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234 Cards in this Set

  • Front
  • Back
fluid portion of the cytoplasm ; approx. 55% of total cell volume(75-90% water plus various dissolved and suspended components)
cytosol
these are stored in the form of D-glucose or glycogen
carbohydrates
Three groups of inclusions:
Stored Food Substances, Pigments, Crystals
Glycogen as solitary granules are in _______
Beta form
Glycogen stored as aggregations called rosettes are in the _____________
alpha form
Glycogen is removed in routine preparations for which type of microscopy?
Light microscopy; exception PAS+ , only alpha form is seen.
Glycogen is/isn't membrane bound.
is Not
Glycogenesis occurs in the ______; especially found in what areas of the body?
cytosol; liver and skeletal
Glycolysis occurs in the _____.
cytosol.
TCA/Krebs cycle occurs where? All TCA enzymes are found in the matrix except which one?
Mitochondria; Succinate dehydrogenase
Stored in the form of triglycerides, phospholipids, or cholesterol.
Lipids
Site of the synthesis of lipid, lipoproteins, and steriod derivatives of cholesterol.
Smooth ER
In routine preparation for this type of microscopy, fat is dissolved leaving empty spaces.
Light Microscopy
A material that possesses color in its natural state.
Pigment
Type of pigment generated outside the body and subsequently taken up by some cells
Exogenous
Yellowish pigment found in vegetables and butter(colors fat also gives color to skin). Pre-cursor to vitamin A.
Carotene.
________ is from plant foods can be oxidatively cleaved in the intestein to form two molecules of retinal.
Beta-carotene.
Carotene belongs to a group of lipid soluble pigments called ________.
lipochrome
An exogenous pigment inhaled and stored in phagocytic cells of the lungs.
Carbon (and other dust particles)
Exogenous pigments eaten in food or abosrebed through the skin. Examples are Mercury, silver and lead.
Minerals.
Pigments generated inside the body from nonpigmented material.
Endogenous pigments.
Most abundant pigment in the body.
Hemoglobin.
Oxygen carrying, red pigment of red blood cells.
Hemoglobin
Black-brown pigment found in oval membrane-bound pigment granules
Melanins
Actively synthesized in melanosomes from tyrosine via a colorless intermediate product dihydrophenylalanine.
Melanins
Yellowish-brown pigment found mainly in permanent cells, increases with age. Found in residual bodies represents deposits of undigestiblee substances.
Lipofuscin
Inclusion rare in healthy cells. Usually a storage form of protein, non-membrane bound.
Crystals
The ER, Golgi and mitochondria are held in their relative locations by attachment to the ________, especially to _______.
cytoskeleton, microtubules.
Name the four distinct famiilies intracellular compartments are grouped into.
1. Nucleus
2. Mitochondria
3. Peroxisomes
4. All organelles that function in the secretory and endocytic pathways, the "ER Pathway". ( ER, golgi, endosomes, lysosomes, transport vesicles.)
Proteins play an important role in ________________.
1. catalyze rxns that occur in each organelle.
2. selectively transport molecules in and out of the organelle.
3. serve as organelle-specific surface markers.
Compartmentalization
Three places that proteins are delivered directly to from the cytosol.
Mitochondria, peroxisomes, and interior of the nucleus.
Virtually all proteins are synthesized on _________ in the cytosol. What is the one exception?
ribosomes; exception is a few mitochondrial proteins that are synthesized on ribosomes inside the organelles.
The fate of proteins synthesized in the cytosol depends on the amino acid sequece that may contain a ___________ _________ that directs the protein to the correct organelle.
Sorting signal
Where do proteins go without a sorting signal?
Stay in the cytosol
Name three different ways cytosolic proteins are transported across the membrane between compartments of the cell.
Gated, transmembrane, and vesicular transport
The nuclear envelope employs this type of protein transport
Gated transport; proteins moving from the cytosol to the nucleus are transported through NUCLEAR PORE COMPLEXES. Proteins do not need to unfold.
