Download Teacher

Teaching plan of bilingual teaching
双语教学教案
Gannan Medical College
Department of pathogenic Biology
Teacher
（教师）
Date
（日期）
Grade
（年级）
Speciality
专业
chapters and sections
(授课章节)
Objective and request
教学目的和要求
Lecture type
(授课类型)
Clinical medical
(临床医学)
Theory Course
(理论课)
Subject
（课程）
Class hour
（学时）
Medical Microbiology
医学微生物学
Chapter 2 Basic Properties of microbes
1.
2.
3.
4.
Master the superficial structure of bacteria.
Master the special structure of bacteria and their functions.
Master the major feature of the replication cycle of viruses.
Understand the size and shape of bacteria.
5. Understand the growth curve of bacteria
6. Understand the morphology and culture properties of fungi
Emphasis and difficulty
授课重点、难点
Reference teaching material
参考教材
Teaching aid
媒体与教具
1. The superficial structure of bacteria
2. The special structure of bacteria
3. The major feature of the replication cycle of viruses.
1．周正任主编.《医学微生物学》第 6 版
2．Medical microbiology(21 edition, Jawetz, Melnick, and Adelberg)
Powerpoint
Teach contents（教学内容）
Basic Principles of Microbiology
Chapter 2 Basic Properties of microbes
Section I Bacteria
I. Size and Shape of bacteria
(I ) Size of bacteria
Measure unit: um(micrometer): Coccus 1 um; bacillus 2-3um
(II) Shape of bacteria
1. coccus (cocci)
1) diplococcus : in pairs
2) streptococcus: long; chain
3) tetrad and sarcina:
4) staphylococcus: irregular cluster
2. bacillus (bacilli): rod
1
6 hours
3. Spirilla bacterium
1) vihrio: v. cholera
2) Spirillum: Helicobacter H. pylori
II. Basic Bacterial Structure
cell wall
Basic structure
cell membrane, mesosome
Cytoplasm: ribosome, plasmid, cytoplasmic granules;
nucleoid
（I）cell wall
1.function :
1) protection
2) keep the constant shape .
3) antigenicity .
4) exchange material
2.structure and chemical composition: peptidoglycan（mucopeptide）
1) polysaccharide
backbone: N-acetyl glucosamine link N-acetyl muramic acid with 1.4-glucosidic bond
2) tetrapeptide side chain: link muramic acid.;ala; glu; lys; ala
3) pentapeptide bridge
3. Special components of Gram-positive cell wall
(1) teichoic acids : wall teichoic acid and membrane teichoic acid
functions :
1) bind Mg2+(magnesium)
supply of this iron to the cell
2) provide the cell with its consistency
3) adhesion
pathogenicity
4) antigenicity
(2) polysaccharides
may contain a variety of sugars.
4. Special components of Gram-Negative cell wall .
(1) Outer membrane: exchange; receptor
1) Lipoprotein
are firmly but non covalently attached to the peptido-glycan and out membrane
2) lipopolysaccharide, LPS
a complex and unique glycolipid consisting of three distinct but covalently linked regions:
a) lipid A: toxin component of endotoxin
b) core polysaccharide
c) specific polysaccharide “O” Ag
（II）Cell membrane
mesosome : invaginated vesicular membrane，to increase membrane area such as chondriosome(线粒
体) and spindle.
Function:
1) spindle-like（类纺锤体）: cell division
2) chondroid(类线粒体)：
2
（III）Cytoplasm
plasmid：extra-chromosomal genetic material, circle double streands DNA, to replicate independently,
to carry genetic information, to control a wide rang of functions to acteria.
factor F ---------control sex pili
factor R----------control drug resistance
col factor ------control E col: to produce bacteriocin.
III. Special structure of bacteria
Specific structure: capsule, flagellum, pillus, endospore
（I）capsule
1. Concept: bacteria secrete a slime layer outside the cell wall, which is composed of polysacchride or
polypeptid.
