Cells Anatomy & Physiology PDF

Anatomy & Physiology I BIOL 2001 C Ibanez Cells pp. 66-83 & 90-102 1. Cells: a. Functional unit of life b. Can be specialized → many different...

Anatomy & Physiology I BIOL 2001 C Ibanez Cells pp. 66-83 & 90-102 1. Cells: a. Functional unit of life b. Can be specialized → many different types i. e.g. liver cells, muscle cells, red blood cells, bacterial cells, etc c. Function is dependent on which genes are active d. Different cell types are more similar than different e. Some differences due to specialization i. e.g. liver cells are specialized to metabolize organic compounds (drugs) ii. e.g. RBC carry oxygen iii. e.g. muscle cells contract 2. Robert Hooke a. Discovered cells in 1665 due to the development of the microscope Anatomy & Physiology I BIOL 2001 C Ibanez 3. Cell Theory a. Developed in 1830’s i. Cells are the basic structural & physiological units of all living organisms ii. Cells can be distinct entities (unicellular) or can function as building blocks of larger organisms (multicellular) iii. All cells come from pre-existing cells iv. All cells are similar chemically v. Most chemical reactions of life occur within cells vi. Cells contain a set of genetic information that is replicated and passed on to offspring 4. Humans a. Approximately 37.2 trillion cells in an adult b. Started out as a singular cell → Zygote (fertilized egg) c. Zygote → Morula (solid ball of cells) → Blastula (hollow ball of cells) → Gastrula (three germ layers and anus begins to form) 5. Surface Area to Volume Ratio a. Cells are (mostly) small in order to maintain a high surface area to volume ratio b. As volume increases, the amount of 'stuff' the cell can do increases c. BUT: it also increases the amount of waste the cell makes d. Cells get rid of waste at surface; therefore, if volume is too much, the cell cannot get rid of waste fast enough = DEATH e. Exceptions: eggs, skeletal muscle cells, & neurons 6. Organelles a. Cell Membrane: selectively permeable membrane surrounding the cell i. Made of a phospholipid bilayer, cholesterol, and membrane proteins Anatomy & Physiology I BIOL 2001 C Ibanez b. Nucleus: stores the cell’s DNA i. Surrounded by a nuclear envelope → double phospholipid bilayer ii. Absent in prokaryotes c. Nucleolus: unused portion of the DNA i. Condensed DNA found within the nucleus d. Ribosomes: composed of rRNA and protein i. Location where proteins are synthesized ii. Free ribosomes synthesize proteins for within the cell iii. A-site (amino acid), P-site (peptide), and E-site (exit) e. Rough Endoplasmic Reticulum (RER): membranous organelle attached to the nucleus i. Synthesizes proteins to leave the cell ii. Contains ribosomes on its membrane f. Smooth Endoplasmic Reticulum (SER): membranous organelle attached to the nucleus, devoid of ribosomes i. Stores calcium ii. Synthesizes membrane lipids iii. Detoxifies drugs iv. Modifies and ships proteins made in the RER Anatomy & Physiology I BIOL 2001 C Ibanez g. Golgi Apparatus: modifies and packages proteins for export (usually) i. Cis side → side facing the nucleus ii. Trans side → side across from the nucleus h. Mitochondria: location where cellular respiration takes place in eukaryotes i. Contains mitochondrial DNA ii. Outer and inner membranes i. Lysosomes: degrade and remove organic complexes or pathogens using catalytic enzymes j. Peroxisomes: degrade and remove organic complexes or pathogens using peroxide k. Cytoskeleton: structure, support, and locomotion for cells Anatomy & Physiology I BIOL 2001 C Ibanez i. Microtubules 1. Make up cilia and flagella, both used for movement ii. Microfilaments: used for structure and transit within the cell l. Centrioles: form spindle fibers that execute cell division i. Centrioles work in pairs called a centrosome 7. Movement across membranes a. Selective permeability applies to movement on both sides of the membrane (moving things in & out) b. Types of movement: i. Passive Movement: moves from high concentration to low concentration; requires no ATP 1. Osmosis: spontaneous net movement of water through a selectively permeable membrane from a region lower solute concentration to a region of higher solute concentration a. Tonicity: measure of osmotic pressure of two solutions separated by a semi-permeable membrane Anatomy & Physiology I BIOL 2001 C Ibanez 2. Diffusion: spontaneous net movement of water & solute molecules from a region higher concentration to a region of lower concentration 3. Facilitated Diffusion: some materials use channels and carrier proteins to move from one side to the other, from a region higher concentration to a region of lower concentration ii. Active Movement: moves from low concentration to high concentration; requires ATP 1. Membrane Pumps: a. Uniport: 1 substance transported, 1 direction b. Cotransport: 2 substances, moved across in the same direction c. Exchange pump: 2 substances, moved in opposite directions i. ex. Na+/K+ ATPase moves 3 Na+ out of the cell and brings 2 K+ into the cell for each ATP used c. Molecules move depending on: i. size of molecule ii. temperature iii. charge (or lack thereof) iv. gradient in system 8. Large movement across membranes: a. Endocytosis: in-pocketing of membrane and making a vesicle (endosome) i. Phagocytosis: cell ingestion of solids (even entire cells) ii. Pinocytosis: cell ingestion of liquids iii. Receptor-mediated Anatomy & Physiology I BIOL 2001 C Ibanez b. Exocytosis: cytoplasmic vesicle fuses with plasma membrane and dumps material out of cell i. Vesicle has proteins on cytoplasmic side ii. Plasma membrane has 'target protein' on cytoplasmic side iii. Membranes recognize each other, fuse and material is released iv. Used for release of waste or secretions (digestive enzymes, sweat, milk, hormones, etc)