Exam 3 Flashcards
(259 cards)
1
Q
cell biology
A
the study of individual cells and their interactions with each other
2
Q
cell theory
A
- all living organisms are composed of 1+ cells
- cells are the smallest units of life
- new cells come from pre-existing cells
3
Q
stages of life theory
A
- nucleotides and amino acids were produced prior to cells
- nucleotides became polymerized to form RNA and DNA ==> amino acids were polymerized to form proteins
- polymers became enclosed in membranes
- polymers enclosed in cell membranes acquired properties associated with living cells via chemical selection
4
Q
primordial soup hypothesis
A
organic molecules formed spontaneously formed through prebiotic and abiotic synthesis
5
Q
prebiotic soup
A
slow acumulation of organic molecules in the early oceans of a long period of time
6
Q
reduced atmosphere hypothesis
A
rich in water vapor, hydrogen gas, methane, and ammonia and lacked atmospheric oxygen => redox reactions are required to form complex organic molecules
7
Q
arguments against reduced atmosphere hypothesis
A
early earth was a neutral gaseous mixture and earth had a high UV that would destroy NH4 and NH3
8
Q
extraterrestrial hypothesis and objections
A
molecules came from asteroids => material would be destroyed by intense heat
9
Q
deep sea vent
A
superheated rich metal ion and hydrogen sulfide vents mixed with cold seawater => molecules are formed in the surrounding mixed water gradients
10
Q
polymers like nucleotides and amino acids like to form under what conditions?
A
non aqueous or mild aqueous conditions
11
Q
protobiont
A
a prebiotically produced molecule/macromolecule that acquired a boundary (lipid bilayer similarity) that allowed an internal chemical environment different from its surroundings
12
Q
protobiont key features
A
- membrane boundary
- polymers inside containing information
- polymers having catalytic functions
- developing capability of self replication
13
Q
liposome
A
vesicles surrounded by a phospholipid bilayer
14
Q
2 special RNA properties:
A
stores information for self replication (1) and performance of catalytic functions (2)
15
Q
ribozymes
A
molecules catalyzing chemical reactions
16
Q
chemical selection
A
chemical mixtures have special advantages that cause it to increase in amounts relative to other chemicals
17
Q
chemical evolution
A
molecules change over time to have different chemical composition
18
Q
micrograph
A
image taken with the aid of a microscope
19
Q
resolution
A
measure of the clarity of an image between adjacent objects
20
Q
contrast
A
difference in light, dark, and color between adjacent regions
21
Q
magnification
A
ratio between image size and actual size
22
Q
transmission electron microscopy
A
electrons go through slices of a biological sample
23
Q
scanning electron microscopy => heavy metal and copper crid
A
views surfaces of biological samples => heavy metals
24
Q
prokaryotes
A
bacteria are 1-10 micrometer
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nucleoid
non membrane bound compartment
26
ribosomes
synthesize polypeptides
27
cell wall composition
peptides and carbohydrates, relatively porous
28
glycocalyx
secreted by many bacteria that traps water and prevents drying out
29
capsule
very thick glycocalyx that only some bacteria have
30
pilli
unique to bacteria and allow cells to attach to surfaces and one another
31
Eukaryotes (animal cells)
32
Eukaryotes (plant cell)
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droplet organelle
molecules are brought close together and can assemble into complexes with different internal chemical environments
34
cytosol
outside organelles but inside the plasma membrane
35
cytoplasm
internal of a cell
36
metabolism
the sum of chemical reactions when cells produce materials for life sustainment
37
catabolism
break down of am molecule into smaller compartments
38
anabolism
synthesis of molecules and macromolecules
39
microtubules
hollow tubes made of tubular that help with cell shape, organization, chromosomal sorting, etc.
40
intermediate filaments
composed of different proteins twisted into filaments to help with cell shape, anchorage of cells, and the nuclear membrane
41
actin filaments
2 intertwined strands of actin (protein) that help with cell shape, strength, muscle contraction, intracellular movement, etc.
