Week 1 (Exam 1): Cell Communication & Development; Cell Form & Function (Diversity, Multicellular Tissues) Flashcards
endocrine signaling
signaling through the circulatory system
paracrine signaling
signaling by diffusion with small, water-soluble molecules such as growth factors
growth factor
causes responding cell to grow, divide, or differentiate
- influences the types of cells their neighbors will become
what are growth factors secreted by
embryonic cells
synaptic signaling
specialized form of short-range signaling
-communication between neurons and between neurons and muscle cells
response to synaptic signaling
-if the adjacent cell is a neuron, it will respond by carrying on the nerve impulse
-if the adjacent cell is a muscle cell, it may respond by contracting
autocrine signaling
self-signaling by diffusion
contact-dependent signaling
a transmembrane protein on the surface of one cell acts as the signaling molecule, and a transmembrane protein on the adjacent cell acts as the receptor
what is contact-dependent signaling important for?
the development of the nervous system of vertebrates
what is Delta?
a transmembrane protein
what happens if a cell has more Delta?
it will become a neuron
what does Delta bind to?
Notch receptors
what happens if a cell has more Notch receptors?
it becomes a glial cell
are there more glial cells or neurons in the central nervous system?
glial cells
ligand
signaling molecule
ligand-bonding site
the specific part of the receptor protein that the signaling molecule binds to
where are receptors for polar signaling located?
cell membrane
what does the location of receptors depend on?
whether the signaling molecule is polar or nonpolar
what domains do transmembrane proteins have
an extracellular domain, a transmembrane domain, and a cytoplasmic domain
extracellular domain
the part of a transmembrane protein that lies outside of the cells
transmembrane domain
the part of a transmembrane protein that lies on the cell membrane
cytoplasmic domain
the part of a transmembrane protein that lies inside the cell
where are the receptors for nonpolar signaling molecules located
inside the cell
totipotent cell potential
can form all the cell types in an organism
-ex zygote
pluripotent cell potential
can generate all the different types of cells in the body
-ex embryonic stem cells
multipotent cell potential
can produce some or all of the mature cell types found within a particular tissue
-ex neural progenitor cells
why is cell communication so important?
it is integral for coordinating cellular division, function, and cell differentiation (specialization)
four requirements to build a multicellular organism
-cell growth & division
-cell communication
-cell specialization
-cell-cell adhesion
which molecules can cross the cell membrane by simple diffusion?
lipids
what happens to a signal after it binds the receptor?
it eventually dissociates from the receptor
-doesn’t necessarily need the termination signal, because it takes a lot more energy to wait for the termination signal
is a protein always active when it is phosphorylated?
no
four major steps of the signal transduction process
-receptor activation
-signal transduction
-response
-termination
receptor activation step
the signal binds to a receptor
signal transduction step
the signal is transmitted to the interior of the cell by a signal transduction pathway
response step
the cell performs a task
termination step
the signal pathway is cut off so no new signals can be received
what is the role of phosphorylation?
phosphorylation is conducted by the kinases enzyme, and it phosphorylates proteins
what is the role of dephosphorylation
removing a phosphate group from a protein with phosphotases
kinase function
phosphorylation
phosphotase function
dephosphorylation
short-term cellular response
trigger movement within the cell, such as changes in cell shape or movement of vesicles to the membrane
long-term cellular response
trigger permanent changes to the cell, such as activation of transcription
four types of tissues
epithelial, connective, muscle, and nervous
tissues
collections of cells that carry out a specific function
organs
a combination of tissues, such as the heart, lung, or kidney
epithelial tissue function
provides a lining for all the spaces inside and outside hte body
where is epithelial tissue found?
-outer lining of the skin
-inner lining of the gut, bladder, & blood vessels
characteristics of epithelial tissue
-closely packed together and connected by cellular junction
-continuous sheet of cells
-layered
-may absorb and secrete substances as well as forming a boundary
simple epithelial tissue
one layer of cells
stratified epithelial tissue
more than one layer of cells
squamous epithelial tissue
made of flat cells
cuboidal epithelial tissue
made of round/square cells
columnar epithelial tissue
made of tall cells
connective tissue
underlies epithelial tissue
-has extensive extracellular matrix & few cells
extracellular matrix
an insoluble meshwork composed of proteins & polysaccharides
function of extracellular matrix
contributes structural support & provides informational cues that determine activity of cells it contacts
types of connective tissue
-basal lamina
-dermis
basal lamina
specialized connective tissue
dermis
made of cells that secrete the components of the extracellular matrix
characteristics of dermis
-strong and flexible bc it contains tough protein fibers
-contains blood vessels
-cushions the body
muscle tissue
made of cells called fibers that are able to shorten or contract
what are muscle fibers composed of
actin thin filaments & myosin thin filaments
myosin
a motor protein that uses ATP energy to change conformationally, which causes individual muscle cells to shorten, & the muscle tissue to contract
-only present in bilateraians
three types of muscle tissue in vertebrates
skeletal muscle, cardiac muscle, & smooth muscle
skeletal muscle
attaches to bone & controls voluntary movements
cardiac muscle
contracts to control the heartbeat
smooth muscle
found in the gut, where it causes waves of contraction that push food along the digestive tract, & blood vessels
nervous tissue
takes in sensory issue, processes info, & sends signals to target organs to elicit a response
organ system
combination of organs
sponge tissue characteristics
only have a simple epithelial lining
cnidarian tissue characteristics
have tissue diversity but no organs
bilaterian tissue characteristics
have true organs
zygote
fertilized egg
morula
ball of cells formed within 4-5 days after fertilization
early cell development stages
zygote -> 2-cell stage -> 4-cell stage -> morula -> blastocyst with inner cell mass -> gastrula with 3 germ layers
gastrula germ layers
ectoderm, mesoderm, endoderm
what does the ectoderm develop into
outer layer of the skin, brain & spinal cord, peripheral nerve cells, pigment cells
what does the mesoderm develop into?
