Tissues and Cell Communities Flashcards
1
Q
What is the model system used in unit 8
A
the intestine
2
Q
What are the 4 types of animal tissues
A
epithelium, connective tissue, smooth muscle, neural
3
Q
What is the cytoskeleton
A
a network of fibres that form scaffolding within the cytoplasm
4
Q
Why is the cytoskeleton important
A
determines the shape of the cell, the position of organelles, allows movement within the cell, and the movement of the cell itself
5
Q
How is the cytoskeleton different than our skeleton
A
cytoskeleton is dynamic, its constantly being reorganized
it serves as both the muscle and bone of the cell
6
Q
Do prokaryotes have cytoskeletons?
A
originally no, but recent advancements have shown that the elements of cytoskeletons are observed in prokaryotes
7
Q
What are intermediate filaments
A
filaments of one cell connect at the walls to the filaments of the neighbouring cell
8
Q
What connects the intermediate filaments between cells
A
desmosomes
9
Q
What do intermediates provide in relation to structure
A
structural strength
10
Q
What makes them different from the other two types of filament
A
they’re not dynamic, unlike the other two
11
Q
Provide an example of what would happen if cells were stretched out
A
intermediate filaments would keep the cells held together and maintain a certain level of structure
12
Q
What is the physical makeup of intermediate filaments
A
long, twisted strands
13
Q
What are the physical components of intermediate filaments
A
N-terminal head, C-terminal tail, and an a-helical rod domain
14
Q
Central rod domains are similar in size to __________
A
AAs
15
Q
Intermediate filaments consist of many different __________
A
proteins
16
Q
What are the three classes of cytoplasmic intermediate filaments
A
keratins, vimentin, and neurofilaments
17
Q
What is the one class of nuclear intermediate filaments
A
nuclear laming
18
Q
Which is the most diverse class of intermediate filaments
A
keratins
19
Q
How can keratin be used to classify tumours with respect to the original cell type
A
if metastatic (not originated with original cell type) & epithelial in origin, the type of keratin can determine the type of cancer and where the cancer came from
20
Q
The keratinized layer on the skin is where
A
the dead flattened cells of the top layer are packed with keratin
21
Q
Intermediate filaments support the _________ ___________
A
nuclear envelope
22
Q
How do intermediate filaments support the nuclear envelope
A
nuclear lamina is found between the nuclear envelope and the chromatin within the nucleus, and is involved in DNA replication and mitosis
23
Q
What are microtubules
A
thickest of the three filament types and project from the core of the cell
24
Q
What are microtubules essential for
A
organizing roles in all eukaryotic cells by creating a system of tracks for the movement of vesicles, while also anchoring organelles in place and forming mitotic spindle for mitosis
25
What small structures do microtubules form on tissues
cilia and villi
26
What are microtubule organizing centers functions
structures from which microtubules originate and radiate outward
27
What is the microtubule organizing centre in animal cells
the centrosome (2 centrioles)
28
What are microtubules made of
Tubulin
- both A and B, bound to each other tightly in a cylindrical formation to form hollow tubes
29
What is a protofilament
one long strand of A and B tubulin dimers
- microtubules are made up of many protofilaments arranged together
30
Are microtubules dynamic or not
they are dynamic
- growing and shrinking subunits are added and removed
31
Which end of the protofilament are dimers added to
the plus end
32
What is the microtubule instability
when they grow, they quickly shrink back to the core of the cell and repeat this process
33
How can microtubules polarize a cell
the microtubules eject from the organizing centre at the nucleus, and attach themselves to capping proteins which pushes the walls of the cell outward
34
How are microtubules important in mitosis
microtubules are crucial for moving chromosomes around during cell division
- they cast out and reach chromosomes hooking up the essential kineticore structure needed to divide
- these microtubules also pull the chromosomes apart to opposing ends of the cell during metaphase
35
How do microtubules provide "rails"
for example in a neuron, motor proteins are able to travel along the microtubules via inward and outward transport
36
What are motor proteins
a class of "motors" that can move along a suitable surface (like a microtubule)
- powered by the hydrolysis of ATP
- convert chemical energy into mechanical work
37
What are the microtubule motors
dyneins (move toward minus end) and kinesics (move toward plus end)
38
What are the globular heads on motor proteins
act as the "feet" and carry out the walking motion
39
What are the tails on motor proteins
the "body" of the motor proteins
40
What is anterograde transport
forward (+ direction) carried out by kinesins
41
What is retrograde transport
backward (- direction) carried out by dyneins
42
How is cargo carried by the motor proteins
the tails (body) of the motor proteins attach to the accompanying cargo and carry it to where it needs to go
43
______ and ______ contain stable microtubules
cilia and flagella
44
What is the '9 + 2' array
in the cilia/flagellum, there are 9 microtubule pairs seen in cross-section around the perimeter, and 1 pair (2 microtubules) in the centre
45
bacterial vs eukaryotic flagellum
bacterial: made of flagellin, move out by rotation, not surrounded by membrane
eukaryotic: made of tubulin, moved by swimming motions, surrounded by plasma membrane
46
What are microfilaments
most concentrated directly under plasma membrane and very thin compared to microtubules
47
What small structure are microfilaments found in
microvilli
48
What are the functions of microfilaments
