Cell Communication & Development + Cell Form & Function Flashcards
What are the three requirements to have complex multicellular life?
- cells must stick together
- cells must communicate with one another
- cells must participate in a network of genetic interactions that regulates cell division & differentiation
What are epithelia?
sheets of cells that line the inside and cover the outside of the body
What are the four essental elements of cell signaling?
- signaling cell
- signaling molecule
- receptor
- responding cell
What are the four steps of the signal transduction pathway?
- receptor activation
- signal transduction
- response
- termination
What happens in receptor activation?
the signal binds to a receptor, which activates it
What happens in signal transduction?
the signal is transmitted to the interior of the cell by a signal transduction pathway
What happens in the cellular response?
the cell carries out some sort of activity depending on the nature of the signaling molecule or responding cell
What happens in termination?
the cellular response is terminated so that new signals can be received and the cell is protected from overreacting to new signals
True or False:
A termination signal is necessary for termination.
False
The termination signal can dissociate by itself.
Which type of signaling travels long distances?
endocrine signaling
Which type of signaling travels short distances?
autocrine and paracrine signaling
Which type of signaling involves direct contact?
contact-dependent signaling
What is a ligand?
alternative term for a signaling molecule
What is the ligand-binding site?
the specific location on the receptor where a signaling molecule binds
What is a cell-surface receptor?
receptors located on the outside surface of the responding cell
Polar/nonpolar signaling molecules pass through cell-surface receptors.
polar
What is an intracellular receptor?
receptors located inside the cell
Polar/nonpolar signaling molecules pass through intracellular receptors.
nonpolar
What is a receptor tyrosine kinase?
a receptor that is an enzyme that undergoes phosphorylation when the signal is bound
kinase
an enzyme that phosphorylates
phosphorylation
the transfer of a phosphate group from ATP to a substrate
What are phosphatases?
enzymes that dephosphorylate other molecules
dephosphorylation
the removal of phosphate groups from another molecule
What is the process of RTK activation?
- signaling molecule travels to the RTK of the responding cell
- signaling molecule binds with the receptor, which causes dimerization
- each member of the active receptor pair phosphorylates the other member
- the phosphate groups provide binding sites for intracellular signaling proteins
What is dimerization?
the process in which the members of a receptor partner together
What is a short-term cellular response?
a temporary change that can be reversed
i.e. changing blood glucose level, activating/deactiviating
What is a long-term cellular response?
a permanent change
i.e. gene expression
G-protein receptors/receptor kinases facilitate short-term cellular responses.
G-protein receptors
G-protein receptors/receptor kinases facilitate long-term cellular responses.
Receptor kinases
What are stem cells?
cells that can differentiate into different cell types
What are totipotent cells?
cells that have the potential to give rise to a complete organism
What is an example of a totipotent cell?
zygotes
What are pluripotent cells?
cells that can give rise to any type of cell
What is an example of a pluripotent cell?
embryonic stem cells
What are multipotent cells?
cells that can form a limited number of types of specialized cell
What is an example of a multipotent cell?
neural cells
Why do differentiating cells lose their developmental potential?
- gene regulation: genes no longer needed are turned off
- genome reduction: as cells differentiate, they delete DNA for genes no longer needed
What is apoptosis?
programmed cell death
What are tissues?
a collection of cells that work together to perform a specific function
What are organs?
two or more tissues that combine and function together
What determines the shape of cells?
the cytoskeleton
What determines the ability of cells to connect to one another?
cell junctions
What are cell junctions?
complexes of proteins in the cell membrane where a cell makes contact with another cell or the extracellular matrix
What is the extracellular matrix?
a meshwork of proteins and polysaccharides that cells adhere to
What are the four types of tissue in the body?
- epithelial
- connective
- muscle
- nervous
What is the function of epithelial tissue?
