Exam #1 Prep Flashcards
Generally cells with ______ stained nuclei are more active in protein synthesis
lightly
p.56
Describe the six steps of tissue preparation
- Fixation: Tissue placed in solutions that preserve the tissue by cross-linking proteins and inactivating degradative enzymes.
- Dehydration: Tissue transferred through increasingly concentrated alcohol solutions, ending in 100%, thus removing all of the water.
- Clearing: Alcohol is removed in toluene or other agents in which both alcohol AND paraffin are miscible.
- Infiltration: Tissue placed in melted paraffin until it becomes completely infiltrated.
- Embedding: Paraffin-infiltrated tissue placed in a mold with melted paraffin and allowed to harden.
- Trimming: Resulting paraffin block is trimmed to expose the tissue for sectioning (slicing) on a microtome.
Hematoxylin binds -ophilic cell components?
Eosin?
Hematoxylin binds Basophilic (acidic) cell components – it is a basic/acidophilic dye
Eosin binds acidophilic (basic) cell components
What does the objective lens do?
enlarges (x4, x10, or x40) and projects illuminated image towards eyepiece.
Define resolution
Measures how close two objects can be and still appear separate.
In freeze fracture, the plane passes through which part of the membrane?
Hydrophobic portion.
Define cell differentiation. Describe a cells function after differentiation.
When cells begin to synthesize increased quantities of specific proteins and become very efficient in specialized functions, often changing their shape accordingly.
Specialized cells have greatly expanded their capacity for one or more functions during differentiation.
p.18
Differentiated cells typically _______.
Specialize in one or more activities.
Cilia are Short, numerous _______ extensions supported by _______.
membrane
microtubules
Microvilli are numerous thin _______ projecting from the free cell surface; supported by ______. What is their function?
Membrane folds
Microfilaments
Increase membrane SA for greater absorption.
Describe the structure and function of the glycocalyx
Composed of oligosaccharides of glycolipids and glycoproteins.
It provides important antigenic and functional properties to the cell surface. They are important components of proteins acting as receptors, which participate in important interactions such as cell adhesion, cell recognition, and the response to protein hormones.
Cytoplasm is defined as…
Contents of cells between the plasma membrane and nuclear envelope.
Cytosol is defined as…
Viscous fluid medium with dissolved solutes (eg, ions, proteins, carbohydrates, lipids).
The nuclear envelope is continuous with which organelle?
RER
What are the fates of proteins synthesized in the RER?
Become components of the plasma membrane, or serve as enzymes of lysosomes.
What are the functions of SER? (3)
- Synthesizes, transports, and stores LIPIDS (eg, steroids); 2. metabolizes carbohydrates; detoxifies drugs, alcohol, and poisons;
- forms vesicles and PEROXISOMES (contain oxidative enzymes related to detoxification).
Describe peripheral (extrinsic) membrane proteins. Which surface are they typically associated with?
Exhibit a looser association with one of the two membrane surfaces, particularly the inner.
What is meant by the concept of membrane asymmetry?
The distribution of membrane polypeptides is different in the two surfaces of the cell membrane (i.e. different chemical composition of inner and outer layers).
Simple diffusion occurs when small ______ molecules can simply pass through the lipid bilayers.
lipophilic (fat-soluble)
What allows water to diffuse through the cell membrane and by what process? Describe the general structure.
Aquaporins – multipass transmembrane proteins that facilitate the transmembrane diffusion of water molecules (by osmosis).
What is the major role of clathrin in endocytosis?
It facilitates the invagination of the membrane into pits for endocytosis, i.e. it provides the lattice that helps shape the membrane into vesicles.
List the steps of receptor-mediated endocytosis (6)
- Receptors on the cell surface for high-affinity ligands such as LDLs and protein hormones bind the ligand, which then associates with cytoplasmic proteins (including CLATHRIN and adaptor proteins).
- The membrane then invaginates (AS A COATED PIT) and pinches off internally as vesicles.
- Invagination begins as a coated pit. Cytoplasmic surface of vesicle is coated with clathrin to form a coated vesicle.
- Clathrin coat is removed and vesicle then undergoes one of three processes.
- Ligands then undergoe one of THREE processes in the endosomal compartment after the clathrin coat is removed:
- ) Degradation: Receptors and ligands may be carried to LATE ENDOSOMES and then to LYSOSOMES for degradation.