Nuclear pore complexes selectively transport specific macromolecules unidirectionally or bidirectionally? Active or passive transport of macromolecules?
Bidirectionally; Active transport, GTP required. Free diffusion of smaller molecules.
Proteins moving from the cytosol into the ER, mitochondria, or peroxisomes are transported across the organelle membrane by ______________________________
Protein translocators, requires ATP. Protein usually has to unfold before corssing the membrane.
Type of transport used to move proteins from the ER onward, requires ATP.
Vesicular Transport
What is the ER retention signal?
KDEL
What is the default pathway for proteins synthesized on ER-associated ribosomes(With no signal sequence)?
ER to Golgi to secretory vesicles to cell surface.
What is the default pathway for proteins synthesized on the free ribosomes with no signal sequence?
Ribosomes, stay in cytosol.
Ribosomes are/are not membrane bound.
Are not membrane bound.
Ribosomes are composed of __ proteins and ___rRNAs.
80;4
These units are catalysts for protein synthesis within the cytoplasm of eukaryotic cells.
ribosomes
The lare and small subunit of ribosomes are manufactured in the ________ and released as separate entities into the cytosol.
Nucleolus
Polysomes bound to the ER make _________ proteins.
glycosylated
Proteins synthesized on _______ ribosomes include integral plasma membrane proteins, ER, golgi, and lysosomal proteins and proteins to be secreted from the cell.
Membrane-associated; make GLYCOSYLATED proteins which are segregated from the cytosol.
_____ ribosomes are responsible for synthesis of proteins destined for the nucleus, mitochondria, and peroxisomes, NON-GLYCOSYLATED.
Free or Membrane-nonassociated
The small ribosomal unit has a ______ responsible for binding peptidyl tRNA, a ____ responsible for binding aminoacyl tRNAs, and a site for binding _______.
P-site, A-site, mRNA
What is the central Dogma?
DNA ->transcribed to RNA -> translated to Protein
The process whereby the nucleotide sequence of mRNA specifies amino acid sequence for a protein molecule
Translation
In the mRNA molecule, each set of three consecutive nucleotide bases is called a _____ and specifies one amino acid.
Codon
In translation the small ribosomal subunit binds to one end of a mRNA molecule and finds the __1__, a sequence where translation will begin. The large subunit then attaches. Each type of tRNA binds to one type of amino acid and on the other end has a triplet of nucleotides called an ___2__. By base pairing the tRNA anticodon recognizes and attatches to a complimentary codon on mRNA. Ex. mRNA codon is AUG, then the tRNA anticodon would be __3__(bringing along the corresponding amino acid)
1.start codon
2.anticodon
3.UAC
Once the first tRNA has attatched to mRNA, the ribosome moves exactly ___ nucleotides along the mRNA, and the next tRNA carrying its amino acid moves into position(the A-Site)
Three
The ____ subunit contains the necessary enzymes to form a peptide bond between the two amino acids (ATP reqd) in the A and P sites of the ribosome.
large
When protein synthesis is complete it gets terminated by a __________.
Stop codon
Protein synthesis progresses at arate of ____ amino acids per ____.
15/second.
Several ribosomes translating a single mRNA strand simultaneously is termed a ______
Polyribosome (polysome)
1 Process by which enzymes brake down proteins down into single amino acids ; 2 enzymes that degrade proteins.
1 proteolysis; 2 proteases
Most proteins degraded in the cytosol are broken down by large complexes of proteolytic enzymes called ______.
Proteasomes; contain a central cylinder formed from proteases. Protein stoppers at the end of the cylinder aid in the digestion.
A primary marker used for protein destruction is a small protein called ______ covalently attatched to the protein designated for destruction
ubiquitin
Ubiquitin is attatched to a candidate protein via a _______ residue.
