Lesson 5: Transcription & Translation LT: Be able to explain the process of DNA transcription.

THE BIG PICTURE!!! Transcription Translation DNA RNA protein

Notes from reading pgs. 425-426 RNA = ribonucleic acid Made of nucleotides Sugar in nucleotides is ribose RNA uses uracil instead of thymine RNA is single-stranded and not double stranded mRNA = messenger RNA Carries the message of DNA from the nucleus to the cytoplasm to be made into a protein Transcription: the process by which DNA is copied into a complementary RNA molecule

Process & Procedure: Modeling Transcription Create a double stranded DNA molecule that is 15 bases long Our Code: RED = adenine (A) BLUE = thymine (T) YELLOW = cytosine (C) GREEN = guanine (G) BLACK = uracil (U) Work through step #3a-f

Stop & Think How is DNA transcription like DNA replication? How are the 2 processes different? In this activity, you transcribed 2 different DNA strands. Each one was only 15 nucleotides long. That seems pretty short. a. How many different arrangements of nucleotides are possible in a strand of DNA that is 15 nucleotides long? Same: complementary bases, DNA acts as a template Different: transcription uses uracil, replication uses thymine 4^15 = 1,073,741,824 possibilities

How would the number in 2a compare with the number of different arrangements of nucleotides possible in a real strand of DNA? 4^80,000,000 is a ridiculously HUGE number

Notes on DNA transcription

Do the cells in your eye and your tongue have the same functions? http://www.rsc.org/images/tongue-250_tcm18-43214.jpg http://div.dyndns.org/EK/eyeball.jpg Do the cells in your eye and your tongue have the same proteins?

Do the cells in your eye and your tongue have the same DNA? http://www.rsc.org/images/tongue-250_tcm18-43214.jpg http://div.dyndns.org/EK/eyeball.jpg

What have we learned? Proteins determine most characteristics of a cell and organism Information stored in DNA determines which proteins can be made by a cell The environment influences which proteins are made by a cell

Where is protein made in a cell?

DNA does not leave the nucleus of eukaryotic cells DNA does not leave the nucleus of eukaryotic cells... but proteins are made outside of the nucleus by ribosomes Elodea leaf cell human cheek cell mitochondria chloroplasts vacuole nucleus (DNA here) (DNA here)

DNA does not leave the nucleus of eukaryotic cells DNA does not leave the nucleus of eukaryotic cells... but proteins are made outside of the nucleus by ribosomes ribosomes (proteins made here) (proteins made here) nucleus (DNA here) (DNA here)

DNA and ribosomes are at different locations in a prokaryoic cell. E. coli bacteria cell ribosomes (proteins made here) DNA

Information flow from DNA to trait Observed trait DNA protein Made by ribosomes outside of nucleus Stored in nucleus So how does DNA get turned into a protein if it can’t leave the nucleus???

messenger RNA mRNA transfers information from the DNA in the nucleus to the ribosomes. mRNA is made in the nucleus and then travels to the cytoplasm through nuclear pores Ribosomes build proteins according to the mRNA information received.

Information flow from DNA to trait messenger RNA Observed trait DNA protein Made by ribosomes outside of nucleus Stored in nucleus

DNA information  mRNA information messenger RNA DNA Transcription is the process used to convert DNA information into mRNA information. Note: DNA does not become RNA; the information in DNA is copied as RNA

RNA is different than DNA Single strand of nucleotides Contains uracil (U) instead of thymine (T) Made of the 5-Carbon sugar Ribose instead of deoxyribose (DNA) http://www.makingthemodernworld.org.uk/learning_modules/biology/01.TU.03/illustrations/01.IL.09.gif

Difference between DNA and RNA 5-Carbon Sugar: deoxyribose 5-Carbon sugar: Ribose A,T,C,G A,U,C,G Double stranded Single stranded

Different Sugars DNA RNA Can you spot the difference? http://www.layevangelism.com/bastxbk/images/deoxyribose.jpg RNA Can you spot the difference?

Different Bases Can you spot the difference? http://images.google.com/imgres?imgurl=http://www.starsandseas.com/SAS_Images/SAS_chem_images/thymine.jpg&imgrefurl=http://www.starsandseas.com/SAS%2520OrgChem/SASNucleic.htm&h=202&w=180&sz=5&hl=en&start=5&tbnid=t1HbUPbbgV4YhM:&tbnh=105&tbnw=94&prev=/images%3Fq%3Dthymine%26svnum%3D10%26hl%3Den%26rlz%3D1T4GFRC_enUS204US204 Can you spot the difference?

