BIOG 1440 Lecture Notes - Lecture 19: Paramecium, Peristalsis, Chemoreceptor
27 Apr 2018
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PRELIM 2 IS WEDNESDAY, APRIL 18
Movement in Earthworms
1. Uses a common theme (peristalsis)
a. Constriction of circular muscles elongates segments, pushing them forward
b. Bristles anchor segments to prevent backward sliding
c. Constriction of longitudinal muscles shortens the segments, pulling trailing
segments forward
2. Locomotion via peristalsis
a. Longitudina muscle relaxed, circular muscle contracted when elongating
b. Longitudinal muscle contracted and circular muscle relaxed in condensing
3. Movement by peristalsis
a. Both earthworm and much of digestive system have arrangement of longitudinal
and circular muscles
i. Used to drive peristalsis for movement
Movement in Millipedes: Metachronal waves
1. Movement in Millipedes
a. Not via peristalsis but by coordinated movement of many leg
b. Everything moves in a wave, not in sync (definition of metachronal waves)
c. Propulsive phase and recovery phase
i. Successive--not everything is happening at once
Movement of Cilia
1. Unicellular protozoan (ex: paramecium) covered w/ few thousand cilia, used to move
and bring in food particles
2. An example of unity underlying the diversity of life: the architecture of cilia in eukaryotes
a. From p. 12 of textbook
b. Simple paramecium and cilia of windpipe cells have the same cross section
3. Cilia located throughout body
a. Respiratory cilia: move debris up and out of airways
b. Not all cilia involved in movement
4. Cilia structure
a. Outer microtubule doublet
b. Motor proteins (dyneins)
c. Central microtubule
d. Radial spoke
e. Cross-linking proteins between outer doublets
i. Radial spokes connect outer doublets to central microtubules
f. This 9+2 structure is a hallmark of cilia that shows metachronal movement
5. Non-motile cilia--critical for signaling
a. Non-motile cilia are mechano-, osmo-, chemosensory units
b. Note 9+0 arrangement, typical of non-motile cilia
6. 9+2 cilia ultrastructure
a. Entire cilia surrounded by cell membrane
b. Outer doublet tubules made of an incomplete B tubule and complete A tubule
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Document Summary
Movement in millipedes: metachronal waves: movement in millipedes, not via peristalsis but by coordinated movement of many leg, everything moves in a wave, not in sync (definition of metachronal waves, propulsive phase and recovery phase. Spokes wave back and forth: dynein: motor protein that attaches to a tubule but faces b tubule (extend away from a tubule, complete tubules in two central singlets, nexin: protein that connects outer doublets to one another. Lung w/ bronchiectasis--airways thicken in lungs since they are chronically inflamed and they cannot get rid of the mucus. Bacterial flagella (not eukaryotic flagella: flagellum: from latin word for whip. Primarily used for movement: flagellar rotations drive cells through liquid, e. coli uses its flagella to push the cell through the liquid. Filament: extends out away from the cell, helical shape: hook: connector between filament and basal body. Basal body: what rotates and drives flagella to rotate: motab: proteins that couple available energy source to rotation (not.