Lysine; Ubiquitination, release of ubiquitin and protein degradation all require ATP.
This organelle is responsible for oxidative phosphorylation and had 2 membranes.
Mitochondria
Mitochondria produce ATP via a process called ____.
Oxidative phosphorylation
Which membrane of the mitochondria possess cristae to increase the surface area?
Inner membrane; the numbe of cristae per mitochondria is directly related to the energy requirements of the cell.
The function of the outer mitochondrial membrane?
Help maintain the shape of the mitochondria.
Porins (beta-barrels) can be found on which membrane of the mitochondria? What is their function?
Outer membrane; they function in transport of molecules in and out of the membrane thus making the cytosol and the intermembranous space chemically equivalent.
The inner membrane of the mitochondria has a higher content of protein thatn any other membrane in the cell. The inner membrane also has the phospholipid _________ which helps make the membrane especially impermeable to ions.
cardiolipin
The inner membrane is studded with numerous minute globular structures with ATP synthase activity; these structures are called _________ or _______.
inner membrane subunits or elementary particles.
The inner membrane also contains the respiratory chain enzyme complexes plus one TCA cycle enzyme. Name them
NADH Cytochrome b-c complex, cytochrome oxidase complex, and the TCA enzyme is succinate dehydrogenase.
What type of cristae is characteristic of steroid producing cells?
Tubular cristae
Where are the fatty acid Beta Oxidation enzymes found?
matrix of the mitochondria
The regions that the outer and inner mitochondrial membranes contact eachother are called _______ and act as pathways for proteins and small molecules to enter or leave the matrix
contact sites
The information for the formation of the 13 mitochondrial proteins is stored in the ___________. The rest of the proteins are imported from the cytosol.
Mitochondrial ciruclar DNA; not complexed with histones
Mitochondria with ______ cristae are the most common type. The number of cristae is directly related to what?
lamellar; the energy requirement of the cell
Cells of the Zona fasciculata of the adrenal cortex have tubular cristae what does this imply?
These cells produce steroids.(Cells like this also contain many lipid droplets and extensive networks of SER.)
How to mitochondria replicate?
Self replicate - generated from pre-existing mitochondria by the process of fission.
The average lifespan of a mitochondria is ____.
10 days
Which cells do not contain any mitochondria?
erythrocytes
Self-replicating, membrane-bound organelle that contain more than 50 oxidative enzymes.
Peroxisomes
The liver and kidney contain _______ of peroxisomes
hundreds
Peroxisomes and mitochondria are major sites of ______ utilization
oxygen
Peroxisomes function in the catabolism of long chain fatty acids a process called _____. This process forms _____ as well as _______.
Beta oxidation; acetyl coA and hydrogen peroxide.
Hydrogen peroxide is decomposed by what enzyme in the peroxisomes?
catalase
Catalase in the liver uses the hydrogen peroxide to oxidize other substrates such as what?
ALCOHOLS, formaldehydes, and formic acid.
H2O2 + RH2 -> 2H2O + R

Important because the liver detoxifies 25% of the ethanol we drink
Superoxide dismutase, peroxidase, and catalase normally dispose of what damaging thing to the cell?
Free radicals
Peroxisomes import or make all of their proteins and lipids?
Import from the cytosol
The double membrane that separates the nucleus from the cytoplasm is called the ______.
nuclear envelope
All proteins that function in the nucleus are synthesized in the _______.
cytosol
What is the structure called that allows a direct passageway across the nuclear envelope?
Nuclear pore complex, NPC.
The nulear pore complex is composed of what four elements?
The scaffold, the transporter subunit, fibrils, and a cage.
Attatched to the inner and outer rims of the nuclear pore are particles arranged in two distinct coaxial rings known as the __________.
scaffold
A proteinaceous ring that occupies that center of the nuclear pore and is supported by the scaffold?
The transporter
_______ protrude from both the cytosolic and nuclear sides of the NPC, on the nuclear side they converge to form cagelike structures.
