Biophysics - Week 1 Lecture 2

Heat Energy

DNA helix size

10 nm

nucleus size

about 10 microns

Universe tends to favor what

disorder

Potential energy (PE)

energy of an object’s position (top of hill. ie. gravity)

Kinetic Energy (KE)

energy of motion K=1/2mv²

Mechanical energy =

PE+KE

temperature

temperature = measure of hotness or coldness of an object (thermometer)

Effects cells and enzymes’ functions, protein folding, composition, volume expansion, etc. (ie. if 37 is optimal enzyme function and it is 50, then enzyme activity decrease)

Zeroth law of thermodynamics

If C is in thermal equilibrium with both A and B, then A and B are in thermal equilibrium with each other.

heat

flow of thermal energy (hot to cold)

What is a cal? (calorie)

amount of heat required to raise the temp of 1 g of water from 14.5 C to 15.5 C

1 cal = ? J

4.186 J

1Kcal = ? cal = ? J

1000cal = 4186 J

Specifice heat (Q) =

Q= mcΔT [m = mass of material, c = specific heat , T = change in temperature_

c (specific heat) of water

4190J/kg*K = 1 cal/g*C

First law of thermodynamics

Change in the interalg energy (U) is = to the heat (Q) - work (Q) done by the system

ΔU = Q-W

Second law of thermodynamics

Thermodynamic processes are irreversible and are spontaneousf in one direction (increase disorder/randomness)

ex. always hot to cold

Refrigerator statement of 2nd law

it is impossible for any process to transfer of heat from a cooler to a hotter object without work being done.

Entropy (S)

measure of disorder/randomness

S= kln(w)

ex. (more S = increase t → unfolding protein (entropy dominates)

ex. (more E = lower T → folding mechanical energy dominates)

When energy flows what happens?

Increase order = Increase entropy

can total entropy decrease

No. No process is possible when all parts of system included