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1、Bacteria and archaeaIntro to bacteria and how we classify them Bacteria and Archaea•Most prokaryotes are unicellular •Prokaryo;c cells typically have diameters in the range of 0.5‐5um Internal organiza;on and DNA •Lack of complex compartments and membrane‐bound
2、 structures in eukaryo;c cell •Nucleoid: a region of cytoplasm where the chromosome located •A circular chromosome with many fewer proteins in nucleoid•Plasmid: a much smaller circular DNA separate from chromosome DNA, carrying only a few genes •70S ribosomes;
3、 smaller than eukaryo;c (80S) General Cell surface structures •Capsules‐ a s;cky layer of polysaccharide or protein –Adhere to their substrate –helps avoid an;bio;cs –Some protect prokaryotes from aQacks by the host’s immune system •Fimbriae‐ hairlike appendage
4、s –Help cells adhere to other cells or to a substrate •Sex pili‐ appendages longer and lesser than fimbriae–Pull two cells together prior to DNA transfer –Can help a bacteria move •flagella –Mo;lity; roughly 50% are capable of movemen
5、t – at rela;vely fast speeds Archaea•Share certain traits with bacteria and other traits with eukaryotes. Kingdom Archaebacteria•“ancient bacteria”•Single‐celled •Prokaryo;c •Live in harsh environments (i.e. hot springs, deep sea vents, VERY salty lakes) Kingd
6、omEubacteria•“True”Bacteria•Prokaryote•Unicellular•CircularDNA•MembranescontainpeptidoglycanHow we classify bacteria! •SHAPE •MOVEMENT •METABOLISM (WAY more diverse than you’ve seen before) •CELL WALL STRUCTURE (tomorrow Dr. Tao will discuss) Classifica;on ‐ Sha
7、pe •3 Shapes –Cocci – spherical/round shape –Bacilli – rod shape –Spirilla – spiral shape CocciStaphylococcusDiplococcusStreptococcusBacilli!Ex: E. coliSpirilla•Ex:SyphilisClassifica;on: movement –Some propelled by flagella •Flagella: whip‐like structures used fo
8、r movement –Others spiral forward –Some glide using slime they secrete –Others do not move at all –Let’s WATCH ☺Classifica;on: Obtain Energy •Phototroph: obtain energy from
