Download Molecular_files/Translation Transcription

DNA v. RNA
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DNA
Nucleic Acid
Made of nucleotides
Double helix (2 strands)
A, T, G, C – nitrogen
bases (AT, CG)
Deoxyribose Sugar
Found in the nucleus
(Eukaryotic cells)
Genetic Material
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RNA
Nucleic Acid
Made of nucleotides
Single stranded
A, U, G, C – nitrogen bases
(AU, CG, TA)
Ribose Sugar
Found in nucleus and
cytoplasm in eukaryotic cell
mRNA, rRNA, tRNA
Protein Synthesis
RNA Functions
• Translate between DNA and protein
Translation versus Transcription
TRANSCRIPTION
TRANSLATION
Transcription = the process of changing
the genetic code from DNA to RNA
• For prokaryotes, this happens in the
cytoplasm- why?
• For eukaryotes, this happens in the
nucleus
Transcription = the process of changing
the genetic code from DNA to RNA
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Steps of Transcription:
1. DNA Helicase – unzips double helix
2. Promoter binds – adds primer so RNA
polymerase binds
3. RNA polymerase – binds and pairs
corresponding RNA nucleotides to form
RNA polymer
4. Forms messenger RNA (mRNA)
http://www.stolaf.edu/people/giannini/flasha
http://www.johnkyrk.com/DNAtranscription.html
nimat/molgenetics/transcription.swf
Translation = the process of changing
RNA to Protein
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In prokaryote, this
happens in the
cytoplasm- why?
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In eukaryotes, this
happens in the
cytoplasm- why?
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mRNA exits the nucleus
through the nuclear pores
in the nuclear envelope
Translation = the process of changing
RNA to Protein
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Translating from language of nucleotides
to the language of codon to the language
of amino acids
– A codon = a 3 nucleotide base sequence
– Each codon codes for an amino acid
– Should have 64 different codons (4
nucleotide choices, 3 bases) but only 20
amino acids- why?
Translation = the process of changing
RNA to Protein
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Ribosomal RNA (rRNA) builds ribosome
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Ribosomes made up of proteins and rRNA
Small subunit and large subunit
mRNA feeds through the ribosome, the
ribosome reads the codons
For each codon, transfer RNA (tRNA) brings
the corresponding amino acid and attaches it
Always start with AUG = methionine
Stop with UGA, UAG, UAA
Translation = the process of changing
RNA to Protein
http://www.biostudio.com/demo_freeman_protein_synthesis.htm
Practice
• Write 2 DNA sequences (of at least 15
base pairs in length)
– Transcribe it from DNA to RNA
– Translate it from RNA to protein
• Trade your 2 DNA sequences with a friend
– Try to transcribe and translate their
sequences
– Check your answers with their answers
– Check over their answers too!
Mutations
• Point Mutation
- A change in a single base nucleotide.
- Leads to a change in a single codon.
Ex. Base Substitution
http://www.bing.com/images/search?q=mutation+substitution&FORM
=HDRSC2&adlt=strict#view=detail&id=8B33D483DFE23A7B98E648
30FC195418DB0359B1&selectedIndex=2
Silent Mutations
• A substitution that…
– 1. … does not result in a change to the amino
acid
– 2. …results in a change that does not
drastically change the final structure of the
protein
– 3. …occurs in a non-coding region of the
genome.
http://bio1151.nicerweb.com/Locked/media/ch17/17_23aPointMutationTypes-L.jpg
Frameshift Mutations
• Insertion or deletion of any number of
nucleotides not divisible by 3
• Alters the entire reading
frame following the
mutation
http://www.ebpi-kits.com/images/TA98%20Frame-Shift%20Mutation.jpg