Fibrils
Each NPC has one or more open aqueous channels with a diameter of 10nm or less ensuring that all protein synthesis takes place in the _____.
cytosol
The bidirectional traffic in and out of the nucleus is mediated by a certain proup of proteins of the NPC which are? (2)
Exportins- transport macromolecules from the nucleus to the cytoplasm (and)
Importins- transpot cargo from the cytoplasm to the nucleus
Exportin and importin fucntion is regulated by a family of ________________________.
GTP-binding proteins known as Ran.
Proteins designated for the nucleus are recognized by the ___________________.
Nuclear localization signal
Larger complexes like ribosomal subunits are transported through the nuclear membranes how?
recpetor-mediated transport, requires ATP.
The basket/cagelike structure of the NPC functions to do what?
Keep the heterochromatin away from the NPC
All cytopasmically synthesized mitochondrial proteins are capable of inserting into the organelle membrane pre or post translationally?
Post
A protein is translocated into the mitochondrial matrix space by passing through sites of adhesion between the inner and outer membranes called ___________. The transported protein crosses the membrane in the ________ state.
contact sites; unfolded
Newly synthesized mitochondrial precursor proteins are guided by members of the ________ family proteins in particular the ___ ____ family of proteins.
Chaperone; HEAT SHOCK (hsp70)
Binding to cystolic _____ proteins prevents the mitochondrial precursor proteins from folding before they bind to the translocator in the target membrane.
hsp70
Once in the matrix, ______ helps the translocated protein fold up (mitochondria).
hsp60
Describe the mitochondrial signal peptide.
Positively charged signal at the N-terminal, 20-80 amino acids in length, alpha helix.
A ________ removes the signal sequence as the protein reaches is designated location.
signal peptidase
Transport from the mitochondrial matrix across or into the innner membrane can occur if a hydrophobic signal peptide is also present in the protein. The second signal is only revealed when?
Only revealed upon removal of the first signal peptide; A second signal peptidase associated with the inner mitochondrial membrane removes the second signal.
Where is the Nuclear localization located on a protein?
It can be located at any site within the protein. The NLS is generally retained and not cleaved to ensure that the protein remains in the nucleus during cell division (0r returns there)
What is the signal to transport proteins to the peroxisomes?
Three AA sequence near the C-terminal, remains part of the proteins after entry; entry requires energy.
How many cis cisternae are there in the golgi? what about trans?
One each; one cis face, one cis cisternae, several medial cisternae, one trans cisternae, and one trans face
What happens to the pH as you go through the golgi?
The pH drops from the cis face to the trans face.
What is the tag for prtoeins to go to lysosomes(via late endosomes)?
Mannose-6-phosphate
A system of interconnected tubules and vesicles whose lumen is referred to as the cistern and extends from the nuclear envelope. There are two types.
Endoplasmic reticulum; smooth and rough
The smooth ER does or does not have ribosomes.
Does not.
Name some functions of the smooth ER.
Phospholipid and cholesterol synthesis (flippases present).
Steroid hormone synthesis in endocrine gland cells.
Drug detoxification in liver cells (not alcohol).
Calcium flux in striated muscle.
The rough ER does or does not have ribosomes.
Ribosomes are present on the cytosolic side.
The RER is the site of production of glycosylated proteins designated for what three locations.
lysosomes, secretory vesicles, and plasma membrane.
Proteins that need to be packaged either for delivery to the outside of the cell or merely isolated from the cytosol must be identified and be delivered ____-transitionally into the rough ER.
co-transitionally
What is the ER signal sequence?
A short segment of 8 or more hydorphobic amino acids at the N terminal. This signal peptide directs the protein where to go. It is found immediately after the start codon on the mRNA.
What recognizes the signal peptide in the cytosol?
The signal recognition particle (SRP).