- ) Receptor recycling: Ligands may be released internally and the receptors recycled to the cell surface.
- ) Transcyctosis: Vesicles may move to and fuse with another cell surface, where the ligands are released again outside the cell (TRANSCYTOSIS).
Give a general definition of endocytosis. What type of process is it?
An active process involving FOLDING and FUSION of the MEMBRANE TO FORM VESICLES that enclose the material being transported into the cell.
The _____ side of RER membrane will be coated with polyribosomes.
cytosolic
Cell with few/no RER and many free polyribosomes likely…
Make no protein for secretion.
Cells that synthesize, segregate, and STORE various proteins in specific secretory granules or vesicles always have _____, a ______, and a supply of ______; e.g. _______.
RER, a Golgi apparatus, and a supply of granules containing the proteins ready to be secreted; e.g. eosinophilic leukocyte.
Describe the two faces of the Golgi apparatus.
Cis face: Faces/is close to the RER. The transport vesicles merge with the Golgi-receiving region, or CIS FACE (faces a CIStern, i.e. RER). On the opposite side of the Golgi network, at its shipping or TRANS FACE, larger saccules or vacuoles accumulate, condense, and generate other vesicles that carry completed protein products to organelles away from the Golgi.
Describe the two primary functions of the Golgi apparatus.
- Enzymes of the Golgi apparatus are important for glycosylation, sulfation, phosphorylation, and limited proteolysis of proteins (i.e POST-TRANSLATIONAL MODIFICATIONS).
- The Golgi apparatus also initiates packing, concentration, and storage of secretory products.
Cells with extensive RER and a well-developed Golgi apparatus show few ______. Why?
Secretory granules. Because the proteins undergo exocytosis immediately after Golgi processing is complete. Many cells, especially those of epithelia, are polarized, meaning that the distribution of RER and secretory vesicles is different in various regions or poles of the cell.
Describe the main differences in the cisternae of SER and RER.
The RER consists of saclike as well as PARALLEL STACKS of flattened cisternae (Figure 2–10), each limited by membranes that are continuous with the outer membrane of the nuclear envelope.
SER cisternae are often more tubular and more likely to appear as INTERCONNECTED CHANNELS of various shapes and sizes than as stacks of flattened cisternae.
The Golgi stains ______ and is identified by ______.
poorly
pallor (paleness)
Synthesis of lysosomal enzymes occurs in the _____, with packaging in the ______.
RER
Golgi
Endocytosis produces vesicles that fuse with ______ before merging with ______.
endosomes
lysosomes
p.38
What is lipofuscin?
The accumulated products in long-lived cells (within residual bodies) of indigestible products of lysosomal digestion.
Autophagy is a process in which the cell uses ______ to __________________.
lysosomes to dispose of excess or nonfunctioning organelles or membranes.
The trans face of the Golgi will typically appear to be (concave or convex)?
Concave.
Lysosomes are a heterogeneous collection of ______ vesicles and vacuoles that derive from ______ vesicles.
membrane-bound vesicles
Golgi complex vesicles
Free ribosomes synthesize proteins for _________, but ribosomes attached to RER synthesize proteins for _______.
internal use by the cell (import to the nucleus, mitochondria, and peroxisomes).
incorporated into membranes, stored in lysosomes, or secreted from the cell.
p.29
In H&E-stained sections, ribosomes impart cytoplasmic _______ (what type of stain affinity) to cells actively _______. Why do they stain that way?
basophilia to cells actively SYNTHESIZING PROTEIN.
They are basophilic because of the numerous phosphate groups of RNAs that act as polyANIONs.
Collectively, the ______ and ______ form the protoplasm of a cell.
cytoplasm and nucleus
_______ are found at the base of cilia and flagella. What are they composed of?
Centrioles; they are composed of microtubules.
Synthesis of lysosomal enzymes occurs in the _____, with packaging in the ______.
RER
Golgi apparatus
The mitochondrial matrix contains a small circular chromosome of…(4 things)
DNA, ribosomes, mRNA, and tRNA.
Name three important structural proteins made from intermediate filaments, and where they are found.
- Keratin: Epithelial cells.
- Lamins: Nuclei of all cells.
- Desmins: Muscle cells
Polymerization of microtubules is directed by ________ (_____), which are predominantly _______ in somatic cells.
Microtubule Organizing Centers (MTOC)
Centrosomes in somatic cells
Growth occurs more rapidly at the ____ end of existing microtubules.
