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Anatomy Test 2
Chapter 3
| Term | Definition |
|---|---|
| Membrane Proteins | • Allow communication with environment • ½ mass of plasma membrane • Most specialized membrane functions • Some float freely • Some tethered to intracellular structures • Two types: – Integral proteins; peripheral proteins |
| Membrane Lipids | • 75% phospholipids (lipid bilayer) – Phosphate heads: polar and hydrophilic – Fatty acid tails: nonpolar and hydrophobic 5% glycolipids • – Lipids with polar sugar groups on outer membrane surface • 20% cholesterol – Increases membrane stability |
| Plasma Membrane | • Lipid bilayer and proteins in constantly changing fluid mosaic • Plays dynamic role in cellular activity • Separates intracellular fluid (ICF) from extracellular fluid (ECF) – Interstitial fluid (IF) = ECF that surrounds cells |
| Generalized Cell | • All cells have some common structures and functions • Human cells have three basic parts: – Plasma membrane—flexible outer boundary © 2013 Pearson Education, Inc. – Cytoplasm—intracellular fluid containing organelles – Nucleus—control center |
| Cell Diversity | • Over 200 different types of human cells • Types differ in size, shape, subcellular components, and functions |
| Cell Theory | • Organismal functions depend on individual and collective cell functions • Biochemical activities of cells dictated by © 2013 Pearson Education, Inc. their shapes or forms, and specific subcellular structures • Continuity of life has cellular basis |
| Cell | structural and functional unit of life |
| Membrane Proteins | • Integral proteins – Firmly inserted into membrane (most are transmembrane) – Have hydrophobic and hydrophilic regions • Can interact with lipid tails and water Membrane Proteins © 2013 Pearson Education, Inc. – Function as transport proteins (cha |
| Membrane Proteins | • Peripheral proteins – Loosely attached to integral proteins – Include filaments on intracellular surface for membrane support Function as enzymes; motor proteins for Membrane Proteins © 2013 Pearson Education, Inc. – shape change during cell divi |
| Six Functions of Membrane Proteins | 1. Transport 2. Receptors for signal transduction 3. Attachment to cytoskeleton and extracellular matrix 4. Enzymatic activity 5. Intercellular joining 6. Cell-cell recognition |
| Lipid Rafts | • ~20% of outer membrane surface • Contain phospholipids, sphingolipids, and cholesterol • More stable; less fluid than rest of © 2013 Pearson Education, Inc. membrane – May function as stable platforms for cellsignaling molecules, membrane invagin |
| The Glycocalyx | • "Sugar covering" at cell surface – Lipids and proteins with attached carbohydrates (sugar groups) • Every cell type has different pattern of sugars © 2013 Pearson Education, Inc. – Specific biological markers for cell to cell recognition – Allow |
| Cell Junctions | • Some cells "free" – e.g., blood cells, sperm cells • Some bound into communities – Three ways cells are bound: © 2013 Pearson Education, Inc. • Tight junctions • Desmosomes • Gap junctions |
| Cell Junctions: Tight Junctions | • Adjacent integral proteins fuse |
| Cell Junctions: Desmosomes | • "Rivets" or "spot-welds" that anchor cells together at plaques (thickenings on plasma membrane) – Linker proteins between cells connect plaques Keratin filaments extend through cytosol to © 2013 Pearson Education, Inc. – opposite plaque giving sta |
| Cell Junctions: Gap Junctions | • Transmembrane proteins form pores (connexons) that allow small molecules to pass from cell to cell – For spread of ions, simple sugars, and other small molecules between cardiac or smooth © 2013 Pearson Education, Inc. muscle cells |
| Plasma Membrane | • Cells surrounded by interstitial fluid (IF) – Contains thousands of substances, e.g., amino acids, sugars, fatty acids, vitamins, hormones, salts, waste products • Plasma membrane allows cell to © 2013 Pearson Education, Inc. – Obtain from IF exac |
| Membrane Transport | • Plasma membranes selectively permeable – Some molecules pass through easily; some do not • Two ways substances cross membrane © 2013 Pearson Education, Inc. – Passive processes – Active processes |
