Transcript translation

Transcription & Translation
 If I have a DNA sequence of
AAG CTC ATA
What will my mRNA sequence be?
 What will the tRNA sequence from that
mRNA sequence be?
Transcription & Translation
1. Fill in the blanks:
____ -> _____ -> ________ -> _______
1. What is the sequence of the RNA molecule that you
get from this strand of DNA?
AATGCG
2. What do you call that kind of RNA?
3. Was that the template strand or the gene strand of
DNA?
Homework
Review Transcription
 Turn to your table partner and explain
how transcription works.
Review Transcription
 I have a DNA strand with these sequences:
CGTTCGACTGATCGT
GCAAGCTGACTAGCA
RNA is made by pairing with the top strand.
What is the RNA sequence that results?
What kind of RNA is it?
What do we call the top DNA strand? The
bottom DNA strand?
Where in the cell did this take place?
Translation
 Translation = Two parts. First,
assembling a tRNA sequence from an
mRNA sequence.
 Once an mRNA molecule is made, it
leaves the nucleus and travels through
the cytoplasm to a ribosome. The rest of
protein synthesis happens in the
ribosome.
Translation
 Two parts.
 First, tRNA matches
up with mRNA.
 tRNA = Transfer
RNA,” an RNA
molecule with 3
nucleotides on one
side and an amino
acid on the other.
 (Amino acids will
be the building
blocks of proteins)
Translation
 Each three
nucleotides on the
mRNA is called a
codon.
 The three
matching
nucleotides on the
tRNA is called the
anticodon.
Translation
 If my mRNA codon is AUG, what will be
the anticodon?
Translation
 If my mRNA codon is AUG, what will be
the tRNA anticodon? UAC
 If my mRNA codon is CCG, what will be
the anticodon?
Translation
 If my mRNA codon is AUG, what will be
the tRNA anticodon? UAC
 If my mRNA codon is CCG, what will be
the anticodon? GGC
 If my mRNA has the codons
AUG UUA CGC GGG AAA UAA, what will be
the anticodon sequence?
Translation
 If my mRNA codon is AUG, what will be
the tRNA anticodon? UAC
 If my mRNA codon is CCG, what will be
the anticodon? GGC
 If my mRNA has the codons
AUG UUA CGC GGG AAA UAA, what will be
the anticodon sequence?
UAC AAU GCG CCC UUU AUU
Translation
 Second step, the
amino acids that
are bonded to the
backs of the
tRNAs bond to
each other.
 A chain of amino
acids is called a
protein. Which
amino acids are
in the chain, and
what order
they’re in,
determines the
type of protein.
Paper models
 http://wwwclass.unl.edu/biochem/gp2/m_biology/animation
/gene/gene_a3.html
 http://sciencehack.com/videos/view/4PKjF7Oum
Yo
 http://www.youtube.com/watch?v=41_Ne5mS2l
s
 http://www.youtube.com/watch?v=983lhh20rGY
Protein Synthesis =
Constantly Happening
Questions I want to
address…
 Why all the hassle? Why coding and decoding,
why RNA? Why not just make the protein from
the DNA? Several reasons why it didn’t happen
this way.
 Amino acids can’t bond to DNA’s nucleic acids directly.
 DNA is in extremely long, bunched up strands that are
too big to pass through the pores in the nucleus.
 The DNA is the cell’s master plan, and if it’s getting
roughed up and zooming around through the cytoplasm,
it’s accumulating damage. This will result in cell
dysfunction and death, and the death of that strategy.
Protein Synthesis Overview
 DNA -> RNA -> Protein -> Trait
 TRANSCRIPTION: mRNA for a gene is made from one
strand of DNA.
 The mRNA leaves the nucleus and goes to the
ribosome.
 TRANSLATION: In the ribosome, tRNAs match up with
their codons in the mRNA.
 The backsides of the tRNAs have specific amino acids
attached to them. When the tRNAs line up, the amino
acids bond to each other and let go of the tRNA.
 The chain of amino acids is called a protein.
 The protein then performs a function which gives the
organism a certain trait. (more on those functions
next)
Protein Synthesis Overview
 DNA -> RNA -> Protein -> Trait
 So if I have a strand of DNA that’s like this:
 TACGGGCTAACT
 ATGCCCGATTGA
 And my cell wants to produce the protein that’s
coded for by this gene, in which the bottom
strand is the gene strand.
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What will be my mRNA sequence?
What will be my tRNA sequence?
What will be my amino acid sequence?
Which ones are identical to the gene strand
sequence, and which ones are opposites?
Vocabulary
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Protein synthesis
Genotype vs phenotype
RNA
Ribose
Uracil
mRNA
tRNA
Transcription
Translation
Codon vs Anticodon
Template strand vs gene strand
Mutation
Amino acid
Protein
Practice Problems
 With your table partner, make a brief
protein synthesis quiz for another pair.
 One of you writes the quiz.
 The other writes an answer key.
 Ten problems.
 Write a DNA template sequence.
 The other group must figure out the codon
(mRNA) and anticodon (tRNA) sequences.
Protein Synthesis
 If I have a strand of DNA that is
CCG ATT TAG
What will the mRNA codons be?
 What will the tRNA anticodons be?
 How many amino acids will that make?
Homework
 Quiz next week on protein synthesis.
Review
 Important misconceptions:
 DNA doesn’t turn into RNA. RNA is
assembled by binding its nucleotides to DNA,
then it pulls away.
 Protein synthesis doesn’t just make “muscle
proteins.” Everything the cell does to stay
alive uses at least one kind of protein.
 So protein synthesis is the process that ultimately
determines everything that a cell does.
Review
 How does transcription work?
 How does translation work?
 Today, a game to help you visualize
transcription and translation better.