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I have a genetics test and it is going to be 25 questions mostly multiple choices questions . I need to work someone major in biology and familiar with genetics course. ( the exam it is only 50 minute) I have attached the lecture slides, please go over themI will start taking the test once are you ready and will copay and paste the questions here to answer.Thank you dna_structure.pptx dnareplication.pptx dna_mutations_and_repair.pptx protein_translation.pptx Unformatted Attachment Preview Introduction to Genetics CHAPTER 1 Lecture Presentation by Dr. Cindy Malone, California State University Northridge History of Genetics 1600–1850: The Dawn of Modern Biology William Harvey: Theory of epigenesis Organisms develop from a fertilized egg Structures such as body organs • are not initially present in the early embryo • are formed later Schleiden and Schwann: The cell theory (1830) All organisms are composed of basic structural units called cells The Origin of the Species 1859: Darwin published his ideas on the theory of evolution in The Origin of Species • Descent with modification • Existing species arose from other ancestral species • Natural selection • The mechanism for evolutionary change • Theory of evolution • Independently proposed by Alfred Russel Wallace However, Darwin did not understand the genetic basis of inheritance of variation Inheritance 1866: Mendel published his findings Mendel worked with peas and used quantitative data to support his ideas • Traits are passed from generation to generation • Transmission of genetic information from parents to offspring Mendel’s work was little known until the 1900’s Chromosomes In the early 1900’s Walther Flemming, Theodor Boveri, and Walter Sutton made a series of significant discoveries about chromosomes: • what chromosomes looked like • how they moved during mitosis • and what role they likely played in the transmission of genetic characteristics Chromosomal Theory of Inheritance Inherited traits are controlled by genes residing on chromosomes: • Genes are transmitted through gametes • Maintains genetic continuity from generation to generation • But chromosomes are made of DNA and protein – no-one knew what the actual genetic material was made of The Age of Genetics Future of Genetics Society is faced with a host of sensitive genetics-related issues: • Prenatal testing • Ownership of genes • Access to/safety of gene therapy DNA: Structure & Analysis CHAPTER 10 Lecture Presentation by Dr. Cindy Malone, California State University Northridge “The structure of DNA holds the key to its function” Genetic Material Genetic material: • Information contained in genes that gets passed onto new generation • Source of variability among organisms • Must have four characteristics Criteria for Genetic Material To serve as genetic material, molecule must be able to: • Replicate • Store information • Express information • Allow variation by mutation Protein as Genetic Material? In the 1940s, geneticists favored proteins as the inherited genetic material: • Proteins and nucleic acids were both major candidates for genetic material • Proteins were diverse and abundant in cells • DNA contains equal amounts of four nucleotides • Postulated identical groups and repeats of four components was basis for DNA structure • Lack of chemical diversity in DNA suggested it could not store extensive genetic information • Proteins favored as genetic material Avery, MacLeod, and McCarty Evidence favoring DNA as the genetic material was first obtained during a study of bacteria and bacteriophages Avery, MacLeod, and McCarty: • 1944 publication on chemical nature of transforming principle in bacteria • First direct experimental proof that DNA is biomolecule responsible for heredity Griffith’s Transformation Experiment Griffith (1927) • Provided foundation for Avery, MacLeod, and McCarty’s research • Showed