sci230r6_week4_reading1

sci230r6_week4_reading1 - c03.qxd 12/10/04 9:23 AM Page 61...

Info iconThis preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
61 Mendelian Genetics: How Are Traits Inherited? It requires indeed some courage to undertake a labor of such far-reaching extent; this appears, however, to be the only right way by which we can finally reach the solution of a question, the importance of which cannot be overestimated, in connection with the history of the evolution of organic forms. —Gregor Mendel, 1866 Chapter opening photo Portrait of Gregor Mendel, the founder of genetics. Mendel’s largely misunderstood paper was published in 1866, less than a decade after Darwin’s book, The Origin of Species . Overview In this chapter, we will examine how traits are passed from generation to generation—a branch of biology called classical, or Mendelian, genetics. We will see that a modest garden, growing within the walls of a 3
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
62 C HAPTER 3 Mendelian Genetics: How Are Traits Inherited? Moravian monastery at about the same time that Darwin was writing The Origin of Species , was to change forever our understanding of how traits are inherited. From that same garden would come answers to some of the nagging questions about Darwin’s controversial new theory, evolution by the mechanism of natural selection. Darwin’s revolutionary insight was immediately recognized by some as a powerful explanation for the variety of species on Earth. Many people, however, remained unconvinced. For those who held certain religious beliefs, including one stating that all species were put on Earth by a supreme being during one week of creation as set forth in Genesis, no amount of scientific evidence could be convincing. But even those who searched for naturalistic explanations for the diversity of life found reason to criticize Darwin. Some features of natural selection were readily accepted; they were obvious and verifiable by observation and study. For example, one could easily see that most organisms produced more offspring than could possibly survive. And it was evident that traits that enhance the ability of individuals to survive and reproduce are passed on to the next generation. But Darwin’s critics were quick to point out that there was no satisfactory explanation for how traits were passed from parents to offspring. The ideas that had been proposed about the mechanism of heredity were highly improbable and not verifiable. Many, including Darwin, mistakenly believed that traits from two parents blended together in their offspring. Thus, the children of a blue-eyed man and a brown-eyed woman would have bluish-brown eyes. Likewise, if the pollen of a red flower landed on a white-flowered plant, the flowers of the offspring should all be pink. But clearly blending does not happen— at least not all the time. Traits of parents may occasionally appear as blended intermediates in their children (more on this in Section 3-3), but more often they do not. Some traits are passed on apparently unaltered from parent to offspring; others hide for generations at a time, only to reappear at unpredictable times in
Background image of page 2
3-1 How Are Traits Passed from Generation to Generation? 63
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 01/08/2011 for the course CJS 212 taught by Professor Smith during the Summer '10 term at University of Phoenix.

Page1 / 28

sci230r6_week4_reading1 - c03.qxd 12/10/04 9:23 AM Page 61...

This preview shows document pages 1 - 4. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online