OCR General Biology 2 Past Paper PDF

GENERAL BIOLOGY 2 A1: LET’S RECALL! WEEK 1: Lesson: Central Dogma of Molecular Biology A. DNA, RNA, Proteins B. Replication, Transcription & Translation MELC: Illustrate the molecular structure of DNA, RNA, and proteins. (STEM_BIO11...

GENERAL BIOLOGY 2 A1: LET’S RECALL! WEEK 1: Lesson: Central Dogma of Molecular Biology A. DNA, RNA, Proteins B. Replication, Transcription & Translation MELC: Illustrate the molecular structure of DNA, RNA, and proteins. (STEM_BIO11/12-IIIa-b-4).  OBJECTIVES 1. Differentiate DNA and RNA based on its structure and role in organisms; 2. Describe the types of protein structures; 3. Explain the process of replication, transcription, and translation; and 4. Apply the concept of central dogma in the continuity of life.  The DNA primary genetic storage of genetic material in all living organisms information The Role of DNA Molecules capacity to be replicated and provide avenues for inherited during mutation to enhance reproduction of cell genetic diversity The DNA Structure The monomer of nucleic acid is a nucleotide. The 5-C Sugar in the DNA is Deoxyribose. The phosphate consists of phosphorus that bonded with oxygen.  The DNA Structure PYRIMIDINE PURINE Single-ringed Double-ringed Thymine Cytosine Adenine Guanine The families of nitrogenous bases are Pyrimidine and Purine. In RNA, Thymine is replaced by Uracil. The DNA Structure Covalent bond between Nitrogenous base & sugar. glycosidic bond  The DNA Structure Covalent bond between Phosphate and Sugar. phosphodiester bond  Base Pairing The helix structure of DNA is composed of nitrogenous bases that are complementary to each other. The hydrogen bonds between bases are weak, but enough to stabilize its structure.  Base Pairing The two strands of DNA are said to be antiparallel. One strand runs in 5′→3′ direction while the other runs in 3′→5′ direction. For example, if a given strand is 5’-AGTGTGGCA-3’ the complementary strand is 3’-TCACACCGT-5’ People behind the Discovery of the DNA Structure  The RNA Structure RNA, a nucleic acid, is known to 1. be single-stranded, 2. have the base uracil instead of thymine in DNA, 3. have ribose instead of deoxyribose in DNA, and 4. a product of transcription of DNA Types of RNA  Other roles of RNA RNA molecules may also assume enzymatic functions: Ribozymes are a group of catalytic RNA molecules. They can able to break and form covalent bonds within a nucleic acid molecule. RNase P is a ribozyme that catalyzes tRNA synthesis.  Amino Acid Structure The carboxyl and amino groups are common to all amino acids, the R- group is the only unique feature in each amino acid.  Amino Acid Structure The peptide bonds connect amino acids. A chain of amino acids joined by peptide bonds is called polypeptide. Types of Amino Acids A2: Levels of Protein Structures Tertiary Structure  The Central Dogma Replication Transcription Translation  The Central Dogma It shows the flow of genetic information from DNA to RNA to make a functional PROTEIN.  DNA Replication - A process where the DNA duplicates itself to maintain the same genetic information in new cells.  DNA Replication This process is semiconservative in nature wherein the two strands of DNA unwind from each other, and each acts as a template for synthesis of a new, complementary strand. DNA Replication https://www.youtube.com/watch?v=TNKWgcFPHqw  Enzymes in DNA Replication These are general enzymes, whereas others are assistant enzymes.  Enzymes in DNA Replication Replication Protein Function Helicase Unwinds the DNA creating a replication fork. Topoisomerase Moves ahead of the DNA helicase at the replication fork (DNA gyrase in and relieves the tension that builds up as the DNA prokaryotic) strands are being unwound. Synthesize short ribonucleotide segments called RNA Primase primers that are complementary to the DNA strand. Synthesizes deoxynucleotide or nucleotides at the end of DNA polymerase the RNA primers and performs DNA proofreading.  Enzymes in DNA Replication Replication Protein Function Single-stranded Bind to the single-stranded DNA to prevent them from binding proteins reforming hydrogen bonds. Exonuclease Catalyzes the removal of the RNA primers. Seals the nicks between the Okazaki fragments DNA ligase (fragments of new DNA strands) through phosphodiester bond formation.  DNA Replication Leading strand - Continuous (RNA Primers and New bases) Lagging strand - Discontinuous (Okazaki Fragments) BIDIRECTIONAL DNA Replication  E1: Let’s Try This: Add the complementary base pairs on the leading strand of DNA. 5’-TACCTGTAGCTCATCAGG-3’ 3’-ATGGACATCGAGTAGTCC-5’  E1: Let’s Try This! Add the complementary base pairs on the lagging strand of DNA. 3’-AGCTAATGCGTATGCATG-5’ 5’-TCGATTACGCATACGTAC-3’  Gene Expression A process where the genetic A process wherein the information information is transcribed into encoded within the mRNA is used for an mRNA molecule. protein synthesis.  Types of RNA Carries amino acids to the Structural and functional ribosomes for protein components of ribosomes synthesis Serves as the transcript for the amino acid sequence GENE TRANSLATION AMINO ACID TRANSCRIPT MACHINERY CONVEYORS  Transcription https://www.youtube.com/watch?v=_Zyb8bpGMR0  Transcription RNA polymerase binds to a specific region known as the promoter, through the sigma factor. Transcription RNA polymerase unwinds the DNA. It will use one strand as a template wherein RNA complementary bases will pair. The sigma factor is released once RNA synthesis begins.  Transcription RNA Polymerase transcribes the coding sequence in a 5’ to 3’ direction. The Cytosine pairs with Guanine but the Adenine will pair up with Uracil.  Transcription The termination process involves the dissociation of RNA polymerase from the synthesized mRNA. Non-coding introns are spliced from the strands leading to the maturation of the mRNA.  Transcription For example: Replication: 5’- AGAGTCTC-3’