BIOL 3200 Bacterial RNA Translation to Proteins

What is used to observe the process of bacterial RNA translation?

Electron microscope

What is mRNA already covered by?

Ribosomes

What is translation?

mRNA is converted to an amino acid sequence

Can replication, translation, transcription, and regulation happen at the same time?

Yes

How is mRNA arranged?

In codons

What are codons?

A sequence of three nucleotides that together form a unit of genetic code in a DNA or RNA molecule.

What are ribosomes?

Machines that read the language of mRNA and translate it into proteins

What do ribosomes use to translate mRNA into proteins?

Genetic Code

What is the Genetic Code?

A collection of codons of mRNA, each of which directs the incorporation of a particular amino acid into a protein during protein synthesis

What do tRNA decoder molecules do?

Convert language of RNA into that of proteins

What is the start codon?

AUG

What are the stop codons?

UAA, UAG, UGA

True or False
Multiple codons can encode same amino acid

True

What is the shape of tRNA?

Clover leaf shape

What is an anti-codon?

Hydrogen bonds with mRNA codon specifying an amino acid

What end binds the amino acid?

3' end

How many nucleotides does the tRNA anticodon consist of?

Three

How does the anticodon bind with the mRNA codon?

In an antiparallel fashion

How many "match and attach" tRNA does a cell have?

20, one for each amino

What do ribosomes have?

Two subunits that each include rRNA and proteins

How many ribosomes do prokaryotes have?

70s (50s and 30s)

What does the 30s subunit contain?

16s rRNA

What is 16s rRNA?

The binding site of the small subunit. It keep mRNA in place

If metionine is carried by tRNA it's UAC, but what is the genetic code for it?

AUG

Define translation

1) Small subunit (30s) binds to mRNA. AUG is now open for tRNA.
2) tRNA binds to the start codon
3) Large subunit (50s) sit on top of mRNA

When making RNA in translation, what end is used?

5' end

What are the three post-translational modifications?

1) After translation, proteins fold to their functional structure
2) If not made or folded correctly, proteins get degraded
3) Others get secreted using the protein traffic control

What is protein traffic control?

Proteins destined for bacterial cell membrane or envelope regions require special export systems

What does it mean when proteins are tagged with hydrophobic N-terminal signal sequences of 15-30 amino acids?

They're meant for the cell membrane

What is a signal recognition particle (SRP)?

Proteins that undergo co-translational or post-translational export. They bind sequences

What are transmembrane proteins?

Some proteins designated for integral membrane location are inserted directly

How are proteins moved to the integral membrane location?

SRP paralyzes a ribosome and then does not resume translating protein until encountering FtsY in the membrane

How are proteins exported to the periplasm?

Periplasmic proteins are delivered to periplasm by SecA-dependent general secretion pathway

What does SecB do?

Keep the protein unfolded. It binds to completed protein and then delivers it to SecA

What does SecA do?

Move proteins to SecYEG

What does SecYEG do?

Exports proteins across the cell membranes of bacteria

Where do secretion systems extend from?

From the cytoplasm all the way to the outside

Where do these processes take place in a eukaryotic system?

Transcription and processing happens in the nucleus and then is transported to the cytoplasm to grow the amino acid chain

Where do these processes occur in a prokaryotic system?

Everything is in the cytoplasm; therefore, they can do everything of central dogma at the same time. DNA polymerase doesn't proofread as much as eukaryotic system.

Which system evolves fastest, eukaryotic or prokaryotic?

Prokaryotic