| Types of Membrane Transport | • Passive processes – No cellular energy (ATP) required – Substance moves down its concentration gradient Active processes © 2013 Pearson Education, Inc. • – Energy (ATP) required – Occurs only in living cell membranes |
| Passive Processes | • Two types of passive transport – Diffusion • Simple diffusion • Carrier- and channel-mediated facilitated diffusion • Osmosis © 2013 Pearson Education, Inc. – Filtration • Usually across capillary walls |
| Passive Processes: Diffusion | • Collisions cause molecules to move down or with their concentration gradient – Difference in concentration between two areas • Speed influenced by molecule size and © 2013 Pearson Education, Inc. temperature |
| Passive Processes | • Molecule will passively diffuse through membrane if – It is lipid soluble, or – Small enough to pass through membrane channels or Passive Processes © 2013 Pearson Education, Inc. channels, – Assisted by carrier molecule |
| Passive Processes: Simple Diffusion | • Nonpolar lipid-soluble (hydrophobic) substances diffuse directly through phospholipid bilayer – E.g., oxygen, carbon dioxide, fat-soluble vitamins |
| Passive Processes: Facilitated Diffusion | • Certain lipophobic molecules (e.g., glucose, amino acids, and ions) transported passively by – Binding to protein carriers Moving through water filled channels |
| Carrier-Mediated Facilitated Diffusion | • Transmembrane integral proteins are carriers • Transport specific polar molecules (e.g., sugars and amino acids) too large for channels © 2013 Pearson Education, Inc. • Binding of substrate causes shape change in carrier then passage across membr |
| Channel-Mediated Facilitated Diffusion | • Aqueous channels formed by transmembrane proteins • Selectively transport ions or water • Two types: © 2013 Pearson Education, Inc. – Leakage channels • Always open – Gated channels • Controlled by chemical or electrical signals |
| Passive Processes: Osmosis | • Movement of solvent (e.g., water) across selectively permeable membrane • Water diffuses through plasma membranes Th h li id bil © 2013 Pearson Education, Inc. – Through lipid bilayer – Through specific water channels called aquaporins (AQPs) • |
| Passive Processes: Osmosis | • Water concentration varies with number of solute particles because solute particles displace water molecules • Osmolarity - Measure of total concentration of solute particles © 2013 Pearson Education, Inc. p • Water moves by osmosis until hydrost |
| Passive Processes: Osmosis | • When solutions of different osmolarity are separated by membrane permeable to all molecules, both solutes and water cross membrane until equilibrium reached When solutions of different osmolarity are © 2013 Pearson Education, Inc. • separated by m |
| Importance of Osmosis | • Osmosis causes cells to swell and shrink • Change in cell volume disrupts cell function, especially in neurons |
| Tonicity | • Tonicity: Ability of solution to alter cell's water volume – Isotonic: Solution with same non-penetrating solute concentration as cytosol Hypertonic: Solution with higher non- © 2013 Pearson Education, Inc. – nonpenetrating solute concentration t |
| Membrane Transport: Active Processes | • Two types of active processes – Active transport – Vesicular transport • Both require ATP to move solutes across a li i l b b © 2013 Pearson Education, Inc. living plasma membrane because – Solute too large for channels – Solute not lipid solubl |
| Active Transport | • Requires carrier proteins (solute pumps) – Bind specifically and reversibly with substance • Moves solutes against concentration gradient © 2013 Pearson Education, Inc. – Requires energy |
| Active Transport: Two Types | • Primary active transport – Required energy directly from ATP hydrolysis • Secondary active transport – Required energy indirectly from ionic di t t d b i ti t t © 2013 Pearson Education, Inc. gradients created by primary active transport |
| 9/29/2013 10 Primary Active Transport | • Energy from hydrolysis of ATP causes shape change in transport protein that "pumps" solutes (ions) across membrane • E.g., calcium, hydrogen, Na+-K+ pumps |
