2014微生物英文课件chapter4eucaryotes a

1、Chapter FourEukaryotic cells and microorganisms4.1 The nature of eucaryotes4.2 Form and function of the Eukaryotic cell: external structures 4.3 Form and function of the Eukaryotic cell: internal structures 4.4 Survey of Eukaryotic microorganismsChapter 44.1 The nature of eucaryotesEndosymbiotic hyp

2、othesis.: mitochondria of modern-day eukaryotes arose from the stable incorporation of a respiring bacterium into other cells, and that chloroplasts similarly arose from the incorporation of a cyanobacterium-like organism that carried out oxygenic photosynthesis.Brock, P453Endosymbiotic Origin of Eu

3、karyotesFigure 16.9 Endosymbiotic models for the origin of the eukaryotic cellEukaryotic cell structureChapter 44.2 Form and function of the Eukaryotic cell: external structure 1. Flagella of eukaryotes: - serve the same purpose as flagella of prokaryotesmotility-100 to 200 m long, much longer and t

4、hicker (by a factor of 10) than flagella of prokaryotes 4.2.1. Cilia and Flagella-locomotor appendages- are membrane bound structures- they have 9 microtubule doublets arranged in a circle around 2 central microtubules, arrangement referred to as 9+2.Dr. Qin LUOLocomotor (运动）运动）patterns in flagellat

5、espermit the microtubules to “walk” by sliding past each other, whipping the flagellum back and forth. 2. Cilia纤毛纤毛- 5 to 20 m long-the same structure as flagella, but shorter and more numerous.-found only on a single group of protozoa and certain animal cells.- function in motility, feeding & f

6、iltering. - move by wave-like beating ，划桨式运动划桨式运动-The placement and number of flagella can be useful in identifying flagellated protozoa and certain algae4.2.2. surface structures-the glycocalyx (糖被糖被, 多多糖糖-蛋白质复合物蛋白质复合物)-an outermost boundary that comes into direct contact with environment-usually c

7、omposed of polysaccharides- appears as a network of fibers, a slime layer or a capsuleFunction:-Protection, -adherence,-reception of signal beneath the glycocalyx -fungi and most algae have a thick, rigid cell wall-protozoa, a few algae, and all animal cells lack a cell wall & have only a membra

8、ne4.2.3. The cell wall-Fungi have thick inner layer of polysaccharide fibers composed of chitin (几丁质几丁质) or cellulose (纤维素纤维素) & a thin layer of mixed glycans (多多糖糖); -Algae varies in chemical composition; substances commonly found include cellulose, pectin (胶质胶质), mannans (甘露聚糖甘露聚糖), and minera

9、ls such as silicon dioxide(二氧化硅二氧化硅), & calcium carbonate(碳酸钙碳酸钙)- It is rigid and provide structure support and shape.4.2.4. The cell membrane- serve as selectively permeable barriers in transport; involved in cell-cell recognition, endo- and exocytosis and adhesion to surface; transport system

10、 is located in membrane- Sterols (固醇) confer stability- typical bilayer of phospholipids and proteins-Eukaryotic cells also contain membrane-bound organelles that account for 60-80% of their volumeThe most obvious difference between Eukaryotic cells and procaryotic cells is in their use of membranes

11、. The partitioning of the Eukaryotic cell interior by membranes makes possible the placement of different biochemical and physiological functions in separate compartments so that they can more easily take place simultaneously under independent control and proper coordination. Abundant membrane syste

12、ms are the need for adequate regulation, metabolic activity and transport in eukaryotic cell.Dr. Qin LUO4.3 Form and function of the Eukaryotic cell: internal structures 4.3.1. The Nucleus: the control center- Nuclei (pl. of nucleus) house the chromosomal DNA of the cell. They usually contain more t

13、han one chromosome.- The double-membrane structure (nuclear envelope,核膜核膜) penetrated by nuclear pores (核孔核孔) that allow materials to be transported into or out of the nucleus(核）核）.- The nucleolus (核仁）核仁） is a highly active region of the chromatin. for rRNA synthesis & ribosome assembly- DNA is

14、complexed with histone proteins4.3.2 Endoplasmic Reticulum (ER)- Used in transport and storage-a complex set of internal membranes that may have ribosomes attached (rough endoplasmic reticulum; RER), or that lacks ribosomes (smooth endoplasmic reticulum; SER) Rough endoplasmic reticulum (RER) origin

15、ates from the outer membrane of the nuclear envelop & extends in a continuous network through cytoplasm; rough due to ribosomes, proteins are synthesized & shunted into the ER for packaging & transport. First step in secretory pathway. Smooth endoplasmic reticulum (SER) closed tubular ne

16、twork without ribosomes, functions in nutrient processing, synthesis & storage of lipids, etc.4.3.3 The Golgi Apparatus consists of a stack of flattened sacs called cisternae (囊囊). closely associated with ER Transitional vesicles from the ER containing proteins go to the Golgi apparatus for modi

17、fication and maturation Condensing vesicles transport proteins to organelles or secretory proteins to the outside Golgi apparatusDr. Qin LUO4.3.4 Natures assembly lineThe cooperation of organelles in protein synthesis and transport:Nucleus RER Glogi vesicles secretionLysosome (溶酶体溶酶体) and Vacuoles(液

18、泡液泡)-Lysosome is originating from the Golgi apparatus.-Lysosomes contain enzymes needed for intracellular digestion of food particles, invading microorganisms and removal of cell debris (残骸残骸).-Vacuoles are formed in phagocytic cells (吞噬细胞 )in response to food and other substances that have been eng

19、ulfed-Vacuoles are used in storing reserve food such as fats and glycogen (糖原), regulate osmotic pressure in some protozoaChapter 4The origin and action of lysosomes in phagocytosis4.3.5. Mitochondria (s. mitochondrion)-the site of respiration and oxidative phosphorylation A. Mitochondria have both

20、an inner membrane and an outer membrane enclosing a fluid matrix. The inner membrane is infolded to form plates or tubes called cristae (s., crista,嵴), which greatly increase the surface area of membrane.B. The enzymes of the tricarboxylic acid cycle and the -oxidation pathway for fatty acids are lo

21、cated within the matrix基质C. Electron transport and oxidative phosphorylation occur only on the inner mitochondrial membraneD. Mitochondria use their own DNA and their own ribosomes (70S) to synthesize some of their proteins4.3.6 Chloroplasts-the site of photosynthesisA. Chloroplasts have an outer me

22、mbrane and an inner membrane system of flattened sacs called thylakoids(类囊体) that often form stacks known as grana(叶绿体基粒); the fluid matrix compartment is called the stroma(基质)C. The formation of carbohydrate from carbon dioxide and water (dark reaction) occurs in the stromaB. The trapping of light

23、energy to generate ATP, NADPH, and oxygen (light reaction) occurs in the thylakoid membranes of the grana4.3.7. Eukaryotic Ribosomes-generally larger (80S ribosome consists of a 40S and a 60S subunit) and more complex than prokaryotic ribosomes; however, like their prokaryotic counterparts (70S: 30S

24、+50S ), they are responsible for the synthesis of cellular proteinsA. Ribosomes may be attached to the ER (Endoplasmic Reticulum) or they may be free.B. ER-associated ribosomes synthesize integral membrane proteins or proteins that are secreted out of the cellC. Free ribosomes synthesize nonsecretor

25、y, nonmembrane proteins4.3.8 Cytoskeleton flexible framework of proteins, microfilaments & microtubules form network throughout cytoplasm involved in movement of cytoplasm, ameboid movement, transport, & structural support4.3.8 CytoskeletonA. Microfilaments微纤丝微纤丝are thin protein strands that

26、 may be scattered throughout the matrix or organized into networks and parallel arrays; they play a major role in cell motion and cell shape changesB. Microtubules微管微管are long, hollow tubes that help maintain cell shape, that are involved (with microfilaments) in cellular movement, and that also participate in intracellular transport of substances, form the mitotic spindle during cell divisionMicrotubules in a pseudopodium from the protozoan Reticul