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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 - PowerPoint PPT Presentation
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Exercise 9:
Cytoskeletal Structures
Announcements• Post Lab 11 is due by your next lab.• LNA Cytoskeletal Structure assigned today, and is due
next lab (week of November 30).• Next Lab Exam 2 Review (week of November 30). • Exam 2: Week of December 7. Your exam time for
Exam 2 is the same as it was for Exam 1• Final Exam: Friday, December 11 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 by December 9 at 5 PM.
Goals
• Become familiar with the three different cytoskeletal systems
• Understand the role and structures of the mitotic spindle during cell division
Cytoskeleton
• Composed of three distinct systems
• (classified by size)– Microfilaments (actin) - thinnest– Intermediate filaments (lamin)– Microtubules (tubulin)- thickest
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.
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.
Microtubules (Tubulin)
Microtubules
• Long, hollow cylinders made up of many molecules of the protein tubulin. Tubulin consists of two subunits, -tubulin and -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.
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
Part I: Muscle Cells
Skeletal: voluntary movement, breathingSmooth: involuntary, movement of internal organs
Cardiac: beating of heart
Skeletal
Skeletal
Cardiac Muscle• Each muscle cell contains only one nucleus.• Adjoining cells interdigitate forming a meshwork
that is resistant to tearing (intercalated disk).
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
Summary of Muscle Types
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
Protozoa Cultures
• Amoeba• Ciliate
– Stentor• Flagellate
– Euglena
Amoeba
StentorCilia
EuglenaFlagella
#3
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
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
Cell Division
The Mitotic Spindle Consists of Microtubules