| Primary Active Transport | • Sodium-potassium pump – Most well-studied – Carrier (pump) called Na+-K+ ATPase – Located in all plasma membranes I l di i d d ti © 2013 Pearson Education, Inc. – Involved in primary and secondary active transport of nutrients and ions |
| Sodium-Potassium Pump | • Na+ and K+ channels allow slow leakage down concentration gradients • Na+-K+ pump works as antiporter – Pumps against Na+ and K+ gradients to maintain high intracellular K+ concentration © 2013 Pearson Education, Inc. and high extracellular Na+ co |
| Cytoplasm | • Located between plasma membrane and nucleus – Composed of • Cytosol – Water with solutes (protein, salts, sugars, etc.) © 2013 Pearson Education, Inc. p , , g , ) • Organelles – Metabolic machinery of cell; each with specialized function; eithe |
| Cytoplasmic Organelles | • Membranous – Mitochondria – Peroxisomes – Lysosomes E d l i ti l © 2013 Pearson Education, Inc. • Membranes allow crucial compartmentalization – Endoplasmic reticulum – Golgi apparatus • Nonmembranous – Cytoskeleton – Centrioles – Ribosomes |
| Mitochondria | • Double-membrane structure with inner shelflike cristae • Provide most of cell's ATP via aerobic cellular respiration R i © 2013 Pearson Education, Inc. – Requires oxygen • Contain their own DNA, RNA, ribosomes • Similar to bacteria; capable of c |
| Ribosomes | • Granules containing protein and rRNA • Site of protein synthesis • Free ribosomes synthesize soluble proteins that function in cytosol or other © 2013 Pearson Education, Inc. organelles • Membrane-bound ribosomes (forming rough ER) synthesize pro |
| Endoplasmic Reticulum (ER) | • Interconnected tubes and parallel membranes enclosing cisterns • Continuous with outer nuclear membrane • Two varieties: © 2013 Pearson Education, Inc. – Rough ER – Smooth ER |
| Rough ER | • External surface studded with ribosomes • Manufactures all secreted proteins • Synthesizes membrane integral proteins and phospholipids © 2013 Pearson Education, Inc. • Assembled proteins move to ER interior, enclosed in vesicle, go to Golgi appar |
| Smooth ER | • Network of tubules continuous with rough ER • Its enzymes (integral proteins) function in – Lipid metabolism; cholesterol and steroidbased hormone synthesis; making lipids of © 2013 Pearson Education, Inc. y gp lipoproteins – Absorption, synthes |
| Golgi Apparatus | • Stacked and flattened membranous sacs • Modifies, concentrates, and packages proteins and lipids from rough ER • Transport vessels from ER fuse with © 2013 Pearson Education, Inc. convex cis face; proteins modified, tagged for delivery, sorted, pa |
| Golgi Apparatus | • Three types of vesicles bud from concave trans face – Secretory vesicles (granules) • To trans face; release export proteins by exocytosis © 2013 Pearson Education, Inc. y – Vesicles of lipids and transmembrane proteins for plasma membrane or or |
| Peroxisomes | • Membranous sacs containing powerful oxidases and catalases • Detoxify harmful or toxic substances • Catalysis and synthesis of fatty acids © 2013 Pearson Education, Inc. • Neutralize dangerous free radicals (highly reactive chemicals with unpaired |
| Lysosomes | • Spherical membranous bags containing digestive enzymes (acid hydrolases) – "Safe" sites for intracellular digestion • Digest ingested bacteria, viruses, and toxins • Degrade nonfunctional organelles © 2013 Pearson Education, Inc. eg ade o u c o a |
| Endomembrane System | • Overall function – Produce, degrade, store, and export biological molecules – Degrade potentially harmful substances Includes ER Golgi apparatus secretory © 2013 Pearson Education, Inc. • ER, apparatus, vesicles, lysosomes, nuclear and plasma mem |
| Cytoskeleton | • Elaborate series of rods throughout cytosol; proteins link rods to other cell structures – Three types • Microfilaments © 2013 Pearson Education, Inc. • Intermediate filaments • Microtubules |
| Microfilaments | • Thinnest of cytoskeletal elements • Dynamic strands of protein actin • Each cell has a unique arrangement of strands © 2013 Pearson Education, Inc. • Dense web attached to cytoplasmic side of plasma membrane is called terminal web – Gives strengt |
| Intermediate Filaments | • Tough, insoluble, ropelike protein fibers • Composed of tetramer fibrils • Resist pulling forces on cell; attach to desmosomes © 2013 Pearson Education, Inc. • E.g., neurofilaments in nerve cells; keratin filaments in epithelial cells |