Such as :pneumococcus, anthracis
>0.2um capsule
<0.2um microcapsule
slime layer:
2. Functions：condition, enviroment host body
1) anti-phagocytosis
2) anti-dry
3) adherence
（II）flagella
1. Concept: long filamentous appendage.
2. Functions:
1) motility
2) antigenicity “H”-Ag , some bacterin
3) pathogenicity and adherence:
（III）pili pilus）
1. Concept: filamentous appendage on the surface of bacteria, shorter straighter, and thinner than flagella.
2. Classification
1) common pili
2) sex pili
(IV) spore
1. Concept: round or elliptic minute body formed inside the bacteria —endospore
dormant form（resting forms）
：spore
vegetative form: bacteria
2. Functions: highly resistant to heat, chemical, dry.
reasons: （1）many layers
（2）little waterr
( 3）large amount of calcium
（4）heat-stable enzyme DPA
destroy spore: autoclave, under 121°C 1.05kg/cm2 for 15—30′
3. forming: inadequate nutrition
IV Special living form of bacteria.
3
Bacterial L-Forms: cell wall deficient form
Some bacteria's form of small filterable protoplasmic elements with defective or absent cell walls.
1) Morphology: spherical body, pleomorphic and plastic.
Colonies: fried egg
2) Media high osmotic, reversion
3) Pathogenicity:
Similar to the infection of virus or mycoplasma （organisms without wall）
V Bacterial metabolism
Metabolic products
1.Catabolic products and biochemical reaction
2.Anabolic products and clinical significance
1) pyrogen
polysaccharide of G-cell wall(LPS) that cause a rise in temperature in an animal or human body is
called pyrogen .
anti-high temperature 121°C, 30’. Cause fluid infusion reaction,
2) toxin and invasive enzymes
exotoxin
endotoxin
enzyme
3) pigment
Water-soluble: P. aerogenosa ---green
fat –soluble: S. aureus —golden
4) antibiotics
Killing or inhibiting substances produced by some kinds of microorganisms, such as Actinomycete.
5)
bacteriocin
protein by certain bacteria, which can kill or inhibit the growth of related strains.
VI. Bacterial multiplication
1. nutrient material
1)water; 2)carbon source; 3)Nitrogen source; 4)inorganic ions ; 5)growth
2. nutrient type 1)autotrophy 2)heterotroph saprophyte; parasite
3. Bacterial growth and reproduction
growth condition: (1)enough nutrients (2) Suitable PH (3) suitable temperature (4)suitable air
obligate aerobe
obligate anaerobe
facultative anaerobe
microaerophilic bacterium
Reasons that obligate anaerobes can’t grow in free oxygen condition:
(1) Lack of cytochrome and cytochromas
(2) lack of superoxide dismutase (SOD) catalase, peroxidase
4. mode and spead of bacterium reproduction
1) Mode:
2) speed: generation time 20-30min
4
For example: E. coli ; Myco. Tuberculosis: 18 hrs
3) growth curve:
a. lag phase; adaptation
b. logarithmic phase/ Exponential Growth Phase: most rapid reproduction
c. stationary phase: rate of reproduction = rate of deed
d. decline phase: the rate of dead > the rate of reproduction.
Section II Viruses
I．Size and Shape
Virion（: The basic infectious particle of a virus is known as the virion.The virion is composed of the nucleic
acid genome, structural protein and in some viruses an enclosing lipid-containing envelope.
Size : 20 -- 300 nm ( the most virus く 150 nm);
Shape: the commonest shape ---- small spherical virus
Others-----filamentous,brick,bullet
II. Structure and Chemical Composition
Viruses contain:
a nucleic acid genome (RNA or DNA)
a protective protein coat (called the capsid)
A Viral envelope
Non-structural protein
(I) Core : Nucleic acid
1. Single kind: consist of DNA or RNA ( never both).
1) DNA :
single-stranded DNA (ssDNA):
double-stranded DNA ( dsDNA ) : --- the commonest type of nucleic acid in viruses of human.
2) RNA:
double-stranded RNA (dsRNA) :
single-stranded RNA (ssRNA): --- the commonest type of nucleic acid in viruses of human..
