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UNCW BIO 105 - Gene Exoression and Biotechnology

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BIO 105 1st Edition Lecture 4Outline of Last Lecture I. Why do people become male or female?II. Why are certain genetic traits more common in men/boys than women/girls?III. How can you tell how human traits were inherited?IV. What happens if a person inherits the wrong number of chromosomes?Outline of Current Lecture I. How does DNA give people their traits?II. What is the relationship between DNA and proteins?III. How do mutations change a person’s traits?IV. Why do people genetically engineer plants and animal? What are the pros and cons?Current LectureBiology 105 Gene Expression and Biotechnology Essential Questions 1. How does DNA give people their traits? 2. What is the relationship between DNA and proteins?3. How do mutations change a person’s traits? 4. Why do people genetically engineer plants and animals? What are the pros and cons? Interactive Class NotesHow does DNA give people their traits?After DNA was found to be the genetic material, scientific attention turned to how the information in DNA was used to create traits in the body. This turned out to be a more difficult challenge. I. DNA use A. The sequence of bases in DNA carries information, like letters of a written word. 1. English uses 26 letters, but only some combinations make words and give information: biology, cat, and baseball. Meaningful words can only have certain letter combinations, but can be many different lengths. 2. DNA language has an alphabet of 4 letters: A, T, C and G. All words are 3 letters long and any combination of the 4 letters is permissible. There are 64 possible words and all are used. Most are the names of amino acids. a. Each DNA word, or codon, consists of a group of 3 bases in a row, and designates the These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.position of one amino acid in a protein chain. 3. A gene is the information needed to make a protein. a. Proteins are long molecules made of many amino acids linked together in an unbranched but twisted chain. b. Proteins are the functional parts of cells. They form structures, carry out reactions, and areresponsible for movement and communication. c. Genes cause proteins to be produced by the process of gene expression. 4. Humans have about 30,000 genes, similar to most other mammals. a. The maximum number of different proteins in a human cell would be 30,000 based on genes, but each cell only makes only a small percentage of them. i. The genes expressed in different cells make each cell type different. A cell expressing muscle proteins becomes a muscle cell; a cell expressing neuron proteins becomes a neuron. B. DNA doesn't make protein itself. It can't leave the nucleus, and protein is made in the cell cytoplasm. 1. The similar molecule RNA makes the protein, using instructions from the DNA. Like DNA, RNA is a nucleic acid with 4 nucleotide bases, which can also form complementary bonds. a. The bases are G, C, A, and U, which substitutes for the T in DNA. i. Complementary bonding in RNA is G-C and A-U. ii. RNA bases can also complementary bond with DNA bases. DNA / RNA G C C G A U T AWhat is the relationship between DNA and proteins?I. Transcription A. the process of making RNA from DNA, very similar to DNA replication 1. First, part of the DNA double helix seperates and RNA nucleotides are attracted to their DNA complements. 2. The enzyme RNA polymerase binds the RNA nucleotides together to make an RNA molecule. 3. At the end, the RNA molecule is released and the DNA winds up again. 4. Since the RNA is complementary to the DNA, it carries the same information. 5. To express a gene, the DNA separates and a complementary molecule called mRNA, or messenger RNA, is transcribed. 6. The mRNA goes from the nucleus to the cell cytoplasm for protein synthesis, which occurs on particles called ribosomes. a. Protein synthesis is also called translation, because the nucleotide language of DNA is being changed, or translated into, the amino acid language of protein. II. Translation A. Formation of protein using the information from DNA B. There are 4 kinds of nucleotides and 20 kinds of amino acids; it takes 3 nucleotides to designate one amino acidC. The genetic code describes which amino acid goes with which codon. 1. Of the 64 codons, 61 cause the addition of an amino acid to the protein and 3 are stop codons that stop protein and release the protein. D. Transfer RNA, or tRNA, brings the correct amino acid to match up with the codons in the mRNA. 1. At the bottom of the tRNA are three bases called the anitcodon. 2. At the top of the tRNA, an amino acid is attached. 3. When a tRNA molecule with its amino acid attached comes to the ribosome, its anticodon binds to the codon on the mRNA. The ribosome attaches the new amino acid to the growing protein chain. Thus, the order of codons on the mRNA determines the order of amino acids put into the protein. KEY POINT:RNA AND DNA ARE SIMILAR NUCLEIC ACIDS; DNA STORES F. Making a protein is like making a cake!! 1. you need a recipe book (chromosome) 2. choose the recipe that you want to use (gene) for your cake (protein) 3. copy the recipe onto a card (mRNA) so the book isn't damaged 4. the recipe copy (mRNA) is put onto the kitchen counter (ribosome) 5. the ingredients (amino acids) are measured out and delivered by the measuring cups (tRNAs) 6. to make different cakes (proteins) you use the same basic set of ingredients (amino acids) but in different amounts. How do mutations change a person’s traits? I. Mutations A. The error rate during DNA replication is very low, but mistakes do occur, and these are mutations. B. The result of a mutation is that the sequence of DNA that a daughter cell gets is not exactly the same sequence that the mother cell had. 1. A change in the genetic material may (or may not) lead to a change in a protein in the body. 2. If a protein is changed, it may (or may not) lead to a detectable change in the phenotype 3. If there is a change in the body, it may (or


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