Molecular Genetics Section 1 DNA The Genetic Material

Molecular Genetics Section 1: DNA: The Genetic Material Section 2: Replication of DNA Section 3: DNA, RNA, and Protein Section 4: Gene Regulation and Mutation Click on a lesson name to select.

Section 1 Molecular Genetics DNA: The Genetic Material Griffith § Performed the first major experiment that led to the discovery of DNA as the genetic material

Section 1 Molecular Genetics DNA: The Genetic Material Avery § Identified the molecule that transformed the R strain of bacteria into the S strain § Concluded that when the S cells were killed, DNA was released § R bacteria incorporated this DNA into their cells and changed into S cells.

Section 1 Molecular Genetics DNA: The Genetic Material Hershey and Chase § Used radioactive labeling to trace the DNA and protein § Concluded that the viral DNA was injected into the cell and provided the genetic information needed to produce new viruses

Section 1 Molecular Genetics

Section 1 Molecular Genetics DNA: The Genetic Material DNA Structure § Nucleotides § Consist of a five-carbon sugar, a phosphate group, and a nitrogenous base

Section 1 Molecular Genetics

Section 1 Molecular Genetics DNA: The Genetic Material Chargaff § Chargaff’s rule: C = G and T = A

Section 1 Molecular Genetics DNA: The Genetic Material X-ray Diffraction § X-ray diffraction data helped solve the structure of DNA § Indicated that DNA was a double helix

Section 1 Molecular Genetics DNA: The Genetic Material Watson and Crick § Built a model of the double helix that conformed to the others’ research 1. two outside strands consist of alternating phosphate 2. deoxyribose cytosine and guanine bases pair to each by and threeadenine hydrogen bonds 3. other thymine bases pair to each other by two hydrogen bonds

Section 1 Molecular Genetics DNA: The Genetic Material DNA Structure § DNA often is compared to a twisted ladder. § Rails of the ladder are represented by the alternating deoxyribose and phosphate. § The pairs of bases (cytosine–guanine or thymine–adenine) form the steps.

Section 1 Molecular Genetics DNA: The Genetic Material Orientation § On the top rail, the strand is said to be oriented 5′ to 3′. § The strand on the bottom runs in the opposite direction and is oriented 3′ to 5′.

Section 1 Molecular Genetics DNA: The Genetic Material Chromosome Structure § DNA coils around histones to form nucleosomes, which coil to form chromatin fibers. § The chromatin fibers supercoil to form chromosomes that are visible in the metaphase stage of mitosis.

Section 2 Molecular Genetics Replication of DNA Semiconservative Replication § Parental strands of DNA separate, serve as templates, and produce DNA molecules that have one strand of parental DNA and one strand of new DNA.

Section 2 Molecular Genetics Replication of DNA Unwinding § DNA helicase, an enzyme, is responsible for unwinding and unzipping the double helix. § RNA primase adds a short segment of RNA, called an RNA primer, on each DNA strand.

Section 2 Molecular Genetics Replication of DNA Base pairing § DNA polymerase continues adding appropriate nucleotides to the chain by adding to the 3′ end of the new DNA strand.

Section 2 Molecular Genetics

Section 2 Molecular Genetics Replication of DNA § One strand is called the leading strand is elongated as the DNA unwinds. § The other strand of DNA, called the lagging strand, elongates away from the replication fork. § The lagging strand is synthesized discontinuously into small segments, called Okazaki fragments.

Section 2 Molecular Genetics Replication of DNA Joining § DNA polymerase removes the RNA primer and fills in the place with DNA nucleotides. § DNA ligase links the two sections.

Section 2 Molecular Genetics Replication of DNA Comparing DNA Replication in Eukaryotes and Prokaryotes § Eukaryotic DNA unwinds in multiple areas as DNA is replicated. § In prokaryotes, the circular DNA strand is opened at one origin of replication.

Section 3 Molecular Genetics DNA, RNA, and Protein Central Dogma § RNA § Contains the sugar ribose and the base uracil instead of thymine § Usually is single stranded

Section 3 Molecular Genetics DNA, RNA, and Protein Messenger RNA (m. RNA) § Long strands of RNA nucleotides that are formed complementary to one strand of DNA Ribosomal RNA (r. RNA) § Associates with proteins to form ribosomes in the cytoplasm Transfer RNA (t. RNA) § Smaller segments of RNA nucleotides that transport amino acids to the ribosome

Section 3 Molecular Genetics

Section 3 Molecular Genetics DNA, RNA, and Protein Transcription § Through transcription, the DNA code is transferred to m. RNA in the nucleus. § DNA is unzipped in the nucleus and RNA polymerase binds to a specific section where an m. RNA will be synthesized.

Section 3 Molecular Genetics

Section 3 Molecular Genetics DNA, RNA, and Protein RNA Processing § The code on the DNA is interrupted periodically by sequences that are not in the final m. RNA. § Intervening sequences are called introns. § Remaining pieces of DNA that serve as the coding sequences are called exons. DNA and Genes

Section 3 Molecular Genetics DNA, RNA, and Protein The Code § Experiments during the 1960 s demonstrated that the DNA code was a three-base code. § The three-base code in DNA or m. RNA is called a codon.

