Term
| Why is gene regulation important for bacterial cells? |
|
Definition
| Gene regulation allows for biochemical and internal flexibility while maintaining energy efficiency by the bacterial cells. |
|
|
Term
| Name 6 different levels at which gene expression might be controlled. |
|
Definition
1. DNA and chromatin structure
2. Transcription
3. mRNA processing
4. mRNA stability
5. Translation
6. Protein modification |
|
|
Term
| Positive vs. negative control |
|
Definition
| Positive transcriptional control requires an activator protein to stimulate transcription at the operon. In negative control, a repressor protein inhibits or turns off transcription at the operon. |
|
|
Term
|
Definition
An inducible operon normally is not transcribed. It requires an inducer molecule to stimulate transcription either by inactivating a repressor protein in a negative inducible operon or by stimulating the activator protein in a positive inducible operon.
Transcription normally occurs in a repressible operon. In a repressible operon, transcription is turned off either by the repressor becoming active in a negative repressible operon or by the activator becoming inactive in a positive repressible operon. |
|
|
Term
| In catabolite repression, |
|
Definition
| the presence of glucose inhibits or represses the transcription of genes involved in the metabolism of sugars other than glucose. |
|
|
Term
| Basal level transcription |
|
Definition
a low level of transcription, that is driven by the pre-initiation complex alone.
Silencers repress the transcription rate i.e decrease the basal level transcription. |
|
|
Term
| DNase I hypersensitivity sites are typically found |
|
Definition
| approximately 1000 nucleotides upstream of a transcription start site. |
|
|
Term
|
Definition
| are differences in gene expression that are passed on to daughter cells and sometimes even to the progeny of the individual. They are due to alterations in DNA structure (eg. Methylation) and chromatin structure BUT THEY DO NOT ALTER THE DNA NUCLEOTIDE SEQUENCE. |
|
|
Term
| Transcriptional activator proteins stimulate transcription by |
|
Definition
| binding DNA at specific base sequences such as an enhancer or regulatory promoter and attracting or stabilizing the basal transcriptional factor apparatus. |
|
|
Term
| Repressor proteins bind to |
|
Definition
| silencer sequences or promoter regulator sequences. These proteins may inhibit transcription by either blocking access to the enhancer sequence by the activator protein, preventing the activator from interacting with the basal transcription apparatus, or preventing the basal transcription factor from being assembled. |
|
|
Term
| An insulator or boundary element |
|
Definition
| a sequence of DNA that inhibits the action of regulatory elements called enhancers in a position dependent manner. |
|
|
Term
| Acetyltransferase enzymes |
|
Definition
| add acetyl groups to histone proteins preventing the proteins from forming the 30-nm chromatin fiber. Essentially, the chromatin structure is destabilized, which allows for transcription to occur. |
|
|
Term
|
Definition
| refers to different expression of a gene depending on whether it was inherited from the male parent or the female parent. |
|
|
Term
|
Definition
| In organisms that follow this system, there is no cytogenetically recognizable difference in the chromosome contents of males and females. Instead of a sex chromosome that differs between males and females, alleles at one or more loci determine the sex of the individual. |
|
|
Term
| Human vs fly sex determination |
|
Definition
In humans, the presence of a functional Y chromosome determines maleness. People with XXY and XXXY are phenotypically male.
In Drosophila, the ratio of X chromosome material to autosomes determines the sex of the individual, regardless of the Y chromosome. Flies with XXY are female, and flies with XO are sterile males. |
|
|
Term
|
Definition
| specify segment identity—expression of the homeotic genes informs cells of their location or address along the anterior–posterior axis. |
|
|
