Chapter 10-How Protein are Made Section 1-From Genes to Proteins – Traits are determined by proteins, that are built by DNA. – Proteins are NOT built by DNA directly – Last chapter was DNA replication, this chapter go further, the making of proteins starting with DNA Ribonucleic acid(RNA)-A nucleic acid, differs from DNA in three ways. 1.RNA is single stranded 2.Sugar is ribose NOT deoxyribose 3.Uracil is used instead of thymine

No thymine is found in the RNA, like thymine though uracil is complementary to adenine whenever RNA base-pairs with another nucleic acid. The instructions for making a protein are transferred from a gene to an RNA molecule through a process called transcription. LOOK AT FIGURE 1, PAGE 208.

Protein synthesis continued Cells use two types of RNA to put together the amino acids that make up the protein using translation.

Gene expression-Process by which proteins are made base on the information encoded in DNA, it is also called protein synthesis. Transfer information from DNA to RNA-KNOW 1.RNA polymerase binds to the gene’s promoter. 2.RNA polymerase unwinds the DNA. 3.RNA polymerase adds and then links complementary RNA nucleotides as it “reads” the gene.

The genetic code mRNA-messenger RNA-Is a form of RNA that carries the instruction for making a protein from a gene and delivers it to the site of translation. Codons-Three-nucleotide sequences of the mRNA, which correspond to an amino acid. Let’s look at page 211, for the codons in mRNA that code for particular amino acids.

Different RNA’s and their part in protein synthesis tRNA-Single strands of RNA that temporarily carry a specific amino acid on one end. Anticodon-Three-nucleotide sequence on a tRNA that is complementary to an mRNA codon. rRNA-ribosomal RNA, molecules that are part of the structure of ribosomes.

RNA’s Roles in Transcription EAo EAo Section 2-Gene Regulation and Structure Prokaryotic cells typically have about 2,000 genes. The human genome, which is the largest genome sequenced to date, has about 30,000 genes. Operator-The piece of DNA that overlaps the promoter site and serves as the on-off switch.

The promoter site, and the operator that controls them all functions together as an operon. The operon that controls the metabolism of lactose is called the lac operon and is shown in Figure 6. page 215. Repressor-Is a protein that binds to an operator and physically blocks RNA polymerase from binding to a promotor site. movie-flash.htm movie-flash.htm

Protein synthesis in Eukaryotes Eukaryotes cells contain much more DNA than that of prokaryotes. Operons have not been found often in eukaryotic cells. WHEN DOES TRANSCRIPTION OCCUR???? – Gene regulation (the ability for a cell to express a gene depending on the cell’s need). Controls the onset of transcription when RNA polymerase binds to the gene. – Enhancer-A sequence of DNA that can be bound by a transcription factor.

Transcription of eukaryotes Intervening DNA in Eukaryotic Genes – Introns-Genes are interrupted by these – Exons-The portions of a gene that are translated (expressed) into proteins. – Interesting note-Some genes in your cells exist in multiple copies, in clusters of a few as three or as many as several hundred.

Mutations Mutations-A change in the DNA of a gene. Gene rearrangements-Mutations that move an entire gene to a new location. Gene alterations-Mutations that change a gene. Point mutations-A single nucleotide change. Insertion-A sizable length of DNA is inserted into a gene. Deletion-Segments of a gene are lost, often during meiosis. Know these mutations for the test.