Week 4 Problem Concepts Flashcards
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….
cancer treatments
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
- pre-proinsulin: [signal peptide-BCA]–> produced in rER
- proinsulin: loss of signal peptide and formation of sulfide bonds (2 between B and A, one within A) produced in rER
- 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
- Alpha and beta cells of pancreas are highly vascularized
- increase in blood glucose increases the amount of glucose entering beta cells through GLUT2
- increased glucose increased ATP
- ATP inactivates K channels
- B cell depolarizes
- Voltage gated calcium channels open
- 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
- linear: superficial
- curvilinear: abdomen
what is attenuation? what is the attenuation of water? air?
how much an object decreases a sound wave (higher attenuation = less signal)
water: 0
air: 12
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
does Type I or II diabetes have a stronger familial correlation? genetic?
type II
What is the function of human leukocyte antigen (HLA) gene complex?
set of genes, some of which code for antigens that are presented by cells
which locus within the HLA complex is associated with T1DM?
DR locus
which alleles within the DR locus of HLA increase risk of T1DM? how?
DR3: B-cells present antigens that are targeted by antibodies
DR4: antigen present that triggers production of antibodies against insulin
which allele within the DR locus of HLA protects against T1DM?
DR2
what is MODY, cause? prevelance?
Maturity onset diabetes of the young. a type of DM (NOT T1DM or T2DM) caused by genetic defects in B cels. 1-2% of diabetes cases
MODY 2 cause
mutation in glucokinase of B-cells (increased B-cell glucose threshold)
MODY 1,3,4,5,6 cause
all caused by mutations of genes in the same pathway; delayed response to glucose uptake
How do you treat MODY? how does it work? is it effective?
treat with sulfonylureas. high effective monotherapy. Increase intracellular calcium and increases proinsulin secretion
what was the goal of the genome-wide association study?
determine if genetic differences predispose people to certain diseases
what did the GWA study conclude with diabetes? 2
> 50 SNPs identified to increase risk for diabetes (slight increase)
new genes have been associated with diabetes
what are 3 weaknesses of the GWA study
association does not mean causation
not generalizable
data collected in 1980s
name two genes that were ORIGINALLY identified in GWA study to increase risk of diabetes
TCF7L2 gene
FTO gene
what is the role of TCF7L2 gene? increased risk for diabetes?
TF in Wnt signaling; proglucagon synthesis
Homozygous carriers 2x increased risk for T2DM
what is the role of TFO? is it an inependent risk factor for diabetes?
originally thought to be an independent risk factor for diabetes. was found to be associated with obesity (a secondary risk factor for diabetes). Fxn: methylates RNA and causes preferential production of fat (epigenetic)
how is lifestyle associated with epigenticc; give 2 diabetes related examples
increase carbs: influence histone modification
stress can change methylation patterns
diabetes is a complex disease; what does that mean
diabetes is influenced by biolgical, behavioral and environmental factors
what causes T1DM? how common?
immune system destroys beta cells; less than 10% of popn with diabetes
what causes T2DM? how common?
insulin resistance and decreased insulin production. more than 90% of popn with diabetes
what causes gestational diabetes? how common?
placental hormones increase amount of glucose in blood. 3-5% of pregnant women
what is polydipsia?
thirst
what is polyuria?
frequent urination
what Fasting blood glucose is normal? diabetic?
125 mg/dL= diabetes
70-100 =normal
what HbA1C value is normal? diabetic?
normal: 6.5%
what is the difference between IGT and IFG
IGT: impaired glucose tolerance
IFT: imparired fasting glucose
both refer to a pre-diabetic state, but represent different mechanisms of insulin resistance
metformin: MOA
inhibits gluconeogenesis in liver. very effective monotherapy
SGLT2 inhibitors: MOA
prevent glucose reabsorption in kidneys
TZD (MOA):
decrease insulin resistance of skeletal muscle/fat
what are the two types of insulin?
Note: insulin should be used always in T1DM and only in special circumstances in T2DM:
Basal insulin: long acting
bolus insulin: fast acting, after meal
hypoglycemia is when blood glucose is below
Below 70 mg/dL