Chp4. Cytoskeleton Flashcards
What are the three proteins found in the cytoskeleton that Dr. Rice wants us to know
- actin
- intermediate filaments
- microtubules
What are the 3 functions of actin in the cytoskeleton
- consistency of cytosol
- cell movement
- cell division
what are 2 functions of actin in the nucleus
- structure
2. gene transcription
What is G actin
globular actin - single subunit
what is F actin
filimentous actin two strands of polymerized G actins wound together
Is F actin polymerization energy dependent
very much - ATP
What end are G actins added to
G+ end
describe each step of actin formation
- lag
- polymerization
- steady state
- 3 G actins join together to make nucleation site
- G actins are added to the + end of the nucleation site
- G actin monomers are added at the same rate they are removed
What is the major role of F actin
regulate state of cytosol sol/gel
What is profilin what does it do
actin regulating protein, binds g actin monomers to prevent polymerization
What is cofilin what does it fo
actin regulating protein, breaks F actin into smaller segments by twisting action
Gelsolin
fragments F actin - requires Ca+ to do it
What does dystrophin do (2)
what happens if there is a genetic defect
- links actin to basement membrane -
- gives muscle its tensile strength
- muscular dystrophy
What is the function of intermediate filaments
structure support
Does the process of creating I.F.’s require energy
no
What is the roll of microtubules in the cytosol (2)
- intracellular transport/highway
2. movement of chromosomes during division
What type of energy does microtubule formation require
GTP
What is a protofilament
linear chain of heterodimers
What is important about the GTP cap on microtubules
where new dimers are added - holds the molecule together without it it peels like a banana
what happens when dimer addition to microtubules slows
they become disassembled
Three functions of microtubules
- chromosomal movement
- cillia and flagella
- intracellular
what cytoskeleton component organizes the mitotic spindles in mitosis
microtubules
what cytoskeleton element is important for vesicle and organelle movement
microtubules
What does contraction of actin in non muscles cells do
- contraction provides support
- Necessary for cell movement
- Necessary for division