avirulent strains of Diplococcus (Streptococcus) pneumoniae could be transformed to virulence • Speculated transforming principle could be part of polysaccharide capsule or compound required for capsule synthesis Griffith’s Transformation Experiment Transforming Principle is DNA Avery, MacLeod, and McCarty • 1944 published results of their experiment • DNase (deoxyribonuclease) utilized to destroy transforming activity • Demonstrated transforming principle was DNA, not protein Avery, MacLeod, and McCarty’s Experiment Hershey and Chase Hershey and Chase (1952) • Used Escherichia coli and bacteriophage T2 Bacteriophage is a virus that infects and replicates in bacteria • Demonstrated that DNA, not protein, is the genetic material • Used radioisotopes 32P and 35S • Demonstrated DNA enters bacterial cell during infection and directs viral reproduction 32P Labels DNA, 35S Labels Protein DNA Amino acids Hershey & Chase: • Infection by only viral nucleic acid • Showed that viral DNA alone contains all necessary information for production of mature viruses Indirect Evidence of DNA as Genetic Material Indirect evidence: Distribution of DNA • Close correlation between gametes and diploids in amount of DNA and number of chromosome sets • No such correlation between gametes and diploids for proteins Indirect Evidence: Mutagenesis Indirect evidence: Mutagenesis Molecule serving as genetic material is expected to absorb UV lights at a mutagenic wavelength Indirect Evidence: Mutagenesis UV light: • Induces most mutations at 260 nm • DNA absorbs UV at 260 nm • Protein absorbs UV at 280 nm no significant mutagenic effects are observed at 280 nm Direct Evidence: Recombinant DNA Studies Recombinant DNA technology • Segments of eukaryotic DNA corresponding to specific genes isolated and spliced into the bacterial DNA • Complex inserted into bacterial cell and monitored Eukaryotic DNA now functional in bacterial cell • Eukaryotic gene product in bacteria containing eukaryotic gene provides direct evidence: DNA is present and functional in bacterial cell • Example: Insulin production by bacteria RNA as Genetic Material in Some Viruses Some viruses have RNA core, not DNA: • TMV: Tobacco mosaic virus (1956) Demonstrated RNA serves as genetic material for these viruses • Hepatitis C • HIV • Coronaviruses Retroviruses and Reverse Transcriptase Retroviruses • Replicate unusually • RNA serves as template for DNA synthesis • Complementary synthesis of DNA by RNA-dependent DNA polymerase reverse transcriptase Reverse transcriptase • RNA-dependent DNA polymerase enzyme The Central Dogma Central dogma of molecular genetics: • DNA makes RNA - transcription • RNA makes proteins - translation • DNA → RNA → Protein The Central Dogma DNA → RNA → protein Knowledge of Nucleic Acid Chemistry Is Essential to the Understanding of DNA Structure Nucleotides Nucleotides • DNA is nucleic acid • Nucleotides: Building blocks of nucleic acid • Nucleotides are building blocks of DNA Nucleotides consist of: • Nitrogenous base (two kinds) • Pentose sugar • Phosphate group Nitrogenous Bases Two kinds of nitrogenous bases: Pyrimidines (six-member ring) • Cytosine (C) • Thymine (T) • Uracil (U) Purines (nine-member ring) • Adenine (A) • Guanine (G) The Bases of DNA and RNA DNA • Bases are A, C, T, G RNA • Bases are A, C, U, G Only DNA contains T Only RNA contains U Ribose and Deoxyribose RNA contains ribose sugar DNA contains deoxyribose • “Deoxy” (without an oxygen) Nucleosides and Nucleotides Nucleoside: • Contains nitrogenous base and pentose sugar • Molecule is composed of purine or pyrimidine base and ribose or deoxyribose sugar Nucleotide: • Nucleoside with phosphate group added Mono-, Di-, and Triphosphates Nucleoside monophosphates (NMP) • A nucleotide Nucleoside diphosphates (NDP) • Nucleotide with addition of two phosphate groups Nucleoside triphosphates (NTP) • Nucleotide with addition of three phosphate groups Triphosphates