Week 9
Helix-turn-helix, leucine zipper, helix-loop-helix, and zinc finger proteins.
What are the motifs that bind to cis-regulatory sequences?
This is one of the most important characteristics of a lipid bilayer.
What is fluidity?
A negatively charged ion is known by this term.
What is an anion?
These are the two main types of membrane transport proteins that move substances across the cell membrane; one moves molecules down their gradient without energy, and the other uses energy to move molecules against the gradient.
What are channels and transporters?
These two types of regulatory proteins control gene expression by either increasing transcription by helping RNA polymerase bind to DNA or decreasing transcription by blocking RNA polymerase or recruiting inhibitory complexes.
What are activators and repressors?
These structures are used as model systems to study membranes experimentally.
What are liposomes?
Channels form these structures that extend across the lipid bilayer.
What are pores?
These membrane proteins move one substance across the membrane by using the energy stored in the movement of another substance, often linking sodium transport to nutrient uptake like glucose.
What are coupled transporters?
One of these operons is typically turned on by the presence of lactose and off when glucose is available, while the other is typically on by default but turned off when tryptophan is abundant.
What are the differences between the Trp operon and the Lac operon?
The fluidity of a lipid bilayer depends primarily on these two factors.
What are composition and temperature?
In this conformational state, a transporter’s binding site is exposed to the outside of the cell.
What is the outward-open state?
One of these channels opens or closes in response to changes in membrane potential, allowing ions to flow when a threshold is reached, while the other is a broader category of membrane proteins that allow ions to pass based on stimuli like ligands, mechanical stress, or voltage changes.
What is the difference between voltage-gated channels and ion channels?
This is the process in which multiple transcriptional regulators bind to nearby DNA sites or on a nucleosome in a coordinated manner, increasing stability of binding and enhancing gene expression.
What is cooperative binding of regulators in the nucleosome?
These enzymes in the plasma membrane are activated by extracellular signals to cleave specific phospholipids.
What are phospholipases?
These cells contain symporters driven by the sodium gradient across the plasma membrane.
What are intestinal and kidney epithelial cells?
These are the three main types of passive transport across a membrane: one allows small nonpolar molecules to pass directly through the lipid bilayer, another uses protein channels, and the third uses carrier proteins to move substances down their gradient.
What is simple diffusion, channel-mediated diffusion, and facilitated diffusion?
This biological concept describes a cell’s ability to rapidly adjust which genes are expressed or silenced in response to environmental changes, stress signals, or developmental cues.
What is dynamic adaptability (changing of gene expression in response to internal and external stimulation)?
These proteins are abundant in the outer membranes of bacteria, mitochondria, and chloroplasts.
What are beta-barrel proteins?
Cytosolic enzymes function best at this type of pH.
What is a close-to-neutral pH (~7.2)?
This type of passive transport shows a linear increase in transport rate as concentration increases because molecules move directly through the lipid bilayer without saturation, while another type shows a saturable, hyperbolic curve due to protein involvement reaching Vmax.
What are the differences in kinetics between simple diffusion and transporter-mediated diffusion?