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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
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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
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Concluded that when the S cells were killed, DNA was released
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.
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Used radioactive labeling to trace the DNA and protein
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
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DNA: The Genetic Material
Section 1 Molecular Genetics DNA: The Genetic Material DNA Structure Nucleotides Consist of a five-carbon sugar, a phosphate group, and a nitrogenous base
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Chargaff’s rule: C = G and T = A
Section 1 Molecular Genetics DNA: The Genetic Material Chargaff Chargaff’s rule: C = G and T = A
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The Structure Question
Section 1 Molecular Genetics DNA: The Genetic Material The Structure Question Four scientists provided information that would be pivotal in solving the structure question
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X-ray diffraction data helped solve the structure of DNA
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
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two outside strands consist of alternating deoxyribose and phosphate
Section 1 Molecular Genetics DNA: The Genetic Material Watson and Crick Built a model of the double helix that conformed to the others’ research two outside strands consist of alternating deoxyribose and phosphate cytosine and guanine bases pair to each other by three hydrogen bonds thymine and adenine bases pair to each other by two hydrogen bonds
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DNA often is compared to a twisted ladder.
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.
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DNA: The Genetic Material
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′.
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DNA: The Genetic Material
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.
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Semiconservative Replication
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.
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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.
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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.
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Section 2 Molecular Genetics Replication of DNA One strand is called the leading strand and 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.
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DNA ligase links the two sections.
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.
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Comparing DNA Replication in Eukaryotes and Prokaryotes
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.
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Contains the sugar ribose and the base uracil instead of thymine
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
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Associates with proteins to form ribosomes in the cytoplasm
Section 3 Molecular Genetics DNA, RNA, and Protein Messenger RNA (mRNA) Long strands of RNA nucleotides that are formed complementary to one strand of DNA Ribosomal RNA (rRNA) Associates with proteins to form ribosomes in the cytoplasm Transfer RNA (tRNA) Smaller segments of RNA nucleotides that transport amino acids to the ribosome
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DNA is unzipped in the nucleus and RNA
Section 3 Molecular Genetics DNA, RNA, and Protein Transcription Through transcription, the DNA code is transferred to mRNA in the nucleus. DNA is unzipped in the nucleus and RNA polymerase binds to a specific section where an mRNA will be synthesized.
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Intervening sequences are called introns.
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 mRNA. Intervening sequences are called introns. Remaining pieces of DNA that serve as the coding sequences are called exons. DNA and Genes
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The three-base code in DNA or mRNA is called a codon.
Section 3 Molecular Genetics DNA, RNA, and Protein The Code Experiments during the 1960s demonstrated that the DNA code was a three-base code. The three-base code in DNA or mRNA is called a codon.
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Each anticodon is complementary to a codon on the mRNA.
Section 3 Molecular Genetics DNA, RNA, and Protein Translation In translation, tRNA molecules act as the interpreters of the mRNA 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 mRNA.
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How to use the Codon Chart!
For mRNA: AUG CCC AAU CGC UGA
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Section 3 Molecular Genetics DNA, RNA, and Protein
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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.
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A permanent change that occurs in a cell’s DNA is called a mutation.
Section 4 Molecular Genetics Gene Regulation and Mutation Mutations A permanent change that occurs in a cell’s DNA is called a mutation. Types of mutations Point mutation Insertion Deletion
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Gene Regulation and Mutation
Section 4 Molecular Genetics Gene Regulation and Mutation
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SUBSTITUTION (Point Mutation)
Original DNA strand mRNA Protein AGG TAT CCG UCC AUA GGC Ser Lleu Gly Mutation – TGG TAT CCG Mutated mRNA sequence – ACC AUA GGC Protein MUTATION created using the codon chart - Thr Lleu Gly
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INSERTION Original DNA strand mRNA Protein
AGG TAT CCG UCC AUA GGC Ser Lleu Gly Mutation – AGG TGA TCC G Mutated mRNA sequence – UCC ACU AGG C Protein MUTATION created using the codon chart - Ser Thr Arg
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DELETION Original DNA strand mRNA Protein
AGG TAT CCG UCC AUA GGC Ser Lleu Gly Mutation – AGT ATC CGC Mutated mRNA sequence – UCA UAG GCG Protein MUTATION created using the codon chart - Ser STOP!!
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Protein Folding and Stability
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
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Can occur spontaneously
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.
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Body-cell v. Sex-cell Mutation
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.
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Chapter Resource Menu Chapter Diagnostic Questions
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.
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Which scientist(s) definitively proved
Chapter Molecular Genetics Chapter Diagnostic Questions Which scientist(s) definitively proved that DNA transfers genetic material? Watson and Crick Mendel Hershey and Chase Avery A B C D CDQ 1
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Name the small segments of the lagging DNA strand.
Chapter Molecular Genetics Chapter Diagnostic Questions Name the small segments of the lagging DNA strand. ligase Okazaki fragments micro RNA helicase A B C D CDQ 2
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Which is not true of RNA? It contains the sugar ribose.
Chapter Molecular Genetics Chapter Diagnostic Questions Which is not true of RNA? It contains the sugar ribose. It contains the base uracil. It is single-stranded. It contains a phosphate. A B C D CDQ 3
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The experiments of Avery, Hershey and
Chapter Molecular Genetics Section 1 Formative Questions The experiments of Avery, Hershey and Chase provided evidence that the carrier of genetic information is _______. carbohydrate DNA lipid protein A B C D FQ 1
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What is the base-pairing rule for purines
Chapter Molecular Genetics Section 1 Formative Questions What is the base-pairing rule for purines and pyrimidines in the DNA molecule? A—G and C—T A—T and C—G C—A and G—T C—U and A—G A B C D FQ 2
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What are chromosomes composed of?