42
centrosome
nondividing animal cells have a microtubule organizing center where they grow
43
centrioles
in the centrosome, pair of structures arranged perpendicular where microtubules grow at the centrosome and minus end is anchored
44
keratinocytes
hair, nails, and surface of our skin form intermediate filaments
45
motor proteins
46
movement of cargo
kinesin
47
movement of filament
Actin
48
bending of filament
Dynein
49
cilia
specific to eukaryotes, cell appendages that are shorter and clustered
50
axoneme
has microtubules, the motor protein dyne, and linking proteins => 9v + 2 arrangement
51
basal bodies
anchored to the cytoplasmic side of the plasma membrane from a triplet structure
52
nucleus
53
nuclear lamina
intermediate filaments that line the inner nuclear membrane
54
internal nuclear matrix
connected to the lamina and fills the interior of the nucleus
55
nucleolus
droplet organelle in the nucleus where ribosomes make RNA molecules that exit and synthesize polypeptides
56
lumen
internal space of an organelle
57
rough ER
studded with ribosomes for sorting proteins destined for other endomembrane destinations and attaching carbohydrates to proteins and lipids
58
smooth ER
conversion of toxic molecules to non toxic, break down glycogen and export liver, synthesize hormones, modify lipids, etc.
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cis golgi
near the ER
60
trans golgi
closest to plasma membrane
61
vesicular model
materials of the golgi fuse from one compartment to another
62
cisternal maturation model
vesicles fuse and push old golgi toward cell membrane
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golgi
processing, protein sorting, secretion
64
Eukaryotes (plant cells)
65
droplet organelle
molecules are brought together where the internal environment is chemically different from the outside
66
proteome
complete set of proteins a cell is currently making or can make
67
cytosol
outside the organelles but inside the plasma membrane
68
metabolism
sum of chemical reactions by which cells produce materials and utilize the energy necessary to sustain life
69
catabolism
breakdown of a molecule into smaller components
70
anabolism
synthesis of molecules and macromolecules
71
microtubules
hollow and composed of tubulin => cell shape, organization, chromosome sorting, etc.
72
intermediate filaments
composed of different proteins => cell shape, anchorage of cells, and nuclear membranes
73
actin filaments
2 intertwined strands composed of actin => cell shape, cell strength, muscle contraction, cell movement, etc.
74
centrosome
has the organizing center where microtubules grow at the positive end
75
centrioles
in the centrosome and arranged perpendicular where the microtubule growth starts at the minus end
76
keratinocytes
proteins called keratins are important for cell shape and mechanical strength in skin, intestinal, and kidney cells
77
nuclear lamins
network of intermediate filaments lining the inner nuclear membrane and providing anchor points for nuclear pores
78
motor proteins
have head, hinge, and tail and use ATP as a source of energy to promote movements
79
kinesin
walk along microtubules form the minus to plus end
80
myosin
fix in place and cause actin filaments to move to the left
81
dynein
linker protein fixed in place that causes microtubules to bend
82
cilia
cell appendages that are shorter and clustered that cause movement by bending and pushing against fluid
83
axoneme
has microtubules arranged in 9v + 2 and dynein
84
basal body
anchored to the cytoplasmic side of the membrane and microtubules form triplet structures
85
nucleus
in eukaryotic cells that contains genetic material
86
endomembrane system
nuclear envelope, ER, golgi, lysosomes, vacuoles, and peroxisomes
87
nuclear lamina
intermediate filaments lining the inner nuclear membrane
88
internal nuclear matrix
connected to the lamina and fills the interior of the nucleus
89
chromosome territory
each chromosome is located in a distinct territory
90
nucleolus
droplet organelle in the nucleus of nondividing cells where ribosomes are made
91
lumen
internal space of an organelle
92
rough endoplasmic reticulum
studded with ribosomes that sort proteins destined for other places and performs glycosolation (attachment of carbs to proteins or lipids)
93
proteases
make cuts in the polypeptides
94
secretory vesicles
fuse with the plasma membrane to release contents
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lysosomes
found in animal cells and break down molecules and macromolecules => contain acid hydrolases that use H2O to break covalent bonds
96
vacuoles
contain fluid and solid substances from fusion of many smaller membrane vesicles
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peroxisomes
found in eukaryotes that catalyze chemical reactions and break down toxic molecules
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catalase
breaks down hydrogen peroxide to make water and oxygen gas
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glyoxysomes
in plant seeds and similar to peroxisomes but store fats instead of carbs
100
cell adhesion
protein-protein interactions in the plasma membrane
101
cristae
inner membrane of the mitochondria where ATP is made
102
mitochondrial matrix
compartment enclosed by the inner membrane
103
chloroplast
contains thylakoid membrane with granum and storm where inner membrane encloses the thylakoid membrane
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plastids
plant organelles that have synthetic ability and contain pigments
105
endosymbiosis theory
mitochondria came from proteobacterium engulfed by an archaea and then chloroplasts later came from cyanobacteria
