Chapter 11 - Cell Communication

Question 1

The three steps in cell communication

Answer 1

1) Signal reception
2) Signal transduction
3) Cellular response

Question 2

__________ are converted to responses within the cell

Answer 2

External signals…

Question 3

Cells _____, ____, and ___ to signals

Answer 3

receive, send, and respond

Question 4

Definition of Epinephrine (adrenaline)

Answer 4

A hormone secreted by the brain into the blood that stimulates the breakdown of stored polysaccharide glycogen within liver cells & skeletal muscle

Question 5

Cells in a multicellular organism communicate via ____ targeted for cells that may or may not be adjacent

Answer 5

…signaling molecules…

Question 6

Local signaling

Answer 6

animal cells communicate by direct contact (w/ cell junctions & cell-surface molecules)

Question 7

Many animal and plant cells have cell junctions that ____ ____ to the cytoplasm’s/adjacent cells

Answer 7

directly connect

Question 8

Plasmodesmata definition

Answer 8

Channels that connect plant cells and water & small solutes (and proteins & RNA) pass from cell to cell

Question 9

Gap junctions provide ___ ___ btwn adjacent cells

Answer 9

cytoplasmic channels

Question 10

Paracrine signaling

Answer 10

Another method animal cells use to communicate.
- uses secreted messenger molecules that travel only short distances
- ex: Growth factors (stimulate nearby target cells to grow & divide)

Question 11

Synaptic signaling definition

Answer 11

• neurotransmitters released in response to electric signal
• occurs in animal nervous system

Question 12

Long distance signaling

Answer 12

Uses hormones (plants & animals)

Question 13

In ___ ___ (in animals) specialized cells release hormones, which travel to target cells via the circulatory system (bloodstream)

Answer 13

…endocrine signaling…

Question 14

The ability of a cell to respond to a signal depends on whether it has a ___________

Answer 14

…receptor specific to that signal

Question 15

3 stages of cell signaling

Answer 15

-Reception, transduction, and response
-A series of steps by which a signal on a cell’s surface is converted into a specific cellular response

Question 16

Signal reception (general)

Answer 16

The target cell detects a signaling molecule (ligand) coming from outside the cell that binds to a receptor protein on the cell surface

Question 17

Signal transduction (general)

Answer 17

The binding of the signaling molecule alters the receptor and initiates a signal transduction pathway

Question 18

Cellular response (general)

Answer 18

The transduced signal triggers a specific response in the target cell

Question 19

A signaling molecule binds to a receptor protein, causing it to _____ ______

Answer 19

…change shape

Question 20

The binding btwn a ligand and receptor is _____ ______

Answer 20

highly specific

Question 21

_______________ is generally the initial transduction of the signal

Answer 21

A shape change in a receptor…

Question 22

Most signal receptors are _____ _______ proteins, but others are located inside the cell

Answer 22

…plasma membrane…

Question 23

The 3 main types of plasma membrane:

Answer 23

-G protein-coupled receptors
-Receptor tyrosine kinases (growth factors)
-Ion channel receptors

Question 24

G protein-coupled receptors (GPCRs)

Answer 24

-Cell-surface transmembrane receptors that work w/ G protein
-Largest family of human cell-surface receptors
-G proteins bind energy-rich GTP (Guanonsine-5’-triphosphate)
-Most water-soluble signal molecules bind to specific sites on receptor proteins that transmit info from extracellular environment to inside of cell

Question 25

Receptor tyrosine kinases (RTKs)

Answer 25

-Membrane receptors that catalyze the transfer of phosphate groups from ATP to another protein
-Can trigger multiple signal transduction pathways at once
-Abnormal functioning of RTKs associated w/ many types of human cancers

Question 26

Ion Channel Receptors

Answer 26

-Ligand-gated ion channel receptor acts as gate that opens & closes when the receptor changes shape
-Allows specific ions to flow through channel after ligand binds to receptor

Question 27

Intracellular Receptors

Answer 27

-Only in target cells (cytoplasm or nucleus)
-Small/hydrophobic chemical messengers
-Activated hormone-receptor complex can act as transcription factor (turn on/off specific genes)
-Ex: Aldosterone (lipid soluble) is steroid hormone that can cross the membrane to get to the target intracellular receptor & main role is to regulate salt & water in body, influencing blood pressure

Question 28

(signal transduction) Cascades of molecular interactions transmits signals…

Answer 28

…from receptors to relay molecules in the cell

Question 29

(signal transduction) Activated receptor activates another protein, which activates another, and so on till…

Answer 29

…the protein producing the response is activated

Question 30

(signal transduction) at each step, the signal is transducted into a different form, commonly a…

Answer 30

…shape change in a protein

Question 31

Many relay molecules in signal transduction pathways are _______, creating a phosphorylation cascade

Answer 31

…protein kinases…

Question 32

What do protein kinases do

Answer 32

They add a phosphate group to activate/inactivate other proteins

Question 33

Phosphorylation & dephosphorylation or proteins are commonly used in cells to _______ (molecular switch that turns activities on/off)

Answer 33

regulate protein activity

Question 34

Second messengers

Answer 34

-small, nonprotein, water-soluble molecules/ions that spread thru a cell via diffusion
-Cyclic AMP (made from ATP) & calcium ions common second messenger
-Participate in pathways initiated by GPCRs and RTKs

Question 35

(Cellular response) Cell signaling leads to regulation of one or more _________

Answer 35

…cellular activities

Question 36

(Cellular response) Many signaling pathways regulate the __________/other proteins usually by turning genes on/off in the nucleus

Answer 36

synthesis of enzymes

Question 37

(Cellular response) Response may occur in ______

Answer 37

nucleus/cytoplasm