Unit 4 Flashcards
What is Juxtacrine Signaling?
Direct cell-to-cell contact. Juxtacrine is gap junctions for animals and plasmodesmata for plants; like passing a note to the person you sit next to.
What is Paracrine Signaling?
Cells are nearby and need a signaling molecule. Paracrine is the stimulation of nerve cells by neurotransmitters and muscle contractions; like a snapchat that goes to the receiver and then goes away.
What is endocrine signaling?
Cells signal distant cells through the bloodstream. Endocrine is the hormones that travel through the circulatory system; like a Facebook post that goes out to everyone, and how they react is up to them.
What type of cell signaling would a covid-19 virus use to infect a healthy human body?
Endocrine
What are the three stages of signal transduction?
Reception, Transduction, Response
What is the role of the ligand in the signal transduction pathway?
Chemical molecules that bond with proteins to pass on a signal.
What is the role of the receptor in the signal transduction pathway?
Membrane protein that bonds with ligands and passes on the signal.
Describe how Phosphatase and Kinase work together in signal transduction pathways.
Phosphatase removes phosphate groups from proteins, but kinases transfer phosphate groups from ATP to other molecules. They are inverses of each other.
What occurs with a G-protein coupled receptor after binding to a ligand?
It changes GDP to GTP and activates the G-protein, which activates another protein. G-protein is like an on/off switch.
What occurs with a tyrosine kinase receptor after binding to a ligand?
Phosphates are attached to tyrosines and bond together to form dimer; can trigger multiple signal transduction pathways at once.
What occurs with an ion channel receptor after binding to a ligand?
The receptor changes shape and allows certain molecules to cross the membrane, the receptor is closed until a ligand binds the receptor.
How are signals amplified after reception?
One enzyme in the pathway can activate several other enzymes or secondary messengers, which makes many intracellular molecules with the signals.
What is positive feedback? Identify two examples of positive feedback loops.
Product of a reaction leads to an increase in that reaction.
What is negative feedback? Identify two examples of negative feedback loops.
Product returns the condition back to its stable target point. Thermoregulation and blood sugar regulation.
What are the three steps of the cell cycle? What occurs in each of these three phases?
Interphase, Mitosis, Cytokinesis; Interphase: the cell performs all of its normal functions except for division, and prepares for division. Mitosis: the cell splits its DNA and creates two genetically identical daughter cells. Cytokinesis: the cytoplasm splits.
What are the phases of interphase?
What occurs in each of these phases?
G1, S, and G2; In G1, the cell grows in size, recovers from mitosis, and increases the number of organelles. In S, chromatids are replicated so that one chromosome has two chromatids. In G2, the cell synthesizes proteins that help it in cell division.