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sorting/traffic signals
proteins containing short amino acid sequencing directing them to certain cellular locations
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cotranslational sorting
begins while translation is occurring and proteins are uptook into the ER before being synthesized and packaged to other endomembrane organs
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post translational sorting
proteins are synthesized in the cytosol and then sent to either nucleus, peroxisomes, mitochondria, and chloroplasts
109
ER signal sequence
sequence on amino acids that directs them to the rough ER (6-12 amino acids long)
110
signal recognition particle (SRP)
signal sequence emerges from a ribosome and is recognized to pause translation
111
chaperones
keeps proteins made in the cytosol in an unfolded state until a receptor protein recognizes its targeting sequence and is released (related to mitochondria)
112
systems biology
study of how new properties of life emerge through interacting of its components
113
4 systems of a eukaryote
1. interior, cytosol, end-membrane, and semiautonomous organelles
114
Vector gene cloning
DNA is taken from a larger strand and introduced into a plasma vector where it can be replicated to produce identical copies of the gene
115
plasmids
circular pieces of DNA found in bacteria
116
viral vectors
derived from viruses that can infect living cells and propagate themselves by taking control of the host cells metabolism => chromosomal genes inserted into viral vectors are replicated when the viral DNA is replicated
117
restriction enzymes
made by bacteria and bind to a specific palindromic sequence to cut
118
annealing
sticky ends of apiece of chromosomal DNA and the vector hydrogen bond with one another until ligated together by ligase
119
recombinant vector
when DNA is ligated to both sticky ends in the vectored and inserted
120
competency
ability of bacterial cells to take up DNA from the extracellular environment
121
selectable marker
the presence of an antibiotic selects for growth of cells expressing certain genes like ampR that encodes for Beta-lactamase that degrades ampicillin
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DNA library
collection of recombinant vectors containing DNA fragments of an organism and used to obtain clones carrying a gene of interest
123
genomic library
inserts are derived from chromosomal DNA
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complementary DNA (cDNA)
recombinant vectors that have inserts from mRNA through reverse transcriptase => lacks introns
125
gel eletrophoresis
separates macromolecules toward the positively charged end
126
PCR
1. DNA
2. 2 primers for denaturation, annealing, and extension
3. Taq polymerase
4. dNTPs
5. buffer solution
6. thermocycler
127
DNA sequencing
determines the base sequence of DNA
128
functional genomics
studies expression and analyzes which genes are turned on and off in various situations
129
dideoxy sequencing
based on DNA replication where DNA polymerase connects adjacent dNTPs by catalyzing a covalent link => synthesize nucleotides ddNTPs that dont have the OH at the 3' end and then added to a primer solution with each complementary dd fluorescently tagged
130
transcriptome
set of all RNA molecules transcribed in a cell or in a population of cells
131
DNA microarray
glass is dotted with many different sequences of single stranded DNA that correspond to a short sequence of a known gene => determines which genes are transribed from a particular sample of cells where fluorescently labeled cDNAs are incubated in the microarray and excess is washed away
132
RNA sequencing
when RNA is obtained, they are fragmented into small pieces and cDNAs are produced through transcriptase that undergoes DNA sequencing to produce a collection of cDNA sequences
133
crisper-cas
RNA is created where tracrRNA and crRNA are covalently linked to a single guide RNA (sgRNA) => sgRNA binds to the proteinCas9 and guides it to the targes gene where cas make a double strand break
134
immunoglobins
class of glycoproteins present in the serum or tissue fluids of all mammals produced by plasma cells as an immune response (Ig G,A,M,D, and E)
135
immunogens
specific types of antigens that trigger an adaptive immune response
136
antibodies
found in the blood or lymph and recognize an epitope => contains a constant light chain (C terminal half) and variable light chain (N terminus)
137
Immunofluorescent microscopy
uses fluorophore to locate antibodies in cells after the solvent is fixed and permeabilized (methanol or acetone) so primary and secondary antibodies can be added
1. can be directly labeled by a detector antibody
2. can label a secondary antibody indirectly that recognizes a detector antibody
138
Western blot
1. tissue is prepared by cells being lysed (sonified by buffers and detergents) to release proteins
2. gel electrophoresis separated molecules by weight and charge => native PAGE separates by charge to mass ratio
3. transferred from the gel electrophoresis onto a membrane
4. immunoblotting where antibodies are added and detected using film
139
co-immunoprecipitation
shows protein complexes
1. lyse cell and centrifuge
2. add antibody to corresponding protein and beads to then pull them down through centrifugation again
3. wash and elute proteins so antibodies and all proteins are separated
4. gel electrophoresis
5. transfer to membrane and use second antibody
6. use film to show where second antibody shows up
140
lipids
(not macromolecules) hydrophobic and composed mainly of hydrogen and carbon => fats, phospholipids, steroids, waxes, etc.
