Translation

Question 1

What is the Central Dogma of Molecular Biology?

Who coined it?

Answer 1

DNA, RNA, Protein.

Crick

Question 2

What are three types of RNA?

What do they do?

Answer 2

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

Question 3

Violation of Central Dogma? examples?

Answer 3

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

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

Question 4

What did Pauling discover?

Answer 4

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

Question 5

Crick’s early work

Answer 5

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.

Question 6

3 Conclusions of Crick and Brenner’s early work

Answer 6

triplet, non-overlapping, degenerate

Question 7

What does polynucleotide phosphoralase do?

Answer 7

Assembles all available nucleotides into a linear polymer.

synthetic RNA

Question 8

What did Nirenberg and Matthei do?

Answer 8

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

Question 9

What did Khorana do?

Answer 9

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

Question 10

Exceptions to near universality of genetic code?

Answer 10

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.

Question 11

Speed of polymerization of peptides in ribosome?

Answer 11

3-5 amino acids per second

Question 12

What is a eukaryotic ribosome composed of?

Answer 12

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

Small subunit: 18S and 33 Proteins

Question 13

What is the start codon?

Which Amino Acid does it code for?

Answer 13

AUG

Methionine

Question 14

How does the synthesis of a polypeptide chain begin?

Answer 14

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

Question 15

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

Answer 15

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

Question 16

What are eIFs?

What do they do?

Answer 16

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

Question 17

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

Answer 17

It is where Aminoacylated tRNA’s bind

Question 18

What are EFs?

Answer 18

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.

Question 19

What is the large rRNA?

Answer 19

catalyze peptidyltransferase reactions in the formation of peptides.