(+) end
Kinesins perform _______ transport (i.e. ______ from the nucleus), which is towards the + or – end?
Anterograde, i.e. away from the nucleus, + end.
Dyenins perform _______ transport (i.e. ______ from the nucleus), which is towards the + or – end?
Retrograde transport, i.e. towards the nucleus, – end
If something exhibits basophilia, how will it stain with H&E?
List SIX basophilic cellular components.
Blue.
Nucleic acids (DNA, RNA)
Heterochromatin (because of ionized phosphate groups in this and nucleic acids)
Nucleolus
GAGs
Cartilage matrix (because of ionized sulfate groups on carbohydrates)
Ground substance
If something is eosinohpilic, how will it stain with H&E?
List SEVEN eosinophilic cellular components.
Pink. General cytoplasm Cytoplasm proteins Collagen fibers Mitochondria Protein granules Reticular fibers Extracellular fibers (due to ionized amino groups)
Describe the general constituents of eukaryotic cell membrane
In eukaryotes, made of phospholipids, cholesterol, proteins, and oligosaccharide chains covalently linked to phospholipid and protein molecules.
PAS is used primarily to stain what type of structures?
Carbohydrates.
- Glycocalyx (surface of epithelia and cell membranes)
- Mucin (Goblet cells)
Connective tissues originate from ______, a tissue developing mainly from the ___________ ( ______ ).
- embryonic mesenchyme
- middle layer of the embryo (the mesoderm).
What are the two components of extracellular matrix (ECM)?
Fibers and ground substance
The terminal web and cytoplasmic cores of microvilli have large numbers of what?
Microfilaments
The nucleolus is most directly associated with the synthesis of what?
rRNA
Where are ribosomal subunits synthesized?
in the NUCLEOLUS
Name three types of intermediate filament associated proteins
Keratins, vimentin, and desmin
Karyotypes are usually obtained during which mitotic phase?
metaphase
Which cell cycle phase is typically the longest and has the most variability?
G1
Which organelle is most likely responsible for the synthesis of intermediate filaments?
Free ribosomes or polyribosomes
During which phase of the cell cycle do cells generally double in size?
G1
What is the best way to visualize reticular fibers? What is an alternate method?
Silver stains.
Also PAS positive.
What is the general composition of GAGs?
Long, unbranched polysaccharides composed of repeating disaccharide units (HEXOSAMINE and URONIC ACIDS).
Name five important GAGs
- Hyaluronan
- Chondroitin sulfate
- Dermatin sulfate
- Keratan sulfate
- Heparan sulfate
What allows GAGs to resist compression?
Negatively charged GAGs attract osmotically active cations (Na+)
What is an important glycoprotein constituent of basement membrane? What does it do?
Laminin: Mediates adhesion of epithelial cells to basement membrane.
What is the name of the structure responsible for the covalent cross-linking in elastic fibers?
Desmosine
-see 5a
Proteolytic digestion of a proteoglycan would result in the release of what?
GAGs
What is responsible for the banding pattern of collagen on EM?
Staggered arrangement of tropocollagen molecules.
What is pyknosis of a nuclei? What does it represent?
Pyknosis is the irreversible condensation of chromatin in the nucleus of a cell undergoing necrosis or apoptosis. It is followed by karyorrhexis, or fragmentation of the nucleus.
______ provide a barrier to the lateral diffusion of membrane proteins and lipids between cells.
Tight junctions/zonula occludens. #3 Histo review
What protein is the principal mediator of membrane ruffling and locomotion in these cultured cells?
Actin #4 Histo review
Desmin and vimentin are _______ proteins found in ______ cells.
intermediate filament proteins found in mesenchymal cells. #4 Histo review
What are the nuclear matrix proteins that stabilize the nuclear membrane and organize chromatin?
Lamins
Which proteins form the spindle apparatus, regulate INTRAcellular transport, and control the movement of cilia and flagella?
Tubulins
Describe holocrine secretion
Loss of plasma due to an initiation programmed cell death in order to release intracellular stores of lipid and wax.
It which organ would you expect to find lots of SER and why?
Liver because of its detoxifying role.
Mucins within goblet cells are heavily ______ _____proteins that protect the intestinal mucosa and lubricate the luminal contents. Which stain would be best used to visualize these cells?
glycosylated GLYCOproteins.
PAS.
