Histology - Lecture 23 - Cell Organelles

Front 1

What is the primary difference between eukaryotic and prokaryotic cells?

Back 1

Eukaryotic cells are subdivided into enclosed compartments - called organelles.

Front 2

What are ribosomes

Back 2

Made in the nucleolus, and leave nucleus and enter cytoplasm. Involved in protein synthesis.
1) Membrane bound ribosomes -

Front 3

What are membrane-bound ribosomes?

Back 3

They are attached to cytoplasmic surface of ER membrane (rough ER).
They synthesize proteins that are translocated to ER and then to gogli.

Front 4

What are free ribosome?

Back 4

These are unattched to any membrance and synthesize all other proteins:
Nuclear proteins
Mitochondrial proteins
Cytosolic proteins
Peroximosol Proteins

Front 5

What is the endoplasmic recticulum (ER)?
Rough ER?

Back 5

It is an interconnected network of branching tubules, central role is in lipid and protein biosynthesis.
Folding generates greater surface area.
-Can be continous with nuclear envelope
Rough ER (rER)
-is abundant in cells specialized for protein synthesis
-membrane bound ribosomes are attached
-only mRNA molecules with an ER signal will bind
Smooth ER (sER)
- region lacks ribosomes
-abundant cells in lipid metabolism
- detoxification (cytochrome P450 system)
- also sequesters calcium

Front 6

Golgi Apparatus

Back 6

Flattened membrane bound that are enclosed in cistern
Has cis face (entry face) and trans face (exit)
-Are well developed in secretory cells (plasma cells - pancreatic acinar cells)
CGN - cis golgi network

Front 7

What are coatomer-coated vesicles?

Back 7

They mediate bidirectional traffic between ER and golgi.
COP-1 - involved in retrograde transport (CGN to rER)
COP-2 - anterograde transport (new proteins from rER to CGN)
-Also involved in post-translation modificaiton, sorting and packaging

Front 8

What are neutrophil granules?

Back 8

3 types
Azurphilic - primary with peroxidase (kill bacteria), defensins, lysozyme, and enzymes
Specific - secondary - lactoferrin (antimicrobial), lysozyme
Teritiray - phosphatase, MMP

Front 9

Lysosomes

Back 9

Membrane-enclosed compartments with with 40 hydrolytic enzymes
-Acid hydrolyses (active at only low pH - H+ pumps)
- Function is digestion of macromolecules
Digest organelles

Front 10

Lysoomes

Back 10

Lysosomes

Front 11

What is the function of Mannose-6-phosphate?

Back 11

It tags proteins entering from rER into golgi. These are lysomomal hydrolases that are tagged for certain receptor (TGN) to be transported only to lysosomes.

Front 12

What is Tay-Sachs diseases?

Back 12

Is a lysosomal storage disease that arises from genetic defects of one or more lysodomal hydrolyses.
- results in death - accumulation of gangliosides

Front 13

What is the pathway of lysosomal digestion?

Back 13

1) Phagocytosis
2) Endocytosis
3) Autophagy - is the major cellular pathway to degrade proteins and organelles in lysosomes.
- components are recycled
-has an essential role in starvation, cellular differentiation and during cell death and cell aging.

Front 14

What are proteasomes?

Back 14

Is a non-membrane bound protein complex that destroys proteins without using lysosomes.
Proteins are tagged with ubiquitin which are targeted for destruction by proteasome.
- inhibitors are used as anti-cancer agents

Front 15

What are inclusions?

Back 15

They are cytoplasmic or nuclear structure that are formed from metabolic products of the cell
Glycogen - non-membrane
Lipid - non-membrane
- are lipid droplets - store fat - too much --> disease (lipidoses) - occurs more in liver
Pigments - membran bound
-Lipofuscin - brown-gold pigment (it is a wear and tear pigment)
-hemosiderrin - is an iron storage complex and used by breakdown of hemoglobin (spleen)
-Melanin - skin pigment

Front 16

Glycogen Slide

Back 16

Front 17

Lipoduscin - sympathetic ganglion

Back 17

Melanin

Front 18

Mitochondria structure function and disease

Back 18

ATP production, TCA cycle, B-oxidation of FA
Outer membrane and inner membrane
Matrix and intermembrane space
-Contain their own DNA and produce their own proteins
-own rRNA and tRNA
-evolved from aerobic bacteria - engulfed by eukaryotic cells
-Maternally derived (from mother)

Front 19

What is MERRF and Leber Hereditary Optic neuropathy?

Back 19

MERRF - myoclonic epilepsy with ragged red fibers
Leber Hereditary optic neuropathy - mutation in mitochondrial gene

Front 20

What is a peoxisome?