The SRP sttatches to the signal peptide and by occupying the _____ on the small subutnit of the ribosome halts translation. It then directs the polysome to the RER.
p-site
What protein in the ER membrane contacts the SRP? Which one contacts the large subunit of the ribosome?
The SRP recpetor or docking protein; ribosome receptor protein.
During translocation, the signal sequence is cleaved off by a ________________.
signal peptidase
What is a stop-transfer sequence?
A hydrophobic sequence in a protein being translocated that drifts into the plane of the membrane anchoring that protein in the membrane. It forms an alpha helical membrane spanning segment. Simultaneously the N-terminal signal sequence is released from the channel into the lipid bilayer and cleaved off.
What orientation does a single pass transmembrane protein have?
N-terminus on the non-cytosolic side; c-terminus on the cytosolic side.
An internal rather than a N-terminal hydrophobic sequence that initiates translocation is called a ? It is never removed from the peptide.
start transfer sequence; hydrophobic signal sequences work in pairs. The start transfer sequence initiates translocation and it continues until a stop transfer sequence is reached. The sequences remain as part of the bilayer as alpha helices. This is how multipass membrane proteins are formed.
What type of bonds form in the ER that do not form in the cytosol?
disulfide bonds; help stabilize protein structure but can't be formed in the cytosol due to the reducing environment.
Where does glycosylation begine? Where can it not occur?
Glycosylation begins in the ER and it CAN NOT occur in the cytosol.
How are sugars attached to proteins in the ER?
They are attatched "en bloc" to all proteins who carry the appropriate site for glycosylation.
What sugars are attatched to proteins in the the ER at the appropriate sites for glycosylation?
There are 14 sugars attatched in the ER, 9 of which are mannose.
Where is the oligiosaccharide attatched prior to being transfered to the designated protein in the ER?
It is attatched to a membrane lipid called dolichol.
What residue is the oligiosaccharide transfered to on the designated protein?
The oligiosaccharide is transferred to an asparagine side chain in a single enzymatic step catalyzed by a membrane-bound transferase enzyme.
Sugars attatched to the NH2 group of asparagine are said to be __________.
N-linked.
What forms the "core region" of this oligiosaccharide?
Five sugars; 3 are mannosee. These are the core sugars that survive the trimming process that takes place in the golgi.
What are the designated locations of glycosylated proteins?
Plasma membrane, lysosomes, ER, and Golgi; ALL NON-CYTOSOLIC sides
How do contents of the ER get to the golgi?
Transfer vesicles.
It is in the __________ that proteins destined to remain in the ER get returned along a microtubule-mediated pathway.
Cis golig network, CGN; proteins are recognized by the KDEL C-terminal signal.
Organelle located near the nucleus and close to the centrosome of the cytoskeleton; involved in modification of glycosylated proteins and packaging.
Golgi Apparatus
How many cisternae does a golgi usually have?
5-10 cisternae
The golgi is a polarized structure. It has a region closest to the RER called the ___________ (convex) and the opposite side is called the _______ (concave).
cis-face or entry face and trans face of exit face.
Proteins are transferred fro the cis to the midial to the trans cisternae via ?
coatomer caoted vesicles.
Name 3 functions of the golgi?
1. Trim/initiate polysaccharide chains
2. plasma membrane recycling
3. sorting of proteins in the TGN
Different cisternae of the golgi have different enzymes to perform different functions, what cisternae is responsible for phophorylation of mannose(Mannose -6-phosphate tag for lysosomes)?
The cis cisternae.
Which cisternae of the golgi are responsible for removing mannose from certain proteins?
cis and medial
Which cisternae of the golgi are responsible for added N-acetlyglucosamine to some proteins:
Medial
Which cisternae of the golgi are responsible for addition of salic acid and glactose of some proteins and sulfation and phosphorylation of amino acids?
Trans
What two amino acids are involved in O-linked glycosylation
hydroxyl groups of serine threonine
What enzyme catalyzes O-linked glycosylation?
glycosyltransferase; occurs only in the golgi.
