Flashcards in Exam 1 questions/concepts Deck (24):
What are the nonpolar amino acids?
Alanine, Valine, Leucine, Isoleucine, Methionine, Phenylalanine (F), and Tryptophan (W).
What are the polar uncharged amino acids?
Serine (S), Threonine (T), Glutamine (Q), Asparagine (N), and Tyrosine (Y).
(Stony with a Q)
What are the polar charged amino acids?
Aspartic acid - (D), Glutamic acid - (E), Lysine + (K), Arginine + (R), and Histidine (H).
Is Phosphotidyl choline (PC) positive, neutral, or negative?
Is phosphotidyl serine (PS) positive, neutral, or negative?
Is phosphotidyl ethanolamine (PE) positive, neutral, or negative?
Is phosphotidyl inositol (PI) positive, neutral, or negative?
What molecules experience simple diffusion?
1. Small gases (O2 and CO2)
2. Small polar molecules (H2O and Ethanol)
3. Large hydrophobic molecules (Estrogen)
What molecules must go through active transport/facilitated diffusion?
Large polar molecules (glucose)
Charged molecules (amino acids, ions)
What is unique to eukaryotes?
ER: Endoplasmic reticulum
Amino acids buried inside the protein complex are likely _____.
What is the major component of lipid droplets found in adipocytes (fat cells)?
How do non-transmembrane proteins associate with the plasma membrane?
1. Lipid-anchored proteins covalently bonded to a lipid group that resides within the membrane.
2. Peripheral proteins noncovalently bonded to polar head groups of the lipid bilayer.
3. Peripheral proteins noncovalently bonded to an integral membrane protein.
Cells exposed to heat shock increase expression of chaperones. How, exactly, are these events linked?
Hsp70, a chaperone, binds to nascent polypeptides and aids in proper folding. When exposed to
heat shock, nascent polypeptides do not fold as easily and previously folded polypeptides begin to
denature. So, under conditions of heat shock, more chaperones are required and the previously
“extra” Hsp70 that had been bound to and sequestering Hsf1 is now required. Hsp70 releases from
Hsf1. Hsf1 trimerizes and acts as a transcription factor for the up-regulation of chaperones.
What is mediated by a non covalent bond?
Stabilization of protein secondary structures.
What is needed regarding protein folding in the cell?
A protein may require the assistance of both Hsp70 chaperones and chaperonins to
reach its native conformation.
Which process is the slowest?
A. Phospholipid flex (rotating).
B. Lateral diffusion of phospholipids.
C. Transverse diffusion of phospholipids.
D. B and C are similar in speed.
C. Transverse diffusion of phospholipids
What serves as an "eat-me" signal for the engulfment of dead cells by phagocytes?
Externalization of phosphatidylserine.
What is a form of active transport?
Transport of glucose by Na+/glucose cotransporters.
Briefly explain how neurotransmitters released from presynaptic terminals trigger action
potentials on postsynaptic membranes.
Neurotransmitters released from presynaptic terminals bind ligand-gated Na+ channels on
the post-synaptic membranes resulting in Na+ influx (into the cell). If depolarization is
sufficient, the action potential is triggered as the voltage-gated Na+ channels open.
Detergents are commonly used to solubilize integral membrane proteins. Explain why.
Amphipathic detergents interact with membrane lipids to disrupt the membrane. The
hydrophobic transmembrane domains of integral membrane proteins (transmembrane
proteins) are stabilized by the hydrophobic regions of the detergent, and hydrophilic
regions interact with the aqueous environment, allowing the protein to be solubilized.
Some strong detergents can also denature proteins (induce protein unfolding/misfolding). Explain
Strong detergents are charged (as well as amphipathic) and they interfere with noncovalent
bonds in proteins (R-group interactions). This forces apart charged regions of the protein
and can even expose hydrophobic regions leading to misfolding.
Glucocorticoids (hydrophobic molecules) is a type of hormone. In what manner does it interact with its target cell to elicit a cellular response. What is that response?
Glucocorticoids diffuse freely through the PM and interact with receptors inside the cell.
These receptors act as transcription factors (in the nucleus) to increase and/or decrease
expression of certain genes.