Section 3 Molecular Genetics DNA, RNA, and Protein Translation § In translation, t. RNA molecules act as the interpreters of the m. RNA codon sequence. § At the middle of the folded strand, there is a three-base coding sequence called the anticodon. § Each anticodon is complementary to a codon on the m. RNA.

Section 3 Molecular Genetics DNA, RNA, and Protein

Section 3 Molecular Genetics

Section 3 Molecular Genetics DNA, RNA, and Protein One Gene— One Enzyme § The Beadle and Tatum experiment showed that one gene codes for one enzyme. We now know that one gene codes for one polypeptide.

Section 4 Molecular Genetics Gene Regulation and Mutation Prokaryote Gene Regulation § Ability of an organism to control which genes are transcribed in response to the environment § An operon is a section of DNA that contains the genes for the proteins needed for a specific metabolic pathway. § Operator § Promoter § Regulatory gene § Genes coding for proteins

Section 4 Molecular Genetics Gene Regulation and Mutation The Trp Operon

Section 4 Molecular Genetics Gene Regulation and Mutation The Lac Operon Lac-Trp Operon

Section 4 Molecular Genetics

Section 4 Molecular Genetics Gene Regulation and Mutation Eukaryote Gene Regulation § Controlling transcription § Transcription factors ensure that a gene is used at the right time and that proteins are made in the right amounts § The complex structure of eukaryotic DNA also regulates transcription.

Section 4 Molecular Genetics Gene Regulation and Mutation Hox Genes § Hox genes are responsible for the general body pattern of most animals.

Section 4 Molecular Genetics Gene Regulation and Mutation RNA Interference § RNA interference can stop the m. RNA from translating its message.

Section 4 Molecular Genetics Gene Regulation and Mutations § A permanent change that occurs in a cell’s DNA is called a mutation. § Types of mutations § Point mutation § Insertion § Deletion

Section 4 Molecular Genetics Gene Regulation and Mutation

Section 4 Molecular Genetics Table 12. 3 Mutations

Section 4 Molecular Genetics Gene Regulation and Mutation Protein Folding and Stability § Substitutions also can lead to genetic disorders. § Can change both the folding and stability of the protein

Section 4 Molecular Genetics Gene Regulation and Mutation Causes of Mutation § Can occur spontaneously § Chemicals and radiation also can damage DNA. § High-energy forms of radiation, such as X rays and gamma rays, are highly mutagenic.

Section 4 Molecular Genetics Gene Regulation and Mutation Body-cell v. Sex-cell Mutation § Somatic cell mutations are not passed on to the next generation. § Mutations that occur in sex cells are passed on to the organism’s offspring and will be present in every cell of the offspring.

Chapter Molecular Genetics Chapter Resource Menu Chapter Diagnostic Questions Formative Test Questions Chapter Assessment Questions Standardized Test Practice connected. mcgraw-hill. com Glencoe Biology Transparencies Image Bank Vocabulary Animation Click on a hyperlink to view the corresponding feature.

Chapter Molecular Genetics Chapter Diagnostic Questions Which scientist(s) definitively proved that DNA transfers genetic material? A. Watson and Crick B. Mendel C. Hershey and Chase D. Avery 1. 2. 3. 4. A B C D

Chapter Molecular Genetics Chapter Diagnostic Questions Name the small segments of the lagging DNA strand. A. ligase B. Okazaki fragments C. micro RNA D. helicase 1. 2. 3. 4. A B C D

Chapter Molecular Genetics Chapter Diagnostic Questions Which is not true of RNA? A. It contains the sugar ribose. B. It contains the base uracil. C. It is single-stranded. D. It contains a phosphate. 1. 2. 3. 4. A B C D

Chapter Molecular Genetics Section 1 Formative Questions The experiments of Avery, Hershey and Chase provided evidence that the carrier of genetic information is _______. A. carbohydrate B. DNA C. lipid D. protein 1. 2. 3. 4. A B C D

Chapter Molecular Genetics Section 1 Formative Questions What is the base-pairing rule for purines and pyrimidines in the DNA molecule? A. A—G and C—T B. A—T and C—G C. C—A and G—T D. C—U and A—G 1. 2. 3. 4. A B C D

Chapter Molecular Genetics Section 1 Formative Questions What are chromosomes composed of? A. chromatin and histones B. DNA and protein C. DNA and lipids D. protein and centromeres 1. 2. 3. 4. A B C D

Chapter Molecular Genetics Section 2 Formative Questions The work of Watson and Crick solved the mystery of how DNA works as a genetic code. A. True B. False 1. 2. A B

Chapter Molecular Genetics Section 2 Formative Questions Which is not an enzyme involved in DNA replication? A. DNA ligase B. DNA polymerase C. hilicase D. RNA primer 1. 2. 3. 4. A B C D

