Click on a lesson name to select. Chapter 12 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

Molecular Genetics DNA Structure  Nucleotides – monomers of DNA  Consist of 3 parts : 1. five-carbon sugar (deoxyribose) 2. phosphate group 3. one of four possible nitrogenous bases (A,T,G, or C) 12.1 DNA: The Genetic Material Chapter 12

Molecular Genetics Chapter 12

Molecular Genetics  Chargaff’s rule:  the # of cytosine bases is = to the # of guanine bases.  The # of adenine bases is = to the # of thymine bases  C = G and T = A 12.1 DNA: The Genetic Material Chapter 12

Molecular Genetics X-ray Diffraction  data helped solve the structure (not details) of DNA  Indicated that DNA was a double helix 12.1 DNA: The Genetic Material Chapter 12

Molecular Genetics Watson and Crick - Built a model of the (DNA) double helix using the following information: 1. two outside strands consist of alternating deoxyribose (sugar) and phosphate 2. cytosine and guanine (C-G) bases pair to each other by three hydrogen bonds 3. thymine and adenine (T-A) bases pair to each other by two hydrogen bonds 12.1 DNA: The Genetic Material Chapter 12

Molecular Genetics DNA Structure : Twisted ladder  Sides of the ladder are alternating deoxyribose and phosphate.  The pairs of bases (cytosine–guanine or thymine–adenine) form the steps of the ladder DNA: The Genetic Material Chapter 12

Molecular Genetics Orientation of strands: Anti -parallel  top strand is oriented 5′ to 3′ direction.  Bottom strand runs in the opposite direction 3′ to 5′ DNA: The Genetic Material Chapter 12

12.1 DNA: The Genetic Material Molecular Genetics Chromosome Structure  DNA coils around histones (protein) to form nucleosomes, which coil to form chromatin fibers.  chromatin fibers supercoil to form chromosomes that are visible in the metaphase stage of mitosis. Chapter 12

12.2 Replication of DNA Molecular Genetics Semi-conservative Replication  Parental (original) strands of DNA separate and serve as templates  produce DNA molecules that consist of one parent strand (original) and one new strand of DNA Chapter 12

Molecular Genetics Unwinding of DNA  DNA helicase - an enzyme, is responsible for unwinding and unzipping the double helix.  RNA primase - enzyme adds a short segment of RNA, called an RNA primer, on each DNA strand Replication of DNA Chapter 12

Molecular Genetics Base pairing  DNA polymerase (enzyme) - continues adding matching nucleotides to the chain by adding to the 3′ end of the new DNA strand.  (If “A” is on the parent strand then a “T” is added to the new strand) 12.2 Replication of DNA Chapter 12

Molecular Genetics Chapter 12

DNA replication animations hill.com/sites/ /student_view0/ch apter14/animations.html# hill.com/sites/ /student_view0/ch apter14/animations.html# ces/MolecularBiology/DNAReplication.swfhttp:// ces/MolecularBiology/DNAReplication.swf

Molecular Genetics  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.  DNA ligase (enzyme) links the fragments Replication of DNA Chapter 12

12.2 Replication of DNA Molecular Genetics Comparing DNA Replication in Eukaryotes and Prokaryotes  Eukaryotic DNA (plants and animals) unwinds in multiple areas as DNA is replicated.  Prokaryotic DNA (such as bacteria), circular DNA strand is opened at one origin of replication. Chapter 12

12.3 DNA, RNA, and Protein Molecular Genetics Central Dogma: DNA > RNA > PROTEIN  RNA  Contains the sugar ribose and the base uracil  Usually is single stranded  Bases: adenine, guanine, cytosine and uracil Chapter 12

Molecular Genetics Messenger RNA (mRNA)  Long strands of RNA nucleotides that are formed in the nucleus 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 12.3 DNA, RNA, and Protein Chapter 12

Molecular Genetics 12.3 DNA, RNA, and Protein Chapter 12

Molecular Genetics Chapter 12

tRNA

 DNA is unzipped and RNA polymerase binds to a specific section where an mRNA will be synthesized (made).  Assembly begins at the promoter sequence ( start codon) and continues until it reaches a 3-base termination sequence (stop codon). Molecular Genetics Transcription  DNA code is transferred to mRNA in the nucleus DNA, RNA, and Protein Chapter 12

Molecular Genetics Chapter 12

Molecular Genetics 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.  Example: TACAACGCA each color represents one codon 12.3 DNA, RNA, and Protein Chapter 12

