Movement

• What are the principal mechanisms of movement?

  Amoeboid, cilia and flagellar, muscular
• Amoeboid movement - amoebas and other unicellular forms, white blood cells, embryonic mesenchyme cells, other mobile cells
• Label the following

  A) Hyaline ectoplasm

  B) Ectoplasmic tube

  C) Hyaline cap

  D) Endoplasmic stream

  
• 1.hyaline cap appears at pseudopod

  2. In the endoplasm, actin subunits attach to regulatory

  proteins (preventing cross linkages from occurring)

  3. endoplasm flows toward hyaline cap

  4. endoplasm fountains out to the periphery.

  
• 5. actin subunits released from regulatory proteins

  (by lipids) and begin polymerizing into cross

  linkages due to acting binding proteins (ABPs)

  6. Actin microfilaments continue to cross-link, and

  a gel-like ectoplasm is form at the outer edges.

  7. Ca2+ at the inner cytoplasm activate actin-

  severing protein

  8. myosin associate with and tug on actin microfilaments,

  generating a contraction that perpetuates endoplasm into

  the hyaline cap. Dissociated actin subunits are reused.

  
• Cilia - minute, hairlike, motile processes which occur in large numbers such as in ciliate protistans, found in all major groups of animals which move organisms through aquatic environment and propel fluids and materials across surfaces
• Flagella - whiplike, present singly or in small numbers and occur in unicellular eukaryotes, animal spermatozoa and sponges
• Axoneme - Bundle of 9 doublets on the surrounding edges + 2 individual microtubules in the center

  
• The outer doublets are connected by what kind of motor proteins?

  Dyneins
• Basal body - Bundle of 9 triplets on the surrounding edges where there's no individual microtubules in the center
• The bending of cilia and flagella is driven by the arms of a motor protein, dynein.
• What anchors the doublets together in motile cilia or flagella?

  Protein cross-links
• Addition to dynein of a phosphate group from ATP and its removal causes conformation changes in the protein.
• A flagellum has an undulatory movement where force that is generated is parallel to the flagellum’s axis
• Cilia move more like oars with alternating power and recovery strokes

  that generate force perpendicular to the cilia’s axis
• A muscle at “rest” exhibits what?

  tone
• A muscle in tetany is at maximum sustained contraction
• actomyosin system - is a protein contractile system, composed of two

  proteins, actin and myosin.
• Label the following.

  A) Muscle fiber

  B) Syncytium

  C) Sarcoplasmic reticulum

  D) Myofibril bundles

  
• A single myofibril is made of what?

  Actin and myosin filaments
• Sliding Filament Model – Individual myosin and actin filaments arranged in sarcomere units
• Label the following.

  A) Sarcomere

  B) Sarcomere

  C) Z-plate

  
• Neuromuscular junction - the synaptic contact between a nerve fiber and a muscle fiber by which nerve impulses bring about the release of a

  neurotransmitter that crosses the synaptic cleft and signals the muscle fiber to contract
• Action potential triggers a cascade of signals that release Ca+2 from the Sarcoplasmic Reticulum
• Where is the storage of the Ca2+ before its release for muscle contraction?

  Sarcoplasmic reticulum
• Troponin bound to Ca+2 moves Tropomyosin from active sites
• Myosin head bound to ADP+P can bind to actin
• Myosin releases ADP+P to perform a power stroke on actin
• Myosin binds to ATP to release from actin binding
• Myosin hydrolyze ATP to ADP+P to prepare for actin binding
• Muscle


  Innervated by motor axons – efferent pathways from the brain
• Muscle contraction

  1. Axons connected on muscles are excited

  2. Action potentials are transmitted along the muscle fiber membrane and into the T-Tubules

  3. Action potentials excite the T-Tubules, which is connected to the Sarcoplasmic reticulum

  4. The Sarcoplasmic reticulum is the storage of Ca+2

  5. Action potential triggers the release of Ca+2 into the actin and myosin

  6. Ca+2 binds to troponin

  7. This frees up space (by moving tropomyosin – which is initially blocking myosin binding sites)

  8. Myosin uses an ADP (ADP goes away) that will cause the power stroke of the actin filaments

  9. ATP will bind to myosin to disconnect myosin from actin filaments

  10. Process will repeat under the condition that Ca+2 is present