+ssRNA : is the same as the viral mRNA ,can direct as viral mRNA
-ssRNA: as a template transcribe complementary mRNA.
Retrovirus: +ssRNA
2. Functions:
1) virus replication: template
2) genome: encodes genetic information.
3) infectious nucleic acid: refer to some viral nucleic acid which can enter cells and reproduce new
viruses,such as dsDNA V and +ssRNA V.
3. Non-structural protein:
(1) viral enzymes: such as：RNA-dependent RNA polymerase or transcriptase .
(2) specific viral protein: such as : transformation protein of tumor virus.
(II) . Capsid：protein coat ,
1. capsid is composed of distinct morphologic units---- capsomeres
--- icosahedral symmetry:
5
--- helical symmetry:
--- complex symmetry:
2. Functions:
1) protection (protect viral nucleic acid from enzymic action).
2) specific binding sites.
3) antigenicity of capsid protein.
(III). Envelope: lipid, glycoprotein
1. Consists of lipid bilayer and glycoprotein:
lipid --- derived from host cell membrane.
Glycoprotein--- coded by the viral genome.
Spikes --- virus-encoded glycoprotein protruding from lipid bilayer, which are important for adsorption
and entry into the host cell.
2. Functions:
1) as the binding sites(for enveloped virus).
2) antigenicity of glycoprotein.
III. Viral Multiplication
(I) Replication cycle:
1. adsorption:
2．penetration: virus enter the cells.
Entry of Naked viruses: endocytosis
Entry of enveloped virus :
(1) simple fusion of membranes --expels nucleocapsid into cytoplasm
(2) entire particle taken up by endocytosis-- virus still in vesicle which fuses with endosome (due to
low pH)
3.uncoating
Rapid change from stable structure to release of genome
4. biosynthesis:
4.1 Three kinds of strategies for RNA viruses:
(1 )Positive-strand viruses
a. SYNTHESIS OF VIRAL PROTEINS
The mRNA is translated into a single polypeptide (polyprotein), which is cleaved.
Products of cleavage include: An RNA polymerase (replicase)、Structural components of the virion、
Proteases .
b. RNA REPLICATION
(2) Negative-strand viruses
a. TRANSCRIPTION
to refer to synthesis of mRNAs.
b. TRANSLATION
Messenger RNAs are translated on host ribosomes and all five viral proteins made at the same time.
c. RNA REPLICATION
d. New negative strands may:
(3).Retroviruses
6
4.2 DNA viruses:
(1) Early gene expression:--------early phase
The early transcript (primary transcript) results in the mRNAs for early proteins. The mRNAs are
translated in the cytoplasm.
(2) DNA replication
DNA replication uses host cell DNA polymerase, which recognizes the viral origin of replication.
This process of DNA replication is very similar to that which occurs in the host cell .
(3) Late gene expression------late phase
Late mRNAs are made after DNA replication.
5. Assembly and release:
--- by lysis of the host cell ( naked viruses).
--- by budding through cell membrane (enveloped viruses).
(II)Anormal multiplication:
1. Abortive infection:
2. Defective virus:
3. Interference:
Section III Medical Mycology
I.morphology
1. monocellular fungi:
(1) yeast form;
(2) yeast-like form
2. multicellular fungi:
(1) hypha—A hypha is a long, branching filament that collectively form the feeding structure of a fungus
called the mycelium.
(2) spore —Spores are dispersal units of fungi.
II. culture properties
1. multiplication modes:
(1) Budding
2. sabouraud medium：Dextrose, peptone, agar, pH 5.6
3. monocellular fungi---37℃; multicellular fungi---28℃
4. grow slowly: 4 days-3 weeks
yeast-form colony
5. colonal types
yeast-like colony
hyphomycete-form colony
question
思考题
1.
2.
3.
4.
5.
What are the differences between gram-positive and gram-negative cell walls?
What is the function of capsules, flagella, and pilli?
What is the relationship between structures of bacteria and pathogenicity?
What is abortive infection of virus?
Compare viruses with bacteria.？
7