Cytoskeleton and Cell Division Flashcards
1
Q
cytoskeleton provides structural support for
A
plasma membrane and cell organelles
2
Q
functions of cytoskeleton (3)
A
- intracellular movement/transport of substances (large molecules/organelles)
- cell locomotion (amoeboid movement, embryonic development, cili, flagella)
- muscle contraction (specialized cells)
3
Q
3 main elements of cytoskeleton
A
microfilaments
intermediate filaments
microtubules
4
Q
microfilaments are important in maintaining
A
cells shape
facilitate shape during movement
5
Q
actin diameter
A
6-8 nm
6
Q
actin strands are made of
A
smaller G-actin subunits
7
Q
G actin
A
small, globular protein monomer, polymerizes to form protofilaments
8
Q
2 protofilaments twist together to form a
A
double helix, F actin
9
Q
actin links with filamin beneath the plasma membrane to form a
A
support meshwork called cell cortex (terminal web)
10
Q
actin prevents the cell from
A
deformation by reenforcing the phospholipid bilayer
11
Q
actin is also found in (2)
A
microvilli
stereocilia
12
Q
myosin thick filament diameter
A
15 nm
13
Q
myosin is classified as
A
motor protein along with dyenin and kinesin
14
Q
myosin shape
A
long and rod shaped with globular heads
15
Q
myosin forms
A
thick, ropy cables with myosin heads sticking out the sides (braiding golf clubs)
16
Q
myosin heads form
A
cross-bridges between adjacent filaments
17
Q
what is required for muscle contraction? (2)
A
Ca
ATP
18
Q
intermediate filaments diameter
A
8-10 or 10-15 nm
19
Q
intermediate filament structural function
A
1’
20
Q
heterogenous group
A
molecular makeup varies between cells
21
Q
generally forms large filaments which bind with
A
intracellular structures
22
Q
there are several different classes of intermediate filaments, meaning
A
1 cell may produce more than 1 type of filament
23
Q
intermediate filaments are useful in (2)
A
immunohistochemistry
tumor ID
24
Q
cytoketatin
A
characteristic of all epithelial cells
25
cytokeratin in the epidermis of the skin forms
tonofibrils
26
vimentin
found in mesodermal cells of mesenchymal origin
| (includes endothelial cells, muscle cells, neuroectodermal cells
27
desmin
unique to muscle cells, mesodermal origin
28
neurofilament proteins
present in nerve cells (neurons)
29
GFAP
found in glial support cells of the nervous system
| astrocytes
30
lamin
forms a layer on the inside of the nuclear membrane
31
intermediate filaments (6)
```
cytokeratin
vimentin
desmin
neurofilament proteins
GFAP
lamin
```
32
microtubule diameter
24 nm
33
microtubules are compoased of which 2 globular protein subunits
alpha and beta tubulin
| arranged in a coiled, spiral pattern
34
microtubules polymerize to form
hollow tubes
| readily assembles and disassembles
35
microtubules are involved in (3)
cell movement
maintenance of cell shape
intracellular transport of substances
36
microtubule movement occurs via
addition or subtraction of tubulin subunits from microtubules
37
motor proteins --- & --- attach microtubules to organelles to allow for movement in the cytoplasm
dyenin
| kinesin
38
various microtubule-associated proteins (MAPs) provide
energy as ATPase
39
stabilize microtubules along with
capping proteins
40
classic example of microtubules during cell division
cell spindle
41
drugs that inhibit polymerization of microtubules and cell division (3)
colchicine
vincristine
vinblastin
42
microtubules are found in (4)
cilia and flagella
centrioles
basal bodies of cilia
mitotic spindles
43
axoneme
9 pairs of microtubules (peripheral doublets) containing dynein arms (link doubles together) arranged in a circle with a central doublet in the middle
(9+2 structure)
44
central doublets connect to peripheral doubles by
radial spokes
45
peripheral doublets connect to each other by the protein
nexin
46
in cilia, the basal axoneme grows from the
basal body
| derived from modified centriole
47
centrioles are normally located in the
centrosome
| cell center, near nucleus and function in cell division
48
centrioles during cell division
pair of centrioles (diplosome) oriented at right angles to each other within the centrosome
49
each centiole consists of
9 triplets of microtubules arranged in a cylinder
50
centrioles acts as a --- --- for microtubules
nucleation center
51
during mitosis, centrioles divide and each pair goes to the opposite poles of the cell to form the
mitotic spindle
52
the mitotic spindle controls the
distribution of chromosomes in daughter cells
53
movement of chromosomes occurs via addition and subtraction of tubulin subunits and attachment proteins (dyenin and kynsesin) to --- at the
chromatids
| kinetochore (centromere)
54
what happens during mitosis?
growth and replication of the cell
55
mitosis phases
```
interphase
prophase
metaphase
anaphase
telophase
```
56
what is interphase?
the resting phase, or time between divisions
57
which phase occupies most of the life of a cell?
interphase
58
subphases of interphase (3)
G1
S
G2
59
G1 phase
first gap phase
60
which phase is the longest?
G1
61
what occurs during G1 phase? (3)
cell growth
maturation
differentiation
62
hypertrophy
increase in cell size
63
hypertrophy occurs during
G1
64
hyperplasia
increase in cell number
65
hypertrophy occurs during
mitosis
66
S phase
synthesis phase
67
what occurs during S phase?
replication of DNA prior to division
68
at the beginning of S phase, chromosome number is --, at the end it is --
2n
| 4n
69
prior to replication, in S phase, each chromosome has a --- --- with an --- ---
single chromatid
| attached centromere
70
following replication in S phase, each chromosome contains - chromatids connected by a ---
2
| centromere
71
when does replication of centrioles occur?
