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39 Cards in this Set
- Front
- Back
Central Dogma-gene to protein
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core belief of protein synthesis
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gene=
protein= mRNA= |
cookbook
food recipe |
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Central dogma states:
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information flows in one direction: DNA-RNA-protein
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Transcription:
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production of mRNA f rom a DNA template
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Translation
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production of a proetin from an mRNA template by a ribosome
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Prokaryotes:
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mRNA from transcription is immediately translated without more processing or transport
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RNA polymerase
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enzyme that builds polymers of RNA in transcription
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Eukaryotes
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mRNA is created and processed (modified), mRNA travels to cytosol, ribosome binds to mRNA to translate into a protein
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Crick and Brenner
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determined that DNA is read in sets of 3 nucleotides for each amino acid
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deciphering the genetic code
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required determing how 4 nucleotides could encode more than 20 amino acids
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codon
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specific set of 3 nucleotides that translates for a specific amino acid
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A-U
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DNA-RNA
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A-T
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DNA-DNA
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Transcription (3)
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Initiation: RNA polymerase bonds to promoter
Elongation Termination: RNA polymerase reaches terminator, mRNA transcript is released |
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A
T C G |
U (replaces T in RNA)
A G C |
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DNA (3)
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double stranded
deoxyribose sugar uses T-A |
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RNA (3)
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single stranded
ribose as sugar uses U-A |
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Coding strand
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DNA that matches mRNA
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template strand
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DNA being used to create mRNA
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transcipt strand
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mRNA strand being created
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RNA polymerase (2)
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uses info within the gene
-promoter:on/off switch -terminator:end of gene |
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RNA processing (3)
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1)enzymes in eukaryotic nucleus modify mRNA
2)both ends are usually altered 3)some interior parts are cut out and remaining parts are spliced together |
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Modification of mRNA (2)
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-5' end recieves a modified nucleotide 5' cap
-3' end gets a poly-A tail |
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duty of modifications (3)
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-facilitate the export of mRNA
-protect mRNA -help ribosomes attach to the 5' end |
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Introns
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noncoding DNA that have to be removed
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Exons
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DNA that is left that will actually be translated to make the protein
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RNA splicing
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removes introns and joins exons, creating the final mRNA molceule which travels to the cytosol
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Translation (4)
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-mRNA is translated into protein with tRNA
-Initiation -Elongation -Termination |
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tRNA (2)
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-carries a specific amino acid on one end
-has an anticodon on the other end |
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anticodon
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has complementary base pairs with the codon (3 nucleotides) on mRNA
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structure of tRNA
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tRNA molecules are lined up with codons on the mRNA by a ribosome
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structure of Ribosome (3)
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-A (amino site) binds the tRNA carrying the next amino acid
-P (peptide site) binds the tRNA attached to the growing peptide chain --E (exit site) binds the tRNA that released the last amino acid |
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Step I: Initiation (4)
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-small ribosome subunit binds to mRNA
-Initiator tRNA binds to mRNA -Large ribosome subunit binds to tRNA -requires GTP |
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Step II: Elongation: (2)
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-Amino acids are added one by one to the preceding amino acid, which forms the protein chain
-each addition involves external proteins called elongation factors -codon recognition -peptide bond formation -translocation |
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synthesis cycle
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ejects the empty 1 to make way for a new one.
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Step III: Termination
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-occurs when a stop codon in the mRNA reaches the A site of the ribosome (cycle continues until this)
-Release factor causes the addition of water molecule instead of an amino acid which: releases the polypeptide causes the translation assembly to come apart |
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During and after synthesis:
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a protein chain spontaneously coils and folds into its three-dimensional shape because proteins are made of amino acids which make them differ in shape
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Additional modifications (2)
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-activation by an enzyme that cleaves the protein
-several peptides may come together to form the subunits of a protein (hemoglobin) |
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point mutations
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chemical changes in just one base pair of a gene
-base pair substitutions -base pair insertions or deletions |