Cell organelles & inclus. at light Flashcards
What is histology?
-is essentially Microanotomy study of the structure (Anatomy) of small (micro) things
->HISTO + LOGOS=
the study of tissues
What are those small (micro) things?
-small things are the cells and their arrangements to constitute tissues and, finally, the association among these to form organ
When was the “cell” discovered? What is the word origin?
- In 1665, Robert Hooke (1635-1703)
- Hooke derived the designation from the Latin, cellula ; i.e., small compartment, having in mind a comparison with a honeycomb (Wabe)
Who was the first to observe the true units that form the tissues of animals?
-Malpighi
Who carried out the first description of the nucleus and when?
- Leeuwenhoek, in 1700, when examining the red blood cells of the salmon
- > from the Latin, nucleus = almond (Mandel)
Who accomplished the first description of the nuclear envelope (Atomhülle) ?
-Jan Evangelista Purkinje (1787-1869), a Czech biologist, in 1839
Who introduced the term nucleus in microscopy?
-Robert Brown (1773-1858), a Scottish botanist, has introduced the term nucleus in microscopy
Which term did Purkinje also introduced in Science?
-protoplasma (1840)
Who is considered (by some authors) to be the founder of Animal Histology?
-Marie François Bichat, a French pathologist (1771-1802)
Who is the father of microscopy? (Holland)
- Anton van Leeuwenhoek of Holland
- the first to see and describe bacteria, yeast (Hefe) plants, life in a drop of water, and the circulation of blood corpuscles in capillaries
Who is the English father of microscopy?
- Robert Hooke
- re-confirmed Anton van Leeuwenhoek’s discoveries of the existence of tiny living organisms in a drop of water
- > made a copy of Leeuwenhoek’s light microscope and then improved upon his design
What did Charles A. Spencer do?
-By middle of the 19th Century-manufacture fine optical equipment and the industry he founded
What is a light microscope?
-Optical microscope, often referred to as light microscope, is a type of microscope which uses visible light and a system of lenses to magnify images of small samples
How can scientists see tiny particles under a microscope?
-To see tiny particles under a microscope, scientists must bypass (umgehen) light all together and use a different sort of “illumination,” (Beleuchung) one with a shorter wavelength.
What is a simple microscope?
-A simple microscope is a microscope that uses a lens or set of lenses to enlarge an object through angular magnification
What is fixation? And which reactions are important?
- Fixation: stop cell metabolism and preservation of tissue structure
- Formaldehyde preserves general structure of the cell and extracellullar components by reacting with amino groups of proteins
Why is it embedded in paraffin?
- for tissue sectioning (Gewebeschneiden)
- sectioning by microtome
- > 5 to 10 um of thickness
With what are sections strained?
-Staining of tissue sections with histological dyes
-Haematoxylin and eosin
Nucleus: blue
Cytoplasm :pink
What are HISTOCHEMISTRY AND CYTOCHEMISTRY
based on?
- based on specific binding of a dye to a particular cell component
or: - on the inherent enzymatic activity
What happens to cell after fixation?
-Some of the components are dissolved such as:
->glycogen and proteoglycans, ions,
small molecules
-Some are reacted with other molecules to form large macromolecules such as:
->Nucleoproteins,
Cytoskeletal proteins,
Membrane phospholipid proteins
What is the mostly used staining method?
-Heamatoxylin and Eosin
What kind of dye reacts with which kind of groups?
- acid dye with negative charge reacts with cationic groups in cell
- basic dye carries positive charge and reacts with anionic groups in cell
What is the major factor for tissue-strain binding ?
-electrostatic linkage
What is basophilia?
-the ability of anionic groups to react (within a cell) with a basic dye
What does hematoxylin cause? (+What is it?)
-is a basic dye and causes basophilia of some cell components
What is acidophilia?
-the ability of cationic groups to react (within a cell) with acidic dyes
What does the prokaryotic cell have? (example bacteria)
- devoid of a membrane-bounded nucleus
- 1 to 5 microns
- have a cell wall outside the cell membrane
- no membrane- surrounded organelles
- ribosomes
- flagella and pili
What do eukaryotic cells have?
- are larger
- have a membrane-surrounded nucleus
- and numerous types of cellular organelles
- also have histones associated with DNA in the nucleus
Name all the organelles which appear in cytoplasm (eukaryotic)
- Mitochondrion
- Endoplasmic reticulum
- Ribosome
- Golgi complex
- Lysosomes
- Peroxisomes
- Inclusions
- Microtubules
- Microfilaments
List the different cell shapes
- -Cylindrical/columnar (säulenartig), cuboidal (quaderformig), polyhedral, flattened epithelial cell shapes to fit into multicellular patterns
- -Spheroid & Ovoid - defensive blood cells
- -Elongated - muscle cells & fibroblasts
- -Multiple branching processes - neurons, glial cells, pigment cells
How thick is the cell membrane? What does it house? With what is it visible?
