The Central Dogma of DNA • The process of making proteins in a cell! RNA Protein DNA Done in 2 steps: Transcription and Translation
RNA • Ribonucleic Acid • RNA is a molecule that helps synthesize (make) proteins
There are 3 kinds of RNA: mRNA, tRNA, rRNA • In RNA A pairs with U (there is no thymine)
So you’ve managed to sneak into the Cheeto’s factory and have found the safe where they hide the secret recipe to make the “hotness” for the Hot Cheetos
You only have 45 seconds before the alarm sounds and the security guards find you. YOU NEED THIS RECIPE!What are you going to do?
WRITE IT DOWN! So you write it down, but when you get back home, you realize that the recipe is in Chinese What do you do?
Have someone translate it into English! - 3 Tomatoes - 4 Tbsp Pepper - 5 cups of salt Now you can make any Cheeto HOT!
What steps did we just do... 1. Write the recipe down 2. Translate the recipe This is exactly what happens when DNA is used to make proteins
Review: What is a protein? • Made of amino acids: • Polypeptide - Amino acids linked together - A protein
Labeling DNA Strands: 5’ vs 3’ • DNA strands are labeled as follows: Strand 1: 5’ ATCGTA 3’ Strand 2: __ ______ __
The Central Dogma of DNA • The process of making proteins in a cell! Transcription Translation RNA Protein DNA
2 Steps: • Transcription: Making a copy of the desired gene using mRNA • Translation: mRNA is used to make the protein with the help of ribosomes
Step 1 DNA RNA Transcription
Transcription • RNA reads and copies the DNA code • This occurs in the NUCLEUS of the cell • Rules to write the mRNA complimentary strand: • Rule: A pairs with U “Aunt-Uncle” C pairs with G “Chewing Gum” • DNA: 5’ A T C G A T 3’ • mRNA: 3’ _ _ _ _ _ _ 5’
Checking for UnderstandingYour turn… 1. DNA: GGATCCATGTTC mRNA: 2. DNA: TATGCGAAACAT mRNA:
Steps of Transcription: • DNA untwists and opens • DNA is copied into mRNA with the help of RNA Polymerase • mRNA travels out of the nucleus to the rough E.R.
What is mRNA? • mRNA = messenger RNA • The type of RNA that delivers the code from the DNA to the ribosomes!
Exit Slip #1 The central dogma of DNA states that RNA is made from DNA. This process is called: A translation B central dogma C transcription D replication
Step 2 Protein DNA RNA Transcription Translation
Translation/Codons • Translation: The process of converting RNA into PROTEIN • THREE nucleotides (bases) on an mRNA sequence is called a codon • One codon codes for one amino acid • Ex: mRNA: AUG-CUU-CUC 3 codons 3 amino acids AUCCUCCGC CODON
CFU 1. How many bases, codons, and amino acids are in the following mRNA sequence? AUG-AUG-AGG-CGG-CAA-UUU bases:________ codons:_______ amino acids:________ 2. Which statement best explains how messenger RNA (mRNA) provides a code for the formation of a protein? a. One base in the RNA codes for three amino acids in the protein b. Three bases in the RNA code for one amino acid in the protein
Translation Steps(RNA Protein) • mRNA travels out of the nucleus to Rough E.R./Ribosomes • ribosomes and tRNA link together amino acids to make a protein
Transfer RNA (tRNA) • tRNA is responsible for delivering the amino acids • tRNA has an anticodon • three bases on tRNA that match up to the codon on the mRNA sequence
Find the amino acid sequence using the given DNA sequence and Codon Box that is provided • DNA: TAC-TTT-GTG-GTC-AAA-ATT • mRNA: AUG-AAA-CAC-CAG-UUU-UAA • Protein: Met-Lus-His-Gln-Phe-Stop
EXIT SLIP #1 1. What is the amino acid sequence for the DNA sequence : ATGCCCGTTATCA pro-leu-met-stopB tyr-gly-gln-stopC met-pro-tyr-glyD not enough information
Exit Slip #2 • In the DNA sequence below, how many amino acids are coded for? 5’ ATGGGCTACGTTATA 3’ A 3 B 2 C 5 D 0
WEDNESDAY: Textbook Questions Directions: Use Chapter 8.4 (pages 239-242) to answer the following questions. THURSDAY: Multiple-Choice Questions Directions:Write five multiple-choice questions that could be used on the quiz. Make them creative and challenging. Each question should have four choices (a-d). Question #1: ______________________________________________________________________ a) _______________________________________________________________ b) _______________________________________________________________ c) _______________________________________________________________ d) _______________________________________________________________
The Code • Each codon codes for a specific amino acid • Ex) CUU = leucine • There are only 20 different amino acids used to make millions of different proteins • It’s all about the sequence (order) of amino acids! CUUCUACGC
The Final Product: Protein • Once all the amino acids are linked together, a protein is formed • Protein = many amino acids = polypeptide • Why do we need proteins? • Structure: Fingernails, Hair, Cells • ENZYMES! - to speed up chemical reactions
Guided Practice We are going to Transcribe and Translate DNA into mRNA into Amino Acids Step 1) Act as the enzyme _____ ____________ inside the nucleus and _____________ this DNA into mRNA: 3’ T A C T T T C A G G G T C A C A C T 5’ 5’ A T C A A A G T C C C A G T G T G A 3’ mRNA _______________________________________ RNA Polymerase transcribe 5‘ A U G A AA G U C CC A G U G U G A 3’
Guided Practice Continued ribosome translate Step 2) Act as a ______________, the organelle that ________________ mRNA into amino acids in the __________________ of the cell. cytoplasm 5’ A U G A A A G U C C C A G U G U G A 3’ Break it down into Codons: UAG, AAA, GUC, CCA, GUG, UGA Now use the Codon Table to translate the amino acids Your amino acids are: ____________ (always START) ____________ ____________ ____________ ____________ ____________ (need an end) Methionine Lysine Valine Proline Valine stop codon