The Central Dogma of DNA

The Central Dogma of DNA

• The process of making proteins in a cell!

DNADNA RNARNA ProteinProtein

Done in 2 steps: Transcription and Done in 2 steps: Transcription and TranslationTranslation

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)

DNA RNA

The sugar is Deoxyribose

The sugar is Ribose

Double stranded Single stranded

Bases = T, A, C, G

Bases = U, A, C, G

DNA never leaves the nucleus

RNA can leave the nucleus

The Central Dogma of DNAPart 1 - Transcription

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 So you write it down, but when you get

back home, you realize that the recipe is back home, you realize that the recipe is in Chinesein Chinese

What do you do?What do you do?

Have someone translate it into English!

- 3 Tomatoes - 3 Tomatoes - 4 Tbsp Pepper- 4 Tbsp Pepper- 5 cups of salt- 5 cups of salt

Now you can make any Now you can make any Cheeto HOT!Cheeto HOT!

What steps did we just do...

1. Write the recipe down1. Write the recipe down

2. Translate the recipe2. Translate the recipe

This is exactly what happens when DNA is used This is exactly what happens when DNA is used to make proteinsto 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!

DNADNA RNARNA ProteinProteinTranscriptiTranscripti

ononTranslationTranslation

2 Steps:

1. Transcription: Making a copy of the desired gene using mRNA

2. Translation: mRNA is used to make the protein with the help of ribosomes

Central Dogma Song

DNADNA RNARNAStep 1Step 1

TranscriptionTranscription

Transcription RNA reads and copies the DNA codeThis occurs in the NUCLEUSof the cellRules 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 Understanding Your turn…

1. DNA: GGATCCATGTTC mRNA:

2. DNA: TATGCGAAACAT mRNA:

Steps of Transcription:

1. DNA untwists and opens2. DNA is copied into mRNA with the help of

RNA Polymerase3. 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 translationB central dogmaC transcriptionD replication

Exit Slip #2

RNARNAProteiProtei

nn

Step 2Step 2

TranslationTranslationDNADNA

TranscriptionTranscription

Translation/CodonsTranslation: The process of converting RNA into PROTEINTHREE nucleotides (bases) on an mRNA sequence is called a codonOne codon codes for one amino acid– Ex: mRNA: AUG-CUU-CUC

3 codons 3 amino acids

AUCCUCCGCAUCCUCCGC

CODONCODON

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

proteinb. Three bases in the RNA code for one amino acid in the

protein

Translation video

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

These are These are all amino all amino

acids!acids!

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

http://www.stolaf.edu/people/giannini/flashanimat/molgenetics/translation.swf

EXIT SLIP #1

1. What is the amino acid sequence for the DNA sequence :

ATGCCCGTTATC

A pro-leu-met-stopB tyr-gly-gln-stopC met-pro-tyr-glyD not enough information

Exit Slip #2

2. In the DNA sequence below, how many amino acids are coded for?

5’ ATGGGCTACGTTATA 3’

A 3B 2C 5D 0

WEDNESDAY: Textbook Questions Directions: Use Chapter 8.4 (pages 239-242) to

answer the following questions.

THURSDAY: Multiple-Choice QuestionsDirections: 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) _______________________________________________________________

Central Dogma Race!

Complementary

mRNA Amino Acids (2)

AAA TTT ATG AAA UAC Lys-Tyr

GTT GCG CAA CGC GUU Arg-Val

ATC TAG GCG AUC CGC Lle-Arg

AGC CTT TCG GAA AGC CUU Ser-Leu

TAC ATG ATG TAC UAC AUG Tyr-Met

The Code

12.Each codon codes for a specific amino acid

– Ex) CUU = leucine

13.There are only 20 different amino acids used to make millions of different proteins

14. It’s all about the sequence (order) of amino acids!

CUUCUACGCCUUCUACGC

The Final Product: Protein19.Once all the amino acids are linked

together, a protein is formed20.Protein = many amino acids = polypeptide21.21.Why do we need proteins?Why do we need proteins?

A) Structure: Fingernails, Hair, CellsB) ENZYMES! - to speed up chemical reactions

Guided Practice

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 _______________________________________5‘ A U G A A A G U C C C A G U G U G A 3’ 5‘ A U G A A A G U C C C A G U G U G A 3’

We are going to Transcribe and We are going to Transcribe and Translate DNA into mRNA into Amino Translate DNA into mRNA into Amino AcidsAcids

RNA PolymeraseRNA Polymerasetranscribetranscribe

Guided Practice ContinuedStep 2) Act as a ______________, the organelle that ________________ mRNA into amino acids in the __________________ of the cell.

5’ A U G A A A G U C C C A G U G U G A 3’ 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: Break it down into Codons: UAG, AAA, GUC, CCA, GUG, UAG, AAA, GUC, CCA, GUG, UGAUGA

Now use the Codon Table to translate the amino Now use the Codon Table to translate the amino acidsacids Your amino acids are:Your amino acids are:

____________ (____________ (always STARTalways START))____________ ____________ ____________________________________________________________________________________ (____________ (need an endneed an end))

ribosomeribosometranslatetranslatecytoplasmcytoplasm

MethionineMethionineLysineLysineValineValineProlineProlineValineValinestop codonstop codon