1.4 Flashcards
RNA polymerase
enzyme that builds polymers of RNA
always adds new nucleotides to the 3’ end of the growing mRNA
where does RNA polymerase attach to a gene to initiate transcription?
the promoter
promoter
a region of DNA upstream of a gene where relevant proteins (such as RNA polymerase and transcription factors) bind to initiate transcription of that gene
which of the two strands of DNA is used in transcription?
noncoding/template strand
how does RNA polymerase know when to stop transcribing on the template strand?
transcription proceeds through terminator sequence, causing RNA polymerase to detach from DNA and release the transcript
parts of transcription
initiation
elongation
termination
what is the TATA box?
a DNA sequence
type of promoter sequence
able to define the direction of transcription and also indicates the DNA strand to be read. Proteins called transcription factors can bind to the TATA box and recruit an enzyme called RNA polymerase, which synthesizes RNA from DNA.
transcription factors
proteins involved in the process of converting, or transcribing, DNA into RNA. Transcription factors include a wide number of proteins, excluding RNA polymerase, that initiate and regulate the transcription of genes.
differential gene expression
the expression of different sets of genes by cells with the same gene
control elements (sometimes known as gene switches)
generic term for a region of dna, such as a promoter or enhancer adjacent to (or within) a gene that allows the regulation of gene Expression by the binding of transcription factors.
can be found before the promotor and serve as binding site for transcription factors that regulate transcription
are non-coding DNA - the serve as binding sites for transcription factors that regulate transcription
“general transcription factor”
transcription factors that act at the promoter of all genes
what is needed to regulate expressions for genes that are not transcribed/expressed all the time?
transcriptional activators or enhancers
proximal
located near the promoter
distal
located farther away from the promoter
when activators are bound to enhancers, transcription is…
on
some control elements bind to transcription factors called repressors, what affect would repressor binding have in transcription?
it would prevent transcription from happening by binding to control element DNA or interfere with activators
enhancer
short (50–1500 bp) region of DNA that can be bound by proteins (activators) to increase the likelihood that transcription of a particular gene will occur
ea enhancer is composed of about 10 control elements
it is the particular combination of control elements in an enhancer associated with a gene (rather than a unique control element) that is important in regulating a gene
point mutation
a change in a single nucleotide pair of a gene
nucleotide pair substitution mutation types
silent
missense
nonsense
silent mutation
substitution
no effect on amino acid sequence
missense mutation
substitution
range of affects depending on location and identity
nonsense mutation
substitution
affect depend on the location of the new stop codon
nucleotide-pair insertion/deletion mutation
frameshift - causing immediate nonsense or extensive missense
usually cause protein to be nonfunctional