inner skin layer, muscle, bone, blood
what does the endoderm develop into
inner gut lining & lung lining, liver, pancreas
blastocyst
hollow sphere that develops from the morula
inner cell mass
attached to the inside of the blastocyst wall & develops into the body of the embryo (pluripotent)
what happens to the blastocyst once it is developed
it implants in the uterine wall
gastrula
cells of the blastula become organized in the three germ layers
stem cells
totipotent, pluripotent, & multipotent cells
nuclear transfer
the nucleus of one cell is placed into the cytoplasm of another cell without a nucleus
regenerative medicine
aims to use the natural processes of cell growth & development to replace diseased or damaged tisses
how to create induced pluripotent stem cells (iPS cells)
activating a few genes in adult cells
signal transduction
an extracellular molecule acts as a signal to activate transmembrane proteins that, in turn, activate molecules
apoptosis
programmed cell death
necrosis
cell death that occurs in response to injury
proteases
enzymes that cleave proteins
-called caspases
cytoskeleton
structural protein networks in the cytoplasm that determine and maintain the shape of the cell
cell junctions
complexes of proteins in the cell membrane where a cell makes contact with another cell or the extracellular matrix
keratinocytes
specialized to protect the underlying tissues & organs
-elaborate system of cytoskeletal fibers
fibroblasts
synthesize the extracellular matrix
-strong & flexible
cytoskeletal elements
microfilaments, microfibers, and sometimes intermediate filaments (only in animal cells)
function of cytoskeletal elements
enable cells to change shape, move about, & transport stuff
microfilament
a double helix of actin monomers
intermediate filament
a strong fiber composed of protein subunits
microtubule
hollow tube formed from tubulin dimers
what protein makes up intermediate filaments in epithelial cells
keratines
what protein makes up intermediate filaments in fibroblasts
vimentins
what protein makes up intermediate filaments in neurons
neurofilaments
epidermolysis bullosa
a mutation in keratin genes that causes the intermediate filaments to not polymerize
how do protein subunits get longer
by adding subunits to their ends
plus end of a protein subunit
faster-assembling end
minus end of a protein subunit
slower-assembling end
dynamic instability
cycles of depolymerization & polymerization
motor proteins
small accessory proteins that allow microtubles & microfilaments to move
what motor proteins are associated with microtubule tracks
kinesin & dynein
kinesin function
transports molecules towards the plus end of microtubules
dynein function
transports molecules toward minus end of a microtubule
subunits of microfilaments
actin monomers
major functions of microfilaments
-cell shape & support
-cell movement
-cytokinesis
-vesicle transport
-muscle contraction
subunits of intermediate filaments
diverse
major functions of intermediate filaments
cell shape & support
subunits of microtubules
tubulin dimers
major functions of microtubules
-cell shape & support
-cell movement
-cell division
-vesicle transport
-organelle arrangement
type of cell junctions
-tight junction
-adherens junction
-desmosome
-hemidesmosome
-gap junction
primary function of a tight junction
epithelial boundary
what proteins are involved in the tight junction
claudins, occludins
does the tight junction attach to the cytoskeleton
no
primary function of the adherens junction
establish a physical connection among the actin cytoskeletons of cells in the epithelial layer
what proteins are involved in the adherens junction
cadherins, actin
does the adherens junction attach to the cytoskeleton
yes - microfilaments
primary function of the desmosome
cell-cell adhesion
what protein is involved in the desmosome junction
cadherins
does the desmosome junction attach to the cytoskeleton
yes - intermediate filaments
what is the main use for desmosomes
anchoring cells together while allowing food & waste to get through
primary function of hemidesmosome
connects cells to the basal lamina
what protein is involved in the hemidesmosome junction
integrins
does the hemidesmosome attach to the cytoskeleton
yes - intermediate filaments
primary function of the gap junction
communication between animal cells
what proteins are involved in the gap junction
connexions
does the gap junction attach to the cytoskeleton
no
microfilaments are composed of _____ in _____ arrangements
repeating actin subunits; a thin double-helix
microfilaments help a cell…
maintain its size & shape
cell movement can be facilitated by microfilaments in what way?
