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18 Cards in this Set
- Front
- Back
Define Cell
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* The cell is the basic structural and functional unit of life.
* Organismal activity depends on individual and collective activity of cells. * Biochemical activities of cells are dictated by sub-cellular structure (principle of complementary of structure and function). * Continuity of life has a cellular basis * is the smallest living unit. * over 200+ different cell types! |
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List the 3 major regions of a generalized or composite cell and indicate the function of each.
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1. Plasma Membrane: fragile barrier, is the outer boundary of the cell.
2. Cytoplasm: internal to this membrane, intracellular fluid that's packed with organelles, small structures that perform specific cell functions. 3. Nucleus - controls cellular activities and typically it lies near the cell's center. |
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Describe the chemical composition of the plasma membrane and relate it to membrane functions.
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* separates intracellular fluids from extracellular fluids
* plays a dynamic role in cellular activity * Glycocalyx is a glycoprotein area abutting (next to) the cell that provides highly specific biological markers by which cells recognize or another. * differ in the kind and amount of lipids they contain. * Glycolipids are found only in the outer membrane surface. * 20% of all membranes lipid is cholesterol. |
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Compare the structure and function of tight junctions, desmosomes, and gap junctions.
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1. Tight Junction: impermeable (not loose) junction that encircles (surround) the cell.
2. Desmosome - anchoring (to be held, surround, or secure) junction scattered along the sides of cells. "strong" 3. Gap Junction - a nexus (connection) that allows chemical substances to pass between cells. |
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Relate plasma membrane structure to active and passive transport mechanisms. Differentiate between these transport processes relative to energy source, substances transported, direction, and mechanism.
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* passive membrane transport: diffusion -- simple diffusion which is NONpolar and lipid-soluble substances
- diffuse directly throughout the lipid bilayer - diffuse through channel proteins * facilitated diffusion - transport of glucose, amino acids, and ions - transported substances bind carrier proteins or pass through protein channels * Passive Membrane Transport: Osmosis - occurs when the concentration of a solvent is different on opposite sides of a membrane - diffusion of water across a semipermeable membrane - osmolarity - total concentration of soluble particles in a solution - tonicity - how a solution affects cell volume * Passive Membrane Transport: Filtration - the passage of water and solutes through a membrane by hydrostatic pressure - pressure gradient pushes solute-containing fluid from a higher-pressure area to a lower-pressure area * Active transport - Uses ATP to move solutes across a membrane. - Requires carrier proteins. - symport system: 2 substances are moved across a membrane in the same direction - antiport system: 2 substances are moved across a membrane in opposite directions - primary active transport: hydrolysis of ATP phosphorylates the transport protein causing conformational change - secondary active transport: use of an exchange pump (such as the Na+ - K+ pump) indirectly to drive the transport of other solutes. ** page 2 on the power point - very important pictures of passive & active transports!! ** |
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Define membrane potential and explain how the resting membrane potential is maintained.
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- voltage across a membrane
- resting membrane potential - the point where K+ potential is balanced by the membrane potential - ranges from -20 to -200 mV (millivolts) - results from Na+ and K+ concentration gradients across the membrane - differential permeability of the plasma membrane to Na+ and K+ - steady state: potential maintained by active transport of ions ** page 3 on generation and maintenance of membrane potential slide, important! ** power point |
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Describe the role of the glycocalyx when cells interact with their environment.
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The glycocalyx enables certain bacteria to resist phagocytic engulfment by white blood cells in the body.
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List several roles of membrane receptors and that of voltage-sensitive membrane channel receptors.
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- contact signaling: important in normal development and immunity
- electrical signaling: voltage-regulated "ion gates" in nerve and muscle tissue - chemical signaling: neurotransmitters bind to chemically gated channel-linked receptors in nerve and muscle tissue - G protein-linked receptors - ligands bind to a receptor which activates a G protein, causing the release of a second messenger, such as cyclic AMP. * operation of a G protein - an extracellular ligand (first messenger), binds to a specific plasma membrane protein - the receptor activates a G protein that relays the message to an effector protein - the effector is an enzyme that produces a second messenger inside the cell - the second messenger activates a kinase - the activated kinase can trigger a variety of cellular responses |
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Describe the composition of cytosol; define inclusions and list several types.
