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1、Microbiology,1.Introduction Microbiology is the study of microorganisms, which are unicellular or multicellular microscopic organisms. This includes eukaryotes such as fungi and algae(藻类) and prokaryotes such as bacteria. Viruses, though not strictly classed as living organisms, are also studied. Mi
2、crobiology is a broad term which includes many branches like virology, mycology, parasitology and others. A person who specializes in the area of microbiology is a microbiologist.,2. Bacteria Most bacteria (singular: bacterium) are unicellular microorganisms. They grow in soil, acidic hot springs, r
3、adioactive waste, seawater, and deep in the Earths crust. There are approximately ten times as many bacterial cells as human cells in the human body, with large numbers of bacteria on the skin and in the digestive tract. A few are beneficial, some are pathogenic bacteria and cause infectious disease
4、s.,2.1 Morphology Bacteria display a wide diversity of shapes and sizes, called morphologies. Most bacterial species are either spherical, called cocci (sing. coccus) or rod-shaped, called bacilli (sing. bacillus). Some rod-shaped bacteria, called vibrio（弧菌）, are slightly curved or comma-shaped; oth
5、ers, can be spiral-shaped, called spirilla（螺菌）.,coccus (cocci),Streptococcus pneumoniae 肺炎链球菌,Sarcina lutea 藤黄八叠球菌,Staphylococcus aureus 金黄色葡萄球菌,Escherichia coli 大肠埃希杆菌,Bacillus bifidus 双歧杆菌,Bacillus anthracis 炭疽芽孢杆菌,bacillus (bacilli),Vibrio cholerae 霍乱弧菌,Spirilla 螺旋菌,2.2 Cell structure,capsule(荚膜)
6、:protection against phagocytosis and desiccation，help attachment of bacteria to other cells or surfaces，composed of polysaccharides and sometimes protein cell wall: prevents osmotic lysis of cell protoplast（原生质体） and confers rigidity and shape on cells Gram-positive bacteria: peptidoglycan（肽聚糖） comp
7、lexed with teichoic acids（磷壁酸） Gram-negative bacteria: peptidoglycan surrounded by phospholipid，lipoprotein and lipopolysaccharide( LPS,脂多糖),Plasma membrane: permeability barrier; transport of solutes; energy generation; location of numerous enzyme systems; composed of phospholipid and protein Ribos
8、ome(核糖体): sites of translation (protein synthesis), composed of RNA and protein Plasmid(质粒): extrachromosomal genetic material, composed of DNA Pili（菌毛） and Flagella（鞭毛） : Swimming movement, composed of protein,nucleoid：an irregularly-shaped region within the cell of prokaryotes which has nuclear ma
9、terial without a nuclear membrane and where the genetic material is localized.,3. Virus 3.1 A virus is a sub-microscopic infectious agent that is unable to grow or reproduce outside a host cell. When independently exist-have no ability of metabolism (exchange material, transfer energy, grow and repr
10、oduce )-nonliving When be in a host-take over control of the metabolic activities of host cell, fulfill replication,3.2 Structure Each viral particle, or virion, consists of genetic material, DNA or RNA, within a protective protein coat called a capsid.,Hepatitis B virus 乙型肝炎病毒,Influenza virus 流感病毒,
11、Human immunodeficiency virus 人免疫缺陷病毒,SARS virus SARS 病毒,3.3 Replication,Attachment（吸附） is a specific binding between viral capsid proteins and specific receptors on the host cellular surface. This specificity determines the host range of a virus. For example, the human immunodeficiency virus (HIV) i
12、nfects only human T cells, because its surface protein, gp120, can interact with CD4 receptor on the T cells surface. Penetration（侵入）: following attachment, viruses enter the host cell through receptor mediated endocytosis or membrane fusion Uncoating（脱壳）: a process in which the viral capsid is degr
13、aded by viral enzymes or host enzymes thus releasing the viral genomic nucleic acid Biosynthesis（生物合成）: synthesis of viral protein and replication of viral genome. Assembly（装配）: assembly of intact virus Release（释放）: Viruses are released from the host cell by lysis,4.Importance of microorganisms to h
14、umankind,4.1 Microorganism and disease Pathogen: infectious agent, or more commonly germ, is a biological agent that causes disease to its host. Viral infection influenza（流感）, measle（麻疹）, chickenpox（水痘）, smallpox（天花），mumps（腮腺炎） Bacterial infection tuberculosis（肺结核），pneumonia（肺炎）， diphtheria（白喉） Para
15、sitol infection malaria（疟疾）：caused by plasmodium(疟原虫) fungal infection: onychomycosis(甲癣),4.2 Microorganism and medicine 4.2.1 Antibiotics the substance, such as penicillin or streptomycin（链霉素）, produced by or derived from certain microorganisms such as actinomycetes(放线菌）, fungi and bacteria（细菌）, th
16、at can destroy or inhibit the growth of other microorganisms. In clinic, it is used to fight against infectious diseases. Metabolism of microorganisms Primary metabolites (初级代谢产物）: amino acids , nucleic acids, vitamins Secondary metabolites(次级代谢产物）: antibiotics, hormones, pigments,Classification according to chemical structure -lactam（-内酰胺） antibiotics：penicillin derivatives，cephalosporins（头孢菌素类） Aminoglycoside（氨基糖苷） antibiotics ：streptomycin， kanamycin tetracycline antibio