by dynamic growing & shrinking at the ends
which would be more likely to cause the development of a microvillus on an intestinal epithelial cell?
plus end growth of microfilaments at the tip of the microvillus but no shrinkage at the minus end
which best describes a role that microfilaments play in the structure and function of red blood cells?
they maintain the bioconcave shape to maximize gas exchange
microtubules form dimers of _____ and _____ subunits that polymerize into a ______.
alpha-tubulin; beta-tubulin; hollow tube
microtubules are _____ because they _____ and depolymerize at their ends.
dynamic; polymerize
the ability of microtubules to undergo rapid _______ and slower ______ is associated with the ability of the ______ to explore the cell and locate chromosomes
depolymerization; polymerization; spindle apparatus
microtubules can grow by the addition of tubulin dimers to ______, and they can shorten by the removal of dimers from ______.
both plus and minus ends; both plus and minus ends
the plus ends of both microtubules and microfilaments differentiate from the minus ends:
in that new tubulin or actin subunits are added more quickly
contraction of muscles is an example of how the motor protein _______ interacts with the cytoskeletal elements called ______ to produce movement
myosin; actin filaments
the basis for the movement of cilia and flagella is the interaction of the motor protein ______ with the cytoskeletal elements called _______
dynein; microtubules
when cells communicate by the signaling process, one cell produces a _______ that must be received by the ______ on or in the responding cell
signaling molecule; signal receptor
signal molecules that are _______ usually have their corresponding receptor ______ of the cell
polar; on the surface
a receptor that is inside the cell would require a _______ signal molecule that can ________ the plasma membrane
nonpolar; pass through
a ______ expresses a gene or genes that direct the production of the signaling molecule, and the ______ expresses a gene or genes that direct the production of the ______
signaling cell; responding cell; receptor protein
true/false: the ability of cells to adhere to each other is fundamental to multicellularity
true
many of the signaling pathways used for signaling between cells in complex multicellular organisms first evolved in…
unicellular eukaryotes
the ability of a specific tissue or organ to respond to the presence of a hormone is dependent on…
the presence of the appropriate receptors on the cells of the target tissue or organ
true/false: signaling pathways have been conserved in a wide range of organisms
true
true/false: a cell can only respond to signals from other cells, not from the physical environment
false
which signaling system involves the longest distance between release of a signaling molecule and activation of a receptor?
endocrine
kohler and lipton first discovered platelet-derived growth factors (PDGF) by observing that fibroblasts
grew better in cell culture containing blood serum containing proteins released by platelets during clotting
growth factors such as platelet-derived growth factor (PDGF) function in:
paracrine signaling
how do signaling molecules involved in paracrine and autocrine signaling travel?
by diffusion
what type of cell-surface receptor undergoes changes in phosphorylation in response to binding of its ligand?
a receptor kinase
true/false: most ligands form covalent bonds with their associated receptors, these complexes are more or less permanent and can only be broken through the hydrolysis of ATP
false
how does an “activated” receptor transfer information into the cell?
through a conformational change of the receptor
which type of protein adds a phosphate group to another molecule?
kinase
what is the end-result of activating the MAP kinase pathway?
a change in gene expression
the first step following platelet-derived growth factor (PDGF) binding of the receptor is
dimerization of the receptor
cells differentiate through
gene regulation
true/false: as cells differentiate, they lose their ability to become other cell types because they delete subsets of genes
false
cellular differentiation progressively restricts cell fate because the unexpressed genes in the cell:
-undergo irreversible repression
-become more densely packed with nucleosomes
signal transduction in development is often amplified by
sequential phosphorylation of proteins in the cytoplasm
signal transduction is the process by which
an extracellular molecule activates a membrane protein, which in turn activates molecules inside the cell
which tissue type is made up of cells that can contract?
muscle tissue
which tissue type can perform absorption or secretion in the body?
epithelial tissue
which tissue type helps form a barrier between the body and the external environment?
epithelial tissue
could melanin granules be moved by dynein and kinesin along an actin microfilament?
no, these motor proteins are specific to microtubules and cannot move along microfilaments
dynamic instability is a feature of
microtubules
myosin is a motor protein that associates with
microfilaments
which of the cell junctions is involved in creating a barrier between cells?
tight junction
cadherins bind to which type of cytoskeletal elements?
both intermediate filaments & microfilaments
what do gap junctions and plasmodesmata have in common?
they both allow direct transport of materials between cells
cadherins are
cell adhesion molecules found in cell junctions
what is the basal lamina?
a specialized form of the extracellular matrix found beneath all epithelial tissues
what is the extracellular matrix?
a network of proteins and polysaccharides outside the cell that play a role in structural support
the strength of collagen comes from
its triple helical structure & bundling
how do cells connect to the extracellular matrix?
through integrins
