elasticity

Question 1

Curl

Answer 1

In 3D the curl is the vector field

It explains the direction of rotation

Question 2

div

Answer 2

volume density of the outward flux

Question 3

normal curvature

Answer 3

the intersection of the surface with a normal plane creates a normal curve

Question 4

gaussian curvature

Answer 4

the minimum and maximum normal curvatures multiplied are the principal curvatures (k1 and k2)
The gaussian curvature is K=k1*k2

K>0 elliptic point
K<0 hyperbolic/saddle point
K=0 parabolic point

Question 5

spontaneous curvature

Answer 5

Is seen in lipids and is simply as spontaneous negative or positive curve. This is only partly responsible for cell shape

Question 6

Name the reason other than spontaneous curvature for cell shape

Answer 6

protein mediated membrane binding -

4 possibilities
Lipid clustering, rigid scaffolding, inserting hydrophobic membrane motifs, protein crowding

Question 7

Persistence length

Answer 7

mechanical property of polymers. If the chain is shorter than persistence it’s a stiff rod like behavior

If it’s much longer than the persistence length is must be described statisticallly , such as with random walks

P = Y*I/kbT
Y is youngs modulus

Question 8

worm like chain

Answer 8

flexible isotropic(same in all direction) rod

stiffness defined by the persistnce length

can be used for double stranded DNA

Question 9

ideal chain

Answer 9

neglects interactions between monomers and describes it as a random walk