Transcription and Translation in Bacteria

These flashcards cover key concepts related to transcription, translation, and protein maturation in bacteria, ensuring a comprehensive understanding of the central processes in molecular biology.

What is the Central Dogma of Molecular Biology?

It describes the flow of genetic information from DNA to RNA to protein.

What is transcription?

The process of synthesizing RNA from a single strand of DNA.

What enzyme is required for transcription?

RNA polymerase.

What is the role of mRNA?

It carries the DNA message as a complementary copy.

What is a codon?

A group of three nucleotides in mRNA that codes for a specific amino acid.

What are the three phases of transcription?

Initiation, Elongation, Termination.

What is the purpose of bacterial promoters?

They are sequences where RNA polymerase binds to initiate transcription.

What are sigma factors?

Proteins that help RNA polymerase recognize promoter sequences.

What distinguishes rho-dependent transcription termination from factor-independent termination?

Rho-dependent requires a protein, while factor-independent relies on hairpin structures.

Why is the reading frame important in protein-coding genes?

It determines how the sequence of nucleotides is translated into amino acids.

What is the universal genetic code?

The same codons specify the same amino acids across different organisms.

What does the wobble hypothesis explain?

It allows organisms to use fewer tRNA molecules by permitting flexible pairing of codons and anticodons.

What is the general structure of a tRNA molecule?

tRNA has an anticodon on one end and an amino acid attachment site on the other end.

What happens during translation initiation?

The tRNA carrying the first amino acid binds to the start codon of mRNA.

What is the function of ribosomes in translation?

They serve as the site where mRNA is translated into a polypeptide.

What are the A, P, and E sites in ribosomes?

A: Aminoacyl site, P: Peptidyl site, E: Exit site.

What are molecular chaperones?

Proteins that assist in the proper folding of other proteins.

What distinguishes translocation from secretion?

Translocation is the movement of proteins to their membrane, while secretion is their release into the external environment.

List one bacterial translocation system.

Sec system.

What is the role of the initiator tRNA in bacteria?

It carries N-formyl methionine as the first amino acid during translation.

What occurs during elongation in translation?

Amino acids are added one by one to the growing polypeptide chain.

What happens during termination of translation?

A stop codon is encountered, signaling release factors to detach the polypeptide.

What is a signal peptide?

A short peptide that directs the transport of a protein to its destined location.

What is the function of the SecA protein?

It translocates unfolded proteins across the cytoplasmic membrane.

What is the Tat system?

A system that translocates fully folded proteins across the membrane.

What enzyme removes the signal peptide after translocation?

Signal peptidase.

What are the two-step secretion systems in Gram-negative bacteria?

Step one involves Tat or Sec systems, and step two involves secretion across the outer membrane.

Identify one one-step secretion system.

Type I secretion system.

How do Type III secretion systems operate?

They inject proteins directly into eukaryotic host cells.

Why is understanding bacterial secretion systems important?

It can help develop methods to combat bacterial infections and engineer bacteria for useful purposes.

What bonds link amino acids together?

Peptide bonds.