141
triglycerides
also known as fats and form when glycerol bonds to 3 fatty acids
142
saturated fatty acid
when all carbons are fully connected to hydrogens and sp3 hybridized => solid at room temp
143
unsaturated fatty acids
fatty acids containing one or more double bonds causing kinks => liquid at room temp and most biological fats exist like this in the cis form
144
phospholipids
the third hydroxyl group contains a phosphate linkted to a small polar or charged nitrogen molecule => hydrophilic head and hydrophobic tail (amphipathic)
145
steroids
fats that are 4 fused rings with one or more polar hydroxyl groups attached => 1 hydroxy group is called sterol(s)
146
plasma membrane
encloses the cytoplasm => selective uptake, cell compartmentalization, protein sorting, anchoring of cytoskeleton, production of energy intermediate like ATP and NADH, signaling, division, and adhesion
147
phospholipid bilayer
2 layers of amphipathic with covalently bonded glycoproteins and glycolipids
148
fluid mosaic model
membrane structure containing all 3 macromolecules resembling a fluid because lipids and proteins can move relative to one another in the membrane
149
leaflet
half of the phospholipid bilayer where the glycolipids are primarily found in the extracellular leaflet
150
transmembrane proteins
have one or more regions physically embedded in the hydrophobic interior
151
integral proteins
cannot be released from the membrane unless it is dissolved => transmembrane and lipid anchored proteins
152
peripheral proteins
noncovalently bound to the hydrophilic regions of the integral membrane proteins or polar heads of the bilayer
153
semi-fluidity
phospholipid molecules can rotate on their own axis or move laterally without energy or be flipped to the opposite side by flippase with ATP
154
lipid raft
group of lipids floating together as a unit in a larger sea of lipids that may play a role in endocytosis and cell signaling
155
length of phosholipid tails
shorter tails make the bilayer more fluid and longer ones make it less fluid due to hydrogen bonding
156
double bonds in the bilayer
unsaturated fats make the bilayer more fluid and saturated makes it less fluid
157
cholesterol and temperature
at high temps it makes the membrane less fluid but at low temps it makes it more fluid
158
lipid synthesis at the ER membrane
occurs in the cytosolic leaflet of the smooth ER where 2 fatty acids and 1 glycerol molecule and 1phosphate with a polar head group are made with enzymes
159
lipid exchange proteins
extract a lipid from one membrane and diffuse it through the cell to be inserted into another lipid membrane
160
transmembrane protein insertion into the ER membrane
most transmembrane proteins have an ER signal sequence and if it contains a 20 amino acid stretch that is mostly hydrophobic to form an alpha helix it goes to the phospholipid membrane bilayer
161
glycosylation
covalently attaching carbohydrates to lipids or proteins
162
N-linked glycosylation
attachment of a carbohydrate to the amino acid asparganine nitrogen on the side chain
163
O-linked glycosylation
only occurs in the golgi where a string of sugars are added to the oxygen of a serine or threonine side chain polypeptide
164
membrane trasnport
movement of ions and molecules across a biological membrane
165
selective permeability
passage of certain ions and molecules but not others across the membrane
166
simple diffusion
when a substance moves across a membrane from a high to low concentration area passing through the bilayer
167
facilitated diffusion
transport proteins provide passage across a membrane from a high to low concentration
168
active transport
moves a substance from a low to high concentration with ATP and a transmembrane protein
169
factors allowed to pass through the bilayer:
170
chemical gradient
171
electrochemical gradient
electrical gradients are due to the different amounts of ions on both sides of the membrane
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isotonic
concentrations are the same on both sides
173
hypertonic
concentrations are higher outside the cell than inside
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hypotonic
concentrations are lower outside the cell than inside
175
osmosis
if a solute cannot readily mobr across a membrane then water will move from a low solute concentration to a high one
176
plasmolysis
water will exit the cell if it is hypertonic and the plasma membrane will pull away from the cell wall
177
channel (gated)
transmembrane protein that forms an open passageway for facilitated diffusion of ions or molecules
178
ligands
controlled by noncovalent binding of small molecules like hormones or neurotransmitters
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aquaporin
transmembrane protein that allows water to diffuse through it
180
transporters
bind to one or more solutes in a hydrophilic pocket and undergo a conformational change to switch exposure on a membrane side
181
uniporter
182
symporter
183
antiporter
184
primary active transport
