A&P Ch3 Cells: The Living Units


Question Answer The loss of cellular ________ underlies virtually every disease homeostasis What are the 3 main parts of every cell? 1. Plasma membrane/cell membrane2. Cytoplasm3. nucleus What is cytoplasm? intracellular fluid containing organelles What is the basic function of the nucleus of a cell? the organelle that controls all cellular activity What is another term for cell membrane? plasma membrane What separates ICF (intracellular fluid) from ECF (extracellular fluid)? plasma/cell membrane The "fluid mosaic model" describes the cell membrane as a bilayer of _________ with protein molecules dispersed through it. bilayer of lipid molecules (mainly phospholipids) Is the head of phospholipid polar or non-polar?Is it hydrophilic or hydrophobic? polarhydrophilic Is the tale of phospholipid polar or non-polar?Is it hydrophilic or hydrophobic? nonpolarhydrophobic Which way do the phospholipid heads face in the phospholipid bilayer of a plasma/cell membrane? They face outwards towards the ECF/ICF on both surfaces of the bilayer (with the tails facing one another) is the plasma membrane a solid structure or dynamic and fluid? dynamic and fluid What 4 types of membrane lipids form the basic fabric of a plasma membrane 1. phospholipids (make up the majority)2. glycolipids3. cholesterol4. lipid rafts What do the glycolipids within the plasma membrane attach to?On which surface of the membrane are they found? sugar groupsthe outer (ECF facing) surface What percentage of plasma membrane lipids are glycolipids?What percentage are cholesterol? 5%20% What function do the cholesterol molecules in a plasma membrane serve they stabilize the membrane What are integral proteins?What functions do they serve? Proteins firmly inserted in the plasma membrane that perform a variety of functions (eg. act as channels, carriers, enzymes, receptors, etc.) Most are transmembrane (touch both inner and outer surfaces.) What are peripheral proteins?What functions do they serve? proteins loosely attached to integral proteins and can easily be removed. They function: -as support structures on the inside of the membrane-as enzymes-motor proteins that help change the shape of the cell during division or muscles contraction What is the glycocalyx?What are it's functions? A unique pattern of glycoproteins and glycolipids on the cell's surface .-Allows cells to recognize each other (eg. immune system & bacteria, sperm and ovum.)-acts like glue between cells What 3 factors act to bind cells together? 1. glycocalyx acts like glue2. wavy contours fit together like puzzle pieces3. CELL JUNCTIONS What are the 3 types of cell junctions? 1. tight junctions- impermeable2. desmosomes- anchoring3. gap junctions- communication What are tight junctions? Impermeable junctions formed by integral proteins of adjacent cells which fuse together.Do not allow molecules to pass through. What are desmosomesWhere are they found -A cell junction that anchors cells together. -Thick plaques on the cytoplasmic surface attach to each other like zippers via protein filaments call CADHERINSFound in areas of great mechanical stress (eg. skin, heart muscle) What are gap junctions? -Communication junctions between cells-Hollow protein cylinders call CONNEXONS allow the passage of specific substances such as ions and simple sugars between cells What are the 4 concepts of cell theory? 1. the cell is the basic structural unit of organisms2. activity of an organism depends on the individual and combined function of cells3. biochemical activities of cells are determined by their shapes/ forms4. Cells can only arise from other cells What passive processes allow substances to cross a cell's plasma membrane? -simple diffusion-facilitated diffusion-osmosis-tonicity (hypo-, hyper-, & isotonic) A molecule can diffuse through a plasma membrane if:(there are 3 factors) 1. if it's lipid soluble2. if it's small enough to pass through membrane channels3. if it's assisted by a carrier molecule What is simple diffusion?what substances can do this? when non-polar and lipid soluble substances diffuse directly through the plasma membrane.-Oxygen and CO2 What is facilitated diffusion?What 2 types are there? passive transport of molecules across the plasma membrane by:1. channel mediated facilitated diffusion2. carrier-mediated facilitated diffusion(eg. sugars, amino acids, ions) What is carrier-mediated facilitated diffusion? Diffusion assisted by transmembrane integral proteins that transport:-polar molecules-molecules too large to pass through channels What is channel-mediated facilitated diffusion?How is this a selective process? Diffusion through water-filled channels created by transmembrane proteins.The size of the passage and charge of amino acids determines what can pass through. What are the 2 types of channels involved in channel-mediated facilitated diffusion? 1. leakage channels- always open2. gated channels- open and closed by chemical or electrical signals What is osmosis? diffusion of water through a selectively permeable membrane from an area of LOW OSMOLARITY to an area of HIGH OSMOLARITY (thus lowering it's concentration) until the concentration on each side of the membrane reaches an equilibrium. What is osmolarity? the total concentration of all solute particles in a solution What is tonicity? The ability of a solution to change the shape or tone of cells by altering the cell's internal water volume What are the 3 types of tonic solutions? 