Cell Communication

Question 1

Direct Contact Communication

Answer 1

2 cells directly communicating

–they have to touch

Question 2

Types of Direct Contact Communication

Answer 2

• Gap Junctions / Plasmadesmata

- Cell Recognition

Question 3

Cell Recognition

Answer 3

involves proteins in the membrane.

-the proteins recognize each other and often a reaction happens with an enzyme

Question 4

Functional Syncytium

Answer 4

All the cells are functioning as one unit

Question 5

Local Signaling

Answer 5

Paracrine signaling
autocrine signaling
Synaptic Signaling

Question 6

Paracrine Signaling

Answer 6

A cell releases a signal affecting all kinds of cells in an area
-the cell secretes a chemical that affects nearby cells through the interstitial fluid

Question 7

Autocrine Signaling

Answer 7

a cell releases a signal affecting cells that are the same type

Question 8

Synaptic Signaling

Answer 8

nerve cells release neurotransmitters directly onto target cells
-Affects one and only one cell

Question 9

synapse

Answer 9

association between two cells (synaptic cleft)

Question 10

Long- Distance Signaling

Answer 10

Endocrine (hormone)

Question 11

Endocrine

Answer 11

Hormones are the chemical signal

• the cell releases the hormone into the blood
• it is systemic
• only targets cells that have receptors

Question 12

Systemic

Answer 12

the whole body

–it will travel everywhere in the body

Question 13

the 3 stages of cell signaling

Answer 13

1. Reception
2. Transduciton
3. Cell Response

Question 14

Reception

Answer 14

Signal molecules (Ligand) bind to protein receptors on the target cell membrane.
--it is very specific

Question 15

Ligand

Answer 15

is the chemical signal in reception

• hormones (protein or amino acid bases)
• neurotransmitters

Question 16

Receptors

Answer 16

• Proteins
• specific (shape)
• shape changes when the Ligand binds–initiates transduction
• the receptor determines the response more than the ligand
• -they will set off different transduction pathways in different cells

Question 17

Types of Receptors

Answer 17

• Ion Channel Receptors
• Tyrosine Kinases
• G protein-coupled receptor

Question 18

Ion Channel Receptor

Answer 18

Protein is the receptor and ion channel

-the binding of the ligand causes the channel to open

Question 19

Receptor Tyrosine Kinases

Answer 19

• Come in pairs
• receptor tyrosine phosphoralates proteins
• receptor is a kinase which in turn activates proteins

Question 20

G protein-coupled receptor

Answer 20

• receptor activates G protein (uses GDP to activate)

- G protein activates the enzyme

Question 21

Transduction

Answer 21

Interactions/chemical reactions relaying the signal from the receptor to the target molecule

• can be very simple process of a long pathway of reactions
  1. Phosphorylation/Dephosphorylation
  2. Second Messengers

Question 22

Phosphorylation / Dephosphorylation

Answer 22

addition or removal of a phosphate group to a protein to activate / deactivate it

• Kinases- Phosphorolayte
• Phosphates- dephosphorlayte enzymes

Question 23

Second Messengers

Answer 23

small, non-protein, water-soluble, molecules, or ions

-often initiated by G protein-coupled receptors

Question 24

Types of Second Messengers

Answer 24

• Cyclic AMP

- Calcium Ions (Ca++)

Question 25

Cyclic AMP

Answer 25

they are cycle shaped AMP | - APT-----AMP ATP, gives off 2 phosphates to make AMP

Question 26

Calcium Ions (Ca++)

Answer 26

Always maintained at low to negligible concentration in the cytosol -pulled in form outside the cell or released from within the cell from enclosed membrane storage sights when calcium is needed

Question 27

Response

Answer 27

Will vary depending on the Ligand/receptor/cell - make more or less of something - movement - increase/decrease cells function - -very specific

Question 28

Termination of signal / response

Answer 28

Varies with ligand/responses - ligand- re-sequestered by cell, dissipate, brokendown... - Response- Components of transduction used up or feedback mechanisms

Question 29

Exception to Ligand-Reception communication

Answer 29

Steroid Hormones - they are lipid soluble compounds that can pass right through the cell membrane - they go directly to the nucleus and affect the DNA - -makes new proteins or stops cells from making new proteins

Question 30

APOPTOSIS

Answer 30

Programmed cell death - normal deletion and removal of cells - happens to a single select cell - external initiation/trigger- chemical signal??? - -don't know much about it - Internal trigger - -DNA damage - -problems with protein production

Question 31

Necrosis

Answer 31

Something the body has not intended to happen. - Usually happens to many cells in the same area - Ruptures the cell membrane - Very messie

Question 32

Process of APOPTOSIS

Answer 32

- Cell releases digestive enzymes - cell is broken down into smaller membrane bound fragments - phagocytosis of fragments by nearby cells - clean no inflamation

Question 33

Diseases Affecting APOPTOSIS

Answer 33

- Hepatitis B & C - Alzheimer's / Parkinson's - Cancer - APOPTOSIS seems to be turned off