Answered Review Questions Cell Structure and Function Cell Location-Structure Function Prokaryote/ Structure Eukaryote Cell Forms outer boundary of Semi-permeable (restricts the Both membrane cell; access of certain compounds (Plasma and ions) membrane) Forms membrane-bound organelles Aids in maintaining the complex internal organization of a cell Cytoplasm Everything between the Site of most chemical reactions Both nuclear envelope (nucleoid of life region in prokaryotes) and the cell boundary Cytosol The semi-fluid portion of the Both cytoplasm Nucleus 10% of the volume of the cell Mission control—manages Eukaryotes protein synthesis only Nucleolus Small dense spheres within Genes for ribosomal RNA Eukaryotes the nucleus (often 2-3 (building block of ribosomes) only visible)—tightly coiled regions of the DNA Nuclear Porous double-membrane Protects the DNA Eukaryotes envelope organelle; only mRNA exits the nucleus Forms outer boundary of through pores after nucleus transcription Bound Small dense granules (each Site of protein synthesis Eukaryotes ribosomes has a large and a small only subunit) made of proteins Ribosomes build proteins and rRNA; Attached to endoplasmic reticulum; Can become free; Part of the endomembrane system Free Small dense granules (each Site of protein synthesis Both ribosomes has a large and a small subunit) made of proteins Ribosomes build proteins and rRNA; Suspended in cytosol; Can become bound Rough Network of membranous Modify proteins Eukaryotes endoplasmic tubes dotted with bound only reticulum ribosomes; Many proteins are modified here by cleaving the Loosely surrounds the polypeptide, forming quaternary nucleus; structures, removing amino acids or adding non-protein Part of the endomembrane substances (e.g. enzymes system often require a metallic ion to work) Smooth Network of membranous Makes carbohydrates and lipids Eukaryotes endoplasmic tubes; only reticulum (e.g. the SER of liver cells Loosely surrounds the convert glucose to glycogen, nucleus; and make triglycerides and cholesterol) Part of the endomembrane system Transport Membrane-bound bubble; Moves modified proteins, lipids, Eukaryotes vesicle and carbohydrates to cis face only Buds off both RER and of Golgi apparatus SER; Part of endomembrane system Golgi apparatus Network of membranous Receives compounds from ER; Eukaryotes tubes; only Attaches a chemical “address Located closer to cell label” for compounds destined boundary than ER; for export Cis face toward nucleus; Trans face toward cell membrane; Part of the endomembrane system Secretory Membrane-bound bubble; Moves finished compounds to Eukaryotes vesicle cell membrane for export only Buds off trans face of Golgi apparatus; Part of endomembrane system Lysosome Membrane-bound bubble Cell’s stomach; Eukaryotes containing hydrolytic only enzymes; Merges with food vacuole and digests organic compounds; Buds off Golgi apparatus Autophagy (recycles old and damaged organelles and cytosol); Apoptosis (programmed cell death/self-destruction) Food vacuole Membrane-bound bubble; Transports food particles and N/A captured microbes from outside Buds off cell membrane the cell into cytoplasm; Fuses with lysosome Mitochondrion Double membrane bound Aerobic cellular respiration; Eukaryotes organelle; only Harvests chemical energy from Inner membrane called organic monomers and stores cristae; the energy in ATP Semi-fluid interior called matrix; Has own DNA and protein- making machinery Descendent of free-living prokaryote Chloroplast Double membrane bound Photosynthesis; Eukaryotes organelle; only Harnesses light energy and (Plants and Inner membrane discs uses it to build sugar Photosynthes called thylakoids; izing Protists) semi-fluid space surrounding thylakoids called stroma; Has own DNA and protein- making machinery Descendent of free-living prokaryote Cytoskeleton All through cytoplasm Gives shape to cell; Supports organelles; Three filament types (Listed below) Aids in motion and cell division; Moves material (organelles) through cytoplasm Actin Filaments One kind of cytoskeletal Movement (e.g. Amoeba Eukaryotes element; pseudopods, cytoplasmic only streaming, formation of Most often located just cleavage furrow, microvilli below cell membrane; extension and retraction) Twisting strand of globular actin subunits Microtubules One kind of cytoskeletal Internal monorail system for Eukaryotes