- provides a lining for all spaces inside and outside the body
- controls the movement of substances into and out of the body
What is the structure of epithelial tissue?
a continuous sheet of cells that are closely packed and connected by cellular junctions
What is the function of connective tissue?
- underlies the epithelial tissue
- provides cohesion and internal support for organs and cells
What is the function of muscle tissue?
- supports movement by shortening or contracting muscle fibers
What is the function of nervous tissue?
- takes in sensory information from the environment
- processes information
- sends signals to target organs to elicit a response
What are the three cytoskeletal elements?
- microfilaments
- microtubules
- intermediate filaments
What is the function of microfilaments?
- assist with cell movement
- reinforce cell membrane
- help organize associated proteins
Rank the size of the three cytoskeletal elements in order from shortest to longest.
- microfilaments
- intermediate filaments
- microtubules
True or False:
Microtubules help increase surface area.
False
Microfilaments help increase surface area.
What is the function of intermediate filaments?
- provide cells with mechanical strength
- anchoring in epithelial cells
What is the function of microtubules?
- facilitate transportation of materials in the cell
What is the structure of microfilaments?
helical, short, and extensively branched
What is the structure of intermediate filaments?
strong and cable-like
What is the structure of microtubules?
hollow and tubelike
In microtubules and microfilaments, the plus end assembles ____ and the minus end assembles ____.
quickly, slowly
What are the two motor proteins associated with transportation within microtubules?
kinesin and dynein
Kinesin transports cargo to the ____ end of microtubules.
+
Dynein carries cargo away from the cell membrane to the ____ end.
-
What are cadherins?
allows for cell-cell adhesion
What are integrins?
allow for cell-extracellular matrix adhesion
What do anchoring-type cell junctions do?
connect adjacent cells and are reinforced by the cytoskeleton
What do barrier-type cell junctions do?
prevent materials from passing freely through the spaces between cells
What do communicating-type cell junctions do?
allow cells to communicate with one another
What is the function of adherens junctions?
cell-cell adhesion
What components make up adherens junctions?
cadherins
Adherens junctions’ shape is ____, while desmosomes’ shape is ____.
beltlike; buttonlike
What is the cytoskeletal attachment of adherens junctions?
microfilaments
What is the function of desmosomes?
cell-cell adhesion
What are the components of desmosomes?
cadherins
What is the cytoskeletal attachment of desmosomes?
intermediate filaments
What is the function of hemidesmosomes?
cell-extracellular matrix adhesion
What are the components of hemidesmosomes?
integrins
True or False:
Hemidesmosomes have a different structure and cytoskeletal attachment than desmosomes.
False
They both are buttonlike and attach to intermediate filaments.
What is the function of tight junctions?
establishes a seal between cells to prevent molecules from passing through
What are the components of tight junctions?
claudins and occludins
What is the structure of tight junctions?
a band of interconnected strands of integral membrane proteins
What is the function of gap junctions?
permits materials to pass directly from the cytoplasm of one cell to another
What are the components of gap junctions?
connexins
What is the structure of gap junctions?
ring-like
What are the three components of the extracellular matrix?
- connective tissue
- collagen
- basal lamina
What does connective tissue do in the extracellular matrix?
connects and supports various parts of the body
What does collagen do in the extracellular matrix?
provides strong, durable support
What does the basal lamina do in the extracellular matrix?
a specialized layer of the extracellular matrix beneath all epithelial tissues
Polar molecules are hydrophilic/hydrophobic.
hydrophilic
Nonpolar molecules are hydrophilic/hydrophobic.
hydrophobic
When a signal loses its ____, it no longer remains bound and dissociates from the receptor.
binding affinity
Why is the fluid nature of the plasma membrane important?
it allows the RTK monomers to move together and dimerize to be activated
The loss of ____ in the skin causes increased susceptibility to blister formation.
extracellular matrix proteins
How does a greater surface area affect the cell membrane?
it increases the amount of membrane transporters on the membrane
