inducible operon
cluster of genes that is turned off unless needed. turned on by an inducer
repressible operon
cluster of genes that is on unless not needed. turned off by co-repressor activating an inactive repressor
short stretch of DNA between the promoter and genes that controls transcription of genes. in operons. activators and repressors bind here to increase or decrease gene expression & transcription
operator
the study of nucleic acids and proteins, often focuses on gene expression
molecular biology
genes that are actively expressed all of the time, needed for cell function
constitutive genes
a cluster of genes with one promoter. these genes follow this. all genes in this cluster get transcribed together (all or nothing)
operon
enhancers
in eukaryotes, sequences that bind to activator proteins and loops back to promoter to make initiation complex so genes can be transcribed. it is located upstream (before) the promoter
late stage of lytic cycle
encodes viral capsid (coat on outside of enzyme) proteins and enzymes to lyse the host cell (make it explode) and release viral particles
use gene regulation and transcription to take over host cell. "a piece of bad news wrapped in protein"
viruses
alternative splicing
this creates different mRNAs from the same gene. splices different exons together and results in new proteins. 1 gene can make multiple proteins. don't need 1 gene for every single protein
proteins that interfere with RNA polymerase. mechanism to try to stop an infection from a virus
transcription terminator
translational repressor
binds to mRNA to prevent mRNA from attaching to ribosome.
common promoter sequence, a recognition sequence. how polymerase recognizes it is in the spot to start transcription
TATA box
regulatory proteins
proteins that control whether a gene is active. activator or repressor binds to a operator in prokaryotes. in eukaryotes, they bind to an enhancer or silencer
viral reproductive cycle. 2 stages: early and late
lytic cycle
molecular biology
the study of nucleic acids and proteins, often focuses on gene expression
lytic cycle
viral reproductive cycle. 2 stages: early and late
binds to mRNA to prevent mRNA from attaching to ribosome.
translational repressor
diffuse and light staining chromatin containing DNA for mRNA transcription
euchromatin
in some cells, one X chromosome (from mom) is inactivated and in other cells the other X chromosome (from dad) is inactivated. in females, patchy
mosaic
epigenetics
changes to DNA and chromatin that regulate (inactivate) large regions of genes (even a whole chromosome). regulating gene transcription on a large scale. reversibly altering large portions of DNA and chromatin. reversible and can be passed on to daughter cells. affected by environmental factors. e.g. DNA methylation
co-repressor
binds to an inactive repressor and activates it so repressor binds to operator which blocks transcription. tryptophan does this. turns off repressible operon
in females, one X is inactivated (this is a kind of heterochromatin). this is a mosaic
Barr Body
at 5' end of mRNA to prevent its breakdown. this can be modified (marked to be translated). if it is not modified, mRNA is not translated
5' cap
TATA box
common promoter sequence, a recognition sequence. how polymerase recognizes it is in the spot to start transcription
DNA wrapped around histone
nucleosome
operon
a cluster of genes with one promoter. these genes follow this. all genes in this cluster get transcribed together (all or nothing)
binds to an inactive repressor and activates it so repressor binds to operator which blocks transcription. tryptophan does this. turns off repressible operon
co-repressor
DNA methylation
when C's in promoter are methylated, a methyl group is covalently added to it. methyl groups block RNA polymerase so that gene can't turn on. these methylated genes are inactivated and turns off. type of epigenetic change. these can be inherited and reversed (so they can be adtivated again)
sigma factors
proteins that bind to RNA polymerase and direct RNA polymerase to specific promoters. allows us to turn on related genes all around the cell together at the same time. only in prokaryotes
