Chapter 11 Flashcards
Constitutive Genes
Actively expressed all the time
Inducible Genes
Expressed only when their proteins are needed by the cell.
Selective Gene transcription
The cell has control over when it wants specific genes to be expressed.
Transcription factors
Control whether or not a gene is active
Repressor
(Negative regulation) Binds near the promoter to prevent transcription.
Activator
(Positive regulation) Binds near promoter to stimulate transcription.
Virus
Injects its genetic material into a host cell, and often turns that cell into a virus factory.
Lytic life cycle
The host cell immediately begins producing new viral particles after being infected
Lysogenic phase
Dormant phase found in some life cycles. The viral genome becomes incorporated into host cell. Replicated along with the host genome. Later triggered by environmental signal to start virus production.
HIV (Human Immunodeficiency virus
Infective agent that causes Aquired immunodeficiency syndrome (AIDS) in humans
Retrovirus
virus whose genome is a single stranded RNA
reverse transcriptase
After infection, this makes a DNA strand that is complementary to the HIV RNA while also degrading it and making a second DNA.
Number of proteins involved in the uptake of lactase by E. Coli
3 proteins
Inducer
switches on expression in inducible genes
structural genes
The genes that encode the three enzymes for processing lactose in E. Coli
Operon
cluster of genes with a single promoter
operator
in lac operon, is near the promoter and controls transcription of the structural genes.
lac Operon
The lac operon is not transcribed unless latose (or other B galactoside) is the predominant sugar. This rmoves the repressor normally bound to the operator
trp operon
Typ operon is switched off when its repressor is bound to the operator. In this case, the repressor beinds to the DNA only in the presence of a corepressor. Tryptophan functions as the corepressor in this case.