BIOM 315 1nd Edition Lecture 4 Outline of Last Lecture I. The human body planII. Body Cavities and MembranesIII. Microscopy anatomya. Light Microscopyb. Electron Microscopyc. Transmission Electron MicroscopyIV. Introduction to cell anatomya. Plasma membraneOutline of Current Lecture I. Plasma membranea. Endocytosisb. ExocytosisII. Cytoplasma. Membrane bound cytoplasmic organellesb. Non-membrane bound cytoplasmic organellesIII. The NucleusCurrent Lecture- The plasma membraneo Functions: barrier between cell and extracellular environment (provides barrier against substances outside the cell)o Forms two body fluid compartments: Intracellular fluid: inside cell (65% of total body water, TBW) Extracellular fluid: outside cell (35% TBW)- Intersitial fliud – surrounds cells- Plasma: fluid portion of blood- Other: fluid in joint capsules, eyeo Determine which substance enter or leave the cello Membrane is selectively permeable Movement of small, lipid-insoluble molecules dependent on integral membrane proteins (transport proteins) Movement of larger molecules  endocytosis (move inside the cell), exocytosis (move outside the cell) Simple diffusion: lipid soluble molecules pass directly through lipid bilayer of membraneThese notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute. Osmosis: the diffusion of water across a membrane- Endocytosiso Mechanism by which molecules or particles not able to pass (either directly or via transporters) through membrane enter cellso Phagocytosis – “cell eating” large particleso Pinocytosis – “cell drinking” smaller particleso Receptor-mediated endocytosis Substance binds to receptor molecules on membrane  Invaginates (folds inward and pinches off) and forms a coated pit Pinches off to become a coated vesicleo- Exocytosiso Mechanism that moves substances out of the cell Substance is enclosed in a secretory vesicle The vesicle migrates to the plasma membrane Proteins from the vesicles (v-SNAREs) bind with membrane proteins (t-SNAREs) The lipid layers from both membranes bind, and the vesicle releases its contents to the outside of the cello- Cytoplasmo Cytoplasm lies internal to plasma membrane except for nucleus Consists of cytosol, organelles, and inclusionso Jelly-like fluid in which other cellular elements are suspendedo Consists of water, ions, and enzymes (control chemical reactions)  gives the viscosity of cytoplasmo Organelles (2 categories) Membrane bound Non-membrane bound- Membrane bound cytoplasmic organelleso Endoplasmic reticulum (ER): “network within the cytoplasm” –flattened envelopes (inside = cisternae) Rough ER – ribosomes stud the external surfaces- Synthesis of proteins to be secreted out of cell Smooth ER – consists of tubules in a branching network- No ribosomes are attached; therefore no protein syntesis- Lipid (fat) synthesis, detoxifying enzymes, calcium storageoo Assembly of proteins at the rough endoplasmic reticulumoo Golgi apparatus: a stack of three to ten disk-shaped envelopes; receives transport vesicles from ER Post-translational processing of proteins Sorts products of rough ER and sends them to proper destinationo Role of Golgi Apparatus in packaging products of rough ERo Mitochondria – two membranes (inner/outer) and matrix (inner membrane folded into cristae) Power house of cell (generates metabolic energy = ATP) Enzymes of critic acid cycle (Kreb’s cycle) in matrix Electron transport chain on cristae of inner membrane (enzymes involved with ATP production)o Lysosomes – membrane walled sacs containing acid hydrolases (enzymes) Digest unwanted substances (both intracellular substances plus substances brought into cells)o Peroxisomes – membrane walled sacs of oxidase enzymes (peroxidases) Catalase (enzyme) neutralizes hydrogen peroxide; protects cell Break down long chains of fatty acids, amino acids, and toxins Are numerous in the liver and kidneys- Non-membrane bound cytoplasmic organelleso Ribosomes: constructed of proteins and ribosomal RNA Site of protein synthesis Fixed – attached to rough ER  synthesis proteins which are secreted by cell Free – loose in cytosol  synthesize non-secreted proteins (remain in cell)o Cytoskeleton: cell skeleton – an elaborate network of rod-like structures Functions: cell movement, mechanical support, contraction, suspension/movement of organelles Consist of three types:- Microtubules – cylindrical structures made of proteins (tubulin) – hollow; largest- Microfilaments – filaments of the contractile protein (actin)- Intermediate filaments – various protein fibers--- ex: keratin (skin)o Centrioles: paried cylindrical bodies Consists of 27 short microtubules (9 triplets) Assist in forming cilia, mitotic spindle Centromes – composed of centrosome matrix- Cytoplasmic Inclusionso Temporary structures – not present in all cell typeso May consist of pigments, crystals of protein, and food stores Lipid droplets – found in liver cell and fat cells Glycosomes – store sugar in the form of glycogen- The Nucleuso Contains DNA – “central core” or “kernel” – control center of cell DNA directs the cells activities Nucleus is approximate 5m in diametero Nuclear envelope – two parallel membranes separated by fluid-filled space Contains poreso Chromatin: composed of DNA and histone proteins Condensed chromatin – contains tightly coiled strands of DNA – wrap around histones Extended chromatin – contains uncoiled strands of DNA- DNA’s genetic code is copies onto mRNA (transcription)o Chromosomes: highest level of organization of chromatin Contains a long molecule of DNA Present only at time of cell duplicationo Nucleolus: little nucleus – in the center of the nucleus Contains parts of several chromosomes Site of ribosome subunit manufacture