CELLULAR PHYSIOLOGY
Ass. Prof. Dr. Emre Hamurtekin
EMU Faculty of Pharmacy
INTRODUCTION
• No cell can be called «typical» of all cells.
• Organelles
CELL MEMBRANE
• Lipids and proteins, semipermeable
• Major lipids are phospholipids:
 phosphatidylcholine
 phosphotidylserine
 phosphatidylethanolamine
• Head: polar, hydrophilic
• Tail: nonpolar, hydrophobic
• Glycosphingolipids,
Sphingomyelin, cholesterol
CELL MEMBRANE
• Many different proteins are embedded in the
membrane.
a) Integral proteins
b) Peripheral proteins
- CAMs
- Pumps
- Carriers
- Ion channels
- Receptors
- Enzymes
CELL MEMBRANE
• Basal lamina
• Holds cells together, development, growth
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MITOCHONDRIA
• Oxidative phosphorylation!!!.............ATP : ENERGY
MITOCHONDRIA
• Have their own genome (less DNA compared to
nuclear genome)
• The enzyme complexes are responsible for
oxidative phosphorylation.
• Through complex I to complex V (ATP synthase), ATP
is generated.
• Ineffective DNA repair system
mutations = diseases
LYSOSOMES
• Irregular shaped structures
• Surrounded by membrane
• Interior is more acidic (proton pump, «H-ATPase»)
• Contain hydrolytic enzymes (acid hydrolases) pH:5
• Digestion of worn-out cell components, bacteria
etc...
PEROXISOMES
Contain enzymes (oxidases and catalases)
Can form by budding of the ER or division
Catalize anabolic and catabolic reactions
CYTOSKELETON
• System of fibres that maintains the structure
of the cell + change shape
– Microtubules
– Intermediate filaments
– Microfilaments
• Proteins and organelles move along
microtubules and microfilaments inside the
cell.
CYTOSKELETON
• Microtubules:
–
–
–
–
Temperature sensitive
Dynamic portion of the cytoskeleton (provide tracks)
Form spindles which moves the chromosomes in mitosis.
Drugs may affect the microtubules (colchicine, vinblastine,
paclitaxel*)
CYTOSKELETON
• Intermediate filaments:
– Connect the nuclear membrane to the
cell membrane
– Resist external pressure
– Cell-type spesific (vimentin: fibroblasts;
cytokeratin: epithelial cell)
• Microfilaments:
– Made up of actin
– F-actin: intact microfilaments
– G-actin: unpolymerized protein actin subunits
– Interact with membrane-bound proteins
– Microvilli-intestinal mucosa
– Lamellipodia
– Focal adhesion
complexes
- Provide tracks
MOLECULAR MOTORS
• Move proteins, organelles, cell parts (cargo)
inside the cell
• ATPases
• 3 superfamilies:
– Kinesin
– Dyneins
– Myosin
MOLECULAR MOTORS
CENTROSOMES
• 2 centrioles + surrounding
pericentriolar material
• Microtubules in groups of
three run longitudinally in
the walls of each
centriole
• When a cell divides, they
duplicate themselves,
pairs move apart to the
poles of the mitotic
spindle, monitor the steps
in cell division
CELL ADHESION MOLECULES
• Cells are attached to basal lamina and to each other by CAMs.
–
–
–
–
–
–
–
–
Fasten cells to their neighbours
Transmit signals
Cell movement
Embriyonic development
Formation of nervous system and other tissues
Holding tissues together
Inflammation and wound healing
Metastasis of tumors
• 4 families:
–
–
–
–
Integrins
Adhesion molecules of IgG superfamily
Cadherins
Selectins
INTERCELLULAR CONNECTIONS
• Tight junctions
(zonula occludens)
• Desmosome
• Zonula adherens
• Hemidesmosomes
• Focal adhesions
• Gap junction
INTERCELLULAR CONNECTIONS
• Tight junctions:
– Surround the apical margins of the cell
– Endothelial barrier function
– Permit the passage of some ions and solutes in between adjacent cells
• Desmosomes:
– Patches characterized by thickenings of the membranes of two
adjacent cells
– Intermediate filaments attaches to these thickened areas
• Zonula adherens:
– Major site of attachments for intracellular microfilaments
• Hemidesmosomes & Focal adhesions:
– Attach cells to underlying basal lamina
– Labile structures associated with actin filaments inside the cell
– Play an important role in cell movement
GAP JUNCTION
• Connexons are lined up with one another to form gap junction.
NUCLEUS & RELATED STRUCTURES
• The nucleus is made up in
large part of the
chromosomes.
• Each chromosome is made
up of DNA.
• DNA is wrapped around a
core of histon protein to
form a nucleosome.
• The whole complex of DNA
and proteins is called
chromatin.
NUCLEUS & RELATED STRUCTURES
• The nucleus of most cells
contain nucleolus.
• Rich in RNA.
• They synthesize the
ribosomes.
• Nuclear membrane is a
double membrane.
• Spaces between the two
folds are called perinuclear
cisterns.
ENDOPLASMIC RETICULUM
• ER is a complex series of
tubules in the cytoplasm
– Rough (granular) ER: protein
synthesis
– Smooth (agranular) ER:
steroid synthesis &
detoxification
• Sarcoplasmic reticulum:
skeletal and cardiac muscle
RIBOSOMES
• 60S AND 40S subunits
• These are the sites of protein synthesis.
• Ribosomes attached to ER synthesize:
– all transmembrane proteins
– most secreted proteins
– most proteins stored in Golgi, lysosomes, endosomes
• Free ribosomes synthesize:
– Cytoplasmic proteins (i.e. hemoglobin)
– proteins found in peroxisomes and mitochondria.
GOLGI APPARATUS
• Glycosylation of proteins and lipids.