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Summary Bio 310 Exam 3 Study Guide
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- Biology
This is a comprehensive and detailed study guide on Exam 3.
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Lecture 20 : Cytoskeleton (Intermediate filaments and microtubules, Ch 17The cytoplasm of a eukaryotic cell is supported and organized by a cytoskeleton.
1. Make sure you know the composition, properties and roles of the three types of cytoskeletal
proteins.
Intermediate Filaments – fibrous protein subunits
Microtubules – tubulin subunits
Actin Filaments – actin subunits
,Lecture 20 : Cytoskeleton (Intermediate filaments and microtubules, Ch 17
2. What are the functions of the cytoskeleton? Remember the functions are regulated by cell
signaling.
- Gives cell its shape, allows cell to organize internal components, move, interact with
environment
- Supports large volume of cytoplasm
,Lecture 20 : Cytoskeleton (Intermediate filaments and microtubules, Ch 17
Intermediate filaments are stable, rope-like polymers – built from fibrous protein subunits – that give
cells mechanical strength. Some intermediate filaments form the nuclear lamina that supports and
strengthens the nuclear envelope; others are distributed throughout the cytoplasm.
Fibrous cytoskeleton element , 10 nm in diameter, forms ropelike networks in
animal cells; helps cells resist external tension
- Main Function: enable cells to without tearing
o
BLUE IS INTERMEDIATE KERATIN FILAMENTS
- In cytoplasm of most animal cells
o
o where plasma
membrane is connected to other cell
- In ucleus)
o Meshwork that underlies and
, Lecture 20 : Cytoskeleton (Intermediate filaments and microtubules, Ch 17
3. What is the structure of intermediate filaments (see animation 17.
- Like rope where strands are twisted together – tensile strength, cable like
o Alpha helical central domain- monomer
§ C- terminal domain marked dark blue, (synthesis occurs from N terminus to C
terminus )
o 2 monomers wrap around each other to from coiled-coiled dimer
o 2 dimers form staggered antiparallel tetramer (OPPOSITE DIRECTION)
o 8 tetramers strands pack together into helical array to form intermediate filaments
o Filaments can elongates with addition of tetramer arrays to either end BECAUSE BOTH
ENDS ARE THE SAME- UNLIKE OTHER CYTOSKELETON FILAMENTS
- Combined strength of overlapping lateral interactions (NONCOVALENT BONDING) along the
length of the proteins that intermediate filaments GREAT tensile strength
4. What types of animal cells have large numbers of intermediate filaments?
- In cytoplasm of cells subject to mechanical stress
o internal reinforcement of long/fine cell extensions
o – distribute effects of locally distributed forces
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