DNA- double stranded RNA- single stranded

RNA and DNA Nucleotides Remember – DNA has A-T or T-A; and G-C or C-G RNA has uracil instead of Thymine and the bases are not in pairs DNA

DNA (double stranded original, protected in nucleus) RNA IS COPIED FROM DNA DNA (double stranded original, protected in nucleus) COPIED RNA (single strand - mobile)

mRNA: the messenger RNA is how the body gets information from the nucleus (DNA) to the place where protein gets made (ribosomes)

3 Types of RNA mRNA: messenger RNA tRNA: transfer RNA rRNA: ribosomal RNA

THE BIG PICTURE!!! Transcription Translation DNA RNA protein

http://fajerpc. magnet. fsu http://fajerpc.magnet.fsu.edu/Education/2010/Lectures/26_DNA_Transcription_files/image006.jpg

Transcription Molecule of DNA is copied into a complimentary mRNA strand http://fig.cox.miami.edu/~cmallery/150/gene/c7.17.7b.transcription.jpg

RNA Polymerase RNA polymerase is an enzyme Attaches to promoters (special sequences on the DNA) Unzips the two strands of DNA Synthesizes the mRNA strand https://publicaffairs.llnl.gov/news/news_releases/2005/images/RNA_polymerase309x283.jpg

Steps of Transcription Step 1: RNA polymerase attaches to DNA Step 2: RNA polymerase unzips DNA Step 3: RNA polymerase hooks together the nucleotides as they base-pair along the DNA template Step 4: Completed mRNA strand leaves the nucleus

Transcription http://fig.cox.miami.edu/~cmallery/150/gene/c7.17.7b.transcription.jpg

If the DNA code is this: TACGAGTTACATAAA ATGCTCAATGTATTT What is the mRNA code? Use the bottom strand as the template for mRNA UACGAGUUACAUAAA

Which proteins are made in a cell? Controlled by activator molecules Bind to enhancers (segments of DNA) “Turns on” transcription of the gene Example: Arabinose and araC protein

Information flow from DNA to trait Observed trait DNA protein Made by ribosomes outside of nucleus Stored in nucleus

Information flow from DNA to trait messenger RNA Observed trait DNA protein Made by ribosomes outside of nucleus Stored in nucleus Transcription Transcription Video

Part II: Translation LT: Be able to explain the process of translation.

THE BIG PICTURE!!! Transcription Translation DNA RNA protein

Information flow from DNA to trait Observed trait DNA protein Made by ribosomes outside of nucleus Stored in nucleus

Information flow from DNA to trait messenger RNA Observed trait DNA protein Made by ribosomes outside of nucleus Stored in nucleus Transcription

Information flow from DNA to trait messenger RNA Observed trait DNA protein Made by ribosomes outside of nucleus Stored in nucleus Translation

mRNA information  protein messenger RNA protein Translation is the process used to convert mRNA information into proteins. - also known as “protein synthesis” Note: mRNA does not become a protein, the information on mRNA is “read” and ribosomes assemble proteins from this code

Translation Ribosomes use mRNA as a guide to make proteins http://fajerpc.magnet.fsu.edu/Education/2010/Lectures/26_DNA_Transcription_files/image006.jpg Ribosomes use mRNA as a guide to make proteins

4 Components used in Translation mRNA- the message to be translated into protein. Amino acids- the building blocks that are linked together to form the protein. Ribosomes- the “machines” that carry out translation. tRNA (transfer RNA)- brings an amino acid to the mRNA and ribosome.

The message mRNA is a strand of nucleotides Ex. AUGCCGUUGCCA… Each combination of three nucleotides on the mRNA is called a codon

tRNA Transfer RNA Single strand of RNA that loops back on itself Has an Amino Acid attached at one end Amino Acids are the building blocks of proteins Has an anticodon at the other end http://www.wiley.com/legacy/college/boyer/0470003790/structure/tRNA/trna_diagram.gif

What is an anticodon? The anticodon is a set of three nucleotides on the tRNA that are complimentary to the codon on the mRNA http://www.wiley.com/legacy/college/boyer/0470003790/structure/tRNA/trna_diagram.gif

The Ribosome

Steps of Translation Step 1: mRNA binds to ribosome Step 2: tRNA anticodon attaches to the first mRNA codon Step 3: the anticodon of another tRNA binds to the next mRNA codon Step 4: A peptide bond is formed between the amino acids the tRNA molecules are carrying.