- It is of 7.5 nm of thickness
- It houses cytoplasmic matrix containing specialized membrane-surrounded components called organelles
- Not visible at light microscope; visible by transmission electron microscope
What is a unit membrane?
-a trilaminar structure of two thin dense lines with a medium light area
What is the major component in the cell membrane?
- the lipid bilayer with:
- proteins
- cholesterol (between hydrophobic fatty acid chain)
- oligosaccharides
- > molecules are held together by non covalent bonds
- > this structure results in dynamic and fluid feature of cell membrane
What acts as a selective barrier?
- the plasma membrane
- >maintains the internal environment of the cell, as different from the extracellular region
Which three possibilities exist in the movement of molecules through the plasma membranes?
- simple diffusion
- carrier protein (opens, closes)
- channel protein (ein Kanal)
What is the basic structure of the membrane?
- lipid bilayer
- double layer of lipid molecules (about 5nm of thickness)
- > relatively impermeable (undurchlässig) barrier to the passage of most water-soluble (wasserlöslich) substances
How are the phospholipid molecule in the lipid bilayer composed?
- composed of a polar head (at the surface) and two nonpolar fatty acid tails (toward enter of plasmalemma)
- Nonpolar components of two layers face each other
- > By noncovalent bonds, hold the bilayer together
What is the hydrophilic region in the lipid bilayer?
-the polar head
What is the hydrophobic region in the lipid bilayer?
-nonpolar fatty acid tails
As which kinds are proteins embedded in the lipid bilayer?
-as “integral” or peripheral proteins or transmembrane proteins
Which proteins usually form ionic channels?
-transmembrane proteins
What does the model Fluid Mosaic Model describe?
-integral proteins have the ability to float (schweben) in the sea of phospholipids
What is glycocalyx? How thick?
- carbohydrate chains covalently bound to transmembrane proteins and phospholpid molecules of the outer leaflet + extracellular matrix molecules
- 50 nm of thickness
What are the functions of glycocalyx?
- protects cell from interaction with inappropriate proteins, cell injury
- provides cell to cell recognition
- adhesion (Haftung) function
Why does glycocalyx stain intensely?
-stains intensely due to negatively charged sulfate and carboxyl groups
What are the functions of membrane?
- maintains the structural integrity (Einheit) of the cell
- control movements of substances in and out of the cell
- > selective permeability (gezielte Durchlässigkeit)
- regulate cell to cell interactions
- recognize the antigen via receptors
- acts as an interface between cytoplasm and external medium
- establishes transport systems for specific molecules
What allows the cell to maintain its shape?
-membrane provides anchoring (Verankerung) sites for cytoskeletal filaments or components of the extracellular matrix
Membrane transduces extracellular physical and chemical signs into?
-intracellular events
What does the membrane also provide and what does it also regulate?
- regulate the fusion of the membrane with other membranes by way of specialized junctions (Verbindungen)
- provide a passageway across the membrane for ionic exchange ,as in gap junctions
- by apical cell modification, it provides cellular motility (Beweglichkeit) and absorption (cilium and flagellum)
In which two components is ER (endoplasmic reticulum) devided ?
-smooth and rough ER
Cells involved in what are rich in RER?
- cells involved in protein synthesis
- >their membranes possess integral proteins that recognize and bind to ribosomes
As what does RER function?
- RER functions in the synthesis of all proteins
- sulfation,folding and glycolisation
For what are SER (smooth endoplasmic reticulum) important?
-important in detoxification (Entgiftung) of toxic substances
SER is very abundant in?
-Very abundant in steroid, cholesterol, and triglycerides synthezising cells
The lumen of SER is continuous with?
-with that of RER
What can cause the SER to double its surface area?
- SER doubles in surface area within a few days because of:
- > When large quantities of drugs enter the circulation, detoxification enzymes are synthesized in the liver in unusually large amounts
Which binding proteins reside on SER?
-Ca2+binding proteins
What is ribosome composed of? What happens there?
- Small particles of 12 nm to 25 nm
- composed of proteins and ribosomal RNA
- site for protein synthesis
- large and small subunits
Which role does each subunits of ribosome have? When do they unite?
- small subunit has a site for binding of mRNA; P site for peptidyl tRNA and A site for aminoacyl T RNA
- large subunit that helps form the peptide bond and holds the peptide chain
- > small and large subunits unite during protein synthesis
How are unattached ribosomes called? Where is the use?
- free ribosomes
- >are involved in the synthesis of protein for use within cytoplasm
In what are ribosomes involved which are attached to the ER?
