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Home , Cytosol, Food vacuole, Nucleoid

Answered Review Questions Structure and Function

Cell Location-Structure Function / Structure Cell Forms outer boundary of Semi-permeable (restricts the Both membrane cell; access of certain compounds (Plasma and ) membrane) Forms membrane-bound Aids in maintaining the complex internal organization of a cell

Cytoplasm Everything between the Site of most chemical reactions Both ( of life region in ) and the cell boundary

Cytosol The semi-fluid portion of the Both

Nucleus 10% of the volume of the cell Mission control—manages synthesis only

Nucleolus Small dense spheres within Genes for ribosomal RNA Eukaryotes the nucleus (often 2-3 (building block of ) only visible)—tightly coiled regions of the DNA

Nuclear Porous double-membrane Protects the DNA Eukaryotes envelope ; only mRNA exits the nucleus Forms outer boundary of through pores after nucleus

Bound Small dense granules (each Site of protein synthesis Eukaryotes ribosomes has a large and a small only subunit) made of Ribosomes build proteins and rRNA;

Attached to ;

Can become free;

Part of the

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 ;

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 or adding non-protein Part of the endomembrane substances (e.g. system often require a metallic 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 , 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 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 ;

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 Membrane-bound bubble Cell’s stomach; Eukaryotes containing hydrolytic only enzymes; Merges with food and digests organic compounds; Buds off Golgi apparatus (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 ; 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 )

semi-fluid space surrounding thylakoids called stroma;

Has own DNA and protein- making machinery

Descendent of free-living prokaryote 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. 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 subunits

Microtubules One kind of cytoskeletal Internal monorail system for Eukaryotes element; moving organelles through only cytoplasm; Spread through out cytoplasm; components of , , cilia, and flagella; Small hollow tube built of tubulin dimers are the spindle fibers that move the 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 ( 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

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 different in Built of microtubules (9+2 structure and arrangement); motion [rotary]) 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 storage; in cytoplasm Alkaloid storage;

Pigment storage

Perioxisome Small membrane bound enzymes in organelle Eukaryotes organelle in aerobic convert hydrogen peroxide eukaryotes (slightly toxic intermediate metabolite of superoxide free radical breakdown) to water and gas

PLASMA MEMBRANE NUCLEUS, NUCLEAR ENVELOPE, NUCLEAR PORES GENERALIZED ANIMAL CELL GENERALIZED

BOUND AND FREE RIBOSOMES RER AND SER

GOLGI APPARATUS LYSOSOME

MITOCHONDRION

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 outside the cell. (endomembrane system). Explain the function of each member. Proteins are synthesized by the bound . The resulting protein is modified ( 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 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.