PDF Outline of Lecture Notes Part 2 - Exam 1 02.07.2025
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Uploaded by FortuitousHeisenberg
2025
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Summary
This document outlines lecture notes on the external structures of prokaryotic cells, focusing on flagella. It describes the different types of flagellar arrangements and their functional roles in bacterial motility. The notes also cover the components of flagella, including filament, hook, and basal body, highlighting the mechanisms involved in bacterial movement toward favorable environments and away from adverse conditions.
Full Transcript
Structures External to Cell Wall (continued): Prokaryotic Cells - Functional Anatomy Flagella Some prokaryotes have flagella (singular: flagellum) Long, filamentous appendages that propel bacteria Number and location of flagella varies between species Bacteria that lack flagella – atrichous Locat...
Structures External to Cell Wall (continued): Prokaryotic Cells - Functional Anatomy Flagella Some prokaryotes have flagella (singular: flagellum) Long, filamentous appendages that propel bacteria Number and location of flagella varies between species Bacteria that lack flagella – atrichous Locations of flagella: Peritrichous – over entire cell Polar: one or both ends of the cell. If polar, then - Monotrichous – single flagellum at one pole Lophotrichous – a tuft of several flagella located at one pole Amphitrichous – flagella located at both poles of the cell Flagella are composed of three parts: Filament – long, outermost region; contains the protein flagellin Hook – slightly wider; also protein Basal Body – anchors the flagellum to the cell wall and plasma membrane Flagellin – makes up the filament; protein arranged in chains that intertwine to form a helix around a hollow core Basal Body – spinning of the filament (external to the cell) occurs when the basal body rotates (within the cell wall/plasma membrane); like the shaft of a motor Bacteria can alter (a) speed and (b) direction of rotation of flagella This provides for different patterns of motility – Runs: movement in one direction for a time Tumbles: abrupt, random changes in direction Swarms: rapid wave-like movement over a solid culture Medium Advantages of Flagella - Bacteria can move toward a favorable environment Away from an adverse one Examples - Nutrients Oxygen Toxins Temperature Light
