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This review explores the intricate relationship between DNA and RNA, focusing on their structures, functions, and the processes of transcription and translation. DNA, a double helix composed of deoxyribose sugar and nucleotides, serves as the master blueprint for life, while RNA acts as a disposable copy that carries genetic information from the nucleus to ribosomes. We delve into the roles of mRNA, rRNA, and tRNA in protein synthesis, discuss codons and mutations, and highlight the critical mechanisms that ensure accurate genetic expression.
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Review of DNA • DNA is a double Helix that is a code for something • What? • Structure/Shape explains how it is replicated, but not how genes work. • Helicase and DNA Polymerase • Chargaff’s Rule • Nucleotide • 5 Carbon Sugar (Deoxyribose), Phosphate and Nucleic Acid (Guanine, Cytosine, Adenine, Thymine)
First Step in Decoding Messages: • Copy DNA (Deoxyribonucleic Acid) into RNA (Ribonucleic Acid) • Note: “Deoxyribo” in Deoxyribonucleic Acid is in reference to the 5-Carbon Sugar in the backbone of the molecule • Deoxyribose • So what do you think the 5-Carbon Sugar is in the backbone of Ribonucleic Acid? • Ribose
Differences (Between DNA and RNA) DNA RNA Deoxyribose Ribose Double Stranded Single Stranded Thymine Uracil
RNA is a disposable copy of DNA • 3 Types of RNA • mRNA • Messengers – they carry copies of the instructions for proteins. (From Nucleus to Ribosome) • rRNA • Ribosomal – where the proteins are assembled. • Reminder: Ribosomes are made up of protein and RNA • tRNA • Transfers each amino acid to the ribosome
How is a copy made? • Transcription • “Transcribe” or write a code • Only 1 strand is made! • RNA Polymerase • Separates DNA strands (at Hydrogen bonds) and acts as “Police” in creating the mRNA • Where does it start? • There are “start sites” called Promoters • Just like promoters for events let people know what is going on.
Introns • “Extra” parts that are cut out of the final mRNA strand. • Exons • “Good” parts that are spliced together to make the final mRNA strand • Codons • 3 (consecutive) nucleotides long • Each one specifies for one of 20 amino acids • 64 different codons
Special Codons: • StartCodon: AUG • StopCodons: UAA, UAG, UGA
Translation • “Translates” from one language to another • Creates a chain of amino acids • Known as a protein. • It is the process of translating codons (mRNA) by using anti-codons (tRNA) into the amino acids they code for (which makes proteins) • Occurs at the Ribosomes • Anti-codons are complementary to codons
Translation Can you identify the following: 1. mRNA 2. Codon 3. Anti-Codon 4. Amino Acid 5. Protein
What is the big picture? • DNA is the Master Plan • Remains safe in the nucleus • mRNA is the Blueprint • Disposable copy • rRNA is the Building site • tRNA are the builders • Workers that make the proteins (amino acid chains) • DNA makes proteins and proteins express genes!
Mutations • Changes in the letter sequence of the DNA • Chromosomal • Whole chromosome has been changed • Change in the number of chromosomes or their structure. • Gene • Single gene change (one or more letters) • Two types • Point • Frameshift
Point Mutation • One nucleotide changes – May change the Amino Acid it codes for (and it may not)
Frameshift Mutation • Typically makes the entire protein not useable. • Deletion • Removal of one or more Nucleotides • Insertion • Addition of a Nucleotide
