Flashcards in Week 4 Problem Concepts Deck (149)
Intermediate filaments: fxn and classes
Fxn: resist mechanical stress (most durbale of all filaments)
Classes: nuclear lamins, keratin filaments, vimentin filaments, neurofilaments
Role of nuclear lamins (3)
found in nucleus of ALL cells. Play a role in gene expression, differentiation, cell cycle
Progeria: cause, symptoms
mutation in nuclear lamins (Lamin A). wrinkling of skin, kidney issues, MSK degeneration (Benjamin button)
Microtubule Fxn: 2
movement within cell, cilia/flagella
MT have a + end and - end. whats the difference?
(+): beta tubulin, more likely to grow
(-): alpha tubulin, more likely to shrink
Motor proteins associated with MT? which is used in flagella and cilia movements?
Dynein (move towards - end, towards centrosome/nucleus), seen in flagella and cilia
Kinesin (move toward + end, cell periphery)
what is the role of basa bodies?
serve as MT organizing center for cilia
dynamic instability is associated with..role
MT. they can grow or shrink at + end (GTP=grow, GDP=shrink), helps "search" for proteint to bind to
Taxol: effects? use?
cancer treatment; stabilizes MTs
B/c MT play a major role in cell division (separates chromosomes) they are often targets of....
Colchicine: effects? use?
prevents MT polymerization; cancer treatment
Vinblastine: effects? use?
prevents MT polymerization
Actin is composed of...ATP bound?
actin monomers combined to form 2-stranded helix. free actin is ATP bound. Actin monomers in filaments are ADP bound
Actin filaments play a role in making what 5 structures?
Stress fibers, microvilli, contractile ring, lamellipodia, filopodia
Congential Myopathy: cause? symptoms?
skeletal muscle weakness caused by mutation in muscle-specific actin
Insulin triggers glucose uptake in what three cell types?
adipose, liver, muscle
describe insulin signaling
Insulin=>RTK=>IRS-1=>PI-3K=>GLUT4 containing vesicle exocytosed
describe the process of insulin production
1. pre-proinsulin: [signal peptide-BCA]--> produced in rER
2. proinsulin: loss of signal peptide and formation of sulfide bonds (2 between B and A, one within A) produced in rER
3. mature insulin: Cleavage of C-peptide within vesicle
describe the storage form of insulin. where is this seen? when is it undone?
3 AB/AB dimers of insulin surrounding a Zn ion. seen in storage vesicles. undone once contents of vesicle are released
compare half-life of insulin vs. C-peptide
insulin has a short half life, but C-peptide is very stable and can be used as a measure of insulin production
pro-enzyme convertase and insulin: role, location
used to convert pro-insulin to insulin. located within vesicle
what is the difference between GLUT2 and GLUT4
GLUT4 is the only insulin sensitive glucose transporter (seen in muscle cells, liver cells, adipocytes). GLUT2 is located in Beta cells (insulin producing) of pancreas and play an important role in insulin release
describe the signal cascade associated with insulin release from beta cell
1. Alpha and beta cells of pancreas are highly vascularized
2. increase in blood glucose increases the amount of glucose entering beta cells through GLUT2
3. increased glucose increased ATP
4. ATP inactivates K channels
5. B cell depolarizes
6. Voltage gated calcium channels open
7. Ca binds insulin vesicle and insulin released
describe insulin release over time?
biphasic. insulin is released in two phases: phase 1=short burst, phase 2=prolonged
(glucagon release is also biphasic)
In ultrasound: high f gives? low f gives?
high f=better resolution
low f= better depth/penetration
what are the four ultrasound probes? uses?
-phased array: adbomen, cardiac
-endoluminal: vaginal, oral, rectal
what is attenuation? what is the attenuation of water? air?
how much an object decreases a sound wave (higher attenuation = less signal)
what are the modes of US?
-A mode: out dated
-B mode: babies!
-M mode: beach
-Pulsed Wave Doppler
-Color doppler: red=towards, blue=going away
-Power doppler: tells if you have flow
what is the piezoelectric effect
this is how ultrasound works. the crystal in the US converts electrical signal to sound waves and a sound waves back to electrical signal