S phase
| 2 diplosomes
72
G2 phase
2nd gap phase
73
what occurs during G2 phase?
preparation for mitosis
74
during G2, --- and --- are synthesized for the mitotic spindle
ATP
| tubulin
75
M phase
cell division portion of mitosis
76
M phase is characterized by --- followed by ---
karyokinesis (nuclear division)
| cytokinesis (cytoplasmic division)
77
M phase results in
2 daughter cells
78
how long does S, G2, and M phase take?
several hours each
79
during S and M phases, chromosomes
condense
| become visible, look like coiled snakes
80
during G1 and Go, chromosomes exist in an
unraveled mass
81
some cells lose the capacity for
cell division
82
is Go permanent or reversible?
it can be either depending on the cell type
83
facultative dividers
retain capacity for division with the proper stimulus
| ex. reserve stem cells
84
terminally differentiated cells
lose capacity to divide
| ex. neurons, cardiac myocytes
85
during prophase, chromosomes are visibly
condensed
86
during prophase, microfilaments an microtubules of cytoskeleton
disaggregate
87
during prophase, centrioles migrate to poles of the cell, form spindle apparatus with --- --- between them
interpolar microtubules
88
--- --- and --- disappear at the end of prophase
nuclear membrane
| nucleoli
89
during prometaphase, mitotic spindle attaches to
chromosomes at the kinetochore
90
during metaphase, chromosomes
line up along the equator (metaphase plate)
91
during anaphase,
centromeres split apart, chromosomes migrate to opposite ends of the cell
92
chromosomes are pulled by microtubules connecting
centriole and kinetochore
93
during telophase, the mitotic spindle
disaggregates
94
what reappears during telophase? (2)
nuclear envelope reassembles
| nuclei reappear
95
during telophase, the plasma membrane forms a --- ---
cleavage furrow
96
cytokinesis results in
2 genetically identical. daughter cells
97
plant cells dont make a cleavage furrow, they make a
cell wall in the middle of the cell
98
mitotic index is used to describe the
proportion of cells in a tissue in mitosis at any given time
99
mitotic index is important in
tumors
| estimated by counting the number of mitotic figures/HPF (normally <1)
100
sexual reproduction requires the production of
haploid gametes (egg and sperm)
101
haploid gametes are produced via
gametogenesis
102
spermatogenesis
occurs only in germ cells of male gonads
103
oogenesis
occurs only in germ cells of female gonads
104
meiosis involves chromosomal duplication followed by -- consecutive cell divisions in haploid gametes
2
105
fusion of gametes (fertilization) produces
diploid zygote (fertilized egg)
106
meiosis result sin the formation of
two daughter cells
107
meiosis 1 differs from mitosis in what two ways?
during prophase 1, homologous pairs of chromosomes form tetrads, with exchange of chromatin via crossing over (chiasmata formation)
results in hybrid chromatids different from parents
each chromosome pair has potential for crossing over during prophase 1 (23 pairs total in humans)
centromeres do not split during anaphase 1
108
why do we want crossing over?
if the environment changes and you want your offspring to survive, you want variation within your offspring so some of them may survive
109
between the first and second meiosis, there is a brief
interphase 2 (interkinesis) with no replication of DNA
110
there is no --- --- in prophase 2
crossing over
111
during anaphase 2,
centromeres split
112
during telophase 2,
cytokinesis yields four haploid gametes, each genetically unique
113
during gametogenesis in males, - or - visible gametes (sperm) are produced
3 or 4
114
during gametogenesis in females, cytoplasmic division is
unequal
| 1 functional gamete (ovum) and 2 or 3 functional polar bodies
115
when does spermatogenesis begin?
| when does oogenesis begin?
puberty
| during fetal development
116
oogenesis timeline
begins during fetal development
female germ cells enter prophase 1 about 5th month of gestation during fetal development and stop
remain in prophase 1 until ovulation (12-50 years later)
117
some cells have a finite, predetermined life span, such as (2)
epithelial cells of skin
| GI tract
118
apoptosis occurs during --- development
fetal
| webbed tissue
119
apoptosis can occur during the growth and regulation of
ovarian follicles and CL
120
apoptosis can be triggered by the destruction of
virus/tumor infected cells
121
clonal deletion in thymus
apoptosis to remove t-cells that react to self molecules
122
failure of clonal deletion may lead to
```
autoimmune diseases
(the body produces antibodies to itself)
```
123
apoptosis mechanism
condensation of nuclear chromatin and shrinkage of the nucleus (pyknosis)
cell swells as a result of influx of water due to loss of ATP to maintain pumps in the cell membrane
lysosomes release catalytic enzymes into the cytoplasm (autolysis)
the cytoplasm becomes bright pink (eosinophilic)
124
pyknosis
shrinkage of the nucleus
125
autolysis
when lysosomes release catalytic enzymes into the cytoplasm
126
the final apoptosis pathway is initiated by
caspace cascade
127
caspases are normally
inactive enzymes
128
karyolysis
chromatin in nucleus begin to degenerate
129
karyorhexis
nuclear material begins to fragment and nuclear membrane disintegrates
130
apoptotic bodies
fragmented nuclear debris
131
apoptosis results in dead, --- cells
necrotic
132
necrotic cells are later phagocytosed by
neutrophils
133
necrosis also refers to death of cells as a result of (3)
inflammation, traumatic injury, or pathology
