Term
| organelle differences between prokaryotic and eukaryotic cells |
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Definition
| only eukaryotes have lysosomes, nucleolus, and mitochondria |
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Term
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Definition
• helps lessen the “diffusion problem” (large volume makes it hard to diffuse ATP, amino acids nucleotides)
• allows incompatible reactions to be segregated
• increase efficiency of reactions by co-localizing and concentrating the required reagents and enzymes |
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Term
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Definition
• among largest organelles
• contain chromosomes (linear, complexed with proteins)
• site of RNA production
• site of ribosome synthesis (nucleolus)
• nuclear envelope has a double membrane
• contains thousands of openings called nuclear pores
o DNA never cross pores, but messenger RNAs and ribosomal subunits exit; proteins enter
• made of two lipid bilayers stacked up
• inside surface is associated with fibrous proteins that form a lattice-like sheet called nuclear lamina
o stiffens structure and maintains shape
• each chromosome has distinct area and is attached to nuclear lamina |
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Term
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Definition
• found either free-floating in the cytosol or attached to rough ER
• sites of protein synthesis
• have a large and small subunit and contain both RNA and protein molecules
• when two subunits come together, form a complex molecular machine that synthesizes proteins
• an organelle by Reedy definition – not membrane-bound
in both eukaryotes and prokaryotes |
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Term
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Definition
• plays important role in synthesis of secretory proteins
• outer surfaces are studded with ribosomes (sites of protein synthesis)
• as a protein chain grows from a bound ribosome, it is threaded through a pore in the ER membrane
• once inside, protein folding occurs
• network of membrane-bound tubes and sacs studded with ribosomes for protein synthesis
• continuous with outer nuclear membrane
• site of production for proteins that will be secreted, inserted into the membrane, or that function inside the Golgi apparatus or lysosomes
• lumen: interior of rough ER; where newly manufactured proteins undergo folding and processing |
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Term
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Definition
| nucleus, ribosomes, rough ER, Golgi apparatus, smooth ER, peroxisomes, |
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Term
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Definition
• modifies, stores, and repackages products of the ER, mostly for secretion
• formed by a series of stacked flat membranes sacs (cisternae)
• each cisternae forms an enclosed space that house a distinct set of enzymes used to process proteins in a sequential manner as they are prepared for transport to different sites
• additional molecular tags direct Golgi proteins to their final destinations
• like a railway depot for protein transport/packaging
• has distinct polarity
• cis surface is closest to rough ER and nucleus; receives products from rough ER
• trans surface faces plasma membrane; ships products from rough ER out toward cell surface
• composition is dynamic – new cisternae constantly created at cis face |
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Term
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Definition
• lipid biosynthesis
• breakdown of hydrophobic toxins
• calcium storage |
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Term
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Definition
• single-membrane-bound globular organelles
• sites of oxidation reactions
• example: oxidative breakdown of long-chain fatty acids
• contain an enzyme called catalase to detoxify hydrogen peroxide
• different types of peroxisomes specialize in different types of oxidation reactions
• don’t have a specific area in cell
• glyxisomes: specialized peroxisomes that are packed with enzymes that convert one of the products of photosynthesis into a sugar that can be used to store energy for the cell |
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Term
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Definition
• serves as a recycling center
• very acidic compared to other organelles and cytoplasm
• contain acid hydrolases to degrade proteins, lipids, nucleic acids and polysaccharides
• materials brought to lysosomes in one of three ways: receptor-mediated endocytosis, phagocytosis, or authophagy
• single-membrane-bound centers for storage and/or waste processing
• phagocytosis (“eat-cell-act”): plasma membrane of a cell surrounds a smaller cell and engulfs it, forming a phagosome
• autophagy (“same-eating”): damaged organelles are surrounded by a membrane and delivered to a lysosome
• endocytosis: any pinching off of the plasma membrane that results in the uptake of material from outside the cell
o can occur three ways
• phagocytosis
• receptor-mediated endocytosis
• pinocytosis (“drink-cell-act”) |
