(4) Chapter 17 Flashcards
What is transcription?
Transcription is the first step in gene expression, where an RNA copy of a gene is made from a DNA template.
What are the key stages of transcription?
The key stages of transcription are initiation, elongation, and termination.
What happens during initiation of transcription?
RNA polymerase binds to a specific region of DNA known as the promoter.
What occurs during elongation in transcription?
RNA polymerase moves along the DNA, synthesizing a complementary strand of RNA.
What is termination in transcription?
RNA polymerase reaches a termination signal, releasing the newly synthesized RNA molecule.
How does transcription differ in prokaryotic cells?
In prokaryotes, transcription occurs in the cytoplasm, with minimal RNA processing.
How does transcription differ in eukaryotic cells?
In eukaryotes, transcription occurs in the nucleus and involves extensive RNA processing.
What is a promoter?
The promoter is a DNA sequence located upstream of the gene that serves as the binding site for RNA polymerase.
What is the function of RNA polymerase?
RNA polymerase catalyzes the synthesis of RNA from a DNA template.
What modifications occur to pre-mRNA in eukaryotes?
Pre-mRNA undergoes the addition of a 5’ cap, a 3’ poly-A tail, and splicing to remove introns.
What is the function of the 5’ cap?
The 5’ cap protects the RNA from degradation and helps ribosomes recognize the mRNA for translation.
What is the function of the 3’ poly-A tail?
The poly-A tail protects the mRNA from degradation and facilitates export from the nucleus.
What is splicing in RNA processing?
Splicing is the process of removing introns and joining exons together.
What is the role of the spliceosome?
The spliceosome is a complex that catalyzes the removal of introns from pre-mRNA.
What is translation?
Translation is the process by which an mRNA sequence is decoded to build a protein.
What are the main components involved in translation?
The main components are mRNA, ribosomes, and tRNA.
What is the start codon in mRNA?
The start codon is typically AUG, which codes for methionine.
What is the structure of tRNA?
tRNA has a cloverleaf shape with an anticodon loop at one end and an amino acid binding site at the other.
When does translation end?
Translation ends when a stop codon (UAA, UAG, or UGA) is encountered in the mRNA.
What are point mutations?
Point mutations are changes in a single nucleotide in the DNA sequence.
What is a silent mutation?
A silent mutation is a change in one nucleotide that does not affect the amino acid sequence.
What is a missense mutation?
A missense mutation results in the substitution of one amino acid for another in the protein.
What is a nonsense mutation?
A nonsense mutation creates a premature stop codon, resulting in a truncated protein.
What is a frameshift mutation?
A frameshift mutation is caused by insertions or deletions that alter the reading frame of the codons.
What are the effects of mutations on protein function?
Mutations can lead to nonfunctional proteins, altered function, or truncated proteins.
