Frage | Antworten |
What are the three stages of translation? | - Initiation - Elongation - Termination |
Initiation | all the enzymes and protein bind together, form transcription bubble (consists of DNA template, RNA polymerase) and promoter begins transcription |
Elongation | RNA is synthesized and transcript gets bigger |
Termination | Formation of hairpin loop in RNA, A-T bonds break and mRNA falls off. DNA reforms double helix. |
how do Eukaryotes differ in transcription? | - Formation of intiation complex, multiple transcription factors. - mRNA contains 5' cap and 3' poly a tail. - splicing of introns |
What are the 3 RNA involved in Translation? | -mRNA (carries information from DNA to encode proteins) -rRNA (structural component of a ribosome) -tRNA (carries amino acids to ribosome for translation) |
What is the structure of tRNA? | One end contains anticodon loop which pairs with mRNA while other end has a charged amino acid attached (to be carried to ribosome) |
What are the 3 sites on a ribosome for tRNA to bind? | - E site (binds to tRNA with last amino acid exit site) - P site (binds to tRNA of growing peptide - A site (binds to tRNA with next amino acid) |
What are the 3 stages of translation? | - Initiation - Elongation - Termination |
Translation initiation | in prokayotes, initiation complex forms with tRNA, small ribosomal unit, mRNA stand |
Translation Elongation | Addition of amino acids occurs in initiation complex, starting at A site, when tRNA with correct codon binds. Moves along to P site and peptide grows |
Translation Termination | When ribosome encoutners stop codon, which is recognized by release factors, the ribsome releases the peptide. (in E site) |
what is the lac operon? | an operon which controls gene expression and breaks lactose for energy |
the lac operon is negatively regulated, what does this mean? | a repressor will bind to an operator to stop transcription from occurring and does this when no lactose is present. |
What does an inducer do in the lac operon? | binds to the repressor, preventing it binding to the operon and transcription proceeds |
What does glucose do to the lac operon? | glucose prevents induction of lac operon via cAMP which binds to the operon. Occurs when glucose levels are low. |
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