Chapter 17 Flashcards
Protein is a 2 step process known as?
Transcription
Translation
Central Dogma of Molecular Biology
DNA
mRNA
Protein
What is gene expression?
Process by which DNA directs protein synthesis
Includes 2 stages: transcription & translation
What is a Codon?
Triplet nucleotide bases of mRNA
What is the role of a Codon?
Bring in AA that is attached to one end of tRNA molecule during translation
During translation, what direction are codons read in ribosomes?
5’ to 3’ direction
What is the Start codon?
UAG
What are the stop codon?
UAA
UAG
UGA
What is Transcription?
The DNA-directed synthesis of RNA
What is the enzyme involved in transcription?
RNA polymerase
RNA polymerase
Catalyze RNA synthesis
Promoter
DNA sequence where RNA polymerase attaches
Terminator
Sequence signalling the end of transcription
Transcription unit
Stretch of DNA that is transcribed
What are the 3 stages of transcription?
Initiation
Elongation
Termination
TATA box
Promoter
Crucial in forming the initiation complex in eukaryotes
What do transcription factors do?
Mediate the binding of RNA polymerase II and the initiation of transcription
What are the 2 steps in eukaryotic RNA processing?
5’cap & 3’ poly-A tail
Splicing of introns
What is the function of the 5’cap and 3’ poly-A tail?
Facilitate the export of mRNA
Protect mRNA from hydrolytic enzymes
Help ribosomes attach to the 5’ end
What is the significance of RNA splicing?
Removes introns & joins exons
Creating a mRNA molecule with continuous coding sequence
What ate Introns?
Noncoding regions
What are exons?
Coding regions
Eventually expressed
Usually translated into amino acid sequences
What role does Spliceosome play?
Carries out RNA splicing
What are the 3 stages of translation?
Initiation
Elongation
Termination
Initiation in Translation
Brings together:
mRNA
tRNA with the first amino acid
Two ribosomal subunits
Elongation in Translation
Amino acids are added one by one to the preceding amino acid
Termination in Translation
Occurs when a stop codon in the mRNA reaches the ribosome
Ribosomes facilitate…
Specific coupling of tRNA anticodons with mRNA codons in protein synthesis
Elongation of the RNA strand (transcription)
RNA polymerase moves along the DNA
Untwists the double helix
Termination of Transcription
In bacteria
The polymerase stops transcription at the end of the terminator
Termination of Transcription
In eukaryotes
The polymerase continues transcription after the pre-mRNA is cleaved from the growing RNA chain
The polymerase eventually falls off the DNA