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cytosol: largely water with dissolved protein, salts, sugars, and other solutes
* inclusions - chemical substances such as glycosomes, glycogen granules, and pigment |
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Discuss the structure & function of mitochondria
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- double membrane structure with shelflike cristae
- provide most of the cell's ATP via aerobic cellular respiration - contain their own DNA and RNA |
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Discuss the structure and function of ribosomes, the endoplasmic reticulum, and the golgi apparatus including functional relationships among the organelles.
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Ribosomes
* granules containing protein and rRna * site of protein synthesis * free ribosomes synthesize soluble proteins * membrane-bound ribosomes synthesize proteins to be incorporated into membranes Endoplasmic Reticulum (ER) * interconnected tubes and parallel membranes enclosing cisternae * continuous with the nuclear membrane * 2 varieties - rough/smooth ER Golgi Apparatus * stacked & flattened membrane sacs * functions in modification, concentration, and packaging of proteins * transport vessels from the ER fuse with the cis face of the Golgi apparatus to the trans face * secretory vesicles leave the trans face of the Golgi stack and move to designated parts of the cell |
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Compare the functions of lysosomes and peroxisomes
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Lysosomes:
* spherical membranous bags containing digestive enzymes * digest ingested bacteria, viruses, and toxins * degrade nonfunctional organelles * breakdown glycogen and release thyroid hormone * breakdown nonuseful tissue * breakdown bone to release Ca2+ * secretory lysosomes are found in white blood cells, immune cells, and melanocytes Peroxisomes * mebranous sacs containing oxidases and catalases * detoxify harmful or toxic substances * neutralize dangerous free radicals * free radicals- highly reactive chemicals with unpaired electrons (i.e., O2-) |
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Name and describe the structure and function of cytoskelton elements.
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* The "skeleton" of the cell
* Dynamic, elaborate series of rods running through the cytosol. * Consists of micro tubules, micro filaments, and intermediate filaments. |
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Describe the roles of centrioles in mitosis and in the formation of cilia and flagella.
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Centrioles
* small barrel-shaped organelles located in the centrosome near the nucleus * pinwheel array of 9 triplets of microtubules * organize mitotic spindle during mitosis * form the bases of cilia and flagella Cilia * whiplike, motile cellular extensions on exposed surfaces of certain cells * move substances in 1 direction across cell surfaces. Flagella * when the projections formed by centrioles are substantially longer, they are called flagella. Ex: sperm "tail". * NOTICE that cilia propel other substances across a cell's surface, where a flagellum propels the cell itself. * |
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Outline the structure and function of the nuclear envelope, nucleolus, and chromatin.
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Nuclear Envelope
* selectively permeable double membrane barrier containing pores * encloses jellylike nucleoplasm, which contains essential solutes * outer membrane is continuous with hte rough ER and is studded with ribosomes * inner membrane is lined w/ the nuclear lamina, which maintains the shape of the nucleus * pore complex regulates transport of large molecules into and out of the nucleus Nucleoli (Nucleolus) "little nuclei" * dark-staining spherical bodies with the nucleus * site of ribosome production Chromatin * threadlike strands of DNA and histones * arranged in fundamental units called nucleosomes * form condensed, barlike bodies of chromosomes when the nucleus starts to divide |
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List the phases of the cell life cycle and describe the key events of each phase.
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* Interphase
- Growth (G1), synthesis (s), growth (G2) - mitotic phase-- mitosis and cytokinesis * interphase G1 (gap 1) metabolic activity and vigorous growth G0 - cells that permanently cease dividing S (synthetic) - DNA replication G2 (gap 2) - preparation for division |
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Describe the process of DNA replication
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* DNA helices begin unwinding from the nucleosomes
* helicase untwists the double helix and exposes complementary strands * the site of replication is the replication bubble * each nucleotide strand serves as a template for building a new complementary strand * the replisome uses RNA primers to begin DNA synthesis * DNA polymerase III continues from the primer and covalently adds complementary nucleotides to the template * Since DNA polymerase only works in 1 direction: - a continuous leading strand is synthesized - a discontinuous lagging strand is synthesized - DNA ligase splices together the short segments of the discontinuous strand - 2 new telomeres are also synthesized - this process is called semiconservative replication |
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Describe gene & genetic code and explain the function of genes
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Gene - as a segment of a DNA molecule that carries instructions for creating 1 polypeptide chain.
* the 4 nucleotides bases (A,G, T and C) are the "letters" used in the genetic dictionary, and the information of DNA is found in the sequence of these bases. Genetic Code- RNA codons code for amnio acids according to a genetic code. |