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BMS241 final exam > Topic 11 - Cellular Communities: Tissues, Stem Cells, and Cancer > Flashcards

Topic 11 - Cellular Communities: Tissues, Stem Cells, and Cancer Flashcards

1
Q

extracellular matrix greatly strengthens plant cells and is made of…?

A

cellulose & polysaccharides (lignin & pectin)

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2
Q

turgor pressure is what?

A

osmotic pressure in plant cells (crisp lettuce)

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3
Q

What gives the Plant Cell Wall Its Tensile Strength

A

cellulose microfibrils

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4
Q

T or F - cellulose is the most abundant organic macromolecule on Earth

A

true

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5
Q

T or F - The orientation of cellulose microfibrils within the plant cell wall influences the direction in which the
cell elongates

A

true

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6
Q

What directs the deposition of cellulose in the plant cell wall?

A

microtubules

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7
Q

T or F - cellulose microfibrils are deposited on the exterior, directly parallel to underlying microtubules

A

true

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8
Q

It is traditional to distinguish four major types of tissues in animals: con- nective, epithelial, nervous, and muscular. But the basic architectural distinction is between … tissues and the rest.

A

connective

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9
Q

Animal Connective Tissues Consist Largely of

A

the extracellular matrix

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10
Q

the tensile strength in animal connective tissue comes from …?

A

collagen

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11
Q

Mammals have about ?? different collagen genes, coding for the variant forms of collagen required in different tissues

A

20

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12
Q

Collagens constitute ??% of the total protein mass in a mammal—more than any other type of protein

A

25%

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13
Q

The characteristic feature of a typical collagen molecule is its ?

A

long, stiff, triple-stranded helical structure

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14
Q

The connective-tissue cells that manufacture and inhabit the matrix go by various names according to the tissue: in skin, tendon, and many other connective tissues they are called …?

A

fibroblasts

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15
Q

The connective-tissue cells that manufacture and inhabit the matrix go by various names according to the tissue: in bone, they are called …?

A

osteoblasts

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16
Q

Collagen is synthesised in the cell and exported as a …? Cleaved by what?

A

procollagen - cleaved by extracellular Procollagen proteinases

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17
Q

Collagen analogy…?

A

Collagens are like ropes or the steel bars in a slab of concrete: anti-stretch

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18
Q

Patients with genetic defects in procollagen proteinases?

A

Lower tensile strength and extremely stretchy tissues (man with stretchy face)

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19
Q

?? organise the collagen matrix, and the organisation of the matrix determines the positioning of ??

A

fibroblasts

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20
Q

What links the cells with the extra cellular matrix?

A

fibronectin

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21
Q

Remember structure of fibronectin… (hint: hand analogy)

A

like thumb & index finger attached to wrist - disulphide linked (integrin dimers) hold collagen fibril

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22
Q

T or F - Integrin active state can be triggered by binding to an extracellular matrix molecule (such as fibronectin) or to intracellular proteins that then link it to the cytoskeleton

A

true

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23
Q

leucocyte adhesion deficiency is caused by what?

A

people who lack integrins on white blood cells help those cells to crawl out of blood vessels at sites of infec-
tion so as to deal with the marauding microbes

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24
Q

While collagen provides tensile strength to resist stretching, a completely different group of macromolecules in the extracellular matrix of animal tissues provides the complementary function, resisting compression and serving as space-fillers. These are the…? what structures do they link to?

A

proteoglycans, link to glycosamoniglycans (GAGs)

