Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

UT BME 245L > Individual/Team Exam > Flashcards

Individual/Team Exam Flashcards

1
Q

simple steps of passaging cells

A
  1. aspirate media
  2. add 10 ml of PBS
  3. aspirate PBS
  4. add 4 ml of trypsin/EDTA to cells for 30 seconds
  5. aspirate trypsin/EDTA and place cells in incubator for 4 minutes
  6. add 4 ml of media
  7. add calculated volume of cell suspension to new flask
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

stress relaxation

A

time-dependent decrease in stress under a constant strain

studied by pulling at a constant rate then holding extension constant for 1 minute

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

hysteresis

A

viscoelastic substances dissipate energy (through internal friction/heat) when a load is applied then removed; area of the loop is equal to the energy lost during the unloading cycle

studied by pulling at a constant rate then returning to initial position at the same rate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

creep

A

if you apply a constant force to a viscoelastic material, then the displacement increases over time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

what role does PBS play in passaging cells?

A

removes traces of BCS (bovine calf serum) that inhibit the action of trypsin and removes media

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

what are the two options for seeding cells at a desired density?

A
  1. by volume
  2. by fixed count
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

elastic modulus

A

measure of stiffness/how easily a given material can bend or stretch

studied by pulling at a constant rate; E is found by Hooke’s law of E = stress/strain (of the linear portion of stress vs. strain curve)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

if all stresses are equal, what is the relationship between strains?

A

1/total strain = 1/strain1 + 1/strain2 + …

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

best way to sterilize metal spatula used to manipulate hydrogels in the BSC

A

autoclave

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

best way to sterilize PEG solution before adding cells to it

A

sterile filtering

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

best way to sterilize T75 flasks/96 well plate to grow cells

A

gamma radiation at the manufacturer facility

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

best way to sterilize serological pipette tips

A

gamma radiation at the manufacturer facility

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

best way to sterilize media that you might have contaminated, but need now

A

sterile filtering

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

what does p < 0.05 mean

A

given that the population means are the same, there is a less than 5% chance we could get the same samples

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

what do you conclude if the ANOVA p-value is less than the cutoff, but the post-hoc p-value is greater than the cutoff?

A

you must go with the post-hoc results and claim that the null hypothesis is NOT proven false (cannot reject the null hypothesis)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

using “*” in an ANOVA test finds…

A

how factors interacted with each other

for the pipettor experiment: R will not compare pipettor and volume because not all cases go together (ex: would never dispense 1000 ul with a 200 ul pipettor), but we can force R to do this

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

why do we utilize box plots in statistical analysis?

A

to visualize the overlap of standard error/standard deviation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

cm^3 corresponds to ml and mm^3 corresponds to…

A

ul

ex: 78.54 mm^3 = 78.54 ul

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

dimensions in hemocytometer

A

overall: 3 mm x 3 mm (9 squares of 1 mm x 1mm)

corner square: 4 rows/columns with 0.25 mm divisions

non-corner square: 5 rows/columns with 0.2 mm divisions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

why does the average cell count of the hemocytometer get multiplied by 20,000?

A

volume counted, cells/ml conversion, dilution from trypan blue

we need to multiply to account for the volume that is counted on the hemocytometer (counting number of cells in 0.1 mm^3) and the dilution from trypan blue

when counting, you count the number of cells in 0.1 mm^3 of suspension (1 mm x 1 mm (from the square) x 0.1 mm (height of liquid allowed by hemocytometer)) and would therefore need to multiply by 10,000 to find cells/ml if only counting the cell suspension

BUT we diluted the counting liquid using trypan blue by a factor of 2 (1:1 ratio of cell suspension and trypan blue) so we must multiply by 20,000

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

how do we use trypan blue?

A

live cells have intact plasma membrane –> trypan blue cannot penetrate (will appear as white cells)

trypan blue will penetrate dead cells (will appear as dark blue spots and will not be included in the count)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

what biomechanical property is demonstrated here?:

pilots are held at a constant force of 9 g’s which caused the blood to drain from their head to their feet due to force

A

creep

a constant force led to an increased displacement over time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

what biomechanical property is demonstrated here?:

after carrying out a maneuver that put a lot of force on the body, pilots let up and remove this force, but their blood takes longer to return to their brain than it took to leave it

A

hysteresis

loading (forceful maneuver) and unloading (when the pilots let up and blood returned in a slower manner)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

what biomaterial is the active ingredient in jell-o that causes it to crosslink?

A

gelatin

25
Q

what is the crosslinking mechanism in jell-o?

A

hydrogen bonding

26
Q

what’s the reason that jell-o will not crosslink if certain fruits are added?

A

certain fruits contain enzymes that will break down the gelatin in jell-o so that it cannot form a strong network

27
Q

maxwell model for stress relaxation: what type of time constant indicates faster relaxation?

A

a lower/smaller time constant (tau) means faster relaxation

28
Q

types of natural hydrogel materials and how they are crosslinked

A

gelatin: covalently crosslinked with glutaraldehyde

collagen: dissolve at acidic pH and neutralize pH to crosslink via hydrogen bonding

hyaluronan: modified for free-radical or click reactions

matrigel: warm up to gelatin temperature; hydrogren bonding

fibrin: fibrinogen + thrombin; can also crosslink with genipin/glutaraldehyde

29
Q

when analyzing data using inferential statistics, you make measurements of _______ and perform statistical tests in order to make conclusions about _________.