passes solutes through the membrane against the concentration gradient
185
pump
transporter that directly uses energy to transport a solute against a concentration gradient
186
secondary active transport
a pre-existing gradient drives the active transport of another solute
187
electrogenic pump (nerve cell)
produces an electrical gradient across the membrane
188
E1
3 Na+ binds and the phosphate on ATP is temporarily bound to the pump (phosphorylation)
189
E2
2 K+ binding causes a release of phosphate to switch back to the E1 conformation
190
exocytosis
materials in the cell are packaged into vesicles and excreted into the extracellular matrix => vesicles usually come the golgi (ex: hormones or digestive enzymes)
191
endocytosis
the plasma membrane invaginates to form a vesicle that brings a substance into a cell
192
receptor mediated
receptor in the plasma membrane is specific to cargo and stimulates endocytosis
193
pinocytosis
formation of a membrane vesicle from the plasma membrane for cells to sample extracellular fluid
194
phagocytosis
formation of an enormous membrane vesicle (phoneme) that engulfs a large particle like a bacterium => done by macrophages
195
apoptosis
programmed cell death
196
signal
agent that can influence the properties of cells
197
receptor
where a signal is recognized by a cellular protein
198
cellular response
ability to respond to change in cells
199
direct intercellular signaling
adjacent cells have cell junctions that enable them to pass ions, molecules, and other materials
200
contact dependent signaling
molecules that are bound to the surface of a cell and provide signals to others that make contact with them
201
autocrine signaling
cells secrete signaling molecules that bind to receptors on their own surface and neighboring cells of the same type
202
paracrine signaling
specific cells secrete a signal that doesn't affect the cell but influences the behavior of target cells in close proximity => neurotransmitters
203
endocrine signaling
signaling over long distances => hormones
204
receptor activation
a signaling molecule will bind to a receptor of the target cell causing a conformational change to activate its function
205
signal transduction
initial signal is converted or transduced to a different signal inside the cell
206
signal transduction pahway
process carried out by signaled cells resulting in the production of intracellular signaling molecules
207
cellular response
cells respond in several ways by altering the activities of one or more enzymes, altering structural proteins, or affecting function of transcription factors regulating genes
208
ligand
the signal molecule that binds covalently when it collides in the correct orientation with enough energy to make a complex
209
cell surface receptors
receptors in the plasma membrane that enable to cell to respond to different kinds of extracellular signaling
210
enzyme linked
signaling molecules bind to the extracellular domain and the conformation change is transmitted through the membrane portion of the protein
211
protein kinases
transfers a phosphate group from ATP to a specific amino acid in a protein => enzyme linked receptor
212
G-protein coupled receptors (GPCRs)
in all eukaryotic cells, contain 7 transmembrane segments that wind back and forth, and interact with the G-protein
213
G-proteins
bind to guanosine triphosphate (GTP) that causes a conformational change into an alpha and beta/gamma dimer => the alpha subunit interacts with other proteins in a transduction pathway and the beta/gamma dimer plays a role in transduction
214
ligand gated ion channels
proteins allowing the diffusion of ions across cell membranes
215
growth factor
signaling molecule that promotes cell division
216
receptor tyrosine kinases
an enzyme-linked receptor category in all animals and protists that plays a role in signaling molecules
217
3 parts of a signal transductino pathway
1. relay proteins (kinase cascade)
2. protein kinase cascade => phosphorylates intracellular proteins like transcription factors
3. phosphorylated transcription factors => stimulates gene expression
218
second messengers
small molecules or ions that relay signals inside the cell => result in second messenger production and act quickly
219
adenylyl cyclase
enzyme in the plasma membrane the is stimulated to synthesize cyclic adenosine monophosphate (cAMP) from ATP
220
cAMP signal transduction pathway
Epinephrine is the signal molecule that binds to a receptor activating a G protein => alpha subunit activates adenylyl cyclase to catalyze cAMP that activates PKA: 2 units phosphorylate specific cellular proteins and 2 regulatory subunits inhibit the catalytic subunits when bound (camp binds to the regulatory subunits and allows the catalytic subunits to activate)
221
PKA cellular repsonse
catalytic subunits of PKA phosphorylates specific cellular proteins such as enzymes, structural proteins, or transcription factors => glycolysis synthesis is to make glycogen and cAMP prevents glycogen synthesis
222
phosphodiesterase
