Chapter 2 (reading) Flashcards
structures that are not usually surrounded by a plasma membrane
inclusions
a lipid bilayer that forms the cell boundary as well as the boundaries of many organelles within the cell
plasma (cell) membrane
a region of endoplasmic reticulum associated with ribosomes and the site of protein synthesis and modification of newly synthesized proteins
rough endoplasmic reticulum
a region of endoplasmic reticulum involved in lipid and steroid synthesis but not associated with ribosomes
smooth endoplasmic reticulum
a membranous organelle composed of multiple flattened cisternae responsible for modifying, sorting, and packaging proteins and lipids for intracellular or extracellular transport
golgi apparatus
membrane-bounded compartments interposed within endocytotic pathways that have the major function of sorting proteins delivered to them via endocytotic vesicles and redirecting them to different cellular compartments for their final destination
endosomes
small organelles containing digestive enzymes that are formed from endosomes by targeted delivery of unique membrane proteins and enzymes
lysosomes
organelles that provide most of the energy to the cell by producing ATP in the process of oxidative phosphorylation
mitochondria
small organelles involved in the production and degradation of H2O2 and degradation of fatty acids
peroxisomes
form elements of the cytoskeleton together with actin and intermediate filaments and continuously elongate and shorten—-dynamic instability
microtubules
short, paired cylindrical structures found in the center of the microtubule-organizing center and whose derivatives give rise to basal bodies cilia
centrioles
structures essential for protein synthesis and composed of rRNA
ribosomes
protein complexes that enzymatically degrade damaged and unnecessary proteins into small polypeptides and amino acids
proteasomes
what does the membrane primarily consist of?
phospholipid, cholesterol, and protein molecules
Microdomains of the plasma membrane, known as ______________, control the movement and distribution of proteins within the lipid bilayer.
lipid rafts
What is the dynamic glue that holds the lipid raft together?
cholesterol
-regarded as the molecular markers of planar lipid rafts and are considered to be scaffolding proteins
-also participate in recruitment of specific membrane proteins into the rafts and work as active partners in various signaling pathways
flotillins
proteins that have the capacity to bind cholesterol and a variety of proteins that are involved in signal transduction
caveolins
What preparation technique allowed for the existence of integral membrane proteins?
freeze-fracture
The E-face is backed by__________and the P-face is backed by ______________.
extracellular space
cytoplasm
-transport certain ions such as Na+ actively across membranes
-also transport metabolic precursors of macromolecules
pumps
allow the passage of small ions, molecules, and water across the plasma membrane in either direction
channels
allow recognition and localized binding of ligands in processes such as hormonal stimulation, coated-vesicle endocytosis, and antibody reactions
receptor proteins
anchor the intracellular cytoskeleton to the extracellular matrix
linker proteins
the process by which extracellular stimuli are received, processed, and conveyed by the cell to regulate its own physiologic responses
cell signaling
Activation of cell surface receptors leads to _________________, which contributes to the amplification of the signal.
posttranslational modification
What are the 6 posttranslational modifications mentioned in the text?
-phosphorylation
-glycosylation
-acetylation
-methylation
-nitrosylation
-ubiquitination
-SUMOylation
How do small, fat-soluble, uncharged molecules, and gases cross the plasma membrane down their concentration gradient without expending metabolic energy or transport proteins?
simple or passive diffusion
-transfer small, water-soluble molecules
-highly selective
-after binding, these proteins undergo a series of conformational changes and release the molecule on the other side of the membrane
carrier proteins
-transfer small, water-soluble molecules
-made of transmembrane proteins with several membrane-spanning domains that create hydrophilic channels through the plasma membrane
-ion selective and regulated on the basis of the cell’s needs
channel proteins
partially penetrates the membrane bilayer and serves as an ion-selectivity filter due to regulation of its three-dimensional structure
pore domain
The major mechanism by which large molecules enter, leave, and move within the cell is called______________
vesicle budding
-the general term for processes of vesicular transport in which substances enter the cell
-controls composition of the plasma membrane and the cellular response to changes in the external environment
-key roles in nutrient uptake, cell signaling, and cell shape changes
endocytosis
-the general term for processes of vesicular transport in which substances leave the cell
-also the process by which all cells deliver the intracellular plasma membrane to the cell surface
exocytosis
What happens when exocytosis is abolished?
no endocytosis takes place because they are coupled together
Following endocytosis, the contents of endocytotic vesicles and their membrane components are either:
recycled to the cell surface or are transported to late endosomes for future degradation
What is the best known protein that interacts with the plasma membrane in vesicle formation?
clathrin
-the nonspecific ingestion of fluid and small protein molecules via small vesicles
-performed by virtually every cell in the organism & is constitutive
-associated with the presence of caveolin and flotillin
micropinocytosis
-nonspecific uptake mechanism for extracellular fluids, solutes, nutrients, and antigens
-actin-dependent
-formation of surface membrane ruffles to entrap extracellular fluid
macropinocytosis
-large endocytic vacuoles
-large fluid carrying capacity is utilized by immune cells in order to sample as much of their extracellular environment as possible
macropinosomes
-the ingestion of large particles such as cell debris, bacteria, and other foreign materials
-pseudopodia from plasma membrane engulf particles into vesicles
phagocytosis
Phagocytosis is performed mainly by a specialized group of cells belonging to the ________________–
mononuclear phagocytotic system (MPS)
What receptors accumulate in well-defined regions of the cell membrane during receptor-mediated endocytosis?
