Cell Signaling Basics
The three sequential steps in which a target cell processes a signal.
What are reception, transduction, and response?
Receptors for nonpolar signals such as steroid hormones are found here.
What is inside the cell (internal receptors)?
The phase of interphase in which DNA replicates.
What is S phase?
This is the main checkpoint at which a cell decides whether or not to divide.
What is the G1/S checkpoint?
The number of chromosomes in a human egg or sperm cell.
What is 23?
Gap junctions in animals and plasmodesmata in plants are used for this type of communication.
What is direct contact?
This effector enzyme converts ATP into the second messenger cAMP.
What is adenylyl cyclase?
In plants, cytokinesis occurs by the formation of this structure between the daughter nuclei.
What is a cell plate?
Cdks are active only when bound to this protein, whose concentration rises and falls through the cycle.
What is a cyclin?
Nonsister chromatids exchange segments in prophase I through this process.
What is crossing-over?
When a local regulator acts on the same cell that produced it, this is the term.
What is autocrine regulation?
Phospholipase C produces these two second messengers from a membrane phospholipid.
What are IP3 (inositol 1,4,5-trisphosphate) and DAG (diacylglycerol)?
The nuclear envelope breaks down, and kinetochores form on each sister chromatid at this stage of mitosis.
What is prometaphase?
The M cyclin-Cdk1 complex goes by this name, and it activates the anaphase-promoting complex (APC).
What is MPF (M phase-promoting factor)?
In this stage, homologous chromosomes separate to opposite poles while each chromosome still has two sister chromatids.
What is anaphase I?
Bacteria release signal molecules in increasing amounts as cell density rises, a process called this.
What is quorum sensing?
A G protein is inactive when bound to this nucleotide and active when bound to this one.
What are GDP (inactive) and GTP (active)?
This is the only phase of the cell cycle that varies in length, and the one from which cells can be shunted into G0.
What is the G1 phase?
Mutated forms of genes that promote uncontrolled cell division are called this.
What are oncogenes?
When the spindle fails to separate homologs or sister chromatids, this error occurs.
What is nondisjunction?
In a bacterial two-component system, the activated surface receptor phosphorylates this protein, which then binds DNA to turn genes on or off.
What is the response regulator?
After dimerizing and autophosphorylating, this receptor type uses adapter proteins to activate the G protein Ras, which starts a MAP kinase cascade.
What is a receptor tyrosine kinase (RTK)?
The 10-nm fiber compacts DNA about this many fold, and the solenoid model has about this many nucleosomes per turn.
What are 7-fold and 6 nucleosomes per turn?
When Johnson and Rao fused a G1 cell with an S-phase cell, the G1 nucleus began DNA synthesis early. This is what it suggested.
What is that molecules in the cytoplasm of S phase cells activate S phase?
An animal has six pairs of chromosomes. Ignoring crossing-over, independent assortment can produce this many chromosome combinations in gametes.
What is 64 (2 to the 6th power)?