Module 6.1 Flashcards
Cellular control
What are the 3 types of gene mutation
Substitution/point
Insertion
Deletion
What is a substitution/point mutation
one base is replaced with another
what are the three types of point mutation
silent
missense
nonsense
what is a silent mutation
when a point mutation changes the base triplet code but still codes for the same amino acid because of the degenerate nature of the genetic code
what is a missense mutation
when a point mutation leads to a change in the amino acid sequence in a protein
what is a nonsense mutation
when a point mutation alters a base triplet to become a termination (stop) triplet meaning the rest of the amino acids after the stop codon will not be coded for
what do insertion and deletion mutations do
removes or adds a base to the genetic code
results in a frameshift meaning all the subsequent base triplets are altered
what is lac operon an example of
regulation of gene expression at the transcriptional level
what does the lac operon do
induces the production of 2 enzymes involved in lactose metabolism when glucose is absent and lactose is present
what organism is the lac operon found in
bacteria
e.coli
what is lacO
operator region
where the repressor protein binds
what is P in the lac operon
promoter region
where RNA polymerase binds to begin transcription of the structural genes lacZ and lacY
What is LacI
regulatory gene
produces the repressor protein
what happens in the lac operon when lactose is not present
the LacI regulatory gene is expressed which codes for a repressor protein
the repressor protein binds to the operator region - preventing RNA polymerase from binding to the promoter region stopping the genes lacZ and lacY from being transcribed and expressed
what happens in the lac operon when lactose is present
lactose binds to the repressor protein molecules - altering the shape preventing it binding to the operator
RNA polymerase can bind to the promoter region and begin to transcribe the structural proteins lac Z and lacY
what does lacZ code for
beta-galactosidase
hydrolyses lactose to glucose and galactose for use in respiration
what does lacY code for
lactose permease
allows lactose to enter the bacterial cell
what are transcription factors
proteins or short non-coding pieces of RNA
What do transcription factors do
Act within the cells nucleus to control which genes in a cell are turned on or off by aiding or inhibiting the attachment of RNA polymerase to the DNA and activate or inhibit the transcription of the gene
what are transcription factors an example of
control of gene expression at the transcriptional level
what are introns
non-coding regions of DNA which are not expressed
what are exons
the coding regions of DNA which are expressed
what is primary mRNA
when all the DNA of a gene is transcribed - the resulting mRNA containing introns and exons in primary mRNA
what happens to primary mRNA
the RNA introns (which correspond to the DNA introns) are removed
remaining RNA exons are joined together
produces mature mRNA
