Translation Flashcards

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1
Q

What is the Central Dogma of Molecular Biology?

Who coined it?

A

DNA, RNA, Protein.

Crick

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2
Q

What are three types of RNA?

What do they do?

A

mRNA - carries the message to be translated
rRNA - molecules of the ribosome
tRNA - transfer the appropriate Amino Acids to the ribosome.

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3
Q

Violation of Central Dogma? examples?

A

Viruses with RNA genomes use this as a template to synthesize RNA molecules.

Reverse transcription - Retroviruses like HIV use RNA to change DNA.

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4
Q

What did Pauling discover?

A

Sickle cells migrate at different rates than healthy cells because they contain an amino acid with a different charge.

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5
Q

Crick’s early work

A

Proflavin, an acridine dye that caused single deletions or additions/frameshift mutations to wild-type bacteriophage T4. 3 additions/deletions in a row caused reversion to wildtype.

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6
Q

3 Conclusions of Crick and Brenner’s early work

A

triplet, non-overlapping, degenerate

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7
Q

What does polynucleotide phosphoralase do?

A

Assembles all available nucleotides into a linear polymer.

synthetic RNA

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8
Q

What did Nirenberg and Matthei do?

A

Made 20 different RNA homopolymers and saw what they synthesized in a cell-free protein-synthesizing system. Figured out a bit of the code.

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9
Q

What did Khorana do?

A

He used polynucleotide phosphoralase to create RNA copolymers. He used this method to figure out what most of the other 64 codons code for.

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10
Q

Exceptions to near universality of genetic code?

A

UGA is normally a stop codon, but in mitochondria translates to tryptophan. Conversely, AGA is a stop codon in mitochondria, but codes for arginine normally.

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11
Q

Speed of polymerization of peptides in ribosome?

A

3-5 amino acids per second

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12
Q

What is a eukaryotic ribosome composed of?

A

Large subunit: 28S rRNA, 5S rRNA, 5.8S rRNA, 50 proteins.

Small subunit: 18S and 33 Proteins

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13
Q

What is the start codon?

Which Amino Acid does it code for?

A

AUG

Methionine

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14
Q

How does the synthesis of a polypeptide chain begin?

A

Met tRNAi^met (a type of tRNA with an activated methionine attached) binds to the P-site on the small ribosomal unit.

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15
Q

Which sites are involved with the binding of non Met tRNAi^met tRNAs?

A

A site is where charged tRNAs bind the amino acid they carry. Then they exit at the E site.

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16
Q

What are eIFs?

What do they do?

A

Eukaryotic initiation factors that bind the GTP than needs to undergo hydrolysis into GDP in order for the ribosome to stabilize on a new mRNA

17
Q

Why is the A-site in ribosomes called the A-site?

A

It is where Aminoacylated tRNA’s bind

18
Q

What are EFs?

A

Elongation factors are special proteins. EF1alpha GTP bound to the correct aminoacylated tRNA for the second codon causes GTP hydrolysis and conformational change of ribosome.

19
Q

What is the large rRNA?

A

catalyze peptidyltransferase reactions in the formation of peptides.