RVHS 7. DNA Replication

River Valley High School 1 2025 JC1 H2 Biology Lecture Topic 7: DNA Replication River Valley High School 2025 JC1 H2 Biology Lecture Topic 7: The Structure of Nucleic Acids and Gene Expression – DNA Replication Name: ( ) Class: 25J____ Date: References Title Author Biology (9th edition) Campbell and Reece Biological Science 1 and 2 (3rd Edition) Taylor, Green and Stout Molecular Biology of the Cell (5th edition) Alberts, Johnson, Lewis, Raff, Roberts and Walter Principles of Genetics (3rd edition) Snustad and Simmons Molecular Cell Biology (6th edition) Lodish, Berk, Kaiser, Krieger, Scott, Bretscher, Ploegh and Matsudaira H2 Biology Syllabus 9477 (2025) Candidates should be able to use the knowledge gained in the following section(s) in new situations or to solve related problems. Related Core Topics Content Transcription and Translation Central Dogma – DNA to RNA, RNA to protein Learning Outcomes 2A: The Structure of Nucleic Acids and Gene Expression a. describe the structure and roles of DNA and RNA (tRNA, rRNA and mRNA) (knowledge of the structure and roles of mitochondrial DNA and chloroplast DNA is not required) b. describe the process of DNA replication and how the end replication problem arises Lecture Outline I. Role of DNA as the Hereditary Material II. Structure of DNA A. Building Blocks of Nucleic Acids B. Physical Structure of DNA III. Replication of DNA A. DNA Strands as Templates for Replication B. Mechanism of DNA replication C. DNA Repair and Maintenance

River Valley High School 2 2025 JC1 H2 Biology Lecture Topic 7: DNA Replication Websites URL Description http://learn.genetics.utah.edu/content/basics/ Website on the basics of genetics with videos and interactive activties https://highered.mheducation.com/sites/98340923 39/student_view0/chapter14/dna_replication.html Animations on DNA replication (Chapter 14)* Chapter quiz to help reinforce concepts *Note: you would need to use a laptop/desktop and download a chrome extension (e.g. “Flash Player for Chrome”) to view the tutorial. http://www.dnaftb.org/ Animations** and video clips for DNA-related content (under Molecules of Genetics). **Note that the animations will take some time to load. https://www.dnalc.org/resources/nobel/crick_wats on_wilkins.html Animations which illustrate how the DNA structure was decoded

River Valley High School 3 2025 JC1 H2 Biology Lecture Topic 7: DNA Replication I. Role of DNA as the Hereditary Material Introduction ⬧ Life depends on the ability of cells to store, retrieve and translate the genetic instructions required to make and maintain a living organism. ⬧ This hereditary information is passed on from a cell to its daughter cells at somatic cell division, and from one generation of an organism to the next through the organism’s reproducti ve cells. ⬧ These instructions are stored within every living cell as its genes, which are the information-containing elements that determine the characteristics of a species as a whole and of the individuals within it. Characteristic properties The hereditary material must be: ⬧ chemically stable to be able to encode information without fail. It must not change easily due to age, nutrition, or environment. ⬧ able to replicate accurately. o The molecule responsible for genetic information should act as a template for an accurate copy of itself during replication so that progeny cells share the same genetic information as the parental cell. Once this genetic material doubles in amount, it must be partitioned equally into two daughter cells. o During the formation of gametes, the genetic material is also replicated but is portioned such that each cell receives only one-half of the original amount of genetic material. Fertilisation of the egg by the sperm restores the original amount of DNA. ⬧ capable of variation. o Without variation, all organisms would look alike and would not be capable of change and adaptation – conditions necessary for the evolutionary process. Evidence that DNA is the hereditary material 1. Chromosome analysis 2. Constancy of DNA within a cell 3. Correlation between mutagens and their effects on DNA 4. Experiments on bacterial transformation (Griffith, 1928)

River Valley High School 4 2025 JC1 H2 Biology Lecture Topic 7: DNA Replication 5. Experiments to identify the transforming principle (Avery, MacLeod and McCarty, 1944) http://www.dnaftb.org/17/animation.html 6. Transduction experiments (Hershey and Chase, 1952) https://tinyurl.com/HersheyChaseExpt *Note: you would need to use a laptop/desktop and download a chrome extension (e.g. “Flash Player for Chrome”) to view the tutorial.

River Valley High School 5 2025 JC1 H2 Biology Lecture Topic 7: DNA Replication II. Structure of DNA A. Building Blocks of Nucleic Acids ⬧ Two types of nucleic acids: o Deoxyribonucleic acid (DNA) o Ribonucleic acid (RNA) ⬧ Nucleic acids are macromolecules composed of repeating subunits (monomers) called nucleotide Structure of a nucleotide ⬧ Each nucleotide is composed of: o a pentose sugar (five-carbon sugar); o a nitrogenous base; and o a phosphate group Pentose ⬧ A five-carbon sugar that occurs as a ring form. ⬧ Two types of pentose are found in nucleic acids: ribose (in RNA) and deoxyribose (in DNA). ⬧ Main difference between ribose and deoxyribose: o hydroxyl group (-OH) at carbon atom 2 in ribose is replaced by a hydrogen atom (H). Nitrogenous base ⬧ Heterocyclic ring of carbon and nitrogen atoms. ⬧ Each nucleic acid contains four different types of bases, which can be categorised into: o Purines (have a six-membered ring fused to a five-membered ring) o Pyrimidines (have one six-membered ring) Structure of a nucleotide Diagrammatic representation of a nucleotide

River Valley High School 6 2025 JC1 H2 Biology Lecture Topic 7: DNA Replication Purine Pyrimidine DNA Adenine (A) and Guanine (G) Cytosine (C) and Thymine (T) RNA Adenine (A) and Guanine (G) Cytosine (C) and Uracil (U) Formation of Nucleotide ⬧ The three components, i.e. pentose, phosphoric acid and a nitrogenous base, join to form a nucleotide via condensation reaction. o 1’ carbon of the pentose is linked via a glycosidic bond to the nitrogenous base. o 5’ carbon of pentose is linked via a phosphoester bond to the phosphate group. Formation of a nucleotide

River Valley High School 7 2025 JC1 H2 Biology Lecture Topic 7: DNA Replication ⬧ Different nucleotides are formed according to the sugars and bases they contain. (Refer to table below: Nucleotide and Nucleic Acid Nomenclature) Formation of Polynucleotide ⬧ Two nucleotides join to form a dinucleotide by condensation reaction between the phosphate group of one nucleotide and the 3’ carbon of pentose of the other nucleotide. ⬧ The two nucleotides are joined by a phosphoester bond between the phosphate group of one nucleotide and the 3’ carbon of pentose of the other nucleotide. ⬧ Addition of further nucleotides produces a polynucleotide, with a backbone consisting of alternating sugar and phosphate groups i.e. sugar-phosphate backbone. ⬧ 5’ end of a polynucleotide ends with a phosphate group attached to 5’ carbon of pentose ⬧ 3’ end of a polynucleotide ends with an OH group on 3’ carbon of pentose

River Valley High School 8 2025 JC1 H2 Biology Lecture Topic 7: DNA Replication B. Physical Structure of DNA Road to Discovery of Structure of DNA ⬧ In the early 1950s, Nobel prize winning chemist Linus Pauling worked out the -helical structure that is common to many fibrous proteins and was applying himself to the problem of DNA structure, which evidence suggested was also a fibrous molecule. ⬧ At the same time, Maur