Molecular Genetics Translation  tRNA molecules act as the interpreters of the mRNA codon sequence.  tRNA carries anti-codons & amino acids (which bind together to form proteins).  t-RNA anti-codons are complimentary to codons on the mRNA sequence example:  mRNA AUG (codon) tRNA UAC (anticodon) 12.3 DNA, RNA, and Protein Chapter 12

mRNA:AUGAAGCUACCGUAA

Proteins Proteins- made of a chain of amino acids linked together by peptide bonds. Chains of amino acids are also known as polypeptides. There are 20 different amino acids What makes one protein different then the next? –Different combinations of amino acids code for different proteins (kind of like locker combinations)

Molecular Genetics 12.3 DNA, RNA, and Protein Chapter 12 1.mRNA is transcribed in nucleus 2.mRNA enters the cytoplasm and binds to a ribosome. 3.Specific amino acids are attached to tRNA’s. 4.tRNA adds their amino acids to the polypeptide chain as the mRNA moves through the ribosome one codon at a time. 5.When a stop codon is reached, the protein is released

Molecular Genetics Chapter 12

12.4 Gene Regulation and Mutation Molecular Genetics 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 Chapter 12

Molecular Genetics The Lac Operon 12.4 Gene Regulation and Mutation Chapter 12 Lac-Trp Operon

Example of gene regulation: (you need to be very familiar with this example!) E. Coli: a symbiotic bacteria that lives in the intestines and produces enzymes to break down lactose Lac operon: a series of genes on the DNA of E-Coli that allows E. Coli to break down lactose. The genes are expressed only in the presence of lactose.

When lactose is not present: Lac operon is turned off, the enzyme is not made. When lactose is present: Lac operon is turned on, the enzyme that breaks down lactose is made.

Molecular Genetics Chapter 12

Molecular Genetics 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 12.4 Gene Regulation and Mutation Chapter 12 SKIP!

Molecular Genetics Mutations  A permanent change that occurs in a cell’s DNA is called a mutation.  Types of mutations  Point mutation: change of a single nucleotide base on the DNA.  Insertion: during replication an extra base is added.  Deletion: a base is deleted Gene Regulation and Mutation Chapter 12

12.4 Gene Regulation and Mutation Deletion Example THE BIG CAT ATE THE RAT- normal THB IGC ATA TET HER AT – mutated

12.4 Gene Regulation and Mutation Insertion Example: THE BIG CAT ATE THE RAT – normal THE XBI GCA TAT ETH ERA T - mutated

12.4 Gene Regulation and Mutation Substitution a base is replaced by a different base which may or may not code for a different amino acid Example THE BIG CAT ATE THE RAT- normal THE MIG CAT ATE THE RAT - mutated

Molecular Genetics 12.4 Gene Regulation and Mutation Chapter 12

Molecular Genetics Chapter 12

Molecular Genetics Protein Folding and Stability  Substitutions also can lead to genetic disorders.  Can change both the folding and stability of the protein 12.4 Gene Regulation and Mutation Chapter 12

Molecular Genetics 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 Gene Regulation and Mutation Chapter 12

Molecular Genetics Body-cell v. Sex-cell Mutation  Somatic (body) 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 Gene Regulation and Mutation Chapter 12

Molecular Genetics Chapter Resource Menu Chapter Diagnostic Questions Formative Test Questions Chapter Assessment Questions Standardized Test Practice biologygmh.com Glencoe Biology Transparencies Image Bank Vocabulary Animation Click on a hyperlink to view the corresponding feature. Chapter 12

1.A 2.B 3.C 4.D CDQ 1 A. Watson and Crick B. Mendel C. Hershey and Chase D. Avery Which scientist(s) definitively proved that DNA transfers genetic material? Molecular Genetics Chapter Diagnostic Questions Chapter 12

1.A 2.B 3.C 4.D CDQ 2 Molecular Genetics Chapter Diagnostic Questions Chapter 12 A. ligase B. Okazaki fragments C. polymerase D. helicase Name the small segments of the lagging DNA strand.

1.A 2.B 3.C 4.D CDQ 3 Molecular Genetics Chapter Diagnostic Questions Chapter 12 A. It contains the sugar ribose. B. It contains the base uracil. C. It is single-stranded. D. It contains a phosphate. Which is not true of RNA?

1.A 2.B 3.C 4.D FQ 1 Molecular Genetics Chapter 12 A. carbohydrate B. DNA C. lipid D. protein The experiments of Avery, Hershey and Chase provided evidence that the carrier of genetic information is _______ Formative Questions

1.A 2.B 3.C 4.D FQ 2 Molecular Genetics Chapter 12 A. A—G and C—T B. A—T and C—G C. C—A and G—T D. C—U and A—G What is the base-pairing rule for purines and pyrimidines in the DNA molecule? 12.1 Formative Questions

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

1.A 2.B FQ 4 Molecular Genetics Chapter 12 The work of Watson and Crick solved the mystery of how DNA works as a genetic code. A. True B. False 12.2 Formative Questions

1.A 2.B 3.C 4.D FQ 5 Molecular Genetics Chapter Formative Questions A. DNA ligase B. DNA polymerase C. hilicase D. RNA primer Which is not an enzyme involved in DNA replication?

