Protein Synthesis Flashcards
What are the three stages of DNA transcription?
Initiation, elongation, and termination.
What enzyme is responsible for transcribing DNA into RNA?
RNA polymerase.
What is the function of the promoter sequence in transcription?
It is a DNA sequence that signals RNA polymerase where to begin transcription.
What is the difference between the 3’-5’ and 5’-3’ DNA strands?
The 3’-5’ strand is the transcribed (template) strand, while the 5’-3’ strand is the non-transcribed (coding) strand.
What is post-transcriptional modification?
The process where introns are removed, and exons are joined to form mature mRNA (splicing).
Where does translation occur in the cell?
At the ribosomes.
What are the three stages of translation?
Initiation, elongation, and termination.
What is the function of tRNA in translation?
It carries amino acids to the ribosome and matches them to the codons on mRNA.
What is the start codon, and what amino acid does it code for?
AUG, which codes for methionine.
What are stop codons?
UAA, UAG, and UGA; they signal the end of translation.
What organelle modifies and packages proteins for transport?
The Golgi apparatus.
What is the role of the endoplasmic reticulum in protein synthesis?
It helps in protein folding and transport.
How are proteins transported within the cell?
Via vesicles.
What does it mean that the genetic code is universal?
Almost all organisms use the same codons to code for the same amino acids.
How can mutations in DNA affect protein synthesis?
They can lead to changes in mRNA, which may alter the amino acid sequence of a protein.
What is a frameshift mutation?
A mutation caused by insertions or deletions that shift the reading frame of the genetic code.
What are the consequences of mutations in start or stop codons?
They can prevent translation from starting or stopping properly, leading to nonfunctional proteins.
What are pulse-chase experiments used for?
To track the movement and processing of newly synthesized proteins in cells.
What did the Nirenberg, Khorana, and Holley experiments demonstrate?
They helped decipher the genetic code and how codons specify amino acids.
What can electrophoresis be used for in genetics?
To analyze DNA or protein sequences and identify mutations.
How is DNA sequencing used in forensics?
To match DNA from crime scenes to individuals.
What is transgenesis?
The introduction of foreign DNA into an organism to study gene function.
How do inducible and repressible operons regulate gene expression?
Inducible operons (e.g., lac operon) activate gene expression in response to a molecule, while repressible operons (e.g., trp operon) suppress gene expression when a product is abundant.
