KH2

Question 1

What does the Central Dogma say?

Answer 1

Information travels in one direction:
DNA –> DNA –> RNA –> Proteins

Question 2

What does “DNA–>DNA” represent in the Central Dogma?

Answer 2

Heredity: “passing on”/”inheritance” of information

Question 3

What does “DNA–>RNA–>proteins” represent in the Central Dogma?

Answer 3

Physiology, biology (form and function): how the information is expressed in the world

Question 4

What’s the process in charge of
“DNA–>DNA”?

Answer 4

Replication

Question 5

What’s the process in charge of
“DNA–>RNA”?

Answer 5

Transcription

Question 6

What’s the process in charge of
“RNA–>proteins”?

Answer 6

Translation

Question 7

True or False? “Ribosome is a type of enzyme”

Answer 7

False. It’s a mix of protein and RNA components.

Question 8

Describe transcription

Answer 8

Polymerase catalyzes the attack of the 3’ OH on the incoming rNTP. A diphosphate is released. It’s a direct Interaction.

Question 9

Where does the rNTP come from for transcription?

Answer 9

It’s floating around and diffuses randomly. It gets linked only if it’s complementary to the growing chain. Otherwise, it’s released.

Question 10

True or False? “The non-template strand and the synthesized mRNA are structurally equivalent”

Answer 10

False. Only difference is U replacing T in the mRNA.

Question 11

What’s the transcription bubble?

Answer 11

It’s an area of unwound DNA corresponding to the what the RNA polymerase reads.

Question 12

What enzymes are responsible for unwinding the DNA molecule?

Answer 12

Helicase with help from the RNA polymerase.

Question 13

True or False? “The nascent RNA stays bonded to the template DNA”

Answer 13

False, it gets kicked out as the DNA strand reforms behind the transcription bubble.

Question 14

True or False? “During transcription, the RNA polymerase stays stationary”

Answer 14

False. It moves unidirectionally along the DNA.

Question 15

True or False? “During transcription, the transcription bubble moves with the polymerase”

Answer 15

True

Question 16

How does RNA polymerase know where to start its functions?

Answer 16

Through promoters. They are DNA sequences that facilitate the binding of polymerase to the template.

Question 17

How does RNA polymerase know where to stop its function?

Answer 17

Through DNA sequences that destabilize its bond with the template.

Question 18

True or False? “RNA Polymerase keeps the resulting mRNA after transcription”

Answer 18

False. It gets released.

Question 19

What are some differences between DNA replication and transcription?

Answer 19

The monomers (rNTP vs dNTP) // Different start sites (promoter vs replication origin) // Replication has no stop site, the template keeps the new strand attached and results in two double-stranded molecules.

Question 20

Is the genetic code redundant or degenerate? Is it ambiguous?

Answer 20

Yes. Same amino acid is coded by different codons. // No, a codon only codes for a specific amino acid.

Question 20

What are codons?

Answer 20

Triplets of nucleotides that code for an amino acid (64).

Question 21

What’s the starting codon in protein synthesis?

Answer 21

“AUG” (codes for methionine/MET)

Question 22

What are the stop codons in translation?

Answer 22

“UAG”, “UAA”, “UGA” (codes for nothing)

Question 23

True or False? “Methionine can’t be present in the middle of a protein chain”

Answer 23

False. It’s not going to stop the chain growth.

Question 24

Why are aminoacyl tRNAs compared to adaptors?

Answer 24

They indirectly connect amino acids to nucleotides. (One signal transformed into the other)

Question 25

True or False? “Displacing an mRNA sequence by a base is better than doing it by 3”

Answer 25

False. You’d deal with frameshift mutations instead of missing out on a single amino acid.

Question 26

What’s the RNA world hypothesis?

Answer 26

Due to its many roles, it’s logical for RNA to predate DNA and proteins. Possibly even cells.

Question 27

Briefly describe translation steps

Answer 27

In the smaller ribosome subunit, complementary aminoacyl-tRNA binds to the mRNA template. In the larger subunit, the protein grows through PEPTIDYL TRANSFERASE (N attacks C, brings side chain along). Moves along template and releases tRNA.