cell shape/support
cell movement
49
What is another term for microfilaments
actin filaments
50
What are the characteristics of microfilaments
smallest in diameter, "threads", polymer of actin subunits, has + and - ends similar to microtubules, and are the most abundant proteins within animal cells
51
What is the most abundant protein in animal cells
actin
52
What end do the actin molecules get added to
the plus end
53
Actins are dynamic or not dynamic
dynamic - they grow and shrink with the addition/removal of actin molecules
54
What is the actin motor
myosin
- muscle contraction, vesicle and organelle transport, cell motility, cytokinesis
- originally discovered in muscle cells but now known to be in all eukaryotic cells
55
Actin and cell movement without flagella
amoebae hunting prey, white blood cells hunting prey, advancing tip of developing neutron
56
what are the basic steps of actin motility
cell pushes out protrusion(s) at leading edge
protrusions stick to surface
rest of cell drags itself forward
57
What're the types of protrusions seen in the case of actin motility
lamelli podium = sheet foot
pseudo podium = false foot
filo podia = thin, stick protrusions
58
Actin ____________ at plus end protrudes lamellipodium
polymerization
59
_______ motor proteins slide actin filaments
myosin
60
Actin acts with myosin to generate cell ___________
movement
61
It is extremely rare for the plasma membrane to be the only thing surrounding the cell, what are examples of others
bacteria, algae, fungi, plants, etc.: cell wall
animals: ECM
62
What is the ECM
extra cellular matrix: cross-linked network of filaments that resist stretching and straining forces - provides strength
semi solid gelatinous matrix that resist compression ('concrete')
63
How is the ECM important in plants
cells are weak and fragile if they're separated from their walls (called protoplasts)
- they have no intermediate filaments
- the cell wall provides the plant cell with a type of ECM
64
What are primary and secondary plant cell walls
primary: secreted as cells are growing, and relatively thin compared to the other
secondary: in mature cells, only some cell types
65
How does cellulose play a role in the cell wall
microfibrils form network filled in by gel-forming pectins
66
What are pectins
a structural acid found in the cell wall, as well as primary and middle lamella
67
What is the middle lamella
gelatinous pectins that "glue" cells together - found between the primary and secondary walls
68
Where are pectins made and processed
made in the ER, processed in the Golgi
69
Where is cellulose made
in the plasma membrane, by protein complexes containing cellulose synthase enzymes
70
When is the secondary cell wall produced
once the cell has stopped growing
71
Characteristics of the secondary cell wall
much thicker, cells become rigid with the addition of this wall and are only found in certain types
- composition of this wall depends on the role in the plant
- has a high cellulose content
- waterproofing via waxes
- protects against pathogens
72
How does the orientation of microfibrils impact expansion of a cell
the direction of microfibrils determines which direction a cell can grow/expand
73
Cellulose synthase complexes are otherwise known as
rosette complexes
74
Microtubules provide the template for _______ synthesis
cellulose
75
What is the structural polysaccharide in plants
cellulose
76
what is the physical makeup of cellulose
polymer of B-glucose, joined by B-1,4 linkages
77
What is the most abundant organic molecule on earth
cellulose
78
How is connective tissue distinguishable from the other 3 types
large amount of ECM
79
Rather than a polysaccharide, tensile strength in connective tissue is provided by ______
protein
80
what is the fibrous component of ECM in animal connective tissue
collagen
81
what is the most abundant protein in mammals
collagen
82
What are derivative amino acids in collagen
amino acids not directly inserted during translation (hydroxyproline - derived from proline)
83
Where do the hydroxylation reactions of derivative amnio acids occur
in the ER lumen
84
What is the cofactor that is required by the derivative amino acids
ascorbic acid (vitamin C)
85
What does a lack of vitamin C do to the body
causes scurvy, a connective tissue disorder where the cofactor of the derivative amino acids isn't present, so collagen is not properly composed
86
What is the physical makeup of collagen fibres
collection of wound triple-stranded collagen molecules brought together in a fibril form
87
What is denatured collagen comparable to
gelatin! so if you don't have properly composed collagen, your skin is super stretchy
88
What are proteoglycans
proteins that are heavily glycosylated; the gel filer in the basement membrane of a cell
89
What are GAGs in relation to proteoglycans
proteoglycans are core proteins attached to chains of GAGs
- GAGs are made up of repeating disaccharide units
90
Are proteoglycans hydrophobic or hydrophilic
hydrophilic (attracts water)
91
What are the functions of proteaglycans
resists compression, forms pores for passage of molecules in ECM, and influence cell migration through ECM
92
How does ECM connect to the cytoskeleton
via integrins
93
What are integrins
groupings of transmembrane proteins that anchor the cell to the ECM
94
What is fibronectin
provides the link between integrin dimers and ECM fibrils
95
How do integrins actually attach to both the ECM and the cytoskeleton
the fibronectin attached to the collagen fibres attaches to the integrin dimers on the plasma membrane. on the inner side of the plasma membrane, the integrin dimer ends are attached to adaptor proteins, which are attached to actin filaments of the cytoskeleton
96
What are some examples of the sheet types that epithelial cells can form
columnar, squamous, cuboidal, and stratified
97
Is there any ECM between epithelial cells?