1.A 2.B 3.C 4.D FQ 6 Molecular Genetics Chapter 12 Which shows the basic chain of events in all organisms for reading and expressing genes? A. DNA  RNA  protein B. RNA  DNA  protein C. mRNA  rRNA  tRNA D. RNA processing  transcription  translation 12.3 Formative Questions

1.A 2.B 3.C 4.D FQ 7 Molecular Genetics Chapter Formative Questions In the RNA molecule, uracil replaces _______. A. adenine B. cytosine C. purine D. thymine

1.A 2.B 3.C 4.D FQ 8 Molecular Genetics Chapter Formative Questions Which diagram shows messenger RNA (mRNA)? A. C. B. D.

1.A 2.B 3.C 4.D FQ 9 Molecular Genetics Chapter Formative Questions What characteristic of the mRNA molecule do scientists not yet understand? A. intervening sequences in the mRNA molecule called introns B. the original mRNA made in the nucleus called the pre-mRNA C. how the sequence of bases in the mRNA molecule codes for amino acids D. the function of many adenine nucleotides at the 5′ end called the poly-A tail

1.A 2.B 3.C 4.D FQ 10 Molecular Genetics Chapter 12 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. C. Certain genes are expressed more frequently than others are. D. Different genes are expressed at different times in an organism’s lifetime Formative Questions

1.A 2.B 3.C 4.D FQ 11 Molecular Genetics Chapter 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.A 2.B 3.C 4.D FQ 12 Molecular Genetics Chapter 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.A 2.B 3.C 4.D FQ 13 Molecular Genetics Chapter Formative Questions Which is the most highly mutagenic? A. chemicals in food B. cigarette smoke C. ultraviolet radiation D. X rays

1.A 2.B 3.C 4.D CAQ 1 Molecular Genetics Chapter 12 Look at the following figure. Identify the proteins that DNA first coils around. Chapter Assessment Questions A. chromatin fibers B. chromosomes C. histones D. nucleosome

1.A 2.B 3.C 4.D CAQ 2 Molecular Genetics Chapter 12 Chapter Assessment Questions A. They determine size. B. They determine body plan. C. They determine sex. D. They determine number of body segments. Explain how Hox genes affect an organism.

Explain the difference between body-cell and sex-cell mutation. Molecular Genetics Chapter Assessment Questions Chapter 12 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

1.A 2.B 3.C 4.D STP 1 Molecular Genetics Chapter 12 What does this diagram show about the replication of DNA in eukaryotic cells? Standardized Test Practice 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.A 2.B 3.C 4.D STP 2 Molecular Genetics Chapter 12 Standardized Test Practice A. mRNA processing B. protein synthesis C. transcription D. translation What is this process called?

1.A 2.B 3.C 4.D STP 3 Molecular Genetics Chapter 12 Standardized Test Practice What type of mutation results in this change in the DNA sequence? A. deletion B. frameshift C. insertion D. substitution TTCAGG TTCTGG

1.A 2.B 3.C 4.D STP 4 Molecular Genetics Chapter 12 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 mRNA into the genes associated with the disease D. by shutting down protein synthesis in the cells of diseased tissues

1.A 2.B STP 5 Molecular Genetics Chapter 12 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

Molecular Genetics Glencoe Biology Transparencies Chapter 12

Molecular Genetics Image Bank Chapter 12

Molecular Genetics Image Bank Chapter 12

double helix nucleosome Molecular Genetics Vocabulary Section 1 Chapter 12

semiconservative replication DNA polymerase Okazaki fragment Molecular Genetics Vocabulary Section 2 Chapter 12

RNA messenger RNA ribosomal RNA transfer RNA transcription RNA polymerase codon intron exon translation Molecular Genetics Vocabulary Section 3 Chapter 12

gene regulation operon mutation mutagen Molecular Genetics Vocabulary Section 4 Chapter 12

Molecular Genetics  Structure of DNA Structure of DNA  DNA Polymerase DNA Polymerase  Transcription Transcription  Visualizing Transcription and Translation Visualizing Transcription and Translation  Lac-Trp Operon Lac-Trp Operon Animation Chapter 12

Molecular Genetics Chapter 12

Molecular Genetics Chapter 12

Molecular Genetics Chapter 12

Molecular Genetics Chapter 12

Molecular Genetics Chapter 12