A wave of pos itively charged calcium ions for exam

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: s like this are coiled bundles of filam ents that expand or contract in res pons e to chem ical cues . A wave of pos itively charged calcium ions , for exam ple, neutralizes the negative charges that keep the filam ents extended. Som e s perm us e s pringlike engines m ade of actin filam ents to s hoot out a barb that penetrates the layers that s urround an egg. And certain virus es us e a s im ilar apparatus to s hoot their DNA into the hos t’s cell. Ratchets are als o us eful for m oving whole cells , including s om e other s perm s and pathogens . Thes e engines are filam ents that s im ply grow at one end, attracting chem ical building blocks from nearby. Becaus e the other end is anchored in place, the growing end pus hes agains t any barrier that gets in its way. Both s prings and ratchets are m ade up of s m all units that each m ove jus t s lightly, but collectively produce a powerful m ovem ent. Ultim ately, Mahadevan and Mats udaira hope to better unders tand jus t how thes e particles create an effect that s eem s to be s o m uch m ore than the s um of its parts . Migh...
View Full Document

This document was uploaded on 03/23/2014.

Ask a homework question - tutors are online