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Exercise 9:

Exercise 9:. Cytoskeletal Structures. Announcements. Post Lab 11 is due by your next lab. LNA Cytoskeletal Structure assigned today, and is due next week in lab. Next Lab Exam 2 Review. Exam 2: Week of May 5 – 7. Your exam time for Exam 2 is the same as it was for Exam 1

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Exercise 9:

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  1. Exercise 9: Cytoskeletal Structures

  2. Announcements • Post Lab 11 is due by your next lab. • LNA Cytoskeletal Structure assigned today, and is due next week in lab. • Next Lab Exam 2 Review. • Exam 2: Week of May 5 – 7. Your exam time for Exam 2 is the same as it was for Exam 1 • Final Exam: Monday, May 12 from 8 – 11 AM • If you have a conflict with the Final Exam, you must fill out the Conflict Final Exam Request Form found on the Course Website.

  3. Goals • Become familiar with the three different cytoskeletal systems • Understand the role and structures of the mitotic spindle during cell division

  4. Cytoskeleton • Composed of three distinct systems • (classified by size) • Microfilaments (actin) - thinnest • Intermediate filaments (lamin) • Microtubules (tubulin)- thickest

  5. Microfilaments (Actin) • Microfilaments • Made up of strands of the protein actin and often interact with strands of other proteins. • They change cell shape and drive cellular motion, including contraction, cytoplasmic streaming, and the “pinched” shape changes that occur during cell division. • Microfilaments and myosin strands together drive muscle action.

  6. Intermediate Filaments (Lamins) Intermediate filaments • Made up of fibrous proteins organized into tough, ropelike assemblages that stabilize a cell’s structure and help maintain its shape. • Some intermediate filaments help to hold neighboring cells together (Cell junctions). Others make up the nuclear lamina.

  7. Microtubules (Tubulin) Microtubules • Long, hollow cylinders made up of many molecules of the protein tubulin. Tubulin consists of two subunits, a-tubulin and b-tubulin. • Microtubules lengthen or shorten by adding or subtracting tubulin dimers. • Microtubule shortening moves chromosomes. • Interactions between microtubules drive the movement of cells. • Microtubules serve as “tracks” for the movement of vesicles.

  8. The Exercise • Part I: Actin and Myosin Filaments • View prepared slides of smooth, skeletal, and cardiac muscle • Draw each muscle type and label nucleus, sarcomere, I-disk, A & I bands • You may find the Muscle Poster helpful • Part II: Flagella and Cilia • Prepare slides • Observe the locomotion of each organism • Also available as prepared slides if needed • Part III: Mitotic Spindle in plant and animal cells • View prepared slides of whitefish blastula and onion root tip • Compare/Contrast mitotic spindles found in plant and animal cells

  9. Part I: Muscle Cells Skeletal: voluntary movement, breathingSmooth:involuntary, movement of internal organs Cardiac: beating of heart

  10. Skeletal

  11. Skeletal

  12. Cardiac Muscle • Each muscle cell contains only one nucleus. • Adjoining cells interdigitate forming a meshwork that is resistant to tearing (intercalated disk).

  13. Smooth Muscle • Long and spindled shaped. • Each cell has a single nucleus • Actin and myosin filaments are not regularly arranged and therefore, do not produce the striated appearance

  14. Summary of Muscle Types

  15. The Exercise • Part I: Actin and Myosin Filaments • View prepared slides of smooth, skeletal, and cardiac muscle • Draw each muscle type and label nucleus, sarcomere, I-disk, A & I bands • Part II: Flagella and Cilia (microtubules) • Prepare slides with Protoslo • Observe the locomotion of each organism • Also available as prepared slides if needed • Part III: Mitotic Spindle in plant and animal cells • View prepared slides of whitefish blastula and onion root tip • Compare/Contrast mitotic spindles found in plant and animal cells

  16. Protozoa Cultures • Amoeba • Ciliate • Stentor • Flagellate • Euglena

  17. Amoeba

  18. Cilia Stentor

  19. Flagella Euglena #3

  20. The Exercise • Part I: Actin and Myosin Filaments • View prepared slides of smooth, skeletal, and cardiac muscle • Draw each muscle type and label nucleus, sarcomere, I-disk, A & I bands • Part II: Flagella and Cilia • Prepare slides • Observe the locomotion of each organism • Part III: Mitotic Spindle in plant and animal cells • View prepared slides of whitefish blastula and onion root tip • Compare/Contrast mitotic spindles found in plant and animal cells

  21. Mitotic Spindle • Constructed to enable the separation of the chromatids formed during replication • Consists of microtubules radiating out from the two centrosomes • Centrosome consists of a pair of centrioles

  22. Cell Division

  23. The Mitotic Spindle Consists of Microtubules

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