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Term
| organelles involved in “making” usable chemical energy for cells |
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Definition
| chloroplasts (plants), mitochondria (animals and plants) |
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Term
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Definition
• in plants
• site of photosynthesis
• has double membrane, analogous to structure of mitochondria
• interior dominated by membrane-bounded, flattened vesicles called thylakoids (stacked into piles called grana)
• stroma: region outside thylakoids where critical enzymes and substrates are found
• each contains circular chromosome |
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Term
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Definition
animals & plants
• main function is cellular respiration (the process of converting the chemical energy of sugars into ATP)
• double-membrane
o outer membrane defines shape
o inner membrane is connected to a series of sac-like cristae
• cristae are foldings of the inner membrane
• increase surface area and can pack more enzymes in
• solution inside inner membrane is mitochondrial matrix
• have their own gene – encodes proteins that function in mitochondria
• manufacture their own ribosomes
• cells that have greater energy demands have more mitochondria (muscle cells)
• constantly moving around in cells
o important b/c without it they don’t survive as well |
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Term
| how do the appropriate enzymes and other proteins necessary for those functions get to the correct organelle? |
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Definition
three-part system
• organellar proteins have distinguishing sequences of amino acids that identify them as “belonging” to a particular organelle (addresses)
• a specific cytoplasmic protein binds to these molecular addresses and bring the protein to…
• …receptors in the membrane of the target organelle that then open up to the let the organellar protein enter |
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Term
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Definition
• nucleoplasmin experiment and the identification of a nuclear organization signal (NLS) on proteins that need to get into the nucleus
• importin and Ran help move nuclear proteins through nuclear pores |
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Term
| endomembrane system (rough & smooth ER, lysosomes, Golgi, cell membrane) |
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Definition
– has lots of protein movement through it
• proteins destined for secretion, for insertion into cell membrane, or for the lysosome go through “secretory pathway”
• molecular address for proteins destined for the secretory pathway is called ER signal sequence
• SRP binds to the newly-formed proteins with an ER signal sequence and helps them enter into the rough ER
• after entering rough ER, proteins pass onto Golgi apparatus, where they are modified and sorted into vesicles that carry them to final location
o primary center for protein and lipid synthesis in eukaryotic cellsx
o proteins move through it in a very directed way
o proteins bound to the endomembrane system have a zip code analogous to the nuclear localization signal
o ER signal sequence: series of amino acids that tells a protein to be sent to the ER
o signal recognition particle (SPR): complex of RNA and protein that acts as a receptor for the ER
• key that is activated by an ER signal sequence
o once proteins are inside rough ER or its membrane, fold into 3D shape with help of chaperone proteins |
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Term
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Definition
o extensive system of protein fibers
o gives the cell shape and aids cell movement and transport of materials within the cell
o not static |
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Term
| actin filaments/microfilaments |
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Definition
part of eukaryotic cytoskeleton
• during muscle contractions, myosin motor proteins move across tracks of microfilaments
• actin-myosin interactions can cause cell movements such as cell crawling, cytokinesis, and cytoplasmic streaming in plants
• responsible for cell locomotion and the cell’s structural characteristics (resists tension)
• strands in double helix
• made of actin
• cell division in animals (cytokinesis) – pinch the cell in two
• can be broken down and rebuilt quickly; dynamic
• structure has distinct polarity
• smallest cytoskeletal elements |
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Term
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Definition
part of eukaryotic cytoskeleton
• provide structural support for the cell
• defined by size, not composition
• nonpolar
• anchor many cell organelles, including nucleus
• assembled from a diverse class of proteins
• the only cytoskeletal fibers not associated with intracellular movement or whole cell locomotion
• rope-like structures that anchor organelles and intercellular junctions called desmosomes
• specialized for bearing tension
• fibers wound into thicker cables
• made of keratin, vimentin, lamin, etc.
