1
Q
in a multicellular organism, cells can come together to form ________
A
tissues
2
Q
tissues
A
collection of cells that work together to perform a specific function
3
Q
what is a organ
A
2+ tissues combine and function toegther
4
Q
classes of cells in an adult multicellular organism
A
stem
somatic
germ
4
Q
stem cells
A
undifferentiated cell that can undergo an unlimited # of mitotic divisions and differentiate into any of large number of specialized cells
5
Q
somatic cells
A
nonreproductive cell and most common type fo cell in body of multicellular organism
6
Q
germ cells
A
reproductive cell that produces gametes
7
Q
cytoskeleton
A
determined and maintained by structural protein networks in the cytoplasm
provide structural support/enable movement of substances within cells
8
Q
______ of cells and organs reflects their function
A
shape
9
Q
cellular junctions
A
bottom of keratinocytes attached to basal lamina
structural integrity of a tissue/organ depends on ability fo cells
adhere to one another
10
Q
extracellular matrix (ECM)
A
adhere to a meshwork of protein and polysaccharides outside the cell
10
Q
the structural integrity of a tissue/organ depends on the ability of cells to:
A
adhere to one another -> cellular junctions
adhere to a meshwork fo proteins/polysaccharides outside the cell called extracellular matrix (ECM)
10
Q
epidermis
A
outer layer of skin
water-resistant and protective barrier
11
Q
2 layers of skin:
A
epidermis
dermis
12
Q
dermis
A
layer of skin beneath epidermis
supports epidermis and supplies with nutrients
13
Q
4 types of tissue in animals
A
epithelial
connective
muscle
nervous
14
Q
epithelial tissue
A
covers outside of body and lines many internal structures of body
14
Q
keratinocytes
A
make up epidermis
epithelial cells
specialized to protect underlying tissues/organs
15
Q
main cells in epidermis
A
keratinocytes
melanocytes
16
Q
melanocytes
A
in epidermis
pigments of skin
17
Q
basal lamina
A
supports epithelial cells
specialized ECM below bottom layer of epidermis
bottom layer of keratinocytes are attached to the basal lamina -> cell junctions
18
Q
what is the dermis made up of
A
mostly connective tissue -> a lot of ECM
main cell type is fibroblast -> produces ECM
nerves and blood cells
19
Q
fibroblast
A
main cell type in dermis
produces ECM
20
Q
what is the cytoskeleton made up of
A
long chains of protein subunits joined together
21
all eukaryotic cells have at least 2 cytoskeletal elements - what are they
microtubules and microfilaments
22
what cytoskeletal element is specific to animal cells
intermediate filaments
23
microtubules
tubelike structures made up of polymers of protein dimers
24
what is a dimer in microtubules made up of
2 tubulin proteins:
alpha tubulin
beta tubulin
25
where are microtubules in animal cells placed in the cell? what is the purpose of this arrangement
radiate outward to cell periphery
make up centrosome
helps maintain cell's shape -> allows to withstand compression
organelles are secured to microtubules, guiding arrangement of organelles in cells
26
what is the structure of a microfilament made up of? what is the structure like and where is it in the cell
polymers of actin monomers that are arranged into a double helix
thinnest of the cytoskeletal fibers
short and extensively branched just beneath cell membrane of cell
27
purpose of microfilaments
reinforce cell membrane/organized proteins associated with it
28
where can microfilaments be found around the cell
various locations in cytoplasm
29
examples of microfilaments in cells
epithelial cells of small intestine contain microvilli on surface -> within them are bundles of microfilaments
30
what are alternative purposes of microfilament functions besides structure
transport mateerials inside cell
shortening of muscle cells during contraction
separation of daughter cells at end of animal cell division
31
do microfilament and microtubules grow at the same pace from both ends?
