BIO2242 Lecture Notes - Lecture 3: Cilium, Amoeboid Movement, Dynein
Lecture 3 – Movement: Muscles
Movement at Molecular level
• Motor proteins move relative to structural proteins:
o Microfilaments (actins) based
▪ Kinesin
o Microtuble (tubulin) based (larger)
▪ Myosin or dynein
• E.g. Amoeboid movement
o Amorphous shape
o Pseudopodia (false feet) extended
and withdrawn
o Actin interacts with myosin and
contracts (sol gel process)
▪ Back of organism
o Actin reassembles into network
o Membrane adhesion proteins assist
o White blood cells move in similar way
▪ Allows to move through environment
• Cilia and flagella movement
o 0.2 – 0.5 um in diameter
o Found in all animals – nearly every cell
o Motile vs. non motile cilia (sensory)
o Basal body provides structure
o Same structure
o Non muscle forces: created by molecules
Functions of Muscles
• Posture
• Movement
• Peristalsis
• Generation of heat and electricity
• Sound
• Internal organ function
• 4 major functional characteristics:
o Contractility
▪ Can shorten in length
o Excitability
o Extensibility
o Elasticity
Cilia
Flagella
• Hair like
• Shorter
• Movement: active stroke (one
direction) then relaxed recovery
stroke
• Beats asymmetrically
• Tails of sperm
• Much longer
• Movement: active stroke in two
directions
• Beats symmetrically
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Types of Invertebrate Muscle
Types of Vertebrate Muscle
• Smooth
o Bivalve adductor muscle
(slow)
o Muscle that is used to
close shell
• Striated (stripes)
o Bivalve valve closure
muscle (fast)
• Fibrillar muscle
o Insect flight muscle (very
fast)
o Elevator muscles – pull up
o Depressor muscles – pull
down
• Striated (skeletal and cardiac)
o Stripy
• Smooth
o Gut and blood vessels
• Differ in morphology and
contraction properties
Comparison of vertebrate muscle types
Mechanical Action of Skeleton Muscles
• Power affected by
o Type of fibre (fast or slow)
▪ Fast with low force
▪ Slow with high force
o Muscle cross sectional area
▪ Thicker – more force
▪ Thinner – less force
o Type of leverage
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