- in the synthesis of proteins for secretion (absondern), lysosomal enzymes and for new membranes
Define polyribosome (polysome)
-numerous ribosomes, each creating a separate peptide chain, are called polyribosome or polysome
How can we see the ribosomes at Light microscope ?
-individual ribosomes and polysomes could not be observed by light microscope
What does their localization in cytoplasm cause?
-their localization in cytoplasm cause BASOPHILIA-Deep staining ability by basic dyes
Why are the cells containing large numbers of free ribosomes (neurons, malignant neoplasms) basophilic?
-due to the presence nucleic acid in the ribosomes
The functions of Golgi complex
-Functions in the synthesis of carbohydrates and modifications and sorting of proteins newly done in RER
Where are vesicles located? (Golgi complex)
-at their periphery (Rand)
What is the Golgi-stacks composed of?
- 3-12 parallel flattened membrane-bound cisterns (membranumschlossenen, meist flachen Hohlräumen)
What is called cis face (entry face) ?
-Convex surface of the stack , near the nucleus
What is called TRANS face (mature face)?
-Concave surface facing the plasma membrane
Where do numerous transfer vesicles appear? (Golgi stack)
-near the entry face (cis) and edges of Golgi stack
What forms at the mature face?
-secretory vesicles and condensing vacuoles
Which kind of shape do mitochondria have?
-rod (Stab)-shaped organelles
Where are mitochondria not present?
-present in all cells except red blood cells and keratinocytes
Can mitochondria self-replicate?
-yes
What is the size of mitochondria?
-05 to 7 um (nano) in size
What are cristae?
-folds (Falten) of inner membrane
smooth outer membrane
What is ATP?
- the primary energy carrier in all living organisms on earth
What are the four methods of creating ATP?
- glycolysis
- oxidative phosphorylation
- beta oxidation
- aerobic respiration
How is ATP produced in oxidative phosphorylation ?
-ATP is produced when electrons flow from chemicals known as NADH or FADH (nicotinamide adenine dinucleotide and flavin adenine dinucleotide respectively) to oxygen
Which kind of protein does the other membrane (mitochondria) contain? What does it (Protein) form ?
- The outer membrane contains numerous number of transmembrane protein porin, as transport proteins
- Porin forms large aqueous channels through the lipid bilayer
For what is the outer membrane (mitochondria) permeable?
-to all molecules of 5000 daltons or less, including small proteins
Intermembrane space (mitochondria) is chemically equivalent to? Why is it equivalent?
- to the cytosol with respect to the small molecules it contains
- most of the molecules could not pass the inner membrane (can enter the intermembrane space though)
Why and where are cristae?
-inner mitochondria are folded to form cristae to increase surface area
What is caridolipin?
-a phospholipid possessing 4 fatty acyl chains
The inner membrane is impermeable to?
-to ions and electrons
What is known as the numerous subunits displayed by the inner membrane?
-protein complexes known as ATP synthetase or ELEMENTARY PARTICLES
Where is respiratory chain enzymes located?
-additional protein complex (as respiratory chain enzymes) are located on the inner membrane
How can ATP generated from ADP?
-by adding inorganic phosphate
How big is the matrix granules?
-30 to 50 nm
What does the mitochondrial matrix contain?
- high content of protein (more than 50 %)
- ribosomes
- tRNA
- mRNA
- matrix granules
- circular DNA
- enzymes necessary to express mitochondrial genome
- > viscous (zähflüssig)
Which enzymatic breakdown happens in the mitochondrial matrix?
- enzymatic breakdown of fatty acids and pyruvate to Acetyl CoA
- > acetly Coa then is oxidated in Krebs cycle
The binging of calcium protects?
- Magnesium and calcium binding
- >Binding of calcium to protect cell from calcium toxicity
What is lysosomes?
- membrane-bounded organelles containing 40 different types of acid hydrolases
- > sulfatases, proteases, nuclease, lipases, glycosidases
- digestive organelles of the cell
What is the function of the lysosomal membranes proton pump?
-to transport H+ ions into lysosome
Which ph is required for an acid medium? (lysosomes)
-5.0
From where is the lysosomes pinched off?
- from trans Golgi cisterns
- >kept inside the cell
What does the primary lysosomes digest?
- extracellular substances (crinophagy)
- cellullar debris (Trümmer)
- damaged, old organelles (autophagy)
How are secondary lysosomes created?
- when primary lysosomes fuse with phagosomes/pinosome (engulfed (verschlungenes) Material)
- > autophagosomes, autophagic vacuoles, digestive vacuole
Hydrolytic breakdown of the contents of secondary lysosomes cause?
-residual (Rest) body formation
As what does Lipofuscin granules?
- age pigment
- Lipofuscin as the residual body
Describe the three steps of lysosomal storage disease
- absence of certain lysosomal enzymes
- > Accumulation of undigested material
- ->Lysososomal storage diseases (Tay-Sach”s disease)
What is exocytosis describing?