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25
The negative charge on the GAGs attracts ... & ...?
cations like Na+ -> water -> ++ swelling pressure
26
GAGs & collagen work together. how? tissue eg's
GAGs: swelling pressure + collagen: tensile strength = tough, resilient, and resistant to compression eg. cartilage matrix in knee joint
27
The majority of cell types in the body are organized into...?
epithelia (skin, gut...)
28
What molecules allow ECM to modulate cell behaviour? These are also important in resisting compression.
proteoglycans
29
What are the 5 types of epithelia? eg. of 2 type...
``` SSSCC Simple - gut lining Stratified - skin Squamous - Columnar - small intestines cuboidal - ```
30
Epithelial cells are ... and rest on a ...?
polarised & basal lamina (cool SEM of chick embryo basal lamina)
31
A sheet of epithelial cells has an 2 surfaces. One is 'free' and the other sits on the basal lamina
apical surface and basal surface
32
Define polarized... eg.
spatial differences in the shape, structure, and function of cells. ie. one side has different properties to the other eg. neuron or epithelial cell
33
The basal lamina is usually tough, consisting of interwoven ... & ...?
Type IV collagen and Laminin
34
Know figure 20-22 (MCQ)...
easy
35
The membrane polarisation of epithelial cells is established by ...?
tight junctions
36
Cytoskeleton-linked Junctions Bind Epithelial Cells Robustly to One Another and to the Basal Lamina. which 3 are they? Remember figure 20-22 (MCQ figure)
1. adherens junctions 2. desmosomes 3. hemidesmosomes
37
Adherens junctions and desmosomes are both built around transmem- brane proteins that belong to the ... family?
cadherins
38
A cadherin is a transmembrane molecule that undergoes extracellular ... reactions with cadherin on an adjacent cell
homophilic (binding of like to like)
39
At an adherens junction, cadherins are tethered via adaptors to ... filaments
actin
40
Formation of the neural tube; the scanning electron micrograph shows a cross section through the trunk of a two-day chick embryo. Part of the epithelial sheet that covers the surface of the embryo has thickened, has rolled up into a tube by ...?
apical contraction
41
At a desmosome, by contrast, a different set of cadherin molecules are anchored inside each cell. These cadherins connect to ... filaments; specifically to ...?
intermediate filaments - keratins
42
Hemidesmosomes anchor the keratin filaments in an epithelial cell to the basal lamina. The linkage is mediated not by cadherins, but by
integrins
43
T or F - Gap junctions in many tissues can be opened or closed as needed in response to extracellular signals.
true
44
The neurotransmitter ... for example, reduces gap-junction communication within a class of neurons in the retina in response to an increase in light intensity
dopamine
45
The counterpart junction in plant cells (the only junction in plants) of gap junctions is called ...?
plasmodesmata
46
Connexon proteins form ?
open channels between adjacent cells ie. gap junctions
47
Moreover, in almost all adult tissues, cells are continually dying and being replacedE;CtBh3ro2u1g.h3o4u/t2th0i.s3h4urly-burly of cell replacement and tissue renewal, the organization of the tissue must be preserved. Three main factors contribute to this stability...
1. cell communication: 2. selective cell-cell adhesion: 3. cell memory:
48
How many cells in the human body?
20 - 100 trillion
49
Different Tissues Are Renewed at Different Rates. Times for the following: bone, neuron, epidermis, RBCs
bone - 10 yrs neuron - persist forever epidermis - 2 months RBCs - 3 months
50
Which differentiated cells that need continual replacement are themselves unable to divide?
RBCs, surface epidermal cells & absorptive goblet cells - terminally differentiated
51
Define terminally differentiated...
Many of the differentiated cells that need continual replacement are themselves unable to divide ie they lie at the dead end of their developmental pathway
52
The gut epithelium as an example of stem cell renewal of tissues. THIS MAY BE A SAQ IN EXAM - know it well! Remember cells of the gut (SI) epithelium & how dividing stem cells give rise to terminally differentiated epithelial cells...
draw...figure 20-36 Paneth cells -> secrete anti-bacterials Enterendocrine cells -> gut hormones Goblet cells -> mucous Brush border cells -> absorb nutrients via microvilli Stem cells -> dividing precursor cells -> nondividing terminally differentiated cells
53
The Wnt protein does what?
serve to keep the stem cells and precursor cells at the base of each intestinal crypt in a proliferative state
54
Define pluripotent...
embryonic stem cells (ESCs) from ICM that retain unrestricted developmental potential ie. stem cell that has the potential to differentiate into any of the three germ layers
55
Define multipotent...eg...
potential to differentiate into multiple, but limited cell types. For example, a multipotent blood stem cell is a hematopoietic cell (blood stem cell)
56
Define totipotent...
the ability of a single cell to divide and produce all of the differentiated cells in an organism eg. zygote cells
57
Define clone...
