* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Chp_7
Survey
Document related concepts
Cell growth wikipedia , lookup
Cell culture wikipedia , lookup
Extracellular matrix wikipedia , lookup
Cellular differentiation wikipedia , lookup
Cell encapsulation wikipedia , lookup
Microtubule wikipedia , lookup
Cytoplasmic streaming wikipedia , lookup
Cell nucleus wikipedia , lookup
Organ-on-a-chip wikipedia , lookup
Signal transduction wikipedia , lookup
Cytokinesis wikipedia , lookup
Cell membrane wikipedia , lookup
Transcript
Chapter 7 - Tour of the Cell Cells vary in size but are typically very small. The more complex the internal components the larger the cell can be . prokaryote->eukaryote cell->protozoan The small size is a consequence of the cell volume requiring adequate surface area to support nutrient demands 1cm sides: SA=? Vol=? Ratio=? 2cm sides: SA=? Vol=? Ratio=? 3cm sides: SA=? Vol=? Ratio=? Prokaryotes: Eukaryotic Animal Cell: The basic eukaryotic cell contains the following: 1.plasma membrane 2.cytoplasm (semifluid) 3.cytoskeleton - microfilaments and microtubules that suspend organelles, give shape, and allow motion 4.presence of characteristic membrane enclosed subcellular organelles Plasma Membrane & Internal Membranes: Selectively permeable barriers Basic structure & makeup is the same. The specific proteins that are present and in what concentration will allow different cell types to respond differently to stimuli and nutrient/waste identification. Glycocalyx identifies cell type. (transplant rejection, hashimoto’s) Nucleus - control center Double membrane surrounding the chromosomes and the nucleolus. Pores allow specific communication with the cytoplasm. The nucleolus is a site for synthesis of RNA used to make up ribosomes. Constant chemical communication between the cytoplasm and the nucleus. Initiation and cessation of life sustaining chemical reactions is ordered by the DNA in the nucleus Endoplasmic Reticulum - assembly line Attached to the nuclear envelope for immediate response to the orders of the DNA. A network of interconnected membranes forming channels and pockets (cisternae) within the cytoplasm. Rough ER Covered with ribosomes (causing the "rough” appearance) which are in the process of synthesizing proteins for secretion or localization in membranes. Ribosome: protein RNA complex that is needed for the synthesis of protein. (free & attached) Smooth ER •assembly of lipids & carbohydrate •detoxifies toxic chemicals (add OH for solubility) •may store, release & recover cell stimulants What determines amount & type of ER in cells? The Golgi - Some manufacture & packaging for export Chemicals assembled and acquired from the ER are placed in a vesicle whose membrane contains target (docking) chemicals identifying the final location of its contents (outside cell or inside organelles) Lysosome - digests & recycles Made by the golgi, contains powerful hydrolytic enzymes that digests organic compounds Cells deprived of O2 or infected by viruses can trigger lysosomes to rupture & release hydrolytic enzymes into cytosol (immune system, tadpole tail, fetal fingers) H+ pump in membrane enables the lysosome to lower pH and digestion started, Formation of Lysosomes The modification and packaging of glycoproteins & glycolipids can establish the glycocalyx on the plasma membrane Endomembrane system A series of closed membranes within eucaryotic cells that are either continuous with each other or communicate with one another via vesicles which are formed at one surface and move to a second where they are incorporated. Vacuoles: Membrane surrounded "bags" that contain water and storage materials in plants. •Contractile Vacuole •Food Vacuole •Structural Vacuole •Storage Vacuole URL for Contractile Vacuole The Mitochondrion - Power generator (Respiration) Organelle that contains its own DNA and ribosomes. It makes its own proteins. EndoSymbiotic Theory. It converts a non-readily available chemical energy (PGAL) into a usable form - ATP as long as O2 is readily available Cytoskeleton - cell structure Quick Time™a nd a Sor ens on Video d ecomp res sor are n eede d to s ee this picture . Cytoskeleton revealed by staining with a fluorescent labeled actin antibody Cytoskeleton is composed of three main types of protein fibers, Microtubules, Microfilaments, and Intermdiate filaments. Microtubules and Microfilaments also aid in cellular transport: Quick Time™a nd a Sor ens on Video d ecomp res sor are n eede d to s ee this picture . Motor proteins (kinesin and myosin) can attach to the microtubules or microfilaments and with the use of ATP glide along the surface. As the motor protein moves along the surface it can drags organelles through the cytoplasm Cytoplasmic streaming The pigment granules move on fixed pathways inside the chromatophore cytoplasm, following radially arranged bundles of microtubules. The process is shown at 24 times the real speed. Movement is caused by light stimulus to he eye or emotion. Nerve fibers discharge transmitters that initiates the movement of the pigment in the microtubules. Quick Time™a nd a Sor ens on Video d ecomp res sor are n eede d to s ee this picture . Chrmatophores The microtubules can be arranged in elaborate bundles creating specialized transport structures (cilia, flagella, centriole) Quick Time™a nd a Sor ens on Video d ecomp res sor are n eede d to s ee this picture . Quick Time™a nd a Sor ens on Video d ecomp res sor are n eede d to s ee this picture . Cell Surfaces and Junctions Occluding Tight Junctions - keratin proteins fuse the adjoining membranes in direct contact (no intracellular space). Weld Anchoring Desmosomes & Adhesion Belts intermediate filaments penetrate & are shared through the membranes of both cells. (collagen, keratin) Intracellular space still present Communication Gap Junctions - pore like conections that allows cytoplasm to flow easily between connected cells (plasmodesmata in plant cells) Plant Cells are structurally very similar to animal cells: Differences? Chloroplast - energy transformer (Photosynthesis) In the presence of light and with the use of chlorophyl, the chloroplast converts CO2 and H2O into carbohydrate. This may be used for the production of ATP, storage, or structural material. Chloroplasts have their own DNA and ribosomes (endosymbiotic theory) and make their own proteins. They develop from an undifferentiated organelle called a Protoplast. Depending on location in the plant and or the presence or absence of light, the protoplast may develop into one of three organelles: •Chloroplast •Chromoplast •Leucoplast Cell Wall Membrane Structure & Transport Functions? Cell growth will require formation of additional membrane and deposition of essential membrane chemicals. This is accomplished by the endomembrane system. The Golgi & ER work together to create the key membrane chemicals which are then concentrated on the inner surface of vessicles that are released. Vessicle membranes and the plasma membrane fuse much in the same way as soap bubbles can fuse. QuickTime™ and a Cine pak decomp ress or are nee ded to s ee this picture. Passive Transport: All cells require nutrients and produce waste. Movement of these substances into and out of the cell at the optimum rate is essential. What mechanisms insures the proper exchange (nutrients in and wastes out)? Molecules own kinetic energy insures movement from an area of high concentration to an area of low concentration. The rate at which this movement will occur depends on? This type of transport is referred to as Passive. Why? Organisms without transport systems depend heavily on this type of movement. What physical characteristics are typical of those organisms lacking transport systems? Methods of Passive Transport Water moves freely between the shifting lipid molecules. Water will also move from an area of higher concentration to an area of lower concentration - Osmosis - diffusion of water through a selectively permeable barrier Quick Time™a nd a Sor ens on Video d ecomp res sor are n eede d to s ee this picture . Active Transport: Microtubules Transport containers filled with basolateral cargo move along microtubules to the cell periphery Microtubules responsible for internal cellular transport were tagged with fluro dyes. Th area that is brightly colored is the golgi. Small packets moving to the cell periphery are vessicles containing golgi or ER products. Sequence of 100 images. Rate was two images per second QuickTime™ and a Video decompressor are needed to see this picture. http://www.mpi-cbg.de/research/simons/Movie.html Carrier Proteins can actively transport substance in or out of cells Endocytosis •Receptor Mediated Endocytosis (example?) •Pinocytosis (no receptor - example?) •Phagocytosis (example?) Exocytosis (example?) QuickTime™ and a Cinepak®Pro