Lecture 1 CC
If water is a bigger molecule than sodium, why won't sodium pass through the plasma membrane?
The charge of the Na+ can't get in because its polar and water is more non-polar
What specifically is the reason that the threshold potential is ~-50 mV?
VGC on cells are sensitive to their electrical environment. When enough + ions come into the cell, this causes a change in the conformation of VG channels to open and allow things to move around
How to primary messengers work?
Ligand binds to the receptor, the receptor protein translates that into a cellular response
____ is higher in the ECF and ____ in the ICF
Sodium (ECF) and Potassium (ICF)
What is the difference between meiosis and mitosis?
Meiosis goes through 2 rounds of division, creates haploid gametes. Mitosis goes through one cell of division, daughter cells are genetically equivalent to the parent cell
What is a basement membrane for and what are they composed of?
Separating tissue, giving structural integrity. Composed of ECM (proteins, glycans, glycoproteins, some cells, lipids)
What are key differences between primary and secondary messengers?
Primary=ligands that bind to receptors, larger than 2ndary, fewer of them. Secondary=amplify and spread, rapid
How do IP3/DAG interact with calcium?
IP3 binds to calcium channels on organelles releasing calcium
_____ molecules can move easily through the plasma membrane
Hydrophobic & small, uncharged (e.g., O2, CO2, N2, H2O, Urea, Glycerol)
What are the four phases of the cell cycle? What occurs during these phases?
G1 phase-gap
S phase- DNA synthesis
G2 phase- RNA and protein synthesis
M phase- mitosis occurs
Contrast the differences between protein and glycans in terms of composition, synthesis and functions.
What is most responsible for maintaining the resting threshold potential?
How does cAMP work as a secondary messenger?
Primary messenger>activates G protein (the subunit) >activates adenylyl cyclase (enzyme in the membrane) > activates cAMP from ATP
A short event marked by the rapid change in the electrical potential of a cell along a trajectory
What occurs at the G1 checkpoint? When does it occur?
Check for cell size, nutrients, growth factors, DNA damage. Occurs during G1
What is the purpose of UPR and what are the three major outcomes?
UPR is used to safeguard protein translation. If there is stress or a problem, there can be a lump of unfolded proteins. Stop cell cycle, start repair, apoptosis.
Which would generate a faster cell response, a secondary messenger created by an enzyme (DAG, IP3…) or ion-based secondary messengers that cross membranes?
How do ions work as secondary messengers?
_____ molecules cannot move through the membrane.
Large, uncharged & ions (e.g., glucose, sucrose, H+, Na+...)
When does the spindle assembly checkpoint occur? What does it do?
Occurs in M phase and checks for chromosome attachment to spindle
How is a cell cycle checkpoint similar to the UPR?
Both sense to see if something is right or wrong. If it is wrong, it slows everything down and tries to fix it with proteins. If it doesn't work, they signal for apoptosis.
How might the movement of sodium from an area of high concentration to low concentration be influenced if the area of low sodium had high amounts of calcium?
They can repel because like charges (too much positive) can repel
How does IP3/DAG work?
Primary messenger > raises GTP concentrations > activates phospholipase C > cleaves phospholipids into IP3 and DAG > IP3 goes to cytoplasm, DAG activates protein kinase C (or other proteins)
What is a threshold potential?
The critical level to which the membrane potential must be depolarized to initiate an action potential
What occurs during G2 checkpoint? When does it occur?
Checks for cell size and DNA replication. End of G2 phase