The Central Dogma Biology I

Story of a castle Once upon a time, there were directions to build a beautiful castle. The only problem was, these directions were locked in a library and couldn’t get out. One day, a person started to make copies of the directions. The copies left the library to be in the world outside of the library, otherwise known as the kingdom. The copies of the directions to build the castle couldn’t build the castle themselves, they needed workers to read their directions and build the castle. The workers arrived to build the castle. The workers had three jobs; they brought supplies to the castle, read the castle-building directions and put the supplies together to build different parts of the castle. Each group of workers got a different part of the directions so that each could build a different part of the castle. When the workers were finished, they had a beautiful castle before them and were happy that they had done such a good job.

Story of transcription & Translation DNA are the directions to build our bodies. The only problem is, DNA is locked inside the nucleus of a cell and can’t get out. To solve this problem, copies of the DNA are made in a form called mRNA. The process of making mRNA from DNA is called transcription. After transcription, the mRNA copies leave the nucleus to be in the part of the cell outside the nucleus, otherwise known as the cytoplasm. mRNA can’t build a cell by itself; it needs workers to read the information coded on it and turn that information into proteins that will make up the cell. The workers that build a cell are called tRNA. tRNA molecules have three jobs; they bring amino acids to the mRNA, they read the mRNA code and use this code to build amino acid chains. Each group of tRNA molecules get a different piece of mRNA which contains different directions, so that each can build a different kind of protein. The process of turning mRNA into amino acid chains is called translation. When all of the tRNA molecules are finished, a cell has been created.

Quick Review DNA vs. RNA DNA Replication DNA: deoxyribose, double helix, thymine (A-T) RNA: ribose, single helix, uracil (no thymine, A-U instead of A-T) DNA Replication Parent: GTA ACC GTC TTA CGG ATT CTC New: CAT TGG CAG AAT GCC TAA GAG

Quick Review: Proteins are essential building blocks of cells (1/4 of the macromolecules) Made of amino acids are the enzymes that help the chemical reactions necessary for life to take place are our hormones and other regulatory chemicals make our bones, skin, hair, teeth, nails, muscles, etc.

How do DNA and genes relate to proteins? DNA provides the genes, or genetic code, for protein synthesis Genes are expressed because DNA codes for RNA which then codes for ALL of our proteins

Central Dogma of Biology DNA -> RNA -> Protein Synthesis Transcription: Process of DNA serving as a template for RNA synthesis Translation: Process of RNA serving as a template for protein synthesis AMAZING video!

Background: 3 Types of RNA mRNA: Messenger RNA 1st RNA’s made DIRECTLY from DNA template Travel from nucleus to ribosome rRNA: Ribosomal RNA Helps form ribosomes in cytoplasm tRNA: Transfer RNA Brings amino acids from cytoplasm to ribosome so proteins can be made

Step 1: Transcription INSIDE of the nucleus DNA is used to make mRNA DNA is unzipped then RNA polymerase makes an mRNA strand from the DNA template New mRNA strand then leaves the nucleus and travels into the cytoplasm DNA is ALWAYS left protected in the nucleus

Step 1: Transcription (p. 337) DNA: 5’ AAA TTT GGG CCC ATC GCA 3’ mRNA: 3’ UUU AAA CCC GGG UAG CGU 5’ DNA: CTA GTT CCC TAA AAG GAG mRNA: GAU CAA GGG AUU UUC CUC DNA: TAC CGA GGT TTA ACT mRNA: AUG UGA CCA AAU UGA

Step 2: Translation The Genetic Code (p. 338) Each nucleotide sequence serves as a code for what amino acid will be added to the protein being made Nucleotides read in triplets, or codons

Step 2: Translation The Genetic Code

Step 2: Translation mRNA is now connected to the ribosome tRNA has a corresponding anti-codon and brings over the corresponding amino acid

The end result… An amino acid sequence that makes a protein GENES code for proteins/enzymes We NEED proteins to function The shape of the protein determines its function

Helpful Websites http://learn.genetics.utah.edu/content/begin/dna/transcribe/ http://www.dnatube.com/video/160/Protein-synthesis http://www.teachersdomain.org/resource/tdc02.sci.life.gen.proteinsynth/