CELL Flashcards
are the basic structural and functional units, the smallest living parts of the body.
cells
fluid containing a system of membranous organelles, non-membranous molecular assemblies, and a cytoskeleton.
cytoplasm
The first zygotic cellular divisions produce cells called
blastomeres
Explanted to tissue culture cells of the inner cell mass are called
embryonic stem cells
Most cells of the fetus undergo a specialization process called ___ in which they predominantly express sets of genes that mediate specific cytoplasmic activities, becoming efficiently organized in tissues with specialized functions and usually changing their shape accordingly
differentiation
Movement
Muscles and other contractile cells
Form adhesive and tight junctions between cells
Epithelial cells
Synthesize and secrete components of the extracellular matrix
Fibroblasts, cells of bone and cartilage
Convert physical and chemical stimuli into action potentials
Neurons and sensory cells
Synthesis and secretion of degradative enzymes
Cells of digestive glands
Synthesis and secretion of glycoproteins
Cells of mucous glands
Synthesis and secretion of steroids
Certain cells of the adrenal gland, testis, and ovary
Ion transport
Cells of the kidney and salivary gland ducts
Intracellular digestion
Macrophages and neutrophils
Lipid storage
Fat cells
metabolite absorption
Cells lining in the intestine
consists of phospholipids, cholesterol and proteins, with oligosaccharide chains covalently linked to many of the phospholipids and proteins.
This limiting membrane functions as a selective barrier regulating the passage of materials into and out of the cell and facilitating the transport of specific molecules.
Plasma membrane
Certain plasma membrane proteins, the ___ , are linked to both the cytoskeleton and ECM components and allow continuous exchange of influences, in both directions, between the cytoplasm and material in the ECM.
integrins
__ are major constituents of membranes
Proteins
__ are incorporated directly within the lipid bilayer. whereas peripheral proteins are bound to one of the two membrane surfaces, particularly on the cytoplasmic side.
Integral proteins
___ transports small, nonpolar molecules directly through the lipid bilayer. Lipophilic (fat-soluble) molecules diffuse through membranes readily. water very slowly.
Diffusion
__ are multipass proteins forming transmembrane pores through which ions or small molecules pass selectively.
Channels
Water molecules usually cross the plasma membrane through channel proteins called __ .
aquaporins
__ are transmembrane proteins that bind small molecules and translocate them across the membrane via conformational changes.
Carriers
are enzymes engaged in active transport, utilizing energy from the hydrolysis of adenosine triphosphate (ATP) to move ions and other solutes across membranes, against often steep concentration gradients.
Membrane pumps
Macromolecules normally enter cells by being enclosed within folds of plasma membrane (often after binding specific membrane receptors) which fuse and pinch off internally as spherical cytoplasmic vesicles (or vacuoles) in a general process known as
endocytosis
(“cell drinking”) involves smaller invaginations of the cell membrane which fuse and entrap extracellular fluid and its dissolved contents.
Pinocytosis
The latter process, called __ , accomplishes bulk transfer of dissolved substances across the cell.
transcytosis
Receptors for many substances, such as low-density lipoproteins and protein hormones, are integral membrane proteins at the cell surface
High-affinity binding of such ligands to their receptors causes these proteins to aggregate in special membrane regions that then invaginate and pinch off internally as vesicles.
Receptor-mediated endocytosis
are macromolecular machines, about 20 x 30 nm in size. which assemble polypeptides from amino acids
Ribosomes
The cytoplasm of most cells contains a convoluted membranous network called the __
endoplasmic reticulum (ER).
This network (reticulum) extends from the surface of the nucleus throughout most of the cytoplasm and encloses a series of intercommunicating channels called __ .
cisternae
is a major site for vital cellular activities, including biosynthesis of proteins and lipids.
ER
is prominent in cells specialized for protein secretion, such as pancreatic acinar cells (making digestive enzymes), fibroblasts (collagen), and plasma cells (immunoglobulins).
The presence of polyribosomes on the cytosolic surface of the RER confers basophilic staining properties on this organelle when viewed with the light microscope.
The major function is production of membrane-associated proteins, proteins of many membranous organelles, and proteins to be secreted by exocytosis.
Rough Endoplasmic Reticulum
Regions of ER that lack bound polyribosomes, which is continuous with RER but frequently less abundant.
Lacking polyribosomes, __ is not basophilic and is best seen with the TEM.
Smooth Endoplasmic Reticulum
completes posttranslational modifications of proteins produced in the RER and then packages and addresses these proteins to their proper destinations.
Golgi Apparatus
Golgi Apparatus, The organelle was named after histologist___ who discovered it in 1898
Camillo Golgi
sites of intracellular digestion and turnover of cellular components
are membrane-limited vesicles that contain about 40 different hydrolytic enzymes and are particularly abundant in cells with great phagocytic activity (eg, macrophages neutrophils).
Lysosomes (Gr. lysis, solution + soma, body)
are membrane- enclosed organelles with arrays of enzymes specialized for aerobic respiration and production of adenosine triphosphate (ATP), with high- energy phosphate bonds, which supplies energy for most cellular activines
Mitochondria
converts glucose anaerobically to pyruvate in the cytoplasm releasing some energy.
Glycolysis
The cytoskeleton contains three types of polymers
Microtubules
Microfilaments
Myosins
are semirigid tubular structures with walls composed of polymerized tubulin heterodimers; their structure is often very dynamic, with steady addition and dissociation of tubulin
Microtubules
are short, flexible, highly dynamic filaments of actin subunits. in which changes in length and interactions with binding proteins regulate cytoplasmic viscosity and movement.
Microfilaments
are motor proteins that bind and move along actin filaments. carrying vesicles or producing cytoplasmic movement.
Myosins