converts cAMP to AMP and causes cAMP levels to decrease => regulatory units of PKA and all 4 units reassociate to reverse the effects of PKA
223
signal amplification
amplification of the signal involves the synthesis of many cAMP moleucules that activate PKA to phosphorylate more target proteins
224
second messenger advantages
signal amplification and speed
225
crosstalk
one or more components of one signal transduction pathway affect a different signal transduction pathway
226
Apoptosis pathway
227
extrinsic pathway
begins with activation of death cells and initiates a pathway to apoptosis
228
death receptors
when bound to extracellular signaling molecules the pathways is initiated to apoptosis
229
caspase
functions as a protease enzyme that digests other proteins to initiate other activations => initiates executioners or effectors that digest intracellular proteins and cause cell death, also initiates DNase enzyme that chops the DNA into fragments
230
intrinsic pathway (mitochondrial pathway )
stimulated by DNA damage that can cause cancer, mitochondria release cytochrome C into the cytosol to form a complex with other proteins called apoptosome to initiate caspases
231
extracellular matric (ECM)
the space outside of cells in animals primarily made of proteins and polysaccharides that form large fibers and attract water
232
cell wall
the space outside of plant cells
233
ECM functions
strength, structural support, organization of bodily cells, and cell signaling
234
collagen
proteins that form fibers and network that provides tensile strength
235
elastin
forms elastic fibers in the ECM that can stretch and recoil through covalent crosslinks
236
laminin
connects cells to the ECM and helps to organize components in the ECM
237
fibroconectin
connects cells to the ECM and helps to organize components in the ECM
238
glycosaminoglycans (GAGs)
the most abundant type of polysaccharides in the ECM containing a repeatable disaccharide unit
239
chitin
in the ECM of many invertebrates and contains nitrogen => forms the protective outer covering
240
cellulose
polysaccharide made of repeating molecules of glucose attached end to end => provide tensile strength for the cell via hydrogen bonding
241
primary cell wall
very flexible and allows new cells to increase in size => mostly made of cellulose and some other parts including hemicellulose (polysaccharide), glycans, and pectin
242
secondary cell wall
synthesized and deposited between the plasma membrane and the primary cell wall after maturation stops => layers of cellulose microfibrils and logins, etc. => very strong
243
cell junction
linkage of 2 cells through specialized structures
244
anchoring junctions
anchor cells to each other or to the ECM in parts of the body where cells are tightly connected to form linings
245
Cell adhesion of molecules (CAMs)
form actual connections at anchoring junctions through cadherins and integrins
246
cadherin
CAMs that create cell to cell junctions by two cadherin proteins in adjacent cells binding to one another with Ca2+ => connected to linker proteins on the inside
247
Integrin
connect adjacent cells together and to the ECM without calcium => 2 subunits and bound to fibronectin (adhesive protein) that binds to other ECM components like collagen
248
tight junctions
forms a tight seal between adjacent cells to prevent material from leaking between them => made by transmembrane proteins occuldin and claudin
249
4 types of anchoring junctions
adherens, desmosomes, hemidesmosomes, and focal adhesion
250
adherens junctions
connect cells via cadherins and organizes them to bind to actin cytoskeletal filaments
251
desmosomes
connect cells via cadherins and are spotlike connecting points that connect cells to intermediate cytoskeletal filaments
252
hemidesmosomes
connect cells to the extracellular matrix through integrins and interact with intermediate filaments
253
focal adhesions
connect cells to the ECM through integrins and bind to actin filaments
254
T/F tight junctions form strong connections with the cytoskeleton?
false => makes them mechanically weak compared to anchoring so the two must occur at the same time
255
gap junction
gap between the plasma membranes of cells allowing small molecules and ions through => composed of integral and membrane protein connexin
256
connexin
6 connexin proteins form a channel in the plasma membrane in vertebrates that cluster close enough to form an intercellular channel for small ions and molecules to go through
257
middle lamella
between most adjacent plant cells (formed before primary cell wall) and is rich in pectins (neg charged polysaccharides) that attract water and produce a hydrated gel and create rigidity
258
plasmodesmata
ducts or intercellular channels in plant cells like gap junctions => has a central desmotubule connecting smooth ER membrane between cell pores
259
T/F Plasmodesmata can open and close?
True, in the open conformation they allow passage of ions and small molecules like sugar or cAMP and close when there are pressure differences