no, one end grows faster than the other
faster growing end -> plus end (adding subunits)
slower end -> minus end (removing subunits)
32
where are microtubule ends placed in animal cells
minus end -> positioned at organizing center of centrosome
plus end -> project outward towards cell membrane
33
rapid shrinkage in microtubules is called
depolymerization
34
slower growth in microtubules is called
polymerization
35
depolymerization
rapid shrinkage in microtubules
36
polymerization
slower growth in microtubules
37
dynamic instability
cycles of polymerization and depolymerization in microtubules
38
dramatic depolymerization in microtubules causes
microtubule catastrophe
39
purpose of microtubule catastrophe
allows cell to rapidly reorganize cytoskeleton when needed
microtubules explore space of cell by growing in new areas and shrinking back
ex. spindle microtubules use proces to quickly find/attach to chromosomes during cell division
40
motor proteins
small accessory proteins that join microtubules and microfilaments
ex. microtubules function as tracks for transport within cell
41
kinesin
carries cargo such as vesicles towards plus ends of microtubules
41
dynein
moves cargo towards minus end of microtubules
42
energy for movement of motor proteins is driven by
conformational changes in motor proteins and powered by ATP
43
microtubules are found in structures that propel the movement of:
cells -> flagella
substances surrounds cells -> cilia
44
in cilia and flagella, microtubules associate with _______ motor protein
dynein
moves cargo toward microtubule minus end
44
immediate filaments are found in _________ cells
animal
45
purpose of immediate filaments
provide mechainal strength to cell
form strong cable-like polymers of proteins
46
what are immediate filaments composed of
strong fiber composed of intermediate filament protein subunits
diameter is intermediate to microfilaments and microtubules
47
how many types of intermediate filaments are there? what differentiates them and provide examples
100+
made up of diff proteins depending on cell type:
epithelial cells -> keratins
fibroblasts -> vimentins
neurons -> neurofilaments
48
multicellular organisms use ____________ to physically connect one cell to another cell or to ECM
cellular junctions
48
intermediate filaments in epithelial cells and fibroblasts
epi -> keratins
fibro -. vimentins
49
what does it mean when cells exhibit polarity
spatial differences in shape structure and function within cell
ex. epithelial cells:
facing outside body/lumen -> apical
attached to basal lamina -> basal
50
apical
epithelial cells facing outside body/lumen
51
basal
epithelial cells attached to basal lamina
52
cadherins
integral transmembrane glycoproteins -> for cell-to-cell attachment
53
extracellular domain of a cadherin molecule binds to:
extracellular domain of a cadherin of the same type on an adjacent cell
54
integrins
integral transmembrane glycoproteins for cells to attach to ECM
55
cytoplasmic domain interacts with cytoskeleton as:
it;s important for structural integrity of tissues under ohysical stress
55
5 types of cell junctions
cennect cells to other cells or basal lamina and are reinforced by cytoskeleton
1. adherens junctions
2. desmosomes
3. hemidesmosomes
4. tight junctions
5. gap junctions
55
where are cadherins found
adherins junctions
desmosomes
complexes of cell junctions anchor cells to one another and are reinforced by cytoskeleton
55
adherens junctions
belt like junctional complex of cadherins that is found around circumference of cell
56
how are adherens junctions structured intracellularly
belt of cadherins attaches to band of actin microfilaments in cytoplasm
near apical side
57
how are adherens junctions structured extracellularly
cadherins in adjacent cells attach to each other
58
desmosomes
button like points of adhesion that hold cell membrane of adjacent cells together
59
purpose of cadherins in desmosomes
strengthen connection between cells
cadherins in desmosome of one cell bind to cadherins in desmosomes of adjacent cells
cytoplasmic domains of cadherins are linked to intermediate filaments of cytoskeleton
60
hemidesmosomes
epithelial cells are firmly anchored to basal lamina
attached via a structure like the desmosome -> hemidesmosome
integrins are most prominent cell adhesion molecules in hemidesmosomes
61
extracellular domains of integrins in hemidesmosomes bind to:
ECM proteins in basal lamina
cytoplasmic domains of integrins are linked to intermediate filaments of cytoskeleton
62
tight junction
adherens junctions and desmosomes do not prevent passage of materials between cells -> tight junction seals extracellular space
only way a substance can travel from one side of a sheet of epithelial cells to other is moving thru cells by means of a cellular transport mechanism
63
gap junctions
cell-to-cell communication
extremely small channels (connexons) span a small gao (2-4nm) between cells -> made of connexin proteins
integrate activities of individual cells
64
purpose of connexons in gap junctions
allow for cytoplasmic continuity between adjacent cells -> only low molecular weight material can pass between cells (ions)
65
ECM
extracellular matrix
layer of material secreted beyond region of cell membrane in extracellular area
65
plasmodesmata
allow plant cells to transfer rna moelcules/proteins
larger than gap junctions
cell membranes between the 2 cels are continuous, allow plants t cell signals to one another despite being enclosed within rigid cell walls
65
functions of ECM
act as supportive and protective material
allow for expression of different cell functions
66
3 layers of plant ECM
1. middle lamella
2. primary cell wall
3. secondary cell wall
66
structure of ECM
formed from insoluble meshwork of proteins and polysaccharides
66
primary cell wall
component of plant ECM
thin and flexible
made of cellulose fibers, pectin and several other proteins
66
middle lamella
component of plant ECM
made of carbs
main mechanism by which plant cells adhere to one another
67
secondary cell wall
component of plant ECM
rigid
made of cellulose and lignin -> hardens cell wall and makes it water resistant
68
animal ECM
connextive tissue of animals is extensive in ECM
mixture of proteins and polysaccharides secreted by cells
69
what is the animal ECM made up of
large fibrous proteins (collagen, elastin, laminin)
found in gel-like polysaccharide matrix
70
most abundant protein in animal ECM
collagen
71
collagen makes up ____ protein in th ebody
1/4
72
how many forms of collagen are there? which is th emost abundant
20 +
type I collagen
73
type I collagen
found in dermis of human skin, provides support
74
structure of collagen
composed of intertwined fibers that make it stronger than if it were a sinle fiber of the same diameter
consists of 3 polypeptides wound around each other
forms triple helix
a bundle of molecules forms a fibril, with fibrils then being assembled into fibres
75
basal lamina
specialized layer of extracellular matrix that is present beneath all epithelial tissues
provides structual foundation for epithelial tissues
consists of several proteins -> including type of collagen
provides flexible support
acts as scaffold -> for other proteins to assemble on
BIOL130
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