Cell Communication Flashcards
Direct Contact Communication
2 cells directly communicating
–they have to touch
Types of Direct Contact Communication
- Gap Junctions / Plasmadesmata
- Cell Recognition
Cell Recognition
involves proteins in the membrane.
-the proteins recognize each other and often a reaction happens with an enzyme
Functional Syncytium
All the cells are functioning as one unit
Local Signaling
Paracrine signaling
autocrine signaling
Synaptic Signaling
Paracrine Signaling
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
Autocrine Signaling
a cell releases a signal affecting cells that are the same type
Synaptic Signaling
nerve cells release neurotransmitters directly onto target cells
-Affects one and only one cell
synapse
association between two cells (synaptic cleft)
Long- Distance Signaling
Endocrine (hormone)
Endocrine
Hormones are the chemical signal
- the cell releases the hormone into the blood
- it is systemic
- only targets cells that have receptors
Systemic
the whole body
–it will travel everywhere in the body
the 3 stages of cell signaling
- Reception
- Transduciton
- Cell Response
Reception
Signal molecules (Ligand) bind to protein receptors on the target cell membrane. --it is very specific
Ligand
is the chemical signal in reception
- hormones (protein or amino acid bases)
- neurotransmitters
Receptors
- 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
Types of Receptors
- Ion Channel Receptors
- Tyrosine Kinases
- G protein-coupled receptor
Ion Channel Receptor
Protein is the receptor and ion channel
-the binding of the ligand causes the channel to open
Receptor Tyrosine Kinases
- Come in pairs
- receptor tyrosine phosphoralates proteins
- receptor is a kinase which in turn activates proteins
G protein-coupled receptor
- receptor activates G protein (uses GDP to activate)
- G protein activates the enzyme
Transduction
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
Phosphorylation / Dephosphorylation
addition or removal of a phosphate group to a protein to activate / deactivate it
- Kinases- Phosphorolayte
- Phosphates- dephosphorlayte enzymes
Second Messengers
small, non-protein, water-soluble, molecules, or ions
-often initiated by G protein-coupled receptors
Types of Second Messengers
- Cyclic AMP
- Calcium Ions (Ca++)
Cyclic AMP
they are cycle shaped AMP
- APT—–AMP ATP, gives off 2 phosphates to make AMP
Calcium Ions (Ca++)
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
Response
Will vary depending on the Ligand/receptor/cell
- make more or less of something
- movement
- increase/decrease cells function
- -very specific
Termination of signal / response
Varies with ligand/responses
- ligand- re-sequestered by cell, dissipate, brokendown…
- Response- Components of transduction used up or feedback mechanisms
Exception to Ligand-Reception communication
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
APOPTOSIS
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
Necrosis
Something the body has not intended to happen.
- Usually happens to many cells in the same area
- Ruptures the cell membrane
- Very messie
Process of APOPTOSIS
- Cell releases digestive enzymes
- cell is broken down into smaller membrane bound fragments
- phagocytosis of fragments by nearby cells
- clean no inflamation
Diseases Affecting APOPTOSIS
- Hepatitis B & C
- Alzheimer’s / Parkinson’s
- Cancer - APOPTOSIS seems to be turned off