How are sugars added in the golgi as opposed to the ER?
Sugars are added one at a time in the golgi as opposed to en bloc in the ER.
Cycle of membrane shuffling during exocytosis and endocytosis is called?
membrane trafficking
What process is the most active transporting process and contributes most to recapturing of membranes?
Pinocytosis
Proteins that leave the TGN are enclosed in vesicles that can do one of 4 things, what are they?
1. insert into plasma membrane(no signal reqd)
2. fuse with plasma membrane and release contents into ECM (constitutive pathway- no signal)
3. congregate as secretory vesicles and granules and release contents only if signaled (regulated secretory pathway-signal )
4. fuse with late endosomes to form lysosomes (signal - M6P)
Exocytosis is especially prevalent in which two types of cells?
Neurons which release neurotransmitters and secretory cells which release a variety of substances including hormones and enzymes.
______ is a process of discharging large cellular products for export through the plasma membrane.
Exocytosis
What are the two steps of incorporatin of a vesicle membrane into the plasma membrane?
1.bilayer adherence via snares
2. bilayer fusion
The surface area of the plasma membrane is maintained by which two processes?
endo and exocytosis.
sorting mechanism in which endocytotic vesicles enter one side of the epithelium are sorted into secretory vesicles that travel through the cytoplasm and fuse with the plasma membrane on the opposite side WITHOUT PARTICIPATION OF THE GOLGI OR LYSOSOMES.
Transcytosis
Continuous vesicle release not mediated by a signaling pathway is called what?
Constitutive secretory pathway
interval vesicle secretion requiring a signal is called?
Regulated secretion via regulated secretory pathway
The constitutive secretory pathway occurs in what cells?
ALL CELLS
What type of proteins would be involved in constitutive secretion?
Peripheral proteins located on the E-surface "non-cytosolic side".
Proteins secreted constitutively have what signal?
Proteins secreted this way have no signal and are therefore secreted by this default pathway.
What are the two important functions of vesicles destined for the constitutive secretory pathway?
1. provides for new poteins and lipids for the plasma membrane. It is the pathway for plasms membrane growth when cells enlarge before dividing.
2. the vesicles have soluble proteins in them that are secreted via exocytosis and are for the cell coat or for the extracellular matrix.
In what cells does the regulated secretory pathway occur?
It occurs in specialized secretory cells where soluble proteins are stored for later release.
What kinds of substances are released via the regulatory secretory pathway?
Hormones, mucus, digestive enzymes
What signal do the proteins of the regulated secretory pathway carry?
They carry a sorting signal that sends them to storage vesicles.
Regulated secretion appears to take place primarily in response to signals from ______ the cell.
Outside; it is received by receptors forming parts of intracellular pathways such as those employing Ca or cAMP as second messengers.
Regulatory secretory vesicles are bound to the cytoskeleton in a _______ dependent manner.
CALCIUM!!
Vesicles involved in regulated secretion bud are _______-coated whereas constitutive secretion vesicles are _______-coated.
regulated=clathrin
constitutive=coatomer.
Which pathway has a coated pit that contains a receptor that concentrates the proteins secreted by the regulated pathway?
The regulated pathway; they concentrate the contents and can be referred to as condensing vesicles. Electron-dense secretory granules are the result.
The regulated secretory vesicles bind to the cytoskeleton network of ___1__ filaments and nonerythroid __2____ (II) and are released by increase in intracellular ___3____.
1. actin
2. spectrin
3. calcium
The fusion event of regulated vesicles with the plasma membrane requires _____.
Calcium
Exocytosis that takes place at specialized locations in some cells.
Polarized secretion
What type of junctions helps create separate domains for things such as with polarized secretion?
Tight Junctions; help create two separate domains of which vesicles will only attatched to the correct one (snares help with recognition)
What are the three functional classifications of exocrine glands?