Triphosphates • Serve as precursor molecule during nucleic acid synthesis • Adenosine triphosphate (ATP) and guanine triphosphate (GTP) • Large amount of energy involved in adding/removing terminal phosphate group Triphosphates Phosphodiester Bonds Phosphodiester bonds: • Nucleotides are linked by phosphodiester bonds between phosphate group at C-5 position and OH group on C-3 position © 2015 PEARSON EDUCATION, INC. © 2015 PEARSON EDUCATION, INC. Structure of DNA: Key to Understanding its Function Watson and Crick, 1953 ◦ Proposed structure of DNA as a double helix Base composition analysis (Chargaff) and X-ray diffraction provided crucial data to Watson and Crick © 2015 PEARSON EDUCATION, INC. Base composition analysis Chargaff (1949–1953) ◦ Proposed base composition ◦ Amount of A is proportional to T ◦ Amount of C is proportional to G ◦ Percentage of C + G does not equal percentage of A + T © 2015 PEARSON EDUCATION, INC. © 2015 PEARSON EDUCATION, INC. X-Ray Diffraction X-ray diffraction ◦ Studies by Rosalind Franklin (1950–1953) showed DNA had a 3.4-angstrom periodicity, characteristic of helical structure © 2015 PEARSON EDUCATION, INC. X-Ray Diffraction Watson & Crick saw the crossshaped pattern of spots in the Xray photograph and knew DNA had to be a double helix From data on the symmetry of DNA crystals, Crick, an expert in crystal structure, realized that DNA’s two chains had to run in opposite directions © 2015 PEARSON EDUCATION, INC. Structure of DNA Watson and Crick model (1953) Proposed DNA as: ◦ Double helix ◦ Two anti-parallel strands connected by base pairing ◦ Stacked nitrogenous bases © 2015 PEARSON EDUCATION, INC. The Double Helix © 2015 PEARSON EDUCATION, INC. © 2015 PEARSON EDUCATION, INC. Base Pairing – Hydrogen Bonds Chemical affinity produces hydrogen bonds in pair of bases ◦ A-T and G-C base pairing provides complementarity of two strands and chemical stability to the helix © 2015 PEARSON EDUCATION, INC. Hydrogen bonding: A-T: Double bond G-C: Triple bond © 2015 PEARSON EDUCATION, INC. © 2015 PEARSON EDUCATION, INC. Alternative Forms of DNA Watson-Crick DNA model of B-DNA ◦ Seen under aqueous, low-salt conditions Alternative forms of DNA ◦ Different conformations of DNA observed under different conditions of isolation © 2015 PEARSON EDUCATION, INC. Alternative Forms of DNA Under different conditions of isolation, different conformations of DNA are seen: ◦ ◦ ◦ ◦ ◦ ◦ ◦ A-DNA – 11 bp per turn, right-handed double helix B-DNA – 10 bp per turn, right-handed double helix C-DNA – 11 bp per turn, right-handed double helix D-DNA - lacks guanine, right-handed double helix E-DNA - lacks guanine, right-handed double helix P-DNA, , right-handed double helix Z-DNA - 12 bp per turn, left-handed double helix © 2015 PEARSON EDUCATION, INC. Alternative Forms of DNA A-DNA ◦ More compact than B-DNA ◦ Forms under high-salt or dehydration conditions C-DNA, D-DNA, E-DNA, and P-DNA ◦ Right-handed forms of DNA ◦ Less compact than B-DNA © 2015 PEARSON EDUCATION, INC. Structure of RNA RNA ◦ Sugar ribose replaces deoxyribose of DNA ◦ Nitrogenous base uracil replaces thymine of DNA ◦ Most are singlestranded (ss) ◦ Exception: Animal viruses have doublestranded helices © 2015 PEARSON EDUCATION, INC. Three Classes of RNAs Three classes of cellular RNAs (function during gene expression) • Messenger RNA (mRNA) • Ribosomal RNA (rRNA) • Transfer RNA (tRNA) Originate as complementary copies of one of two DNA strands during transcription Three Major Classes of RNAs rRNAs: Ribosomal RNAs • Structural components of ribosomes for protein synthesis mRNAs: Messenger RNAs • Template for protein synthesis • Carry genetic information from gene to ribosome tRNAs: Transfer RNAs • Carry amino acids for protein synthesis Unique RNAs in Eukaryotes Unique RNAs Telomerase RNA and RNA primers • Involved in DNA replication at chromosome ends snRNA: Small nuclear RNA • Process mRNAs Antisense