| Microtubules | • Largest of cytoskeletal elements; dynamic hollow tubes; most radiate from centrosome • Composed of protein subunits called tubulins © 2013 Pearson Education, Inc. • Determine overall shape of cell and distribution of organelles • Mitochondria, l |
| Motor Proteins | • Protein complexes that function in motility (e.g., movement of organelles and contraction) • Powered by ATP |
| Centrosome and Centrioles | • "Cell center" near nucleus • Generates microtubules; organizes mitotic spindle • Contains paired centrioles © 2013 Pearson Education, Inc. – Barrel-shaped organelles formed by microtubules • Centrioles form basis of cilia and flagella |
| Cellular Extensions | • Cilia and flagella – Whiplike, motile extensions on surfaces of certain cells – Contain microtubules and motor molecules Cilia move substances across cell surfaces Cellular Extensions – – Longer flagella propel whole cells (tail of sperm) |
| Cilia and Flagella | • Centrioles forming base called basal bodies • Cilia movements alternate between power stroke and recovery stroke |
| Cellular Extensions | • Microvilli – Minute, fingerlike extensions of plasma membrane – Increase surface area for absorption Core of actin filaments for stiffening |
| Nucleus | • Double-membrane barrier; encloses nucleoplasm • Outer layer continuous with rough ER and bears ribosomes • Inner lining ( nuclear lamina) maintains shape ofg ) p nucleus; scaffold to organize DNA • Pores allow substances to pass; nuclear pore com |
| Nucleoli | • Dark-staining spherical bodies within nucleus • Involved in rRNA synthesis and ribosome subunit assembly © 2013 Pearson Education, Inc. • Associated with nucleolar organizer regions – Contains DNA coding for rRNA • Usually one or two per cell |
| Chromatin | • Threadlike strands of DNA (30%), histone proteins (60%), and RNA (10%) • Arranged in fundamental units called nucleosomes © 2013 Pearson Education, Inc. • Histones pack long DNA molecules; involved in gene regulation • Condense into barlike bodie |
| Cytosolic Protein Degradation | • Autophagy – Cytoplasmic bits and nonfunctional organelles put into autophagosomes; degraded by lysosomes • Ubiquitins © 2013 Pearson Education, Inc. – Tag damaged or unneeded soluble proteins in cytosol – Digested by soluble enzymes or proteasom |
| Extracellular Materials | • Body fluids—interstitial fluid, blood plasma, and cerebrospinal fluid • Cellular secretions—intestinal and gastric fluids, saliva, mucus, and serous fluids © 2013 Pearson Education, Inc. • Extracellular matrix—most abundant extracellular material |
| Developmental Aspects of Cells | • All cells of body contain same DNA but cells not identical • Chemical signals in embryo channel cells into specific developmental pathways by turning some genes on and others off © 2013 Pearson Education, Inc. • Development of specific and distinc |
| Apoptosis and Modified Rates of Cell Division | • During development more cells than needed produced (e.g., in nervous system) • Eliminated later by programmed cell death (apoptosis) © 2013 Pearson Education, Inc. – Mitochondrial membranes leak chemicals that activate caspases |
| Apoptosis and Modified Rates of Cell Division | • Organs well formed and functional before birth • Cell division in adults to replace short-lived cells and repair wounds © 2013 Pearson Education, Inc. • Hyperplasia increases cell numbers when needed • Atrophy (decreased size) results from loss |
| Theories of Cell Aging | • Wear and tear theory—Little chemical insults and free radicals have cumulative effects • Mitochondrial theory of aging—free radicals in mitochondria diminish energy production • Immune system disorders—autoimmune y responses; progressive weakening |
| Theories of Cell Aging | • Most widely accepted theory – Genetic theory—cessation of mitosis and cell aging programmed into genes • Telomeres (strings of nucleotides protecting ends of chromosomes) may determine number of times a cell can divide • Telomerase lengthens telom |
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sarahflagg
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