DNA Structure, Replication, Gene Expression and Mutation

**DNA structure, replication, gene expression; mutation** **Chapter 10** **3w** **A study guide and overview of what we have done in our lessons:** **The main functions of DNA is replication and gene expression (protein synthesis)** 1. **DNA structure -** Use your class notes; read in the te...

**DNA structure, replication, gene expression; mutation** **Chapter 10** **3w** **A study guide and overview of what we have done in our lessons:** **The main functions of DNA is replication and gene expression (protein synthesis)** 1. **DNA structure -** Use your class notes; read in the text book; watch the 2 videos; do the 2 worksheets in the DNA structure folder **Intro to DNA structure: ch 10 pages 219 -- 225; 230 -- 233 (green represents the green text book; blue the blue text book)** **Begin with an overview of the experiments that showed that DNA is the genetic material: pages 219, 220, 221 and power point presentations** - Key words - **Nucleic acid** - DNA and RNA - **Macromolecule** - a polymer made up of monomers or building blocks - The **monomer** or building blocks of DNA are called **Nucleotides** - **Nucleotides** are made up of 3 parts- **phosphate group; deoxyribose sugar; nitrogenous base** - **There are 4 nitrogenous bases -** Adenine (A); Thymine (T); Guanine (G); Cytosine (C) - A DNA strand looks like a ladder: - the **phosphate - sugar backbone makes up the sides of the ladder** - **the nitrogenous bases make up the rungs of the ladder** - **RNA** has Uracil (U) instead of Thymine (T); RNA is single stranded; RNA has a ribose sugar - **Base pairing** of nitrogenous bases - T; A; C; G; (U replaces T in RNA) - **Purines/pyramidines** - **hydrogen bonds**. T-A have 2 hydrogen bonds; C- G have 3 hydrogen bonds. Why? How? - **the DNA molecule is anti-parallel** - **Identify the 3\' 5\' sides of each of the 2 the DNA strands** - Count carbon atoms on the Deoxytribose sugar - **New DNA nucleotides are only added to the 3\'side of a DNA molecule** **This has consequences for DNA replication!!!** Videos Crash course https://www.youtube.com/watch?v=8kK2zwjRV0M&t=56s Bozeman science: 2. **DNA replication: Text book pages -- 226; 227, 234- 235 worksheet in the teams folder, power point, videos** **Watch the videos below and think about the problems that 3' -- 5' bring to DNA replication** **Video 1: ** **Video 2: [DNA replication - 3D](https://www.youtube.com/watch?v=TNKWgcFPHqw)** Questions: 1. What is the purpose of DNA replication? 2. What is the name of the accepted model for DNA replication? 3. Briefly summarise the steps involved in DNA replication - explain how replication occurs on the **leading strand** and then the **lagging strand**, making sure to explain the role of Helicase; DNA polymerase; Ligase, RNA primers; Okazaki fragments **3. From Gene to Protein -- Ch 10 pages 228 -- 236; 238 - 244** **Use the following to help you study: Your notes; text book; work sheets and study guides; power point presentations; videos** **Fron DNA to Protein 3D: [From DNA to protein - 3D](https://www.youtube.com/watch?v=gG7uCskUOrA)** **Nucleus** contains DNA - DNA consists of chromosomes - chromosomes contain genes in specific positions on the chromosome - humans have 23 pairs of chromosomes - the nucleus controls all cell activities - **a gene contains the code to make a protein** **What is a protein?** see slide 1 - 11 on **powerpoint number 1** - **amino acids** = building blocks or monomers - 20 amino acids - 9 are essential, 11 are non - essential - We need to eat proteins to obtain all of the amino acids - A protein is made up of many amino acids in a **specific sequence** - the amino acids are joined together by **peptide bonds** to make a polypeptide chain - **the specific sequence of amino acids** in a protein, **determines which protein it is and what function it has.** - Proteins have **specific shapes** that are determined by the **amino acid sequence** - The **shape** of the finished protein determines its **function** - Proteins have **4 possible levels of folding** -- primary; secondary; tertiary; quaternary **DNA has 2 main functions -** 1. to reproduce itself (replication) **2. it contains the information that controls all cell activities - it contains the code for making a protein´´´0** To begin, watch the video which goes through the 2 main processes of Protein synthesis - **Transcription and Translation**. Video: from DNA to Protein 3d: - Make sure that you understand the following: what is RNA? What are the differences between RNA and DNA? **Transcription:** - where does this process occur? - **Explain how mRNA carries the code of DNA**. What is a **codon**? What is the Genetic code? - Be able to explain in detail how **mRNA** is synthesised (made), using the template strand of DNA and RNA polymerase. (initiation (start) codons ; mRNA polymerase; termination (stop codons) powerpoint; mRNA is processed and spliced before it leaves the nucleus powerpoint; **Translation** - - Where does this occur? **Explain how the code contained in mRNA is translated into a specific sequence of amino acids**. Use the following words: mRNA, codon: ribosome; initiation of polypeptide synthesis; tRNA; anti codon, base pairing, amino acid, peptide bonds, elongation of the polypeptide chain; termination. Using the diagram on page 243 could be useful The following video: protein Synthesis translatiuon is good: [Protein Synthesis A nimation Video](https://www.youtube.com/watch?v=Ikq9AcBcohA) - You need to be able to use the Dictionary of the Genetic Code and be able to translate a sequence of codons into a polypeptide chain. See the genetic code activity (and answers) in the folder 4. **Gene or Point Mutation**: **page 237** Use the following resources: mutation power point in the protein synthesis folder; mutation activity in same folder; Biozone worksheet - mutation - - What is a mutation? - What causes mutations? (see biozone worksheet) - What is a **gene (or point) mutation**? - Explain **nucleotide substitution** mutation. What possible effects does this kind of mutation have on the resulting polypeptide? (silent mutation; missense mutation; nonsense mutation) Explain **nucleotide insertion/deletion**. What are the possible effects of these mutations on the polypeptide chain -- frame shift Examples of mutations: Sickle cell anaemia