campbell book

campbell book

Sponsors

test

Friday, September 7, 2012

The Molecule That Supports All of Life

1:19 AM 0
The Molecule That Supports All of Life
As astronomers study newly discovered planets orbiting distant stars, they hope to find evidence of water on these far-off celestial bodies, for water is the substance that makes possible life as we know it here on Earth. All organisms familiar to us are made mostly of water and live in an environment dominated by water. Water is the biological medium here on...

Charles Darwin and the Theory of Natural Selection

12:32 AM 0
Charles Darwin and the Theory of Natural Selection
The history of life, as documented by fossils and other evidence, is a saga of a changing Earth billions of years old, inhabited by an evolving cast of living forms (Figure 1.17). This evolutionary view of life came into sharp focus in November 1859, when Charles Robert Darwin published one of the most important and influential books ever written. Entitled...

Wednesday, July 18, 2012

Evolution Accounts for the Unity and Diversity of Life

1:38 AM 0
Evolution Accounts for the Unity and Diversity of Life
The list of biological themes discussed under Concept 1.1 is not absolute; some people might find a shorter or longer list more useful. There is consensus among biologists, however, as to the core theme of biology: It is evolution. To quote one of the founders of modern evolutionary theory, Theodosius Dobzhansky, "Nothing in biology makes sense except in the...

Monday, July 16, 2012

Feedback mechanisms regulate biological systems

5:59 AM 0
Feedback mechanisms regulate biological systems
A kind of supply-and-demand economy applies to many biological systems. Consider your muscles, for instance. When your muscle cells require more energy during exercise, they increase their consumption of the sugar molecules that provide fuel. In contrast, when you rest, a different set of chemical reactions converts surplus sugar to storage molecules. Like most...

Systems Biology at the Leyels of Cells and Molecules

5:34 AM 0
Systems Biology at the Leyels of Cells and Molecules
The entire sequence of nucleotides in the human genome is now known, along with the genome sequences of many other organisms, including bacteria, archaea, fungi, plants, and animals. These accomplishments have been made possible by the development of new methods and DNA-sequencing machines. The sequencing of the human genome is a scientific and technological...

Friday, July 13, 2012

The continuity of life is based on heritable information in the form of DNA

3:23 AM 0
The continuity of life is based on heritable information in the form of DNA
Inside the dividing cell in Figure 1.7 (on the previous page), you can see structures called chromosomes, which are stained with a blue-glowing dye. The chromosomes have almost all of the cell's genetic material, its DNA (short for deoxyribonucleic acid). DNA is the substance of genes, the units of inheritance that transmit information from parents to offspring.Your...

Cells are an organism's basic units

2:47 AM 0
Cells are an organism's basic units
In life's structural hierarchy, the cell has a special place as the lowest level of organization that can perform all activities required for life. Moreover, the activities of organisms are all based on the activities ofcells. For instance, the division of cells to form new cells is the basis for all reproduction and for the growth and repair of multicellular...
Page 1 of 212Last