalopathy (BSE) or mad cow disease Creutzfeldt Jakob disease (CJD) and variant CJD (vcjd) Kuru