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Cell Biology - Summer 2023 > Theme 1 > Flashcards

Theme 1 Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

what is a cell?

A

the fundamental unit of life

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2
Q

what is needed to grow/culture cells?

A

glucose and nutrients, insulin, growth factor (serum) –> for growth
trypsin –> to break cells apart
EDTA –> sponge
at 37 degrees in CO2 for pH balance

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3
Q

what are primary cells? adv and disadv.

A

cells directly from the body
more accurate for observing diseases/reactions etc.
cannot grow indefinitely

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4
Q

what are cell lines? adv and disadv.

A

transformed immortal cells
grow indefinitely and are more versatile
potentially cancerous (genetic differences to primary)

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5
Q

what are HeLa cells? adv and disadv.

A

immortal cells from henrietta lacks
first human cell line
good for research
but illegal/ethical reasons to not use

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6
Q

what are HeLa cells? adv and disadv.

A

immortal cells from henrietta lacks
first human cell line
good for research
but illegal/ethical reasons to not use

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7
Q

what is contact inhibition?

A

when cells stop dividing due to lack of space (not cell line)

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8
Q

what is the role of trypsin?

A

break apart cells so you can replate them

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9
Q

what is the hayflick limit?

A

how many times cells can divide before senescence
determined by the telomere length

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10
Q

what is a fibroblast?

A

connective tissue cells

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11
Q

what does it mean for a cell to be transformed?

A

behaves differently because of mutations to the cell

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12
Q

what are the differences between normal and transformed fibroblasts?

A

hair-like processes, larger, overlap, rounded, no pattern to growth, no contact inhibition

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13
Q

what is the difference between symmetrical and asymmetrical cell division? importance of each.

A

symmetric = 1 cell –> 2 identical cells
asymmetric = 1 cell –> 2 diff cells or 1 same 1 diff cells
symmetric important for renewal, by primary/ immortalized cells.
asymmetric important for differentiation, by adult stem cells.

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14
Q

what are stem cells?

A

cells that can divide into any cell in the body

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15
Q

what are adult stem cells?

A

cells that can divide into any cell for a specific organ/function (progenitor or functional cells)

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16
Q

what are embryonic stem cells?

A

stem cells from the embryo, used to create organelles

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17
Q

what is stem cell renewal?

A

during symmetric and asymmetric division, divide into a cell identical to the “mother” cell

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18
Q

what are differentiated cells?

A

during asymmetric division, divide into a cell different to the “mother”.
in its final stage of division/ready for job/function

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19
Q

what is the difference between multipotent and pluripotent?

A

pluripotent = can divide into all cell types (germ layers)
multipotent = can divide into some but not all cell types

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20
Q

what is necessary for culturing ESC’s?

A

embryos –> inner cell mass (aka blastocyst) –> fibroblast feeder –> trypsin –> sieve –> feeder cells (again, re-plated)

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21
Q

what is the purpose of culturing ESC’s?

A

induced to create pluripotency/precursors for various cell types

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22
Q

why do we use adult stem cells instead of embryonic stem cells?

A

maintain/repair tissues, embryonic can only create organelles (not actual organs)

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23
Q

what is the pathway of adult stem cell differentiation?

A

adult stem cell (crypt) –> migrate (out crypt) –> differentiated cell (villi) –> death (top of villi)

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24
Q

what is the distinction between a stem cell and a differentiated cell?

A

differentiated cell is at the last stage, stem cells continue to divide

25
Q

what is a stem cell niche?

A

the few cells surrounding (adjacent to) stem cells, used to alert stem cells to differentiate or renew

26
Q

do all tissues have stem cells?

A

yes, except for neurons and nerves. (this is why when they are damaged, they do not repair themselves)

27
Q

how can you go backwards from differentiated cells to pluripotent stem cells?

A

induced pluripotency (done by reprogramming)

28
Q

what are Oct4, Sox2, Lkf4 and c-Myc? What do they do?

A
  • Yamanaka/transcription factors
  • introduced to induce pluripotency (artificial overexpression in differentiated cells)
  • c-Myc = cancerous and may disrupt the cell cycle
29
Q

what are induced pluripotent stem cells?

A

iPS cells
adult stem cells that have been changed to be pluripotent –> reprogrammed fibroblasts

30
Q

what is the medical application of iPS?

A

use for transplantation, won’t be rejected because it’s your own cells, and will not have ethical concerns.

