History of Biophysics

Biophysics is not a young subject, but its emphasis has gradually changed over the years. In the first part of the 20th century, biophysicists primarily concerned themselves with things quite closely related to medicine, and many large hospitals had a resident member of this fraternity. The issues of interest were the flow of blood through pumps and the associated tubing (drawing on the work of George Stokes, among others), the monitoring of heart function through the related electrical activity, and later of brain activity with much the same instrumentation (with valuable input from Hans Berger), and also the fracture of bone (with a borrowing of the ideas developed by Alan Griffith, in a quite different context).

Around the same time, the field was gradually acquiring a new type of activity related to processes at the atomic level, this having been provoked by Wilhelm Rontgen's discovery of X-rays. His astonishment at discovering their power of penetrating human tissue, but apparently not bone, soon led to the use of X-rays for diagnostic purposes, of course. Only later did it emerge that there are grave dangers associated with such radiation, and physicists then found their advice being sought in connection with the monitoring of X-ray doses. Through their efforts, recording by film was supplemented by recording with electronic devices. One of the pioneering theoretical efforts in understanding the interaction of radiation with matter was published by Niels Bohr, who had earlier put forward the first successful picture of the atom.

These developments were of obvious importance to medicine, but another use of X-rays, originally confined to the inorganic domain, was later going to have an enormous impact on all of biology, and through this on medicine itself. Max von Laue and his colleagues, Walter Friedrich and Paul Knipping, had discovered the diffraction of X-rays, and William Bragg and Lawrence Bragg were soon applying the phenomenon to the determination of crystal structures. The latter Bragg, William's son, encouraged the extension of the technique to the biological realm, and researchers such as William Astbury, John Bernal, Peter Debye and Max Perutz soon took up the challenge. The early work in the area, before the Second World War, contributed to the determination of the sizes of protein molecules, and within twenty years it was producing pictures of proteins at the atomic level.

Define the words

To concern oneself with, to put forward, to be confined to, to encourage, grave, a realm, a challenge.

Continue the sentences

1. The issues of interest were…

2. Around the same time, the field was gradually…

3. Only later did it emerge that…

4. Through their efforts, recording by film was…

5. One of the pioneering theoretical efforts in understanding...

6. These developments were of obvious importance…

7. The early work in the area,…

Put the following words and word combinations into the gaps

pump / heart function / fractures / supplement / interaction / matter / put forward / confined

Nearly all members of this class that live in shallow waters harbor symbiotic algae, which ______________ the nutrition of their hosts through photosynthesis.

The ______________ of epinephrine with each type of receptor activates a different second-messenger system in the target cell.

For open and compound bone ______________, the injured bones can show through the skin because the jagged edges of the broken bones can destroy the covering muscles and tissues.

The purpose of the heart is to ______________ fresh blood to the organs and tissues of your body that need the oxygen and nutrients it carries.

The smallest stable particles of ______________ are protons, neutrons, and electrons, which associate to form atoms.

A variety of other ideas have been ______________ to establish criteria for defining species.

Photosynthetic organisms are ______________ to the upper few hundred meters of water.

Reduced ______________ is the condition when the heart doesn’t function properly.

Wind

As living organisms, we are most acutely aware of three things about the wind. We know that it exerts a force on us and other objects against which it blows, it is effective in transporting heat from us, and it is highly variable in space and time. A fourth property of the wind, less obvious to the casual observer, but essential to terrestrial life as we know it, is its effective mixing of the atmospheric boundary layer of the earth. This can be illustrated by a simple example. On a hot summer day about 10 kilograms (550 moles) of water can be evaporated into the atmosphere from each square meter of vegetated ground surface. This amount of water would increase the vapor concentration in a 100 m thick air layer by 100 g m^-3 (136 mmol/mol) if there were no transport out of this layer or condensation within it. This is much more water than the air could hold at normal temperature. The observed increase in vapor concentration in the first 100 meters of the atmosphere is typically less than 1 g m^-3, so we can see how effective the atmosphere is for transporting and mixing. A similar calculation (Monteith, 1973) shows that photosynthesis in a normally growing crop would use all of the CO₂ in a 30 m air layer above a crop in a day, yet measured CO₂ concentrations have diurnal fluctuations of 15 percent or less. Without the vertical turbulent transport of heat, water vapor, CO₂, oxygen, and other atmospheric constituents, the microenvironment we live in would be very inhospitable.

The influence of the surface on the atmosphere of the earth can extend from hundreds of meters at night to several thousand meters during days when surface heating is strong. This depth of influence of the surface on the atmosphere is called the planetary boundary layer. Through the depth of this planetary boundary layer, like all boundary layers that form between moving fluids and stationary surfaces, fluxes of momentum, heat, and mass decrease with height. The lowest 50 m of this planetary boundary layer is referred to as the surface layer; this is the region of most interest. In this region fluxes of momentum, heat, and mass are virtually constant with height and profiles of wind speed, temperature, and concentration are logarithmic.

Define the following words

To be aware of, property, terrestrial, diurnal, microenvironment, inhospitable, momentum, boundary.

Complete the sentences

1. We know that the wind…

2. As living organisms, we are..

3. This can be illustrated by…

4. A similar calculation shows that…

5. Without the vertical turbulent transport of heat,..

6. The influence of the surface on the atmosphere of the earth…

7. Through the depth of this planetary boundary layer,…

8. The lowest 50 m of this planetary boundary layer…

Put the following words and word combinations into the gaps

aware / exert / properties / evaporation / condensation / constituents / extend / referred to as

The amino and carboxyl groups on a pair of amino acids can undergo a ______________ reaction, losing a molecule of water and forming a covalent bond.

The turgor pressure, which is a physical pressure that results as water enters the cell vacuoles, is ______________ pressure potential.

Keystone species are species that ______________ a particularly strong influence on the structure and functioning of a particular ecosystem.

Fungi are virtually the only organisms capable of breaking down lignin, one of the major ______________ of wood.

The pneumatophores commonly ______________ several centimeters above water, facilitating the oxygen supply to the roots beneath.