1. hypertonic2. hypotonic3. isotonic What is an isotonic solution? A solution that has the same concentration of non-penetrating solutes as those found inside the cell. What is a hypertonic solution? A solution that has a HIGHER concentration of non-penetrating solutes than inside the cell. What is a hypotonic solution? A solution that has a LOWER concentration of non-penetrating solutes than inside the cell. Is extracellular fluid hypo-, hyper- or isotonic?Why is this important? Isotonic. If it wasn't, it would cause cells to either shrink or expand (and even burst) What happens to cells in a hypertonic solution? -the cell shrinks-water diffuses out of the cell (from low osmolarity to high osmolarity in an effort to reach concentration equilibrium) What happens to cells in a hypotonic solution? What is channel-mediated facilitated diffusion?How is this a selective process? Diffusion through water-filled channels created by transmembrane proteins.The size of the passage and charge of amino acids determines what can pass through. What are the 2 types of channels involved in channel-mediated facilitated diffusion? 1. leakage channels- always open2. gated channels- open and closed by chemical or electrical signals What is osmosis? diffusion of water through a selectively permeable membrane from an area of LOW OSMOLARITY to an area of HIGH OSMOLARITY (thus lowering it's concentration) until the concentration on each side of the membrane reaches an equilibrium. What is osmolarity? the total concentration of all solute particles in a solution What is tonicity? The ability of a solution to change the shape or tone of cells by altering the cell's internal water volume What are the 3 types of tonic solutions? 1. hypertonic2. hypotonic3. isotonic What is an isotonic solution? A solution that has the same concentration of non-penetrating solutes as those found inside the cell. What is a hypertonic solution? A solution that has a HIGHER concentration of non-penetrating solutes than inside the cell. What is a hypotonic solution? A solution that has a LOWER concentration of non-penetrating solutes than inside the cell. Is extracellular fluid hypo-, hyper- or isotonic?Why is this important? Isotonic. If it wasn't, it would cause cells to either shrink or expand (and even burst) What happens to cells in a HYPERtonic solution? -the cell shrinks-water diffuses out of the cell (from low osmolarity within to high osmolarity in an effort to reach concentration equilibrium) What happens to cells in a HYPOtonic solution? -the cell expands (or even bursts-water diffuses into the cell (from low osmolarity outside the cell to higher osmolarity within the cell in order to reach a concentration equilibrium) What 3 types of active transportation processes are there? 1. primary active transport2. secondary active transport3. vesicular transport Where does the energy for primary active transport come from? Directly from ATP Where does the energy for secondary active transport comes from? -indirectly from ATP-from energy stores in ionic gradients via coupled systems (symport system and antiport system) What is the sodium-potassium pump an example of primary or secondary active transport? Both1. Primary: Na+ is actively transported against a concentration gradient by the pump2. Secondary: Na+ diffuses back across the membrane via a cotransporter protein, and the cycle to repeats.***glucose is simultaneously swept into the cell*** What are the steps in the sodium potassium pumps? 1. 3 Na+ bind to pump inside cell2. ATP is hydrolysed leaving behind phosphate3. pump expels Na+ outside4. 2 K+ bind to pump outside cell5. the remaining phosphate is released6. new ATP binds to pump, K+ is released inside cell (cycle repeats) What is vesicular transport? Fluids containing large particles are transported across cell membranes inside sacs called vesicles. What types of vesicular transport are there? 1. endocytosis- moving substances into the cell2. exocytosis- expelling substances from the cell3. transcytosis- moving substances into, through, and out of cells How does endocytosis work? the plasma membrane folds around the substance to be absorbed forming a vesicle, which then detaches from the plasma membrane and moves inwards where it fuses with a lysosome for digestion What 3 types of endocytosis are there? 1. phagocytosis: pseudopods wraps around material forming a vesicle (eg. macrophages engulfing bacteria)2. pinocytosis: non-selective drinking of ECF3. receptor-mediated: receptors bind to specific substances which are then internalized What type of endocytosis do macrophages use to attack bacteria and foreign bodies? phagocytosis What type of endocytosis do viruses take advantage of in order to enter cells? receptor-mediated endocytosis What is exocytosis? The removal of substances from the cell via secretory vesicles (eg. hormone secretion, neurotransmitter release, mucous secretion, ejection of wastes) What is resting membrane potential? an electrical potential energy due to the separation of charged particles (voltage) across the plasma membrane What is the purpose of the sodium-potassium pump? to maintain proper resting membrane potential (especially important for neuron and muscle cell function) What are CAMs?What do they do? Cell Adhesion MoleculesAct as velcro anchoring cells to each other and their environment What do plasma membrane receptors do? -Contact signaling- cells recognize each other by contact.