CELLS - HISTO LEC Flashcards
Two Basic Parts of the Cell:
- Cytoplasm
2. Nucleus
- metabolically active structures or complexes, with or without membranes, in the cytoplasm of eukaryotic cells
Organelles
outermost component of the cell
-separates cytoplasm from extracellular environment
PLASMA MEMBRANE
- defines the outer limit of the cell
- continuum exists between extracellular and intracellular macromolecules
PLASMA MEMBRANE
- contains integrins
- made of phospholipids, cholesterol, proteins, oligosaccharide chains
PLASMA MEMBRANE
- a selective barrier regulating passage of materials into and out of the cell
- facilitates transport of molecules
PLASMA MEMBRANE
- range from 7.5 to 10 nm in thickness
- visible only in electron microscope
PLASMA MEMBRANE
consisting of two nonpolar long-chain fatty acids linked to a charged polar head bearing a phosphate group
Amphipathic –
*Phospholipids are most stable when organized into a
double layer (hydrophobic toward the middle).
*Phospholipids in each half of the bilayer are
different.
restricts movement of phospholipid fatty acids; stabilizes lipid bilayer
Cholesterol –
areas of less movement
-have higher concentrations of cholesterol and saturated fatty acids
Lipid rafts -
proteins/linkages which produce a continuous exchange of influences, in both directions, between ECM and cytoplasm
Integrins –
– fluid component of cytoplasm
Cytosol
– proteins which determine the shape and motility of eukaryotic cells
Cytoskeleton
minor cytoplasmic structures which are generally deposits of carbohydrates, lipids, or pigments
Inclusions –
outer lipids which include oligosaccharide chains that extend outward from the cell surface
-contribute to glycocalyx
Glycolipids –
– delicate cell surface coating formed by glycolipids
Glycocalyx
major constituent of membranes
Proteins –
TYPES OF PROTEINS
- Integral
- Peripheral
- Multipass Transmembrane
– small electron-dense particles
- all have 2 subunits of different sizes
- act to catalyze the process of protein translation
Ribosomes
– extends from the surface of the nucleus to the cell membrane
- encloses a cisternae
- SINGLE MEMBRANE
Endoplasmic Reticulum
series of intercommunicating channels and sacs
Cisterna –
Functions of Endoplasmic Reticulum
1. Synthesis • SER – lipid synthesis and carbohydrate metabolism • RER – protein synthesis 2. Transport 3. Storage 4. Detoxification
specialized for protein secretion
- synthesizes and segregates proteins not destined for cytosol
- initial glycosylation of glycoproteins
- assembly of mutlichain proteins
- granular, basophilic cytoplasmic surface due to the presence of polysomes
Rough Endoplasmic Reticulum –
not basophilic; best seen with TEM
- More tubular
- phospholipid synthesis
- steroid synthesis
- abundant in many liver cells
- sequesters and releases Ca2+ (sarcoplasmic reticulum)
- has enzymes for lipid and glycogen metabolism
Smooth Endoplasmic Reticulum –
– completes posttranslational modifications of proteins synthesized in the RER
-packages and addresses these proteins to proper destinations
Golgi Apparatus or Golgi complex
GA is named after
-named after Camillo Golgi
originated as condensing vesicles in GA
-found in cells that store a product until its release by exocytosis is signaled by a metabolic, hormonal or neural message
Secretory granules –
secretory granules with dense contents of digestive enzymes
Zymogen granules –
– sites of intracellular digestion and turnover of cellular components
Lysosomes
-membrane-limited vesicles that contain about 40 different hydrolytic enzymes
Lysosomes
- abundant in cells with great phagocytic activity
- also function for autophagy
Lysosomes
type of lysosome
– emerge from GA
-contain inactive acid hydrolases specific for degrading a wide variety of cellular macromolecules
Primary Lysosomes
type of lysosome
more heterogenous lysosomes, having fused with vesicles produced by endocytosis that contain material to be digested by hydrolytic enzymes
Secondary lysosomes –
removal of excess or nonfunctional organelles and other cytoplasmic structures
Autophagy –
very small abundant protein complexes not associated with membrane
- degrade denatured or nonfunctional polypeptides
- remove proteins no longer needed by the cell
Proteasomes –
– membrane-enclosed, elongated organelles with arrays of enzymes specialized for aerobic respiration and production of ATP
Mitochondria
-cells which have high-energy metabolism have ____________mitochondria
abundant
2 membranes of mitochondria
outer and inner
membrane of mitochondria
porous; encloses the intermembrane space
outer
membrane of mitochondria
many folds or cristae; encloses a gel-like matrix
-include enzyme assemblies of the electron-transport system and ATP synthase
Inner membrane –
spherical organelles enclosed by a single membrane and named for their enzymes producing and degrading hydrogen peroxide
Peroxisomes –
– complex array of microtubules, microfilaments, intermediate filaments
Cytoskeleton
semirigid tubular structures with walls composed of polymerized tubulin heterodimers
- structure is often very dynamic
- important in maintaining cell shape and as tracks for transport of vesicles and organelles
Microtubules –
– directs polymerization of tubulins
-contain tubulin assemblies that act as nucleating sites for polymerization
Microtubule organizing centers
dominant MTOC in most somatic cells; organized around centrioles (9+3)
Centrosome
motor proteins that bind and move along actin filaments
Myosins –
the most stable cytoskeletal component, conferring strong mechanical stability to cells
intermediate filaments –
have little or no metabolic activity but contain accumulated metabolites or other substances not enclosed by membrane
-primarily storage sites
Cytoplasmic inclusions –
Small membrane-bound sac
Transports or stores materials within cells
Pinch off from GA and move to the cell surface
Secretory vesicles
Small membrane-bound sac
Transports or stores materials within cells
Pinch off from GA and move to the cell surface
Secretory vesicles
Membrane bound vesicles formed from the GA
Contain a variety of enzymes that function as intracellulat digestive system
Lysosomes
Membrane bound vesicles formed from the GA
Contain a variety of enzymes that function as intracellulat digestive system
Lysosomes
Consists of proteins that support the cell
Hold organelles in place
Enable cell to change shape
Cytoskeletob
Consists of proteins that support the cell
Hold organelles in place
Enable cell to change shape
Cytoskeletob
Hollow structures formed fron protein subunits
Help support cell cytoplasm
Assist in cell division
Form components of cilia and flagella
Microtubules
Hollow structures formed fron protein subunits
Help support cell cytoplasm
Assist in cell division
Form components of cilia and flagella
Microtubules
Small fibrils from protein subunts that structurally support cytoplasm
Some are involved with cell movement
Microfilaments
Small fibrils from protein subunts that structurally support cytoplasm
Some are involved with cell movement
Microfilaments
Fibrila formed from protein subunits
Smaller than microtubules larger than microfilaments
Provide mechanical support
Intermediate filament
Fibrila formed from protein subunits
Smaller than microtubules larger than microfilaments
Provide mechanical support
Intermediate filament
Specialized zone of cytoplasm close to the nucleus
Where microtubule formation occurs
Centrosome
Specialized zone of cytoplasm close to the nucleus
Where microtubule formation occurs
Centrosome
Energy using proteins that interact with cytoskeletal elements to move cell parts or the whole cell
Motor proteins
Microtubular config of cilia
9+3
Microtubular config of flagella
9+2
Intermediate filament proteins with particular biological, histological or pathological importance
Keratin
Vimentin
Lamins
Neurofilament
