There are two main systems that transmit physiological information over longer distances within the bodies of animals: the nervous system and the endocrine system. After looking at the endocrine system

The dependence of biochemical reactions and cellular processes in general on external conditions has several important effects on organisms. Multicellular organisms often maintain a constant internal

By examining the development of the Drosophila fruit fly, we can explore how specific genes influence pattern formation. Many aspects of Drosophila development are unique, but the general mechanisms are

A major mechanism involved in differentiation is induction, in which cells stimulate each other to develop in different ways. Several landmark experiments that identified the role of induction in

Developmental processes not only create many cells but also cause those cells to differentiate into many different types of cells. A zygote can give rise to any type of cell, but its daughter cells eventually

Though animals are dramatically diverse, the basic mechanisms of their development are similar across groups. Today we examine the four earliest stages of development fertilization, cleavage, gastrulation,

We know that a single cell develops into a fully formed organism, but how? Today we describe the two basic puzzles of development,and outline the earliest attempts to solve these puzzles. We then provide

Cells respond by mechanisms through which extracellular signals exert control over cell function. We begin by explaining the basic ideas behind signal transduction pathways, emphasizing how these pathways

The question of how cells talk to each other is best understood by exploring how molecular messages control cell function. All cells respond to external signals, and it is especially important for the

Impressive tools are now available for manipulating DNA and changing the genomes of organisms to our benefit as a species. The fundamental mechanisms cells use to replicate and transcribe DNA provided

Simply producing the right proteins at the right time is only the first step to regulating cell function on the molecular level. Equally important is the problem of how proteins find themselves in the

Protein-DNA interaction in gene expression and the complex architecture of eukaryotic genes, emphasizes the role of multiple interacting regulatory factors. The same basic principles apply in eukaryotic

Cells differ in the proteins they express. The same cell may express different proteins at different times in its life, and in multicellular organisms, different types of cells typically express different

This post introduces the second major section of our series, Development and Homeostasis, by setting up two major questions: First, how do single cells proliferate and form complex multicellular organisms

This post will be taking a final look at the concept of information and evolution in biology. Returning to the question of how an original, primordial life form might have given rise to the enormously

Introduction This informative series of posts will explore modern biology; the fundamental principles of how living systems work. This material will always be presented at the level of a first-year college

Introduction This informative series of posts will explore modern biology; the fundamental principles of how living systems work. This material will always be presented at the level of a first-year college

Introduction This informative series of posts will explore modern biology; the fundamental principles of how living systems work. This material will always be presented at the level of a first-year college

Introduction This informative series of posts will explore modern biology; the fundamental principles of how living systems work. This material will always be presented at the level of a first-year college

Introduction This informative series of posts will explore modern biology; the fundamental principles of how living systems work. This material will always be presented at the level of a first-year college