Translation

Steps of Translation cont. Step 5: After the peptide bond is formed, the first tRNA leaves. The ribosome moves down to the next codon. Step 6: This process continues until the ribosome reaches a stop codon. Step 7: The chain of peptides (protein) is released and the mRNA and ribosome come apart.

Translation http://www.medicine.uottawa.ca/Pathology/devel/images/text_figure8.gif

Remember… mRNA nucleotides are translated in groups of 3 called codons. AUGCACUGCAGUCGAUGA CODONS

Decoding the message… Each codon codes for a specific amino acid. 20 different amino acids can be used in different combinations to form a protein. For example: mRNA codon amino acid AAU asparagine CGC arginine GGG glycine

The Genetic Code http://www.cbs.dtu.dk/staff/dave/roanoke/fig13_18.jpg

Simulation! I need 6 volunteers who don’t mind holding hands.  And then one more volunteer. Translation Video

Amino Acid sequence determines the 3-D protein shape Interactions between amino acids cause folding and bending of the chain Examples: positive (+) and negative (-) parts of amino acids are attracted to each other. hydrophobic regions are attracted to each other Folding http://www.stolaf.edu/people/giannini/flashanimat/proteins/hydrophobic%20force.swf Structure levels http://www.stolaf.edu/people/giannini/flashanimat/proteins/protein structure.swf

How is the amino acid sequence determined? The mRNA Each codon is a code for one amino acid DNA sequence: T A C C G A G A T T C A mRNA sequence: A U G G C U C U A A G U amino acid sequence: Met -- Ala -- Leu -- Ser Whole Process Video

Special Codons Start codon: AUG Stop codons: UAA, UGA, UAG

Your turn: For each of the codons below, determine the amino acid it corresponds with: AUG: Methionine (Met) CCA: Proline (Pro) UUG: Leucine (Leu) GCA: Alanine (Ala) UAG: STOP!

The Activity My desk: NUCLEUS Your desk space is the CYTOPLASM In your group of 3, decide who will be: mRNA: transcribes the DNA template and delivers the message to the cytoplasm rRNA: makes up the ribosome and interprets the message in codons tRNA: brings correct amino acids to the ribosome using anticodons

Steps: 1: mRNA comes to desk to transcribe the message (can’t just copy the DNA sequence) 2: Take message back to cytoplasm & ribosome. 3: rRNA: breaks message into codons 4: tRNA: use the codons to find the amino acids – look for the ANTICODONS that are complementary to the codons. 5: Bring back the card with the correct anticodon. 6: Record the word that is on the back of the card in your notebook. 7: Make sure to take the card back to where you got it so other teams can use it! 8: Continue finding the correct anticodon cards and record the sequence of words in order. Check your end result with me.

Share sentences in order

Repeat steps, but change roles for round 2. 1: mRNA comes to desk to transcribe the message (can’t just copy the DNA sequence) 2: Take message back to cytoplasm & ribosome. 3: rRNA: breaks message into codons 4: tRNA: use the codons to find the amino acids – look for the ANTICODONS that are complementary to the codons. 5: Bring back the card with the correct anticodon. 6: Record the word that is on the back of the card in your notebook. 7: Make sure to take the card back to where you got it so other teams can use it! 8: Continue finding the correct anticodon cards and record the sequence of words in order. Check your end result with me.

Share sentences in order

Repeat steps, but exchange roles for round 3. 1: mRNA comes to desk to transcribe the message (can’t just copy the DNA sequence) 2: Take message back to cytoplasm & ribosome. 3: rRNA: breaks message into codons 4: tRNA: use the codons to find the amino acids – look for the ANTICODONS that are complementary to the codons. 5: Bring back the card with the correct anticodon. 6: Record the word that is on the back of the card in your notebook. 7: Make sure to take the card back to where you got it so other teams can use it! 8: Continue finding the correct anticodon cards and record the sequence of words in order. Check your end result with me.

Share sentences.

Follow-up Questions: What do the following analogies from the simulation represent in a real cell? Words Sentence What may have happened in round 3 of the simulation to give us the outcomes we got? Do you think this happens in nature? Amino Acids Proteins (polypeptides)