BIOL 120- Chapter 8 (part 3) -Molecular Biology

What is a gene?

An organized unit of DNA sequences that enables a segment of DNA to be transcribed into RNA.

What is the function of a promoter in transcription?

It is the site in DNA where RNA polymerase binds to begin transcription.

What are regulatory sequences?

Sites that bind to regulatory proteins to control whether a gene is turned on or off.

What is the transcribed region of DNA?

The region that is transcribed into an RNA molecule.

What is a terminator in the context of transcription?

A sequence that specifies an amino acid sequence and causes the RNA strand to be released from the transcription complex.

What is required for the initiation of transcription?

Transcription factors (TFs) binding to the promoter region of a gene.

What is the direction in which RNA is synthesized?

RNA is synthesized from the 5' to 3' direction.

What is the role of RNA polymerase during elongation?

It catalyzes the transcription process, incorporating uracil (U) instead of thymine (T) into RNA.

What signals the end of transcription?

A termination site (terminator) such as the sequence AAUAAA.

What is the purpose of capping in eukaryotic mRNA processing?

A 7-methylguanosine cap is added to the 5' end to protect the mRNA and assist in ribosome attachment.

What is the function of the poly-A tail in mRNA?

It is added to the 3' end to enhance mRNA stability and facilitate export from the nucleus.

What does a fully processed mRNA include?

A 5' cap, 5' UTR, coding region, 3' UTR, and poly(A) tail.

What is the genetic code?

The nucleotide information that specifies the amino acid sequence of a polypeptide, consisting of triplets (codons) of nucleotides.

How many possible codons are there in the genetic code?

64 possible codons.

What is the start codon and its significance?

The start codon is AUG, which indicates the starting point of translation.

What are the stop codons in the genetic code?

UAA, UGA, and UAG, which signal the end of translation.

What is the significance of codon usage bias?

Different organisms may preferentially use certain codons that encode the same amino acid.

What is the difference between eukaryotic and prokaryotic transcription?

Eukaryotic transcription occurs in the nucleus with multiple RNA polymerases, while prokaryotic transcription occurs in the cytoplasm with a single RNA polymerase.

What are exons and introns?

Exons are coding portions of a gene, while introns are non-coding portions that are removed during RNA processing.

What is mRNA splicing?

The process of removing introns and joining exons to form a continuous coding sequence in mRNA.

What is the role of the spliceosome?

It is a large RNA-protein complex that facilitates mRNA splicing.

How does alternate splicing contribute to protein diversity?

It generates different mRNA molecules from the same RNA transcript, leading to the production of different proteins.

What is the role of introns in gene expression?

Introns may contribute to genetic diversity and regulate gene expression.