regulating gene expression Flashcards
(23 cards)
what is an exon
the coding region of dna
what is an intron
non coding region of dna
what is the operon
a group of genes which function as a transcription unit, first identified in prokaryote cells
what is a transcription factor
protein which combines to a specific site on a dna length to inhibit or allow gene transcription
what is the lac operon
a group of genes which are controlled by the same promoter on a length of dna, present in ecoli bacteria, controls the production of enzymes and proteins
what are the two enzymes induced by lactose in e.coli when glucose is absent
lactose permease- allows lactose to enter the bacteria cell
b-galactosidase- hydrolyses lactose to glucose and galactose
how many base pairs long is the lac operon
6000
describe the structure of the lac operon
has an operator in between the structural genes lac z and lac y and the promoter region. the regulatory gene on the end
what do structural genes lac y and lac z do
they code for the enzymes b galactosidase and lactose permease
what is the function of the promoter region on the lac operon
a site for rna polymerase to bind to, in order to begin transcription of structural genes lacz and lac y
what is the regulatory gene
codes for repressor protein
what are the two function of the repressor protein
they have 2 binding sites-
1 site- binds to operator
2 site- binds to lactose
what happens when the repressor protein binds to the operator
prevents transcription of structural genes as rna polymerase cant attach to the promoter.
what happens when repressor protein binds to lactose
the tertiary structure of the repressor protein is altered and it can no longer bind to the operator. Structural genes are transcribed as rna polymerase can bind to the promoter
in what conditions will the repressor protein bind to the operator
when lactose is absent in the medium, the protein binds to the operator so the rna polymerase cant bind to the promoter.
what happens when the repressor protein binds to the operator and the rna polymerase cant bind to the promoter
transcription of structural genes cant occur, lactose metabolism enzymes arent synthesised .
in what conditions does lactose bind to the repressor protein
when lactose is present in the medium the bacteria is in,
lactose binds to the second binding site on the repressor protein and distorts the shape so it cant bind to operator and so the rna polymerase can bind to the promoter.
structural genes are translated and 2 enzymes are produced.
what is the function of transcription factors
they bind to specific promoter regions, they then aid or supress rna polymerase attachment to dna- turning on or off gene expression.
within a gene there are non coding and coding regions of dna, what are the two names
non coding- introns
coding- exons
when dna is transcribed, both introns and exons are transcribed, what is the name of the mrna produced
primary mrna
when primary mrna is produced it needs to be edited, what happens when it is edited
introns are removed.
what enzyme is used in the editing and splicing process
endonuclease enzyme
what is the difference between translation and transcription
transcription- Synthesizes RNA from a DNA template, converting the DNA code into complementary RNA (mRNA)
Translation: Synthesizes proteins from an mRNA template, converting the mRNA code into an amino acid sequence in a protein.
