LT Be able to explain the process of DNA transcription THE BIG PICTURE DNA RNA protein Transcription Translation Notes from reading pgs 425426 RNA ribonucleic acid Made of nucleotides ID: 656092
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Slide1
Lesson 5: Transcription & Translation
LT: Be able to explain the process of DNA transcription.Slide2
THE BIG PICTURE!!!
DNA
RNA
protein
Transcription
TranslationSlide3
Notes from reading pgs. 425-426
RNA = ribonucleic acid
Made of nucleotides
Sugar in nucleotides is
riboseRNA uses uracil instead of thymineRNA is single-stranded and not double strandedmRNA = messenger RNACarries the message of DNA from the nucleus to the cytoplasm to be made into a proteinTranscription: the process by which DNA is copied into a complementary RNA moleculeSlide4
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-fSlide5
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 templateDifferent: transcription uses uracil, replication uses thymine4^15 = 1,073,741,824 possibilitiesSlide6
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 numberSlide7
Notes on DNA transcriptionSlide8
Do the cells in your eye and your tongue have the same functions?
Do the cells in your eye and your tongue have the same proteins?Slide9
Do the cells in your eye and your tongue have the same DNA?Slide10
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 cellSlide11
Where
is protein made in a cell?Slide12
DNA does not leave the nucleus of eukaryotic cells...
but proteins are made outside of the nucleus by
ribosomes
human cheek
cell
mitochondria
chloroplasts
nucleus
vacuole
Elodea
leaf cell
(DNA here)
(DNA here)Slide13
DNA does not leave the nucleus of eukaryotic cells... but proteins are made outside of the nucleus by
ribosomes
nucleus
(DNA here)
(DNA here)
ribosomes
(proteins made here)
(proteins made here)Slide14
DNA and
ribosomes
are at different locations in a prokaryoic cell.
E. coli
bacteria cell
DNA
(proteins made here)
ribosomesSlide15
Information flow from DNA to trait
DNA
protein
Observed trait
Stored in nucleus
Made by ribosomes outside of nucleus
So how does DNA get turned into a protein if it can’t leave the nucleus???Slide16
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 poresRibosomes build proteins according to the mRNA information received.Slide17
Information flow from DNA to trait
DNA
messenger
RNA
protein
Observed trait
Stored in nucleus
Made by ribosomes outside of nucleusSlide18
DNA information
mRNA information
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
DNA
messengerRNASlide19
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.gifSlide20
Difference between DNA and RNA
DNA
RNA
5-Carbon Sugar: deoxyribose
5-Carbon sugar:
Ribose
A,T,C,G
A,U,C,GDouble stranded
Single strandedSlide21
Different Sugars
DNA
RNA
Can you spot the difference?Slide22
Different Bases
Can you spot the difference?Slide23
DNA- double stranded
RNA- single strandedSlide24
RNA and DNA Nucleotides
DNA
RNASlide25
RNA
IS COPIED FROM
DNA
COPIED
RNA
(single strand - mobile)
DNA
(double stranded original, protected in nucleus)Slide26
mRNA: the messenger
RNA is how the body gets information from
the nucleus
(DNA) to the place where
protein gets made (ribosomes)Slide27
3 Types of RNA
mRNA: messenger RNA
tRNA: transfer RNA
rRNA: ribosomal RNASlide28
THE BIG PICTURE!!!
DNA
RNA
protein
Transcription
TranslationSlide29
http://fajerpc.magnet.fsu.edu/Education/2010/Lectures/26_DNA_Transcription_files/image006.jpgSlide30
Transcription
Molecule of DNA is copied into a complimentary mRNA strand
http://fig.cox.miami.edu/~cmallery/150/gene/c7.17.7b.transcription.jpgSlide31
RNA Polymerase
RNA polymerase is an enzyme
Attaches to
promoters
(special sequences on the DNA)Unzips the two strands of DNASynthesizes the mRNA strand
https://publicaffairs.llnl.gov/news/news_releases/2005/images/RNA_polymerase309x283.jpgSlide32
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 nucleusSlide33
Transcription
http://fig.cox.miami.edu/~cmallery/150/gene/c7.17.7b.transcription.jpgSlide34
If the DNA code is this:
U
ACGAG
UU
ACA
UAAA
TACGAGTTACATAAAATGCTCAATGTATTT
What is the mRNA code?
Use the bottom strand as the template for mRNASlide35
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 proteinSlide36Slide37Slide38
Information flow from DNA to trait
DNA
protein
Observed trait
Stored in nucleus
Made by ribosomes outside of nucleusSlide39
Information flow from DNA to trait
DNA
messenger
RNA
protein
Observed trait
Stored in nucleus
Made by ribosomes outside of nucleus
Transcription
Transcription VideoSlide40
Part II: Translation
LT: Be able to explain the process of translation.Slide41
THE BIG PICTURE!!!
DNA
RNA
protein
Transcription
TranslationSlide42
Information flow from DNA to trait
DNA
protein
Observed trait
Stored in nucleus
Made by ribosomes outside of nucleusSlide43
Information flow from DNA to trait
DNA
messenger
RNA
protein
Observed trait
Stored in nucleus
Made by ribosomes outside of nucleus
TranscriptionSlide44
Information flow from DNA to trait
DNA
messenger
RNA
protein
Observed trait
Stored in nucleus
Made by ribosomes outside of nucleus
TranslationSlide45
mRNA information
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
messengerRNA
proteinSlide46
Translation
Ribosomes use mRNA as a guide to make proteins
http://fajerpc.magnet.fsu.edu/Education/2010/Lectures/26_DNA_Transcription_files/image006.jpgSlide47
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. Slide48
The message
mRNA is a strand of nucleotides
Ex. AUGCCGUUGCCA…
Each combination of three nucleotides on the mRNA is called a
codonSlide49
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 proteinsHas an anticodon at the other end
http://www.wiley.com/legacy/college/boyer/0470003790/structure/tRNA/trna_diagram.gifSlide50
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.gifSlide51
The RibosomeSlide52
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.Slide53
TranslationSlide54
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.Slide55
Translation
http://www.medicine.uottawa.ca/Pathology/devel/images/text_figure8.gifSlide56
mRNA nucleotides are translated in groups of 3 called
codons
.
AUGCACUGCAGUCGAUGA
CODONS
Remember…Slide57
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 glycineSlide58
The Genetic Code
http://www.cbs.dtu.dk/staff/dave/roanoke/fig13_18.jpgSlide59
Simulation!
I need 6 volunteers who don’t mind holding hands.
And then one more volunteer.
Translation VideoSlide60
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 otherFoldinghttp://www.stolaf.edu/people/giannini/flashanimat/proteins/hydrophobic%20force.swfStructure levelshttp://www.stolaf.edu/people/giannini/flashanimat/proteins/protein structure.swfSlide61
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 AmRNA sequence: A U G G C U C U A A G Uamino acid sequence: Met -- Ala -- Leu
-- Ser Whole Process VideoSlide62
Special Codons
Start codon: AUG
Stop codons: UAA, UGA, UAG Slide63
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!Slide64
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 cytoplasmrRNA: makes up the ribosome and interprets the message in codonstRNA: brings correct amino acids to the ribosome using anticodons Slide65
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 codons4: 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.Slide66
Share sentences in orderSlide67
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 codons4: 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.Slide68
Share sentences in orderSlide69
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 codons4: 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.Slide70
Share sentences.Slide71
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 AcidsProteins (polypeptides)