set of individuals that are genetically identical by virtue of their descent from a single ancestor
58
Define therapeutic cloning...
...embryo -> culture -> various personalised ES cells -> tissue repair
59
Define reproductive cloning...
...embryo -> foster mother -> offspring genetically identical to the nuclear donor
60
Transgenic expression of three genes in human adult fibroblasts will revert them to embryonic stem cell character. what are these cells called? what are the 3 genes?
induced pluripotent stem cells (iPS cells) - Oct 3/4 - Sox2 - Klf4
61
Cancer cells are defined by two heritable properties: they and their progeny:
1. proliferate in defiance of the normal constraints | 2. invade and colonize territories normally reserved for other cells
62
If cells break the 1st property: proliferate in defiance of the normal constraints - what is caused?
benign tumour
63
A tumor is cancerous only if its cells have the ability to invade surrounding tissue, in which case the tumor is said to be ...?
malignant
64
Define metastases...
Malignant tumor cells with this invasive property can break loose from the primary tumor, enter the bloodstream or lym- phatic vessels, and form secondary tumours
65
Define epidemiology...
the statistical analysis of human populations that is used to look for factors that correlate with disease incidence
66
In order to produce metastases, cancer cells must be able to: (5 steps)
1. migrate 2. Digest the ECM of the basal lamina 3. Enter the bloodstream 4. Exit the bloodstream 5. Colonise and thrive in a new environment
67
T or F - In the great majority of human cancers, however, viruses do not appear to play a part
true
68
By far the most important environmental cause of cancer in the modern world, however, is ...?
tobacco-smoking
69
T or F - Cancer is fundamentally a genetic disease
true
70
Cancer differs from other genetic diseases in that the mutations underlying cancer are mainly germ-line or somatic?
somatic
71
Define genetic instability...
human cancer cells mutations that interfere with the accurate replication and maintenance of the genome and thereby increase the mutation rate itself
72
How many gene mutations in a hunam i their whole life?
> 10^9
73
Different cancers require different combinations of properties. Never- theless, we can draw up a general list of key behaviors of cancer cells that distinguish them from normal cells... (could be SAQ in exam)
1. don't rely on signals from other cells as cues for growth, survival & proliferation - often as mutation is in cell signalling pathway eg. Ras gene mutation -> proliferation even in absence extracellular signal 2. less prone to apoptosis cos mutations in genes that regulate cell death eg. about 50% of all human cancers have lost or suffered a mutation in the p53 gene 3. can proliferate indefinitely by reactivating production of the telomerase enzyme 4. genetically unstable, with a greatly increased mutation rate 5. abnormally invasive due to lack specific cell-adhesion molecules, such as cadherins 6. survive and proliferate in foreign tissues (metastases) whereas most normal cells die when misplaced
74
What is the role of VEGF?
vascular endothelial growth factor - stimulate the neovascularisation of tumours (and normal tissue for wound repair) -> supply a highway for metastases to colonise the rest of the body
75
normal cellular gene that can be converted to an oncogene?
proto-oncogene
76
What are the 4 mechanisms of proto-oncogene -> oncogene...?
1. mutation in coding sequence - hyperactive protein in normal amounts 2. gene amplification - normal protein greatly produced 3. chromosome rearrangement 1 - regulatory DNA sequences -> normal protein overproduced 4. chromosome rearrangement 2 - fusion to actively transcribed gene -> hyperactive fusion protein
77
Get your head around 20-49 (big mother fucker)
may be SAQ in exam
78
The role of the Adenomatosis Polyposis Coli (APC) protein in the development of colorectal carcinoma happens how?
APC keeps Wnt gene in check thus... loss of APC -> Wnt pathway hyperactive (crypts in gut lining) -> proliferate to excess, generating a polyp -> further mutations may occur, resulting in invasive cancer
79
What % of colorectal cancers have lost APC function?
60%
80
How we know: What approach that was taken to characterize APC?
co-immunoprecipitation (Ab)
81
What does APC bind to?
beta-catenin
82
Diagnosis of a tumour at the 1cm stage = ? cells
10^9
83
first line of therapy?
sx
84
Cancer cells that lack DNA damage control can be targeted by ?
chemotherapy or radiotherapy
85
Drugs against VEGF aimed to prevent ?
angiogenesis
86
why might several anti-VEGF drugs are not as helpful as was hoped?
some tumour blood vessels originate in cancers
87
Chronic myeloid leukaemia is caused by a specific translocation that affects a particular tyrosine kinase by removing its negative regulatory domain (Fig. 20-48) to propagate a mitogenic signal. A specific inhibitor for that kinase that kills cancer cells and gives remission of symptoms is called what?
gleevec
88
How does gleevec prevent leukaemia?
binds to oncogenic kinase (where ATP usually binds & activates it) -> inactive kinase -> no signal

BMS241 final exam (5 decks)

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