A

samples; populations

samples are what we can obtain and measure to help form conclusions about populations

ex: to make a conclusion about the entire population of 5 foot tall individuals, we would need to test a sample of them

30
Q

what test on the rheometer can be used to characterize the shear thinning behavior of hagfish slime?

A

frequency sweep

31
Q

airflow in the bsc

A

downward flowing air is STERILE in vertical flow BSCs (what we have)

air becomes non-sterile when it touches anything that isn’t sterile (do not pass anything above an open container that has a sterile interior)

70% of air that the BSC takes in is circulated; other 30% is pumped out

once air comes down, it moves forward and backwards towards grates (do make these grates inaccessible - especially the front gate)

avoid sweeping motion as items are brought into the hood - use gentle, straight motions instead

32
Q

why do we not use horizontal laminar flow hoods?

A

they are not suitable for biohazardous material since contaminated air is blown outward toward the user

33
Q

3 main rules of working in the BSC?

A
  1. know the difference between sterile and non-sterile (non-sterile includes sanitized, disinfected, clean)
  2. understand air flow in the BSC
  3. know where your hands are and have been at all times
34
Q

list of numbers estimated in mechanical testing data

A

E = Young’s modulus, elastic modulus
tau = stress-relaxation constant
EI = flexural rigidity or effective bending modulus
G’ = storage modulus
G’’ = loss modulus
G* = complex modulus

35
Q

what are some ways to work around not having enough cells to seed as planned?

A

reseed cells into more flasks and reschedule the experiment

reduce number of samples (ex: n = 3 instead of n = 4)

36
Q

what are some ways to work around not having enough cells to seed as planned?

A

reseed cells into more flasks and reschedule the experiment

reduce number of samples (ex: n = 3 instead of n = 4)

seed smaller number of cells

37
Q

best way to sterilize metal spatula and tweezers that will be used to move tissue engineering scaffolds?

A

autoclave

38
Q

statistical tests used to determine if one group had a better outcome in an experiment and which one

A

ANOVA and post hoc tukey hsd testing

39
Q

example “materials and methods” sentence for how to describe seeding of cells onto tissue engineering scaffolds

A

100,000 cells were seeded onto PCL, PLGA, and PGS scaffolds (n = 4 each).

make sure to adjust for the context that is given in the problem this is just one example from the practice exams

40
Q

why did we not use pure gelatin as one of the cases in the cell adhesion experiment?

A

gelatin would melt in the incubator at 37 degrees celsius

41
Q

3T3 cells are from which animal?

A

mouse

specifically mouse embryonic fibroblasts that spontaneously immortalized in swiss albino mice

42
Q

what is a sterilization method that is not FDA approved?

A

ultraviolet light exposure

43
Q

describe a scenario where this test would be used: a rheometer is set up to apply a constant 2 degrees of strain at a constant frequency of 1 Hz continuously for 20 min

A

used to determine how long it takes for a prepolymer liquid solution to crosslink into a solid hydrogel

OR: the temperature could be varied to find thermal properties (gelation, glass-transition, melting, etc.)

44
Q

cytotoxicity assay: how could you determine if one experimental group killed ANY cells? if one experimental group killed ALL cells?

A

tests that can be utilized:
1. one-way ANOVA with post-hoc testing
2. student’s t-test with the Bonferroni correction

to determine if ANY cells were killed: if p-value is < 0.05 between experimental group of interest and the POSITIVE control, then there is a different number of cells –> therefore the chemical killed some cells

to determine if ALL cells were killed:
if p-value is > 0.05 between experimental group of interest and the NEGATIVE control, then there is not a different number of cells –> therefore the chemical killed all the cells just as the negative control did

ex: of negative controls for cytotoxicity, no cells or bleach (which kills all the cells)

45
Q

bonferroni correction

A

multiple-comparison correction used when several dependent or independent statistical tests are being performed

adjustment made to p values

46
Q

what is the difference between the mechanical and material properties of tissue?

A

mechanical: force and displacement
material: stress and strain

stress = force/area
strain = change in length/original length

47
Q

what is the toe region and what causes it during the tension test of biological tissues?

A

caused by crimp of collagen fibers

48
Q

covalent crosslinking mechanisms

A

glutaraldehyde

disulfide bonds

thiol-ene click reaction

free-radical acrylate/methacrylate

copper catalyzed alkyne-azide click reaction

strain promoted alkyne-azide cycloaddition

49
Q

what is the percentage of carbon dioxide maintained in the incubator for most mammalian cell culture applications? what is the purpose of the carbon dioxide?

A

5% CO is needed to maintain proper pH in the media (pH = 7.4) in conjunction with the bicarbonate buffers in the media

50
Q

maxwell element

A

spring and dashpot in series

51
Q

kelvin-voight element

A

spring and dashpot in parallel

52
Q

maxwell version of SLS

A

spring in parallel with maxwell element

53
Q

kelvin-voight version of SLS

A

spring in series with kelvin-voight element

54
Q

in series, items can stretch _________

A

independently; therefore, strain is additive and stress is equal

55
Q

how to solve spring/dashpot problems

A
  1. identify stress and strain relationships of the entire system - we will use the summation equation to solve
  2. identify stress and strain of individual branches; if you have a branch with multiple elements, you must solve separately then sub back

3.

56
Q

laplace form of derivatives of stress or strain

A

s * variable (with a bar over it)

57
Q

laplace form of stress or strain

A

variable (with a bar over it)

58
Q

strain rate dependence

A

how the speed in which you apply a force affects how the material reacts

UT BME 245L (1 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions