1. Cofilin is an actin binding protein that severs actin filaments. Katanin is an ATPase that binds to microtubules and severs them. In class, we discussed how acute activation of cofilin inside cells triggers a burst of actin polymerization off the newly created filament (+) ends. In contrast, activating katanin in cells typically results in fast microtubule depolymerization from newly created microtubule (+) ends. Why do actin filament (+) ends grow following cofilin mediated severing but newly generated microtubule (+) ends shrink following katanin mediated severing? The correct answer requires a clear discussion of critical concentrations and the role of nucleotide hydrolysis in polymer dynamics.
2. Pure actin and pure tubulin can be induced to polymerize in vitro. In both cases, there is a long lag phase that precedes fast polymerization. 2a) What is the physiological significance of the long phase prior to assembly? 2b) What are the key factors thought to control the length of the lag phase for actin and for microtubules? 2c) Describe the basic biochemical and/or structural mechanism underlying the activities of the factors described in question 2b. In other words, how do these factors control the length of the lag phase.
3. All biology students are asked to distinguish prokaryotes from eukaryotes. The following lines are from wikibooks.org:
“Cytoskeleton[edit] Prokaryotes have none of this sort. The Eukaryotes have complex array of cytoskeleton which composed of microtubules, intermediate filaments and actin filaments. This protein-developed cytoskeleton reinforces the cell’s outer structure to help with the rigidity of cell and intracellular transport.”
Please assess the validity of the statement that prokaryotes do not have a cytoskeleton. If they do not have a cytoskeleton, then just simply state that. If they do have a cytoskeleton then compare their cytoskeletal elements to eukaryotic actin, tubulin, and intermediate filaments. Are they of the same structure? Do they have the same basic turnover dynamics? Or did they evolve a completely different cytoskeleton than eukaryotes?
Why Choose Us
Top quality papers
We always make sure that writers follow all your instructions precisely. You can choose your academic level: high school, college/university or professional, and we will assign a writer who has a respective degree.
Professional academic writers
We have hired a team of professional writers experienced in academic and business writing. Most of them are native speakers and PhD holders able to take care of any assignment you need help with.
Free revisions
If you feel that we missed something, send the order for a free revision. You will have 10 days to send the order for revision after you receive the final paper. You can either do it on your own after signing in to your personal account or by contacting our support.
On-time delivery
All papers are always delivered on time. In case we need more time to master your paper, we may contact you regarding the deadline extension. In case you cannot provide us with more time, a 100% refund is guaranteed.
Original & confidential
We use several checkers to make sure that all papers you receive are plagiarism-free. Our editors carefully go through all in-text citations. We also promise full confidentiality in all our services.
24/7 Customer Support
Our support agents are available 24 hours a day 7 days a week and committed to providing you with the best customer experience. Get in touch whenever you need any assistance.
Try it now!
How it works?
Follow these simple steps to get your paper done
Place your order
Fill in the order form and provide all details of your assignment.
Proceed with the payment
Choose the payment system that suits you most.
Receive the final file
Once your paper is ready, we will email it to you.
Our Services
No need to work on your paper at night. Sleep tight, we will cover your back. We offer all kinds of writing services.
Essays
You are welcome to choose your academic level and the type of your paper. Our academic experts will gladly help you with essays, case studies, research papers and other assignments.
Admissions
Admission help & business writing
You can be positive that we will be here 24/7 to help you get accepted to the Master’s program at the TOP-universities or help you get a well-paid position.
Reviews
Editing your paper
Our academic writers and editors will help you submit a well-structured and organized paper just on time. We will ensure that your final paper is of the highest quality and absolutely free of mistakes.
Reviews
Revising your paper
Our academic writers and editors will help you with unlimited number of revisions in case you need any customization of your academic papers