Chapter Molecular Genetics Section 1 Formative Questions What are chromosomes composed of? chromatin and histones DNA and protein DNA and lipids protein and centromeres A B C D FQ 3
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The work of Watson and Crick solved the mystery of how DNA works as a
Chapter Molecular Genetics Section 2 Formative Questions The work of Watson and Crick solved the mystery of how DNA works as a genetic code. True False A B FQ 4
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Which is not an enzyme involved in DNA replication?
Chapter Molecular Genetics Section 2 Formative Questions Which is not an enzyme involved in DNA replication? DNA ligase DNA polymerase hilicase RNA primer A B C D FQ 5
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Which shows the basic chain of events
Chapter Molecular Genetics Section 3 Formative Questions Which shows the basic chain of events in all organisms for reading and expressing genes? DNA RNA protein RNA DNA protein mRNA rRNA tRNA RNA processing transcription translation A B C D FQ 6
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In the RNA molecule, uracil replaces _______.
Chapter Molecular Genetics Section 3 Formative Questions In the RNA molecule, uracil replaces _______. adenine cytosine purine thymine A B C D FQ 7
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Which diagram shows messenger RNA (mRNA)?
Chapter Molecular Genetics Section 3 Formative Questions Which diagram shows messenger RNA (mRNA)? A. C. B. D. A B C D FQ 8
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Chapter Molecular Genetics Section 3 Formative Questions What characteristic of the mRNA molecule do scientists not yet understand? intervening sequences in the mRNA molecule called introns the original mRNA made in the nucleus called the pre-mRNA how the sequence of bases in the mRNA molecule codes for amino acids the function of many adenine nucleotides at the 5′ end called the poly-A tail A B C D FQ 9
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Chapter Molecular Genetics Section 4 Formative Questions Why do eukaryotic cells need a complex control system to regulate the expression of genes? All of an organism’s cells transcribe the same genes. Expression of incorrect genes can lead to mutations. Certain genes are expressed more frequently than others are. Different genes are expressed at different times in an organism’s lifetime. A B C D FQ 10
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Which type of gene causes cells to become specialized in structure in
Chapter Molecular Genetics Section 4 Formative Questions Which type of gene causes cells to become specialized in structure in function? exon Hox gene intron operon A B C D FQ 11
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What is an immediate result of a mutation in a gene?
Chapter Molecular Genetics Section 4 Formative Questions What is an immediate result of a mutation in a gene? cancer genetic disorder nonfunctional enzyme amino acid deficiency A B C D FQ 12
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Which is the most highly mutagenic?
Chapter Molecular Genetics Section 4 Formative Questions Which is the most highly mutagenic? chemicals in food cigarette smoke ultraviolet radiation X rays A B C D FQ 13
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chromatin fibers chromosomes histones nucleosome
Chapter Molecular Genetics Chapter Assessment Questions Look at the following figure. Identify the proteins that DNA first coils around. chromatin fibers chromosomes histones nucleosome A B C D CAQ 1
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Explain how Hox genes affect an organism.
Chapter Molecular Genetics Chapter Assessment Questions Explain how Hox genes affect an organism. They determine size. They determine body plan. They determine sex. They determine number of body segments. A B C D CAQ 2
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Explain the difference between body-cell and sex-cell mutation.
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 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. CAQ 3
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Standardized Test Practice
Chapter Molecular Genetics Standardized Test Practice What does this diagram show about the replication of DNA in eukaryotic cells? DNA is replicated only at certain places along the chromosome. DNA replication is both semicontinuous and conservative. Multiple areas of replication occur along the chromosome at the same time. The leading DNA strand is synthesized discontinuously. A B C D STP 1
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What is this process called?
Chapter Molecular Genetics Standardized Test Practice What is this process called? mRNA processing protein synthesis transcription translation A B C D STP 2
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TTCAGG TTCTGG What type of mutation results in this change
Chapter Molecular Genetics Standardized Test Practice What type of mutation results in this change in the DNA sequence? TTCAGG TTCTGG deletion frameshift insertion substitution A B C D STP 3
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Standardized Test Practice
Chapter Molecular Genetics Standardized Test Practice How could RNA interference be used to treat diseases such as cancer and diabetes? by activating genes to produce proteins that can overcome the disease by interfering with DNA replication in cells affected by the disease by preventing the translation of mRNA into the genes associated with the disease by shutting down protein synthesis in the cells of diseased tissues A B C D STP 4
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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. True False A B STP 5
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Glencoe Biology Transparencies
Chapter Molecular Genetics Glencoe Biology Transparencies
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Chapter Molecular Genetics Image Bank
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Chapter Molecular Genetics Image Bank
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Section 1 Vocabulary double helix nucleosome Section 1
Molecular Genetics Vocabulary Section 1 double helix nucleosome
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Section 2 Vocabulary semiconservative replication DNA polymerase
Molecular Genetics Vocabulary Section 2 semiconservative replication DNA polymerase Okazaki fragment
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Section 3 Vocabulary RNA messenger RNA ribosomal RNA transfer RNA
Molecular Genetics Vocabulary Section 3 RNA messenger RNA ribosomal RNA transfer RNA transcription RNA polymerase codon intron exon translation
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Section 4 Vocabulary gene regulation operon mutation mutagen Section 4
Molecular Genetics Vocabulary Section 4 gene regulation operon mutation mutagen
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Visualizing Transcription and Translation Lac-Trp Operon
Chapter Molecular Genetics Animation Structure of DNA DNA Polymerase Transcription Visualizing Transcription and Translation Lac-Trp Operon
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