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Flashcards in CELLS - HISTO LEC Deck (68):
1

Two Basic Parts of the Cell:

1. Cytoplasm
2. Nucleus

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- metabolically active structures or complexes, with or without membranes, in the cytoplasm of eukaryotic cells

Organelles

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outermost component of the cell
-separates cytoplasm from extracellular environment

PLASMA MEMBRANE

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-defines the outer limit of the cell
-continuum exists between extracellular and intracellular macromolecules

PLASMA MEMBRANE

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-contains integrins
-made of phospholipids, cholesterol, proteins, oligosaccharide chains

PLASMA MEMBRANE

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-a selective barrier regulating passage of materials into and out of the cell
-facilitates transport of molecules

PLASMA MEMBRANE

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-range from 7.5 to 10 nm in thickness
-visible only in electron microscope

PLASMA MEMBRANE

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consisting of two nonpolar long-chain fatty acids linked to a charged polar head bearing a phosphate group

Amphipathic –

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*Phospholipids are most stable when organized into a

double layer (hydrophobic toward the middle).

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*Phospholipids in each half of the bilayer are

different.

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restricts movement of phospholipid fatty acids; stabilizes lipid bilayer

Cholesterol –

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areas of less movement
-have higher concentrations of cholesterol and saturated fatty acids

Lipid rafts -

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proteins/linkages which produce a continuous exchange of influences, in both directions, between ECM and cytoplasm

Integrins –

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– fluid component of cytoplasm

Cytosol

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– proteins which determine the shape and motility of eukaryotic cells

Cytoskeleton

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minor cytoplasmic structures which are generally deposits of carbohydrates, lipids, or pigments

Inclusions –

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outer lipids which include oligosaccharide chains that extend outward from the cell surface
-contribute to glycocalyx

Glycolipids –

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– delicate cell surface coating formed by glycolipids

Glycocalyx

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major constituent of membranes


Proteins –

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TYPES OF PROTEINS

• Integral
• Peripheral
• Multipass Transmembrane

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– small electron-dense particles
-all have 2 subunits of different sizes
-act to catalyze the process of protein translation

Ribosomes

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– extends from the surface of the nucleus to the cell membrane
-encloses a cisternae
-SINGLE MEMBRANE

Endoplasmic Reticulum

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series of intercommunicating channels and sacs

Cisterna –

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Functions of Endoplasmic Reticulum

1. Synthesis
• SER – lipid synthesis and carbohydrate metabolism
• RER – protein synthesis
2. Transport
3. Storage
4. Detoxification

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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 –

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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 –

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– completes posttranslational modifications of proteins synthesized in the RER
-packages and addresses these proteins to proper destinations

Golgi Apparatus or Golgi complex

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GA is named after

-named after Camillo Golgi

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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 –

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secretory granules with dense contents of digestive enzymes

Zymogen granules –

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– sites of intracellular digestion and turnover of cellular components

Lysosomes

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-membrane-limited vesicles that contain about 40 different hydrolytic enzymes

Lysosomes

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-abundant in cells with great phagocytic activity
-also function for autophagy

Lysosomes

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type of lysosome
– emerge from GA
-contain inactive acid hydrolases specific for degrading a wide variety of cellular macromolecules

Primary Lysosomes

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type of lysosome
more heterogenous lysosomes, having fused with vesicles produced by endocytosis that contain material to be digested by hydrolytic enzymes

Secondary lysosomes –

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removal of excess or nonfunctional organelles and other cytoplasmic structures

Autophagy –

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very small abundant protein complexes not associated with membrane
-degrade denatured or nonfunctional polypeptides
-remove proteins no longer needed by the cell

Proteasomes –

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– membrane-enclosed, elongated organelles with arrays of enzymes specialized for aerobic respiration and production of ATP

Mitochondria

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-cells which have high-energy metabolism have ____________mitochondria

abundant

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2 membranes of mitochondria

outer and inner

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membrane of mitochondria
porous; encloses the intermembrane space

outer

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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 –

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spherical organelles enclosed by a single membrane and named for their enzymes producing and degrading hydrogen peroxide

Peroxisomes –

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– complex array of microtubules, microfilaments, intermediate filaments

Cytoskeleton

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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 –

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– directs polymerization of tubulins
-contain tubulin assemblies that act as nucleating sites for polymerization

Microtubule organizing centers

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dominant MTOC in most somatic cells; organized around centrioles (9+3)

Centrosome

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motor proteins that bind and move along actin filaments

Myosins –

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the most stable cytoskeletal component, conferring strong mechanical stability to cells

intermediate filaments –

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Small membrane-bound sac
Transports or stores materials within cells
Pinch off from GA and move to the cell surface

Secretory vesicles

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Membrane bound vesicles formed from the GA
Contain a variety of enzymes that function as intracellulat digestive system

Lysosomes

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Consists of proteins that support the cell
Hold organelles in place
Enable cell to change shape

Cytoskeletob

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Hollow structures formed fron protein subunits
Help support cell cytoplasm
Assist in cell division
Form components of cilia and flagella

Microtubules

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Small fibrils from protein subunts that structurally support cytoplasm
Some are involved with cell movement

Microfilaments

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Fibrila formed from protein subunits
Smaller than microtubules larger than microfilaments
Provide mechanical support

Intermediate filament

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Specialized zone of cytoplasm close to the nucleus
Where microtubule formation occurs

Centrosome

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Energy using proteins that interact with cytoskeletal elements to move cell parts or the whole cell

Motor proteins

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Microtubular config of cilia

9+3

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Microtubular config of flagella

9+2

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Intermediate filament proteins with particular biological, histological or pathological importance

Keratin
Vimentin
Lamins
Neurofilament

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Specialized zone of cytoplasm close to the nucleus
Where microtubule formation occurs

Centrosome

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Fibrila formed from protein subunits
Smaller than microtubules larger than microfilaments
Provide mechanical support

Intermediate filament

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Small fibrils from protein subunts that structurally support cytoplasm
Some are involved with cell movement

Microfilaments

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Hollow structures formed fron protein subunits
Help support cell cytoplasm
Assist in cell division
Form components of cilia and flagella

Microtubules

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Consists of proteins that support the cell
Hold organelles in place
Enable cell to change shape

Cytoskeletob

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Membrane bound vesicles formed from the GA
Contain a variety of enzymes that function as intracellulat digestive system

Lysosomes

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Small membrane-bound sac
Transports or stores materials within cells
Pinch off from GA and move to the cell surface

Secretory vesicles

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have little or no metabolic activity but contain accumulated metabolites or other substances not enclosed by membrane
-primarily storage sites

Cytoplasmic inclusions –

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