RNA, microRNA, siRNA • Involved in gene regulation Analytical Techniques Analytical techniques useful during DNA and RNA investigations: • Denaturation and renaturation of nucleic acids - PCR • Molecular hybridization • FISH: Fluorescent in situ hybridization • Electrophoresis of nucleic acids Denaturation and Renaturation of Nucleic Acids DNA denatures due to heat or stress: • Denaturation used to determine melting temperature (Tm) • Property is used in Polymerase Chain Reaction (PCR) Molecular Hybridization Molecular hybridization ◦ Denaturation and renaturation of nucleic acids are the basis for molecular hybridization techniques, such as fluorescence in situ hybridization (FISH) © 2015 PEARSON EDUCATION, INC. Electrophoresis Nucleic acid electrophoresis • Separates DNA and RNA fragments by size • Smaller fragments migrate through gel at faster rate than large fragments Agarose gel • Porous matrix restricts migration of larger molecules more than it restricts smaller ones Agarose gel electrophoresis DNA Replication CHAPTER 11 Lecture Presentation by Dr. Cindy Malone, California State University Northridge DNA Replication DNA is copied during S phase before cell division • Each daughter cell receives a complete set • Two new strands of DNA must be identical to the original strand DNA is a template Arrangement and nature of nitrogenous bases allow DNA strands to serve as templates Complementarity of DNA strands allows each strand to serve as template for synthesis of the other Three Modes of Replication Three potential modes of DNA replication: 1. Conservative Two newly synthesized strands come together – original helix is conserved 2. Semiconservative Each replicated DNA molecule consists of one “old” and one new strand 3. Dispersive Parental strands are dispersed into two new double helices Meselson-Stahl Meselson and Stahl (1958): • 15N-labeled E. coli grown in medium containing 14N • Each new DNA molecule consists of one old and one newly synthesized strand • Provided strong evidence that DNA replication is semiconservative in prokaryotes Meselson-Stahl Experiment Meselson-Stahl Experiment Origin of Replication (ORI) DNA replication: • In prokaryotes, DNA replication begins at the ORI (origin of replication) • At site of replication, helix is unwound, creating replication fork • Replication is bidirectional; therefore, there are two replication forks • Replicon: Length of DNA replicated Bacterial Replication Bacteria have only one ORI: • Single circular DNA • DNA synthesis originates at OriC • E. coli replicon consists of entire genome (4.6 million base pairs) Transmission electron micrograph of human DNA from a HeLa cell, illustrating a replication fork characteristic of active DNA replication. DNA Synthesis in Bacteria Bacteria have five DNA polymerases (DNA Pol): • DNA polymerase I • DNA polymerase II • DNA polymerase III • DNA polymerase IV • DNA polymerase V DNA Polymerase I DNA polymerase I • Isolated enzyme from E. coli • Enzyme directs DNA synthesis • Requires DNA template and all four deoxyribonucleoside triphosphates (dNTPs) • Enzyme consists of polypeptide with 928 amino acids Chain Elongation Chain elongation by DNA polymerase I • Occurs in 5 to 3 direction by adding one nucleotide at a time to 3 end • Nucleotide added, two terminal phosphates cleaved off, providing newly exposed 3-OH • 3-OH can participate in addition of another nucleotide as DNA synthesis proceeds Chain Elongation Chain elongation by DNA polymerase I Chain Elongation DNA Repair DNA polymerases I, II, IV, and V • Involved in various aspects of DNA repair • Repair DNA damaged by external forces such as UV light DNA Pol III Holoenzyme DNA polymerase III: • Holoenzyme contains core enzyme complexes made up of subunits • Subunits each have separate functions •  – 5–3 polymerization •  – 3–5 exonuclease •  – Core assembly DNA Replication Issues Seven key issues must be resolved during DNA replication: • Unwinding of helix • Reduce increased coiling generated during unwinding • Synthesis of primer for initiation • Discontinuous synthesis of second strand • Removal of the RNA primers • Joining of gap-filling DNA to adjacent strand • Proofreading DnaA – Unwinding the Helix DnaA • Initiator protein encoded by dnaA gene • Binds to ORI causing conformation change • Causes helix to destabilize and open up • Exposes ssDNA DNA Helicase DNA helicase: • Assembles around exposed ssDNA • Recruits DNA polymerase to bind replication fork and initiate replication • Helicases require energy supplied by hydrolysis of ATP – denatures hydrogen bonds and stabilizes double helix Single-stranded binding proteins (SSBPs) Single-stranded binding proteins (SSBPs) • Stabilize the open conformation of helix • Bind specifically to single strands of DNA Supercoiling DNA gyrase • Enzyme relieves coiled tension from unwinding of helix (DNA supercoiling) • Member of larger enzyme group: DNA topoisomerases • Makes single- or double-stranded cuts • Driven by energy released during ATP hydrolysis RNA Polymerase: Primase Primase: RNA polymerase • Recruited to replication fork by helicase • Synthesizes RNA primer • Provides free 3-OH required by DNA polymerase for elongation RNA Priming DNA polymerase I • Removes primer and replaces it with DNA RNA priming • Universal phenomenon • Found in bacteria, viruses, and eukaryotic organisms Polymerase Chain Reaction Polymerase chain reaction (PCR) is a powerful technique for copying DNA: • Copies specific DNA sequence via in vitro reactions • Can amplify target DNA sequences present in very small quantities Continuous and Discontinuous DNA Synthesis Two strands of double helix are antiparallel: 5–3 and 3–5 • DNA polymerase ONLY synthesizes 5–3 Continuous DNA synthesis Leading strand Discontinuous DNA synthesis Lagging strand Okazaki Fragments Lagging strand synthesized as Okazaki fragments, each with RNA primer DNA Ligase DNA polymerase I: - Removes primers on lagging strand DNA ligase: - Catalyzes formation phosphodiester bonds between Okazaki fragments - Seals nicks and joins fragments Concurrent Synthesis: Leading & Lagging Strand Both DNA strands synthesized concurrently • Concurrent DNA synthesis achieved on both strands at single replication fork • Lagging strand is looped • Inverts physical but not biochemical direction Proofreading Proofreading and error correction: • Integral part of DNA replication • DNA polymerase not always perfect E. coli enzyme has an error rate of 1 in every 1,000,000 nucleotides. • Enzyme “proofreads” and correct the new strand DNA polymerase exonuclease activity of 3–5 allows for excise of nucleotides • End result is 1 error per 10,000,000,000 nucleotides 1 error every 3 cells Summarizing It All… Enzymes and proteins are essential to DNA synthesis • DNA polymerase • SSBPs: single-stranded binding proteins • DNA gyrase • DNA helicase • RNA primers • DNA ligase Computer Animation of DNA Replication https://www.youtube.com/watch?v=6j8CV3droDw Drew Barry, Walter & Eliza Hall Institute, Melbourne, Australia Eukaryotic DNA Replication Eukaryotic and bacterial DNA replication shares many features • Double-stranded DNA unwound at ORI • Replication forks formed • Bidirectional synthesis creates leading and lagging strands • Eukaryotic polymerases require four deoxyribonucleoside triphosphates, template, and primer Eukaryotic – More Complex Eukaryotic DNA replication is more complex • More DNA than prokaryotic cells • Linear chromosomes • DNA complexed with nucleosomes An electron micrograph of a eukaryotic replicating fork demonstrating the presence of histone protein-containing nucleosomes on both branches. Eukaryotes – Multiple ORIs Eukaryotic replication: Multiple ORIs • Eukaryotic chromosomes contain multiple ORIs • Facilitates rapid synthesis of large quantity of DNA Multiple origins of replication ... Purchase answer to see full attachment