31
Q

what are the basics of a compound microscope lens?

A

contains 3 lenses to help focus
1. condenser
2. objective
3. ocular

32
Q

how does the size of an object correspond to which microscopy technique should be used?

A

animal/plant cells = brightfield
atoms and intracellular components = electron

33
Q

what is resolution? how is it derived?

A

D = 0.61 gamma/ Nsin alpha
how close things can be together where the are still differentiable as 2 things.

34
Q

what is numerical aperture?

A

bottom (N sin alpha).
1/2 angle and refractive index of light.

35
Q

what changes D?

A

any of the variables, D is smaller when the top is decreased or the bottom is increased.

36
Q

what are the refractive properties?

A

oil/glass = refractive.
how light bounces off that surface, of the medium between specimen and objective lens.

37
Q

what is phase contrast microscopy?

A

better quality than brightfield (for intracellular, outside will have a halo).
for live, unstained cells.
changes light phases, out of sync/has interference.

38
Q

what is fluorescence?

A

a specific colour/wavelength excites electrons to express a different colour. uses dichroic mirrors, and in immunofluorescence, uses antibodies.

39
Q

what is a stoke shift?

A

the difference between the peak of the excitation wave and the emission wave.
the bigger the stoke shift, the more different the colour is.

40
Q

what is the relationship between energy of a photon, wavelength and colour?

A

increased energy = short wavelength = more purple (UV)

41
Q

what is the light path of a fluorescent microscope compared to normal?

A

light –> excitation light –> dichroic mirror –> objective lens –> specimen.
specimen –> emission light –> objective lens –> dichroic mirror –> emission filter –> emitted light –> ocular lens –> detector.

42
Q

what is an antibody?

A

made of proteins, bind to proteins they were designed to recognize

43
Q

how are antibodies made?

A

from primary cells (spleen) that fought antigens

44
Q

how can antibodies be used for research?

A

detect disease (immunobiology) –> detect and show (immunofluorescence)

45
Q

monoclonal vs polyclonal antibodies?

A

detects 1 vs detects >1 disease.

46
Q

how do you make monoclonal antibodies?

A

myeloma (cancer) + spleen (with antigens) = immortalized antibodies (in HAT medium).
myeloma alone will die in HAT medium.
spleen alone will die due to hayflick limit.

47
Q

what are antigens?

A

disease cells

48
Q

what are epitopes?

A

attachment sites for specific antibodies on antigens

49
Q

what is dual labelling microscopy?

A

uses 2 antibodies (with 2 fluorochromes) –> 2 microscopy filters (one for each fluorochrome) –> digitally overlay images

50
Q

what is green fluorescent protein? how is it used?

A

GFP = fluorescence from jellyfish.
bioluminescence with a chromophore (excited with blue light, emits green light) (beta-barrel).
transfected into live cells to fluoresce/image them.

51
Q

what is confocal microscopy? what does confocal mean?

A

laser scanning, 3D reconstruction + clarity, focuses in-focus light through pinhole (higher intensity), rejects out-of-focus light from the image.
confocal = same foci (aka block’s out out-of-focus light with pinhole)

52
Q

what is conventional fluorescence vs confocal?

A

changes intensity/focus of light for better/sharper quality.
eliminates out-of-focus light to make a clearer image.

53
Q

what is FRET? How does it work?

A

fluorescence resonance energy transfer (uses CFP and YFP), excitation from one fluoro –> emission excites #2.
shows/measures protein interactions, if interaction is present, colour #2 will be expressed.

54
Q

what is two-photon excitation microscopy?

A

two photons fired almost instantaneously –> no cone of excitation light but emits the same.
for thicker samples without the need for pinholes.

55
Q

what are the two basic types of electron microscopy?

A

TEM (transmission) and SEM (scanning/scattered)
TEM = detailed interior sections of the cell
SEM = detailed overview, surface details (3D)

56
Q

why does electron microscopy have increased resolution?

A

uses electrons/energy, instead of light.
D = 0.61 gamma / alpha
no Nsin so D is increased.

57
Q

how does immunoelectron microscopy work?

A

antibody to detect changes in charge.
detects specific proteins using antibodies.

58
Q

when would you use each microscopy technique over others?

A

brightfield = cheap and can be done on live cells
confocal = for sharper images
fluorescence = more than 1 protein/cell structure
electron = whole cell/more detail
FRET = detect protein interactions

Cell Biology - Summer 2023 (1 decks)

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