BIOL125_Ch4 Lecture Notes

BIOL125_Ch4 Lecture Notes - BIOL 125(Microbiology Lecture...

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BIOL 125 (Microbiology) Lecture Notes Chapter 4: Introduction to Cells and Prokaryotic Cell Structure 1. CHARACTERISTICS OF LIVING CELLS a. All living things build from cells. b. All cells have the following characteristics: i. Basic shapes are spherical, cubical, and cylindrical. ii. Plasma membrane encloses a cytoplasm. iii. They have genetic material in the form of DNA (chromosomes, ribosomes). c. Two basic cell types. i. Eukaryotes – have a true nucleus and membrane bound organelles. Examples include plants, animals, fungi, and protista. ii. Prokaryotes – do not have a nucleus, nor membrane bound organelles. Examples include bacteria and Archaea. 2. CHARACTERISTICS OF LIFE a. All living things have: i. Metabolic capabilities. 1) Need energy to live and their source of energy is nutrition. 2) Perform metabolic activities such as protein synthesis, photosynthesis, or respiration. 3) Use special organelles such as ribosomes, chloroplasts, or mitochondria. 4) In the process of living, they grow and develop. ii. Reproductive capability. 1) Genome is composed of DNA packed in chromosomes. 2) Offspring are produced either sexually or asexually. iii. Irritability and motility. 1) Respond to internal or external stimuli. 2) Move by self-propulsion using locomotary organelles (ex. flagella, cilia). iv. Protection and Storage. 1) The cell wall provides support and protection. 2) Store nutrients with the help of vacuoles, granules, and inclusion bodies. File: 17c31cf6c2949a093c33bfd577aece76b55c217e.doc Updated 8/14/09
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Lecture Notes Chapter 4 Page 2 3) Transport of molecules across the membrane. a) Use the help of plasma membrane to obtain nutrients for metabolic activities and to remove waste products. 3. PROKARYOTIC CELLS – BACTERIA AND ARCHAEA a. Structures. i. External. 1) Appendages – arise from the surface of the cell and assist with movement. a) Flagella and axial filaments ( periplasmic flagella ) assist with motility. i) Flagella. 1 Three main parts: a Filament – long, thin, helical structure composed of flagellin protein and exposed to the exterior. b Hook – curved sheath, anchored to the cell crossing thought the cell wall and attached to the basal body. c Basal Body – stack of rings firmly anchored to the membrane. 2 Flagella vary in arrangement and number. a Monotrichous – single flagellum at one end. b Lophotrichous – small bunches arising from one end of the cell. c Amphitrichous – flagella at both ends of the cell. d Peritrichous – flagella dispersed over surface of the cell. This is the slowest. 3 Flagella helps in motility of the cell through the environment by stimuli. Bacteria tend to move toward “food” (nutrients or sunlight). a
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BIOL125_Ch4 Lecture Notes - BIOL 125(Microbiology Lecture...

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