-Chemical Signaling- LIGANDS bind to cell membrane receptors and alter the structure of the membrane receptor and cell proteins. What are LIGANDS?Give key examples of ligands chemicals that bind to plasma membrane receptors.Different cells have different responses to the same ligand(eg. most neurotransmitters, hormones, paracrines) What types of receptors do ligands bind to?How do each of them respond to ligands? -Catalytic Receptor Proteins: become activated enzymes-Chemically Gated Channel-Linked Receptors: open or close ion gates-G-Protein Linked Receptors: causes the G-protein to act as a middleman, activating/deactivating a membrane enzyme or ion channel. What do voltage gated membrane channel proteins do?Where are they most commonly found? They respond to changes in membrane potential by opening or closing the channel, thereby maintaining the membrane potential.Found in neural and muscle tissue. What is cytoplasm? The cellular material between the plasma membrane and the nucleus. What 3 major elements is cytoplasm composed of? 1. Cytosol- viscous, semi-transparent fluid2. Organelles- metabolic machinery; each have a specific function3. Inclusions- chemical substances stored in the cytoplasm Name the organelles (8) 1. Mitochondria2. Ribosomes3. Rough Endoplasmic Reticulum4. Smooth Endoplasmic Reticulum5. Golgi Apparatus6. Peroxisomes7. Lysosomes8. Cytoskeleton What is MITOCHONDRIA and what does it do? -powerplant of cell, supplies most of the ATP-Breaks down glucose into water and CO2 releasing the energy required to produce ATP-contains it's own DNA, RNA, and ribosomes-able to reproduce themselves What are RIBOSOMES and what do they do? -synthesize proteins which are transported by vessicles to the Golgi Apparatus for further processing-composed of protein and ribosomal RNA What is Endoplasmic Reticulum (ER)? -a system of interconnected tubes and parallel membranes enclosing fluid filled cavities (cisterns) What is Rough Endoplasmic Reticulum and what does it do? -ER associated with Ribosomes (they are what makes it rough)-manufacture proteins, integral proteins and phospholipids for the plasma membrane-release enzymes to catalyze lipid synthesis What is Smooth Endoplasmic Reticulum and what does it do? Its enzymes catalyze the following reactions:-metabolize lipids-synthesize cholesterol/lipids for lipoproteins (liver)-synthesize steroid hormones (sex hormones testes/ovaries)-detoxify (liver/kidneys)-break down glycogen to glucose (liver) What specialized type of smooth ER do skeletal and heart muscles contain?What does it do? Sarcoplasmic Reticulum-releases calcium ions during muscle contraction What is Golgi Apparatus and what does it do? -Stacked flattened membranous sacs with membranous vesicles-Receives proteins from ER, modifies, and then exports them What are peroxisomes and what do they do? -spherical membranous sacs containing powerful enzymes that detoxify substances such as alcohol and neutralize free radicals What are lysosomes and what do they do? -spherical membranous organelles containing digestive enzymes-digest almost all biological molecules-digest particles taken in by endocytosis especially bacteria, viruses, toxins-degrade worn out organelles-break down bone release calcium to blood What happens when lysosomes rupture? Cell suicide- The cell digests itself (autolysis) Which organelles are part of the endomembrane systemWhat does it do? ER, Golgi Apparatus, secretory vesicles, lysosomes, nuclear membrane, plasma membrane.These organelles work together to:1. produce, degrade, store, and export biological molecules2. degrade potentially harmful substances What is the cytoskeleton and what does it do? -A network of rods running through the cytosol and hundred of accessory proteins that link the rods to other cell structures-Supports cellular structures-responsible for cell movement What are the 3 types of rods in the cytoskeleton? 1. microfilaments- thinnest, semi-flexible2. intermediate filaments- most stable and permanent3. microtubules- largest elements, hollow tubes, determine shape of cell***centrosome acts as the microtubule organizing center What are the 3 major types of cellular extensions?What are they responsible for? 1. Celia- whip-like extensions formed from centrioles (basal bodies) move substances across surface in one direction (respiratory tract)2. Flagella- projections used for movements (ONLY sperm)3. Microvilli- increase surface area (absorptive cells) What is the nucleus?What does it do/contain? -control center of cell-largest organelle in the cell-3 regions: nuclear envelope (membrane), nucleoli, chromatin Do all cells have one nucleus? No!-multinucleate: large cells that contain multiple nuclei (eg. skeletal, liver cells)-Anucleate: no nucleus. Cannon reproduce or repair themselves. (eg. red blood cells) Do red blood cells contain a nucleus? No (therefore they cannon reproduce or repair themselves) The resting membrane potential is mainly established by what ion? Na+ (but also K+) What is the nuclear envelope? a selectively permeable double membrane that encloses the nucleoplasm (similar to cytoplasm) What are nucleoli? dark staining bodies inside the nucleus that contain DNA and synthesize rybosomal RNA (rRNA) What is chromatin? A system of bumpy threads composed of nucleosomes:30% DNA60% histone proteins (package and regulate DNA)10% RNA chains (newly formed and forming) What happens to chromatin when cells divide? Chromatin threads coil and condense to form short bodies called CHROMOSOMES

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