What Is a Gene

To figure out how genes work and how they direct the production of specific proteins that allow organisms to inherit traits, scientists started with the fact that chromosomes were known to be made up of protein and DNA. A series of experiments using bacteria and viruses that infect bacteria established that DNA, not protein, was the basic genetic material. Scientists figured out how DNA worked as the genetic material, how it was copied when a cell divided into two identical cells, and how DNA determined traits—that is, determined the sequence of amino acids in each protein that allow different traits to be expressed. 

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John E. Lesch, Science and Medicine in France (Harvard University Press, 1984) M. Norton Wise, Energy and Empire (Cambridge University Press, 1989) Raphael Falk, What Is a Gene. Studies in Fiistory and Philosophy of Science 17, 1986, 133-173. 

Gerstein MB, Bruce C, Rozowsky JS, et al. What is a gene, post-ENCODE History and updated definition. Genome Res 2007 17(6) 669-8L... 

A23. Pearson, H. Genetics What is a gene Nature 441... 

Describe the structural differences between DNA and RNA. The monomers in nucleic acids are called nucleotides. What are the three parts of a nucleotide The compounds adenine, guanine, cytosine, and thymine are called the nucleic acid bases. What structural features in these compounds make them bases DNA exhibits a double-helical structure. Explain. Describe how the complementary base pairing between the two individual strands of DNA forms the overall double-helical structure. Flow is complementary base pairing involved in the replication of the DNA molecule during cell division Describe how protein synthesis occurs. What is a codon, and what is a gene The deletion of a single base from a DNA molecule can constitute a fatal mutation, whereas substitution of one base for another is often not as serious a mutation. Explain. 

Detterman One complication I wondered about, is exactly what is a deleterious mutation Many of these genes that in the homozygous state produce mental retardation, in the recessive state actually confer some reproductive advantage, even though they may lower IQ. There is evidence for phenylketonuria, for instance, and Tay Sach s disease. 

A global analysis of gene expression can be accomplished by using a DNA microarray. What Is a DNA micro-array How are DNA microarrays used for studying gene expression How do experiments with microarrays differ from Northern hotting experiments described In question 7 ... 

What is a primary consequence on gene regulation of the folding of chromatin ... 

What is a chromosome How many chromosomes are in a human cell What is the approximate number of genes in a human cell ... 

Transcription control sites in DNA include start and stop messages and promoter and enhancer sequences. The main promoter region for any gene is about 25 bases before (upstream of) the beginning of the gene to be transcribed. It acts as a signal that what follows is a gene to be transcribed. 

Unlike what happens in DNA replication, where both strands are copied, only one of the two DNA strands is transcribed into mRNA. The strand that contains the gene is often called the coding strand, or primer strand, and the strand that gets transcribed is called the template strand. Because the template strand and the coding strand are complementary, and because the template strand and the transcribed RNA are also complementary, the RNA )no ecule produced during transcription is a copy of the DNA coding strand. The only difference is that the RNA molecule has a U everywhere the DNA coding strand has a T. 

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