Gene expression

What is the main difference between transcription and replication in terms of DNA output?

In replication, a complete copy of the cell's DNA is produced; in transcription, only a specific section is copied into mRNA.

What are promoters in the context of transcription?

Special sequences of the DNA strand where transcription begins.

What is the template strand used during transcription called?

The antisense strand.

What is the purpose of RNA polymerase during transcription?

To build RNA by adding nucleotides from the 5′ to the 3′ direction.

What does mRNA translate into?

Protein.

Where does translation occur within a cell?

On ribosomes in the cytoplasm and on the rough endoplasmic reticulum.

What is a codon?

A sequence of three nucleotides on mRNA that corresponds to a specific amino acid.

What are the two ends of tRNA and their functions?

One end carries an amino acid; the other end has an anticodon that pairs with the mRNA codon.

What is wobble pairing in translation?

The ability of the third position in a codon to have non-standard base pairing, allowing flexibility, such as guanine pairing with uracil.

What are the three phases of translation?

Initiation, elongation, and termination.

What role do transcription factors play?

They can encourage or inhibit the transcription process.

What are epigenetic changes?

Alterations to DNA packaging that affect the transcription machinery's access to genes.

What is an operon in bacterial genetics?

A cluster of genes under the control of a single promoter.

What are the four major parts of an operon?

Structural genes, promoter genes, operator, and regulatory gene.

What is the role of the operator in an operon?

It controls whether transcription will occur by allowing or blocking RNA polymerase.

What is the function of the regulatory gene in an operon?

It codes for the repressor protein that can block transcription.

What is post-transcriptional regulation?

The process where RNA is created but not translated into protein, often involving RNA interference (RNAi).

How do RNAi molecules function?

They bind to RNA via complementary base pairing, creating double-stranded RNA.

What is post-translational regulation?

The control of protein activity after a protein has been synthesized, determining if it is needed by the cell.