浙江大学医学院：《现代医学导论》课程教学资源（PPT讲稿）医学微生物学概论 Understanding the medical microbiology

现代学手论 2食品安与营养专业求是科学痤 国口留 医学微生物学概论 a Understanding the medical microbiology Dr. Jing qian Zhejiang University School of Medicine April 09, 2014

医学微生物学概论 Understanding the medical microbiology Dr. Jing Qian Zhejiang University School of Medicine April 09, 2014 现代医学导论 2012级食品安全与营养专业求是科学班

Definitions Microorganisms( Microbes)微监物 Microbiology微生物学 Medical Microbiology匮学微物学

Definitions – Microorganisms(Microbes) 微生物 – Microbiology 微生物学 – Medical Microbiology 医学微生物学

Microorganisms/Microbes The word“ microbe” comes from the greek words mi秋kros, meaning small, and bios, meaning life. So microorganisms/microbes are small living things that are too small to be seen with the unaided eye Microorganisms were probably the first organisms to appear on the earth. However, these organisms were not seen until about 3 centuries ago when lenses powerful enough to make them visible were made Viruses, bacteria, fungi, protozoa and some algae are all in this category

•The word “microbe” comes from the Greek words mikros, meaning small, and bios, meaning life. So microorganisms/microbes are small living things that are too small to be seen with the unaided eye. •Microorganisms were probably the first organisms to appear on the earth. •However, these organisms were not seen until about 3 centuries ago when lenses powerful enough to make them visible were made. •Viruses, bacteria, fungi, protozoa and some algae are all in this category. Microorganisms/Microbes

Distribution The distribution of microorganisms is universal in nature including air, soil, water, animals, human body Habitat Approximate nuber of bacteria Garden soil (surface) 9.7X10/g Garden soil (30 cm deep) 5.7X10/g Lakewater(shallow 104ml Lakewater(deep) 102ml Seawater 1.1X10/m1 Human skin 10°/sqcm Human mouth 1037ml Human intestine 4X10/g Milk 103to10m1 Cheese 10°g Sunlit surface few Air few

•The distribution of microorganisms is universal in nature including air, soil, water, animals, human body. Distribution

Relationship with human beings There is a close relationship between microorganisms and human beings Beneficial activities most microbes are of benefit to human beings, some are necessary. eg. nitrogen, carbon cycles, etc Harmful activities: Only a small portion of microbes cause diseases and are poisonous to human, and these pathogenic microbes are really that concern us in the study of medicine

•There is a close relationship between microorganisms and human beings. • Beneficial activities: Most microbes are of benefit to human beings, some are necessary. eg. nitrogen, carbon cycles, etc. • Harmful activities: Only a small portion of microbes cause diseases and are poisonous to human, and these pathogenic microbes are really that concern us in the study of medicine. Relationship with human beings

Nitrogen in atmosphere(N2) Plants Assimilation Denitrifying bacteria Nitrogen-fixing Nitrates bacteria in root (No3) nodules of Decomposers(aerobic legumes and anaerobic bacteria and fungi) Nitrifying Ammonification bacteria Nitrification Ammonium(NH : e3). Nitrites( No2) Nitrogen-fixing soil bacteria Nitrifying bacteria Microbes in nitrogen cycle

Microbes in nitrogen cycle

C02 Air and water Cellular respiration Photosynthesis Cellular Chiefly plants, respiration algae] burning decay Decay by fung nd bacteria an Caco limestone), coal and oil Organic compounds Consumed by Organic compounds of autotrophs heterotrophs of heterotrophs [chie fly animals] Microbes in carbon cycle

Microbes in carbon cycle

et all baete验 cause disease Few bacteria are always pathogenic Many bactera are potentially pathogenic Most bacteria are never pathogenic 00

Organizational structure Background knowledge: Cell is the fundamental unit of all living things to carry out metabolic processes that transform energy and materials for growth and propagation(multiplication) There are two fundamental types of cells: Prokaryotes and Eukaryotes with the major difference in whether or not the cell have membrane bound organelles and nucleus

Background knowledge: •Cell is the fundamental unit of all living things to carry out metabolic processes that transform energy and materials for growth and propagation (multiplication). Organizational structure •There are two fundamental types of cells: Prokaryotes and Eukaryotes with the major difference in whether or not the cell have membrane bound organelles and nucleus

Differences between prokaryotes/eukaryotes The prokaryotic cell, in contrast to the eukaryotic cell, has no nuclear membranes, mitochondria, endoplasmic reticulum, golgi body, phagosomes and lysosomes Prokaryotes generally possess only a single circular chromosome Since there is no nuclear membrane the chromosome is bound to a specific site on the cell membrane- the mesosome Prokaryotic ribosomes are 70S(S means Svedberg unit, a measure of size for centrifugation), whereas eukaryotic ribosomes are larger (80S) Prokaryotic ribosomal subunits are 30S and 50s (eukaryotic are larger). The 30S ribosome has 16S RNA, while the 50S ribosome contains 23S and 5S rna

• The prokaryotic cell, in contrast to the eukaryotic cell, has no nuclear membranes, mitochondria, endoplasmic reticulum, Golgi body, phagosomes and lysosomes. Differences between prokaryotes/eukaryotes • Prokaryotes generally possess only a single circular chromosome. Since there is no nuclear membrane, the chromosome is bound to a specific site on the cell membrane - the mesosome. • Prokaryotic ribosomes are 70S (S means Svedberg unit, a measure of size for centrifugation), whereas eukaryotic ribosomes are larger (80S). •Prokaryotic ribosomal subunits are 30S and 50S (eukaryotic are larger). The 30S ribosome has 16S RNA, while the 50S ribosome contains 23S and 5S RNA