cargo receptors
What are coated pits?
accumulation of electron-dense material that represents aggregation of clathrin molecules on the cytoplasmic surface of the plasma membrane
Name the clathrin adaptor proteins which is instrumental in selecting appropriate cargo molecules for transport into the cells.
adaptin AP180
large mechanoenzyme GTPase that mediates the liberation of forming clathrin-coated vesicles from the plasma membrane during receptor-mediated endocytosis
dynamin
the process by which a vesicle moves from the cytoplasm to the plasma membrane, where it discharges its contents to the extracellular space
exocytosis
-exocytosis pathway in which substances designated for export are continuously delivered in transport vesicles to the plasma membrane
-these cells lack secretory granules
constitutive pathway
-exocytosis pathway in which specialized cells, such as endocrine and exocrine cells and neurons, concentrate secretory proteins and transiently store them in secretory vesicles within the cytoplasm
regulated secretory pathway
what stimulates secretory vesicles to fuse with the plasma membrane and discharge their contents
influx of Ca2+ into the cytoplasm
Rab-GTPase interacts with _____________located on the target membrane.
tethering proteins
What does SNARE stand for?
soluble NSF attachment receptor
expressed on both the vesicles and target membranes to mediate accurate vesicle trafficking and subsequent membrane fusion
SNARE
A vesicle-specific SNARE (v-snare) interacts with the target plasma membrane that contains a ______________
target-specific SNARE
Successful assembly of the __________________guarantees the specificity of interaction between a particular vesicle and its target membrane.
trans-SNARE compelx
an 18 kDa integral membrane protein found in the synaptic vesicle (v-SNARE)
synaptobrevin
a 33 kDa integral membrane protein found in the presynaptic plasma membrane (t-SNARE)
syntaxin
a 23 kDa peripheral membrane protein attached to the intracellular surface of the presynaptic plasma membrane via modified lipid called palmitoylation
SNAP-25
Removal of cytoplasmic components, particularly membrane-bounded organelles, by digesting them within lysosomes
Autophagy
diseases that are characterized by dysfunctional lysosomes
lysosomal storage diseases
The absence of what enzyme causes Tay-Sachs disease?
a lysosomal galactosidase (B-hexaminidase) that catalyzes a step in lysosomal breakdown of gangliosides in neurons
The ________________________ in secretory cells is the light microscopic image of the organelle called rough endoplasmic reticulum.
ergastoplasm
In many instances, the rough ER is continuous with the outer membrane of the__________________.
nuclear envelope
Groups of ribosomes form short spiral arrays called polyribosomes in which many ribosomes are attached to a thread of _________________.
messenger RNA
What type of proteins do “free” ribosomes synthesize?
those that will remain in the cell as cytoplasmic, structural, or functional elements
large basophilic bodies of nerve cells that consist of both rER and large numbers of free ribosomes
Nissl bodies
_____________________is well developed in secretory cells and does not stain with hematoxylin or eosin.
the golgi apparatus
the flattened cisternae located closest to the rER represent the forming face or the_________________
cis-Golgi network
the cisternae located away from the rER represent the maturing face or the _____________________
trans-Golgi network
How do mitochondria increase in number?
by dividing throughout interphase
Mitochondria are believed to have evolved from an ___________________________________ that lived symbiotically within primitive eukaryotic cells.
aerobic prokaryote (Eubacterium)
Mitochondria are present in all cells except_______________
RBC and terminal keratinocytes
small membrane-limited spherical organelles that contain oxidative enzymes, particularly catalase and other peroxidases
peroxisomes
What enzyme universally present in peroxisomes carefully regulates the cellular hydrogen peroxide content by breaking down hydrogen peroxide, thus protecting the cell?
catalase
nonbranching and rigid hollow tubes of polymerized protein that can rapidly assemble and equally rapidly disassemble
microtubules
Where do microtubules grow from?
y-tubulin rings within the MTOC
-can modify the speed of polymerization and depolymerization of microtubules
-regulate microtubule assembly and anchor the microtubules to specific organelles
microtubule-associated proteins (MAPs)
the process of switching from a growing to a shrinking microtubule is often called a:
microtubule catastrophe
-cytoplasmic or nuclear structures with characteristic staining properties that are formed from the metabolic products of cell
-contain products of metabolic activity of the cell and consist largely of pigment granules, lipid droplets, and glycogen
inclusions
What is the most common “wear-and-tear” pigment?
lipofuscin
rope-like filaments that add stability to the cell and interact with cell junctions
intermediate filaments
which hydrolyze ATP to provide energy for movement along the actin filament and are responsible for muscle contraction
actin motor proteins
What does the nucleus of a nondividing (interphase) cell consist of?
-chromatin
-nucleolus
-nuclear envelope
-nucleoplasm
what is the nucleoplasm?
nuclear content other than the chromatin and nucleolus
the disappearance of nuclei due to complete dissolution of DNA by increased activity of DNAase
karyolysis
condensation of chromatin leading to shrinkage of the nuclei
pyknosis
fragmentations of nuclei; usually preceded by pyknosis
karyorrhexis
densely staining, highly condensed chromatin
heterochromatin
lightly staining, dispersed chromatin
-active chromatin
euchromatin
What type of heterochromatin are Barr bodies?
facultative
