In this lab you will measure the speed of vesicle transport. If the transport mo

Question

In this lab you will measure the speed of vesicle transport. If the transport molecule (molecular motor) needs to use the energy of one ATP to make one step, the step length is (delta x), and the rate of ATP hydrolysis (i.e. the rate of using up ATP) is given by R,

a.) what would be the correct equation for the speed of the transport?

b.) Since you mesure the speed in the lab, how would you determine R (assuming you know (delta x))?

c.) How does knowing R tell you how much energy is used to move the vesicle?

d.) What role does the efficiency play in this calculation?

Explanation / Answer

Answer a)

The step length delta x, is the distance (D) travelled by the vesicle transport molecule by expending energy R (rate of using ATP).

Now, power is defined as the rate of energy (R) which is being expended per time,

Equation 1,

P = R/T

Where, P is the power, R is the rate of expenditure of energy and T is the time.

The distance travelled at some speed for this energy expenditure will be,

Equation 2,

D = vt

Where, D is the distance or step length, v is the speed and t is Time,

Now, according to eq. 1 T = R/P and using this in eq. 2 will change eq. 2 to,

Equation 3,

D = v * R/P(v)

Which can be rewritten as,

v = D * P(v)/R

Where, v is the speed, D is the distance/step length, P(v) is the power at speed v and R is the rate of using energy,

Now, if the speed is known of the vesicle transport molecule for calculating R you should know the distance or steplength and the power. And by using equation 3, R can be calculated.

Answer b)

Efficiency is the measure of the conservation of the energy in the process, therefore, it plays a major role in the calculations regarding energy. Because, efficiency is the ratio of energy output and input so we will be able to calculate the other if know any one of them along with at what efficiency they are working.

Efficiency = Energy output / energy input * 100%

The efficiency is calculated in percentage using the above equation. The efficiency is denoted by eta and unit of energy is joules.

So, if we know the R, we can calculate the energy by putting the value of R (energy output) and efficiency rate to calculate the energy input using the above equation.

When, the energy input is calculated we can minus the energy output from that to know exactly how much energy is used for moving the vesicle.

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