Final - Chapter 9.1-9.3, Chapter 10.1-10.2 Flashcards
Conformational changes in a receptor
lead to a response within the cell
Signals allow cells to
respond to a changing environment and communicate
What are the five types of signals between cells?
1) direct intercellular signaling, 2) contact-dependent signaling, 3) autocrine signaling, 4) paracrine signaling, and 5) endocrine signaling
With direct intercellular signaling,
cell junctions allow signaling molecules to pass from one cell to another
In contact-dependent signaling,
molecules bound to the surface of cells serve as signals to cells coming into contact with them
In autocrine signaling,
cells secrete signaling molecules that bind to their own cell surface or similar neighboring cell
In paracrine signaling,
the signal doesn’t affect the originating cell, it influences nearby cells
In endocrine signaling,
hormones travel long distances and have longer lasting effects
What are the three stages of cell signaling?
1) receptor activation, 2) signal transduction, and 3) cellular response
During cell signaling, what occurs during receptor activation?
A signaling molecule binds to the receptor
During cell signaling, what occurs during signal transduction?
The activated receptor stimulates a sequence of changes - signal transduction pathway
During cell signaling, what are three types of possible cellular responses?
A change in enzymatic activity, a change in the function of structural proteins, or a change in gene expression
A ligand is
a signaling molecule
Ligands bind with
high specificity
What are the three types of cell surface receptors?
1) enzyme-linked receptors, 2) G-protein-coupled reactions, and 3) ligand-gating ion channels
What happens to the domains of enzyme-linked receptors?
The extracellular domain binds the signal while the intercellular domain becomes a functional catalyst
How are G-protein-coupled reactions/receptors activated?
A G protein binds to a receptor
G protein releases
GDP and binds GTP instead
GTP binding causes what to a happen to a G protein?
The G protein dissociates into an a subunit and a B/y dimer, which affects signaling pathways
What happens when a ligand binds in a ligand-gating ion channel?
It causes ion channels to open so ions can flow through the membrane
Ligand-gating ion channels can transmit synaptic signals between ___ and muscles or between two ___
neurons, neurons
With G-protein-coupled reactions, ___ relay signals within cells
second messengers
GPCR
G-protein-coupled receptors
Signal binding to GPCR actiavtes
the G protein to bind to GTP, causing dissociation and frees a a subunit
With G-proteins, what does the a subunit do?
a subunits bind to and activate adenylyl cyclase which promotes CAMP synthesis
cAMP activates
PKA
What are two advantages of cAMP?
1) signal amplification, and 2) speed
How does cAMP help with signal amplification?
Binding of a signal to one receptor can cause many cAMP molecules to be made which activate PKA - PKA can phosphorylate lots of proteins
How does cAMP help with speed?
cAMP can rapidly diffuse through a cell
What are the purposes of the ECM in animal cells?
surrounds animal cells, supports and organizes the cell, and aids in cell signaling
What is the ECM made of?
proteins and polysaccharides
What are the two adhesive proteins of the ECM?
fibronectin and laminin, which adhere ECM components together and to cell surface
What are the two structural proteins of the ECM?
collagen (tensile strength) and elastin (elasticity)
What are glycosaminoglycans (GAGs)?
long, unbranched polysaccharides with a repeating disaccharide unit
Why are GAGs needed?
They are sometimes linked to proteins to form proteoglycans and they help resist compression
What is the purpose of plant cell walls?
rigidity, maintenance of cell shape, and the direction of cell growth
Where does the primary cell wall develop?
between newly made cells
What is the primary cell wall made of and why is it important?
cellulose, is flexible and allows for size increase
Where is the secondary cell wall?
it’s deposited between the plasma membrane and the primary cell wall
What do cell junctions do?
adhere cells to each other and to the ECM
What are the five types of cell junctions and to what type of cell do they belong to?
1) anchoring junctions (animal), 2) tight junctions (animal), 3) gap junctions (animal), 4) middle lamella (plant), and 5) plasmodesmata (plant)
What do anchoring junctions do?
attach cells to each other and to the ECM
What molecules are needed in anchoring junctions?
cell adhesion molecules (CAMs) like caherin and integrin
What do tight junctions do?
form tight seals between adjacent cells, prevent the ECM from leaking between cells
What are tight junctions made of?
occludin and claudin
What do gap junctions do?
allow for the sharing of metabolites and signals between adjacent cells
What’s the structure of gap junctions like?
6 connexin proteins in one cell align with 6 connexin proteins in another cell to create a connexon
What does the middle lamella do?
cement cell walls of adjacent cells together
What is the first layer that forms during cell division in plant cells?
The middle lamella
What is the middle lamella rich in?
pectins
What does the plasmodesmata do?
allows for movement of ions and molecules between adjacent cells