Merocrine, Apocrine, and Holocrine.
This type of secretion is released by exocytosis. The only thing lost is the secretory product. It is the most common mechanism for product release. What type is it?
Merocrine secretion.
This form of secretion is characterized by a protruding apical pole with secretory material separating from the cell, enters the glandular lumen and becomes a product of secretion. A thin layer of cytoplasm is also lost. What type is this and provide an example?
Apocrine secretion; lipid componene of the milk from lactating mammary glands.
A type of secretion in which cells become filled with secretory products and after moving far enough away from the capillaries, the cells die and then disintegrate. What is this type and provide an example.
Holocrine; only example is the sebaceous glands of the skin. The secretion is called sebum and is secreted on the surface of the skin.
organelle respondible for ingesting/digesting intracellular and extracellular debris
Lysosomes
Lysosomes contain at least 40 differnt types of _________. Among the enzymes are sulfatases, proteases, nucleases, lipases, and glycosidases; 60% are _______; _____________ is known to be in all lysosomes.
Acid Hydrolase; phosphatases, acid phosphatase.
What type of environment does the enzymes in a lysosomes require? How does a lysosome maintain that type of environmentd?
Acid environment maintained by ATP-driven H+ pumps.
what is the pH lysososme?
pH is approx. 5.0
What adaptation do lysosomes have to protect them from the environment of the lumen?
The membrane proteins are highly glycosylated. These sugars help protect the proteins of the lysosome from being digested.
Lysosomes that have not entered into a digestive event are identified as ?
Primary lysosomes
Lysosomal proteins are tagged with ________ in the cis golgi network.
Mannose -6- Phosphate
Mannose 6 Phosphate is recognized in the TGN by the __________, and thereby sorted and packaged into ______-coated vesicles.
mannose 6 phosphate receptor; clathrin
Transport vesicles deliver their contents to lysosomes via __________.
Late endosomes
What is the pH of a late endosome?
pH about 6.0
Whenlate endosomes possess both enzymatic and membrane components, then the late endosome either 1 or 2.
1. fuses with a lysosome
2.matures to become a lysosome
What are the three ways materials flow to lysosomes? What is the structure called once this fusion occurs?
1. phagosomes
2. pinosomes
3. autophagosomes

Secondary lysosome
What is the amino acid sequence cytosolic proteins carry to be degraded by lysosomes:
KFERQ
The low pH of a lysosome causes the ________ to disassociate from the receptors, which are returned to the golgi. The phosphate is also removed to ensure that this will not return to the golgi with the receptor
hydrolases.
Endocytosis occurs both ______ and as a triggered response to ______ signals.
constitutively; extracellular
The process whereby lysosomes digest materials taken into the cell from its environment by endocytosis is called
Heterophagy
A substance being taken up by this method of endocytosis is recognized and bound to the cell by a receptor. The receptors, which are glycoproteins, recognize and bind only certain molecules. The molecules typically become more concentrated as they are tied to the cell. What mechanism is this?
Receptor-mediated endocytosis
A mechanism in which materials are taken up by the cell as insoluble aggregates of molecules, cell parts, or even whole cells.
Phagocytosis
Describe the process of phagocytosis.
A particle binds to a plama membrane receptor, causing the cell to extend projections of its plasma membrane and cytoplasm called pseudopods. Pseudopods surround the particle outside the cell, and the membrane fuses to form a vesicle called a phagosome, which enters the cytosol.
What is it called when a primary lysosome fuses with a phagasome?
phagolysosome
Any undigested material in a phagosome is called a
residual body *lipofuscin pigment. AKA phagolysosome with exhausted enzyme activity
What are the professional phagocytes?
Macrophages and neutrophils
What is fluid-phase endocytosis?
Pinocytosis
A process involving the non-selective uptake of tiny droplets of extracellular fluid; no binding of receptors occurs.