-exocytosis expels material from the cell into the extracellular space or into a lumen
What are the steps in exocytosis?
- 1.Actin filaments bring vesicle to cell membrane
- 2.Vesicle & cell membranes fuse
- 3.Fused membranes rupture
- 4.Vesicle content discharged Vesicle membrane incorporated in plasmalemma
What is endocytosis?
-ENDOCYTOSIS brings in material from outside to the interior, but still confined within a membrane-enclosed body an endosome, or, if large (e.g., a bacterium), a phagosome
Describe the steps of Endocytosis
- 1.Plasmalemma
- 2.Binding & Invagination
- 3.Membrane separation Fusion to make vesicle
- 4.Coated (beschichtetes) vesicle
- > Actin filaments move vesicle in endocytic pathway
What are peroxisomes (microbodies)?
-membrane-bounded organelles (0.5 um)
-containing oxidative enzymes to breakdown hydrogen peroxide (H2O2) such as :
-D-amino acid oxidase,
ureate oxidase, and
catalase
(->Peroxidasen reduzieren giftige Wasserstoffperoxide zu Sauerstoff und Wasser)
What is characteristic feature for peroxisome?
-a crystalline structure inside a sac which also contains amorphous gray material is a characteristic feature for peroxisome
How are new peroxisomes formed?
-through fission
Where are peroxisomes in a numerous form?
-are numerous in the liver where toxic by-products are going to accumulate
What is the cytoskeleton?
- a tridimensional meshwork of protein filaments
- specialized cytoplasmic proteins supporting the cell
- a contractile system
- > properties serve for maintaining, changing the cell shape an its motility
What does the cytoskeleton include?
- the microtubules
- microfilaments
- intermediate filaments
What is Microtubules? With what is it assembled (zusammengebaut)?
- 25 nm of diameter
- Cylindrical structures
- readily assembled and disassembled from cytoplasmic pools of the protein tubulin
- > rigid structure for maintenance of cell shape
Microtubules is involved in?
- cilia formation (basal body formation)
- mitotoic spindle formation (the centriole) for cell division
- cilia and flaggella formation
- centriole formation
- axon structure
What are filaments?
- fadenförmigen Zellstrukturen
What does the microtubules consist of?
- 13 parallel protofilaments with alpha and beta tubulin subunits
- During mitotic division, rapid polimerization of subunits provide formation mitotic spindle
What are microfilaments? What does it provide?
- fine, thread like (fine fadenförmige) structures about 6 to 7 nanometers in diameter
- provide for movement and shape change
- > acts as the muscles
What are the microfilaments composed of?
- composed of the contractile protein actin
- > represent a primitive contractile system, forming large bundles called stress fibers
- usually found as a band just under the plasma membrane
What are the functions of microfilaments?
- anchorage (verankerung) and movement of membrane proteins
- movement of plasma membrane (as endocytosis-exocytosis and cytokinesis)
- structural core of microvilli
- cell process elongation
- cellular locomotion
- contract to result in “cytoplasmic streaming”
- -wound healing (stress fibers)
- stress fibers may extend between two focal points to assist the cell in exerting a tensile force on extracellular matrix
- -connect internal structures or organelles to transmembrane proteins of neighboring cells or to extracellular matrix filaments(esp. in muscle and epidermis of skin)
- a close link between tumor diagnosis and intermediate filaments
What are intermediate filaments?
- Supporting role
- non-contractile
- frequently grouped into delicate bundles (fibrils) in the cytoplasm
What are the 5 major classes of intermediate filaments?
- Cytokeratin
- Vimentin
- Desmin
- Neurofilaments
- Glial fibrillary acidic protein
-spectrin and laminin
What is centrioles?
-cylindrical paired cell structure composed mainly of a protein called tubulin
Where is centrioles located? How long? Which microtubules are fused? How many protofilaments?
- -centrosome
- 0.2 nm long
- A, b and c microtubules are fused to one another
- 13 protofilaments
When do centrioles replicate? What do they do after duplication? For which kind of formation are centrioles important?
- Centrioles replicate prior to cell division in S phase
- After duplication, they separate from each other
- Centrioles are important in the formation of new microtubule system in new cells
For what are basal bodies important? How are they formed? Where does it migrate?
- Important for cilium formation
- basal bodies are formed by repeated replication of centrioles
- migrate to apical cell surface
What is the function of basal bodies?
-serves as organizer of microtubules for cilium formation
What are inclusions?
- Transient (vorrübergehende) elements of cell:
- Secretory granules
- Pigment granules
- Lipofuchsin granules
Name some examples of inclusions?
- Lipid droplets
- Glycogen
- Crystals
- Virus
- > Non-membrane bounded