Chapter Molecular Genetics Section 3 Formative Questions Which shows the basic chain of events in all organisms for reading and expressing genes? A. DNA RNA protein B. RNA DNA protein 1. C. m. RNA r. RNA t. RNA 2. 3. 4. D. RNA processing transcription translation A B C D

Chapter Molecular Genetics Section 3 Formative Questions In the RNA molecule, uracil replaces _______. A. adenine B. cytosine C. purine D. thymine 1. 2. 3. 4. A B C D

Molecular Genetics Chapter Section 3 Formative Questions Which diagram shows messenger RNA (m. RNA)? A. C. B. D. 1. 2. 3. 4. A B C D

Chapter Molecular Genetics Section 3 Formative Questions What characteristic of the m. RNA molecule do scientists not yet understand? A. intervening sequences in the m. RNA molecule called introns B. the original m. RNA made in the nucleus called the pre-m. RNA C. how the sequence of bases in the m. RNA 1. molecule A 2. B codes for amino acids 3. C 4. D D. the function of many adenine nucleotides at the 5′ end called the poly-A tail

Chapter Molecular Genetics Section 4 Formative Questions Why do eukaryotic cells need a complex control system to regulate the expression of genes? A. All of an organism’s cells transcribe the same genes. B. Expression of incorrect genes can lead to mutations. 1. A C. Certain genes are expressed more frequently 2. B than 3. C others are. 4. D D. Different genes are expressed at different times in an organism’s lifetime.

Chapter Molecular Genetics Section 4 Formative Questions Which type of gene causes cells to become specialized in structure in function? A. exon B. Hox gene C. intron D. operon 1. 2. 3. 4. A B C D

Chapter Molecular Genetics Section 4 Formative Questions What is an immediate result of a mutation in a gene? A. cancer B. genetic disorder C. nonfunctional enzyme D. amino acid deficiency 1. 2. 3. 4. A B C D

Chapter Molecular Genetics Section 4 Formative Questions Which is the most highly mutagenic? A. chemicals in food B. cigarette smoke C. ultraviolet radiation D. X rays 1. 2. 3. 4. A B C D

Chapter Molecular Genetics Chapter Assessment Questions Look at the following figure. Identify the proteins that DNA first coils around. A. chromatin fibers B. chromosomes C. histones D. nucleosome 1. 2. 3. 4. A B C D

Chapter Molecular Genetics Chapter Assessment Questions Explain how Hox genes affect an organism. A. They determine size. B. They determine body plan. C. They determine sex. 1. A 2. B D. They determine number of body segments. 3. C 4. D

Chapter Molecular Genetics Chapter Assessment Questions Explain the difference between body-cell and sex-cell mutation. Answer: A mutagen in a body cell becomes part of the genetic sequence in that cell and in future daughter cells. The cell may die or simply not perform its normal function. These mutations are not passed on to the next generation. When mutations occur in sex cells, they will be present in every cell of the offspring.

Chapter Molecular Genetics Standardized Test Practice What does this diagram show about the replication of DNA in eukaryotic cells? A. DNA is replicated only at certain places along the chromosome. B. DNA replication is both semicontinuous and conservative. C. Multiple areas of replication occur along the chromosome at the same time. D. The leading DNA strand is synthesized discontinuously. 1. 2. 3. 4. A B C D

Chapter Molecular Genetics Standardized Test Practice What is this process called? A. m. RNA processing B. protein synthesis C. transcription D. translation 1. 2. 3. 4. A B C D

Chapter Molecular Genetics Standardized Test Practice What type of mutation results in this change in the DNA sequence? TTCAGG A. deletion B. frameshift C. insertion D. substitution TTCTGG 1. 2. 3. 4. A B C D

Chapter Molecular Genetics Standardized Test Practice How could RNA interference be used to treat diseases such as cancer and diabetes? A. by activating genes to produce proteins that can overcome the disease B. by interfering with DNA replication in cells affected by the disease C. by preventing the translation of m. RNA into 1. the A 2. B genes associated with the disease 3. C D. by shutting down protein synthesis in the 4. cells. D of diseased tissues

Chapter Molecular Genetics Standardized Test Practice The structure of a protein can be altered dramatically by the exchange of a single amino acid for another. A. True B. False 1. 2. A B

Chapter Molecular Genetics Glencoe Biology Transparencies

Chapter Molecular Genetics Image Bank

Chapter Molecular Genetics Image Bank

Section 1 Molecular Genetics Vocabulary Section 1 double helix nucleosome

Section 2 Molecular Genetics Vocabulary Section 2 semiconservative replication DNA polymerase Okazaki fragment

Section 3 Molecular Genetics Vocabulary Section 3 RNA intron messenger RNA ribosomal RNA transfer RNA transcription RNA polymerase codon exon translation

Section 4 Molecular Genetics Vocabulary Section 4 gene regulation operon mutation mutagen

Chapter Molecular Genetics Animation § Structure of DNA § DNA Polymerase § Transcription § Visualizing Transcription and Translation § Lac-Trp Operon

Chapter Molecular Genetics

Chapter Molecular Genetics

Chapter Molecular Genetics

Chapter Molecular Genetics

Chapter Molecular Genetics