Pinocytosis; plasma membrane folds inward forming a pinocyte vesicle called a pinosome.
This process helps maintain the surface area of a cell from constitutive secretion.
Pinocytosis.
Organelle serving as a defense system for an organism and as an itracellular digestive system.
lysosome
The process by which worn-out organelles are digested
autophagy
In autophagy, an organelle to be digested is enclosed by a membrane derived from the ____ to create a vesicle called a __________. It goes on to fuse with a late endosome to be come an _____________.
ER, autophagosome, autophagolysosome.
Lysosomal enzymes may destroy their own cell a process called
Autolysis
What are some examples of lysosomal enzymes operating in extracellular digestion?
Sperm releasing enzymes to penetrate the surface of the ovum; bone resorbing cell, the osteoclast.
describe the shape of clathrin.
clathrin consists of three large and three small polypeptide chains that together form a three-legged structure called a triskelion. The triskelions form a basketlike convex framework of sex hexagons and twelve pentagons that drives the curvature of the membrane and the budding process that leads to a coated vesicle.
Name three movemments clathrin-coated vesicles mediate.
1. from trans golgi to late endosomes
2. regulated secretion at the pm
3. receptor mediated endocytosis
What is the protein that aids in binding cargo molecules in clathrin coated vesicles?
Adaptin
What protein pinches off the membrane in clathrin-coated vesicles?
dynamin
What type of coated vesicle mediates nonselective vesicular transport of the default pathway?
coatomer coated
Where would vesicles with a coatomer coat be going? (3)
1. from ER to golgi
2. from one golgi cisternae to another
3. from the TGN to Plasma membrane
Which type of vesicle coating requires energy? Which type does self-assembly?
Coatomer coated require ATP to drive their formation; clathrin coated self-assemble
How long does a coatomer coat remain on the vesicle?
It remains on until the vesicle docks with the target membrane
What are the two types of coatomers?
COP I and COP II
Which coatomer protein mediates retrograde transport from the CGN back to the ER?
COP I
Which coatomer protein mediates anterograde transport from the ER to the CGN (and beyond)?
COP II
KDEL receptor binds to which coatomer coat protein?
COP I sending it back to the ER.
Describe how a vesicle knows where to dock.
All types of transport vesicles in the cell display molecular markers on their surface that identify the vesicle and its cargo. The markers are recognized by complementary receptors on the appropriate target membranes. This process is thought to involve the family of proteins called SNARES. A v-snare on the vesicle and a t-snare on the target membrane. The unique snares carried on transport vesicles help insure that transport vesicles fuse only with the correct membrane.
Once a vesicle has recognized and docked (adhered) to its target membrane, the vesicle must _____.
fuse
Does fusion always immediately follow vesicle docking?
No, fusion can and often waits to be triggered by a specific signal.
Fusion requires that the two lipid bilyers must come within ______ of eachother.
1.5 nm
Before fusion can take place what must be displaced from theh surface of the membrane?
the thin film of water; very energetically unfavorable.
Membrane fusion requires special __________ (like NSF and SNAPs) that assemble at the fusion sight to fomr a _______ that provides the means to cross the energy barrier of fusion.
fusion proteins ; fusion complex
A 3-d network of several differnt kinds of protein filaments distributed throught the cytosol of eukaryotic cells.
Cytoskeleton
Name some functions of the cytoskeleton
1. cell movement
2. support and strength for cell
3. phagocytosis
4. cytokinesis
5. cell to cell and cell to ECM adherence
6. changes in cell shape
Based on size and chemical composition what are the three main types of filaments, in order of their decreasing diameter:
1. microfilaments
2. intermediate filaments
3. microtublues
The cytoskeleton can be built into a variety of structures according to its associated proteins....
-control assembly
-strengthening filaments
-cross-linking
-structural interactions with other cell components
-production of motility
two stranded helical polymers of the protein actin
microfilaments
What is the diameter of a microfilament?
5-9nm