• very stable – found in lots of static cells (most permanent of the three)
• what gives certain tissues the bulk of their structural stability |
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Term
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Definition
part of eukaryotic cytoskeleton
• fibers that slide past one another due to the activity of dynein proteins
• assembled from protein dimers in centrosomes
• serve as intracellular highways for transporting vesicles and organelles
• required for cellular locomotion in flagella and cilia
• hollow tube
• made of α-tubulin and β-tubulin dimers
• resists compression
• mobility via flagella or cilia
• move chromosomes during cell division
• formation of cell plate during plant cell division
• very dynamic
• tends to grow faster at + end and shrink faster at – end (polar) |
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Term
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Definition
| strands containing DNA and associated protein |
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Term
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Definition
| identical in structure to basal bodies |
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Term
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Definition
| chloroplasts, central vacuole (regulates cytoplasm composition, creates internal pressure, and stores cell compounds), cellulose cell wall (largely polysaccharide) |
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Term
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Definition
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Term
| found in both plant and animal cells |
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Definition
• mitochondrion
• Golgi apparatus
• nucleus
• endoplasmic reticulum
• cytoskeleton
• plasma membrane |
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Term
| Proteins destined for the nucleus have a __________ |
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Definition
17-amino-acid nuclear localization signal (NLS)
o shuttle proteins called exportins help molecules containing a nuclear export signal to exit the nucleus (almost exactly the reverse of import) |
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Term
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Definition
| anything inside the cell (nucleus, proteins, etc.); densely packed |
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Term
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Definition
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Term
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Definition
| intermediate filaments in periphery of nucleus, on which nuclear envelope is built |
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Term
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Definition
| lipids that contain carbohydrate groups |
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Term
| differential centrifugation |
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Definition
| based on breaking cells apart to create a complex mixture and then separating components in a centrifuge |
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Term
| at scale of a ribosome or organelle or cell, gravity is nonconsequential; dominant forces are ________ |
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Definition
| charge- or polarity-based electrostatic attractions |
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Term
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Definition
| parasites that use the cell’s machinery to make copies of themselves |
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Term
| examples of motor proteins |
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Definition
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Term
| proteins are synthesized by ribosomes in cytosol but are headed for ________ |
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Definition
| the nucleus contain a “zip code” or nuclear localization signal (NLS) |
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Term
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Definition
| protein that plays an important role in the assembly of chromosomes |
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Term
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Definition
| addition of one or more carbohydrate groups; resulting molecule is a glycoprotein |
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Term
| axoneme of cilia and flagella |
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Definition
have a complex arrangement of microtubules connected by bridges and spokes
• when the motor protein dynein on one side of the axoneme walk, cilia and flagella bend instead of elongating because the spokes and bridges constrain movement of the microtubule doublets
• axoneme is the “9 + 2” structure (9 microtubule pairs around two central microtubules)
• attaches to the cell at the basal body
o plays central role in growth of axoneme |
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Term
| in prokaryotes, DNA located ______ |
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Definition
| in a chromosome or plasmids that are not encapsulated in an internal membrane |
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Term
| prokaryotic cells and their chromosome shape |
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Definition
o usually have a single, long, circular chromosome
• supercoiled to allow it to fit inside the cell
• localized to a region of the cell called the nucleoid |
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Term
| most prominent structure in prokaryotic cytoplasm |
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Definition
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Term
| main differences between prokaryotic and eukaryotic cells |
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Definition
• prokaryotic cells 10-100x smaller than eukaryotic cells
• DNA in eukaryotic cells surrounded by nucleus
• eukaryotic cytoskeleton is more complicated and elaborate than that of prokaryotes
• eukaryotes always have internal organelles; prokaryotes sometimes do |
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Term
| only prokaryotes have a ____ |
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Definition
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Term
| both eukaryotes and prokaryotes have _____ |
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Definition
| ribosomes, flagella, and plasma membranes |
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Term
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Definition
• serves as recycling center in plants
• large
• contain enzymes that digest large macromolecules or serve as storage centers for water |
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Term
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Definition
| where synthesis and assembly of ribosomal components occurs |
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Term
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Definition
| network of protein filaments that maintain shape of nucleus |
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Term
| before RNA can be translated into protein, it first must be exported from the nucleus through a _________ |
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Definition
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Term
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Definition
| microtubule motor protein that converts chemical energy into mechanical work |
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Term
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Definition
• motor protein that forms that arms between doublets and changes shape when ATP is hydrolyzed to walk up the microtubule
• when the dynein arms on just one side of the axoneme walk, cilia and flagella bend instead of elongating because the spokes and bridges constrain movement of the microtubule doublets |
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