NO - they are tightly packed and held together by tight junctions to eliminate space between each cell
98
What are the types of cell-cell junctions in epithelium
tight junctions, adherens junctions, desmosomes, and gap junctions
99
What are tight junctions
previously mentioned in unit, tight junctions are sealing strands of occluding and claudin proteins that eliminate ECM space between cells
100
As a result tight junctions and the elimination of ECM, material must go ________ rather than ________ cells
through, between
101
What real life object can be used in comparison to tight junctions
a fence
102
What are examples of tight epithelium
gut, some blood vessels
103
What are adherens junctions
invaginate epithelial cells by an organized tightening, so the cells curve down (like a vesicle would) and eventually, some of the cells are completely broken off to form a tube-like structure
104
What real life objects can adherens junctions be compared to
a belt
105
What are desmosomes
provide strong adhesion between cells - eg. desmosomes are responsible for keeping the cell connected to the basal lamina
106
How could disease be caused in the malfunctioning of desmosomes
epithelial cells would not be fused to the basal lamina and would lift, causing chronic wounds
107
What are gap junctions
connective passages made up of connexion subunits between cells that allow very small molecules to pass over in a non-selective manner
108
Where are gap junctions found in the human body
in nearly all epithelia and many other tissues
109
What do gap junctions allow for in the cell
allows cell coordination and collaboration, with SOME ability to open/close with signals
110
What are plasmodesmata
channels between plant cells
111
Explain the characteristics of plasmodesmata
like gap junctions in animals: connect cytoplasm of adjacent cells
unlike gap junctions in animals: plasmodesmata are lined with plasma membrane, and they can dilate to regulate the movement of molecules in/out
112
What are the three differentiations of cell types
cell communication, selective cell-cell adhesion, and cell memory
113
What happens when a cell can no longer divide
it is terminally differentiated
114
What are stem cells
undifferentiated cells found throughout the body that divide to provide supply of some types of terminally differentiated cells
- replenish dying cells
- repair damaged tissues
115
What are the two properties of stem cells
self-renewal: ability to go through numerous divisions while remaining undifferentiated
multi potency: ability to generate progeny of several distinct cell types
116
If stem cells are mutlipotent, what would unipotency be
restriction to a single cell type
117
Can stem cells carry out functions of specialized differentiated cells
NO
118
In an epithelial cell, where are the stem cells located
at the base of each crypt
119
Explain the organization of cell types along a villus
the base of crypt = stem cells and terminally differentiated secretory cells
walls of crypt = dividing precursor cells and differentiated precursor cells
walls of villi = terminally differentiated epithelial cells
120
Where are stem cells found in skin cells
the basal cell layer (lowest layer of the epidermis)
121
All the blood cell types descend from ______________ stem cells
hematopoietic
122
What stem cell is the "stemiest"
hematopoietic stem cells
123
What is the difference between unipotent, pluripotent, and multipoint
unipotent = only gives rise to one cell type (but still a stem cell because it has self-renewal)
multipotent = gives rise to cells limited within a specific tissue type
pluripotent = gives rise to all types of cell in an organism
124
What is an example of a pluripotent stem cell
embryonic!
125
How to stem cells form organoids in culture
types of cells are reprogrammed to become de-differentiated (ie. skin cell) and used in culture to create differentiated organoids such as kidney and intestinal organoids
126
What are the applications of adult stem cell-derived organoids (normal cell)
physiology and disease modelling
127
What are the applications of adult stem cell-derived organoids ( tumour cell)
drug screening, bio banking, and disease modelling
128
When do tumours form
when one or more cells begin uncontrolled division
129
Benign vs malignant
benign = non-invasive and non-cancerous
malignant = invasive and cancerous (spread throughout the body via blood/lymph and can initiate secondary tumours)
130
Loss of adhesion in the connective tissues leads to what in relation to cancer
loss of adhesion = metastasis
131
What is dominant mutation vs recessive mutation
dominant = gain of function
recessive = loss of function
132
What happens if the proto-oncogene in one gene is mutated
a hyperactive oncogene is produced
133
What happens if the tumour suppressor in one gene is mutated? What happens if both are mutated?
1. no effect (higher risk for cancer?)
2. complete loss of tumour suppressor gene activity
134
What mutations are often found in cancer cells
somatic mutations
135
What are some characteristics of cancer cells
not dependant on signalling, less likely to go through apoptosis, can divide indefinitely, genetically unstable, invasive
136
How do polyps turn into cancer
1. inactivation of both tumour suppressor genes
2. one copy of photo-oncogene activated
3. sequential inactivation of another set of tumour suppressors
4. sequential inactivation of more tumour suppressor genes
5. metastatis
137
What is the most common classification of cancer
carcinoma - epithelial
138
What are other classifications of cancer aside from carcinoma
sarcoma (from mesenchymal cells)
hematopoietic (leukemia, lymphoma, etc.)