Back 20

Are micro bodies - small organ less
They compartmentalize and degrade toxic oxygen and contain CATALSE
Also important in fat metabolism - have beta-oxidation of fatty acids.
- Also make plasmalogens - needed for myelin
Are produced by cytoplasmic ribosomes
Zellweger Syndrom - is a defective import of peroxsomal proteins

Front 21

What are actin filaments?

Back 21

Are microfilaments made of protein act
-G-actin and F-actin (ATP dependent)
- They are polarized with fast growing (+) end
and (-) slow growing end.
Function is to anchor and structure and locomotion

Front 22

What is phalloidin?

Back 22

Is a toxin from Amanita phalloides (angle of death of death caps from mushroom_
-Binds to F-actin tightly and inhibits depolymerization, causes liver and kidney failure and death

Front 23

What are cytochalasin?

Back 23

Are other fungal product that block polymerization of actin, they inhibit cell movement and division.

Front 24

MicroVilli

Back 24

Are cylindrical, membrane bound and have 25-30 micofilaments and crosslinked by villain

Front 25

Steriocilia

Back 25

Are long microvilli, and are actin filament bundle anchored to terminal web.
- epididymis, ductus deferens and sensory hair

Front 26

What are myosin?

Back 26

Are actin molecular motors,
they generate the force for skeletal muscle contraction (myosin II)
Are formed from 2 heavy and 4 light chains.

Front 27

What are intermediate filaments?

Back 27

Are rope like filaments and are structural proteins.
They stabilize cell structure and resist shearing forces.
Connect desmosomes and hemidesmosomes and are essential for integrity of cell-cell junctions.

Front 28

What are the 6 classes of intermediate filaments?

Back 28

1&2: Keratins -
3: Vimentin and Vimentin like: is mesenchymal cells (desmin - muscle cells)
4: Neurofilaments - in neurons (axons) support
5: Lamins - nuclear lamina
6: Beaded Filaments - lens specific

Front 29

What are centrioles, centrosomes?

Back 29

Are 9-triplets of microtubules around a central axis
Form centrosome and for assembly of cilia and flagella.
Centrosomes - is large protein with microtubules and help anchor the nuclease at negative (-) end.

Front 30

What are microtubules and what are MAPS?

Back 30

Contain alpha and beta protein subunits.
Are polar (-) and (+) end - extend out.
Function for intracellular cell transports, cell motility, mitotic spindle.
Is GTP dependent
Have MAPs (microtubule associated proteins)
-which are Tau proteins and abundant in CNS
- linked to Alzheimer's Disease

Front 31

What is the affect of Colchicine?

Back 31

Is an anti-cancer compound that prevents polymerization of microtubules by binding to tubulin molecules.
Results in programmed cell death

Front 32

What is the affect of Taxol?

Back 32

Is another anticancer drug that stabilizes and prevents mictoubule disassembly - arrests mitosis.
Leads to programmed cell death.

Front 33

What are the microtubule molecular motor movies?

Back 33

Kinesin Family:
- move toward the positive (+) end and have binding sites for vesicles, organelles or mictotubule
Dynein:
-move to negative end
-have cytoplasmic and axonemal branches
-Are ATP dependent
-are fastest

Front 34

What are cilia?

Back 34

Are microtubule base
- Have 9-2 microtubule arrangement
- Pair of dyenin arms
-move fluid and particles
Primary Cilia - antennae like (9+0) and anchored by basal body
Has sensory role
-photoreceptors - outer segment of rods
-chemoreceptors - odor detection
-mechanoreceptor - primary cilia (defect results in Polycystic Kidney Disease)

Front 35

Cell Motility

Back 35

Protrusion - actin structures pushed out
Attachment - actin cytoskeleton connect to plasma membrane
Contract - cell contracts

Front 36

What are filopodia, lamellipodia and pseudopodia?

Back 36

Are all actin organization filaments responsible during cell motility.

Front 37

What is actin polymerization?

Back 37

Actin filaments with (+) facing forward, (-) end is attached to sides of actin filaments . Disassembles at rear and assembles at front. - treadmill affect

Front 38

What are Rho, Rac and CDC42?

Back 38

Are specific family proteins that have to do with cell motility.
Rho - bundles of actin filaments with myosin II
Rac - actin polymerization and lamellipodia
CDC42 - actin polymerization and filopodia

Front 39

What is the process of neutrophil extravasation?

Back 39

Inflammation (histamin) promotes selectin receptors on endothelial cells, neutrophils roll ong surface and chemokines express integrins on these leukocytes which bind to receptors on cell surface.
Then move into connective tissue via MMP.