Cell Signaling

Question 1

anchoring junctions

Answer 1

cell junctions that hold two different cells together through attachment of cytoskeletal components (microtubules, intermediate filaments, microfilaments)

There are three types of anchoring junctions: desmosomes, hemidesmosomes, and adheren junctions

Question 2

adheren junctions

Answer 2

use cadherin (type of cell adhesion molecule) to connect actin filaments with other cells and extracellular matrix

Question 3

desmosomes

Answer 3

use cadherin (type of cell adhesion molecule) to connect intermediate filaments to other cells

Question 4

hemidesmosomes

Answer 4

integrins (transmembrane receptors that mediate cell signaling) connect intermediate filaments of cells to the extracellular matrix

Question 5

gap junctions

Answer 5

pull the two cells very close to one another and connect with connexin (intercellular membrane channels) proteins to enable communication between the cells through diffusion

however, there is no contact between cytoplasmic fluids of each cell

less common - mostly used in cardiac muscle so that cells can contract at the same time

Question 6

tight junctions

Answer 6

found in the epithelial cells

linked closely together to prevent solutes from being able to move freely from one tissue into another

ex: blood-brain barrier

Question 7

acetylcholine

Answer 7

the neurotransmitter that is released from a neuron and crosses the synapse to attach to receptors found on the presynaptic terminal. That will allow Na+ to enter the cell and cause a depolarization at the neuromuscular junction which travels down T-tubules until it hits the sarcoplasmic reticulum and will release Ca2+ into the sarcoplasm where it can bind to troponin and cause muscle contractions

Question 8

peripheral proteins

Answer 8

they react with the surface of the cell membrane but don’t actually cross into the cell membrane. So they just float on the side clinging for dear life

Question 9

integral proteins

Answer 9

are transmembrane proteins within the cell membrane - will have a hydrophilic portion that is exposed to the extracellular cytosol and a hydrophobic portion which is tucked away in the cell membrane

Question 10

osmosis

Answer 10

water flows down its concentration gradient from areas of low solute to areas of high solute to try to equalize the concentration

does not require energy

Question 11

simple diffusion

Answer 11

molecules flow down their concentration gradient (passive transport) and do not require any additional energy

generally used by small, nonpolar molecules

Question 12

facilitated diffusion

Answer 12

molecules that flow down their concentration gradient and don’t require energy, but do require a channel to pass through the hydrophobic cell membrane

used by molecules that are generally too large or too polar –> glucose, insulin, charged ions

Question 13

primary active transport

Answer 13

energy to move molecules comes from breakdown of ATP

Question 14

secondary active transport

Answer 14

energy to move molecules against concentration gradient comes from using other molecules moving down their concentration gradient to provide the energy needed to move a molecule against its concentration gradient

ex: antiports and symports

Question 15

endocytosis

Answer 15

moving molecules into the membrane to be digested through pinocytosis (liquid engulfment) or phagocytosis (solid particle engulfment)

extracellular contents are transported into the cell within a vesicle formed from the plasma membrane

Question 16

exocytosis

Answer 16

releases hormones, NT, membrane proteins and lipids, and other materials out of the cell

Question 17

receptor mediated endocytosis

Answer 17

highly specific process in which a ligand binds to the corresponding receptor on the cell surface

the binding triggers the plasma membrane to close around the ligand to become a vesicle inside the cell

this vesicle will mature into an endosome

Question 18

voltage gated ion channels

Answer 18

will only open at a certain voltage

ex: action potentials -> opening of sodium and potassium gated channels

Question 19

ligand gated ion channels

Answer 19

will only open if a specific ligand is present

ex: during depolarization of muscle cells –> acetylcholine is released from the presynaptic terminal and will bind to nicotinic acetylcholine receptors which are on sodium channels. When acetylcholine binds, it opens up the channel and allows sodium to influx and depolarize the postsynaptic neuron