Transcription, RNA Processing & Translation

What is the central dogma of biology?

DNA → RNA → Protein

What is gene expression?

Using genetic information to make a functional product

What is transcription?

Copying a DNA sequence into RNA

Why is transcription important?

It makes mRNA copies of DNA instructions so they can be used to make proteins.

What are the three stages of transcription?

Initiation

What happens first in transcription?

Activator proteins bind enhancers and recruit mediator proteins and transcription factors to the promoter

What happens during transcription initiation?

RNA polymerase is recruited and activated to begin transcription

What happens during transcription elongation?

RNA polymerase moves along the DNA template and builds a complementary RNA strand

What happens during transcription termination?

RNA polymerase reaches the terminator

What happens after transcription?

The RNA transcript is processed and can leave the nucleus for translation

What enzyme builds the RNA strand during transcription?

RNA polymerase

Which DNA strand does RNA polymerase read?

The template strand

What happens to the RNA transcript after it leaves the nucleus?

It can be translated into a protein

What is the correct order of transcription?

Activators bind enhancer → RNA polymerase begins → RNA strand is built → transcript is released → RNA exits nucleus

What is pre-mRNA?

The initial RNA transcript that must be processed before translation

What is post-transcriptional processing?

Changes that turn pre-mRNA into mature mRNA

What are the two main steps of post-transcriptional processing?

Adding a 5′ cap and poly-A tail

What is the function of the 5′ cap and poly-A tail?

Protect mRNA from degradation and help with binding and processing

What are introns?

RNA sequences removed from pre-mRNA that do not code for the protein

What does excised mean?

Cut out and removed

What are exons?

RNA sequences joined together and retained in mature mRNA

What happens during RNA splicing?

Introns are removed and exons are joined together

What is the final product of post-transcriptional processing?

Mature mRNA ready for translation

What is RNA translation?

The process of using mRNA to build a polypeptide chain

Why is translation important?

It converts genetic information into a protein

What are the three stages of translation?

Initiation

What happens during translation initiation?

The ribosome binds mRNA and finds the start codon

What happens during translation elongation?

tRNAs bring amino acids

What happens during translation termination?

A stop codon triggers release of the completed polypeptide

What are the three ribosomal sites?

A site

What happens at the A site?

Incoming tRNA anticodons match mRNA codons

What happens at the P site?

Holds the tRNA carrying the growing polypeptide chain

What happens at the E site?

Empty tRNAs exit the ribosome

What is a codon?

Three mRNA nucleotides that specify an amino acid or stop signal

What is an anticodon?

Three tRNA nucleotides complementary to an mRNA codon

What does tRNA do?

Carries amino acids to the ribosome

What bond joins amino acids during translation?

Peptide bonds

What signals the start of translation?

A start codon

What signals the end of translation?

A stop codon

What does a release factor do?

Helps release the completed polypeptide at a stop codon

What happens to the growing polypeptide during elongation?

It transfers to the incoming tRNA as a peptide bond forms

What is the correct order of translation?

Ribosome finds start codon → tRNA matches codon → peptide bond forms → empty tRNA exits → stop codon releases polypeptide