element; moving organelles through only cytoplasm; Spread through out cytoplasm; components of centrosome, centrioles, cilia, and flagella; Small hollow tube built of tubulin dimers Microtubules are the spindle fibers that move the chromosomes in cell division Intermediate One kind of cytoskeletal Scaffolding that supports Eukaryotes filaments element; organelles; only Spread through out Gives shape to cells cytoplasm; Anchored to cell membrane and organelles Centrosome Within cytoplasm; Region of the cytoplasm that Eukaryotes (Microtubule makes spindle fibers for cell Organizing In animal cells the location division Center is covered by a pair of [MTOC]) centrioles Centriole Small pair of hollow tubes; Associated with cell division but Eukaryotes not necessary (Animal cells) Built of microtubules Organized into a 9+0 arrangement Covers centrosome in animal cells Cilia Small oar-like structure Synchronized rhythmic rowing; Eukaryotes projecting outside the cell membrane; Movement for single-celled microbes; Built of microtubules (9+2 arrangement); Ciliary escalator in trachea Basal body has 9+0 arrangement like centriole Flagella Long whip-like tail Wiggles back and forth moving Both projecting outside the cell cell through liquid; (prokaryotic membrane; flagella are Sperm cells have a flagellum different in Built of microtubules (9+2 structure and arrangement); motion [rotary]) Basal body has 9+0 arrangement like centriole Central Large membranous sac in Maintains structural integrity of Eukaryotes Vacuole plant cells; plant cells (turgidity); (Plants only) Takes up most of the space Water storage; in cytoplasm Alkaloid storage; Pigment storage Perioxisome Small membrane bound Catalase enzymes in organelle Eukaryotes organelle in aerobic convert hydrogen peroxide eukaryotes (slightly toxic intermediate metabolite of superoxide free radical breakdown) to water and oxygen gas PLASMA MEMBRANE NUCLEUS, NUCLEAR ENVELOPE, NUCLEAR PORES GENERALIZED ANIMAL CELL GENERALIZED PLANT CELL BOUND AND FREE RIBOSOMES RER AND SER GOLGI APPARATUS LYSOSOME MITOCHONDRION CHLOROPLAST PEROXISOME CENTRIOLES FLAGELLA AND CILIA MICROTUBULES ACTIN FILAMENT INTERMEDIATE FILAMENT Trace the path of the production of a protein from the DNA in the nucleus to its secretion outside the cell. (endomembrane system). Explain the function of each member. Proteins are synthesized by the bound ribosome. The resulting protein is modified (glycoprotein is attached, plus any other modifications) by the rough endoplasmic reticulum. A small section of the RER containing the protein pinches off the end enclosing the protein inside a transport vesicle. The transport vesicle moves to the Golgi apparatus where it fuses with the cis face of the Golgi apparatus. The protein receives a chemical address label (glycoprotein is modified) as it is moved through the layers of membranous sacs of the Golgi apparatus. On the trans face of the Golgi apparatus the finished protein is enclosed inside a secretory vesicle that moves to the cell membrane and dumps the protein out of the cell. Secretory vesicle Lipids or carbohydrates are synthesized by the smooth endoplasmic reticulum. A small section of the SER containing the compound pinches off the end enclosing the protein inside a transport vesicle. The transport vesicle moves to the Golgi apparatus where it fuses with the cis face of the Golgi apparatus. The compound receives a chemical address label (glycoprotein is modified) as it is moved through the layers of membranous sacs of the Golgi apparatus. On the trans face of the Golgi apparatus the finished compound is enclosed inside a secretory vesicle that moves to the cell membrane and dumps the compound out of the cell. Explain the endosymbiosis theory. Mitochondria and chloroplasts have many characteristics that make them look like prokaryotic cells (see table below). Lynn Margulis hypothesized that these two energy-producing organelles were once free-living prokaryotes with a special talent that were engulfed but not digested by a larger prokaryote. A mutalistic relationship developed. The smaller aerobic cellular respiring bacterium was protected and in return the larger symbiont was supplied with energy. In plants and photosynthesizing protists, symbiotic cyanobacteria were added to the mix making the larger symbionts autotrophic. Contrast plant and animal cells. See comparison below..