* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download Structures of the Cell
Survey
Document related concepts
Signal transduction wikipedia , lookup
Tissue engineering wikipedia , lookup
Cytoplasmic streaming wikipedia , lookup
Cell growth wikipedia , lookup
Extracellular matrix wikipedia , lookup
Cellular differentiation wikipedia , lookup
Cell nucleus wikipedia , lookup
Cell culture wikipedia , lookup
Cell encapsulation wikipedia , lookup
Cell membrane wikipedia , lookup
Organ-on-a-chip wikipedia , lookup
Cytokinesis wikipedia , lookup
Transcript
Structures of the Cell Cell Theory 1. All living things are composed of cells. 2. Cells are the basic unit of structure and function in living things. 3. All cells come from preexisting cells. Cell Size • Microscopic to the size of an ostrich egg yolk Microscopes • Light Microscope - visible light passes through a specimen and then through glass lenses, which magnify the image SEM • Scanning electron microscopes (SEMs) focus a beam of electrons onto the surface of a specimen, providing images that look 3-D TEM • Transmission electron microscopes (TEMs) focus a beam of electrons through a specimen • TEMs are used mainly to study the internal structure of cells Cell fractionation • Cell fractionation takes cells apart and separates the major organelles from one another Fig. 6-5b TECHNIQUE (cont.) 1,000 g (1,000 times the force of gravity) 10 min Supernatant poured into next tube 20,000 g 20 min 80,000 g 60 min Pellet rich in nuclei and cellular debris 150,000 g 3 hr Pellet rich in mitochondria (and chloroplasts if cells are from a plant) Pellet rich in “microsomes” (pieces of plasma membranes and cells’ internal membranes) Pellet rich in ribosomes Cell Types- Eukaryotes • Eukaryotes (animals, plants, protists, fungi) -have a nucleus bound by an envelope -have membrane bound organelles -large cells Cell Types- Prokaryotes • Prokaryotes- (bacteria) - No nucleus, they have a nucleoid - an unbound region where their DNA is found - No membrane bound organelles. - Small cells Cell Parts (a) • Organelles –cell structures with specialized functions • Cell Membrane- organelle that regulates what comes in and out of the cell, provides protection, and support. • phospholipid Bilayer- structure of the cell membrane • Hydrophilic Carbohydrate side chain head • Hydrophobic Hydrophilic Tail region Hydrophobic region Hydrophilic region Phospholipid Proteins (b) Structure of the plasma membrane Cell Wall • Cell wall- surrounds cell membrane only in plants • Made out of cellulose (starch) • Adds extra support Nucleus (center of the cell) Nucleus- center of the cell, contains nucleic acid (DNA) • • Enclosed by a nuclear envelope –lipid bilayer. It has pores. • Nucleolus – inside the nucleus. Makes ribosomal RNA that form ribosomes. Nucleus Nucleolus Chromatin Nuclear envelope: Inner membrane Outer membrane Nuclear pore Pore complex Rough ER Cytoplasm • Cytoplasm- in between cell membrane and nucleus. Made of a fiber matrix and a liquid called cytosol. • Holds organelles in place • Kind of like “Jello With fruit in it” • Mitochondria Mitochondria- release energy stored in glucose in the form of ATP through cell respiration. • Double membrane (inner and outer) , the inner has folds called cristae and that form the mitochondrial matrix and the inner membrane space. Intermembrane space Outer membrane Inner membrane Cristae Matrix 0.1 µm Plastids • Store materials in plants – (chloro- plasts- Chloroplasts • Chloroplasts- make glucose from sunlight (only in plants) through photosynthesis. • Contains the pigment chlorophyll that makes plants green • Thylakoid – discs containing chlorophyll stacked in granum • Stroma – fluid in the space outside the granum. Stroma Inner and outer membranes Granum Thylakoid Ribosomes • Make proteins Endoplasmic Reticulum (ER) • ER – makes and transports materials through the cell in vesicles -Smooth ER – makes and transports lipids and carbohydrates -Rough ER – contains, ribosomes to make and transport proteins (gives it its rough look) Golgi Apparatus • Labels, packages, sorts and sends molecules from the ER out of cells in vesicles. Lysosome • Lysosomes – membrane sacs filled with enzymes that break down materials (food or old organelles) • Lysosomes will merge with food vacuoles break down food or engulf (phagocytosis) an old organelle to digest and recycle it. • Peroxisomes - are like mini lysosmes that contain an enzyme called catalase that converts peroxide in to water and oxygen. Vacuoles • Store materials (food, water, etc) • Plants have a large central vacuole, animals have may small scattered vacuoles • • • • • • • Endomembrane system All connected by membrane or vesicles Nuclear envelope Rough ER Smooth ER Golgi Lysosomes Vacuoles Cytoskeleton – frame work • Made of 3 types of fibers Microtubules • Three main types of fibers make up the cytoskeleton: – Microtubules are the thickest of the three components of the cytoskeleton, help separate cells during cell division, make up flagellum, and guide moving vesicles like a train track – Ex. 9 microtubules make up a centriole. Intermediate Filaments – Intermediate filaments are fibers with diameters in a middle range. They, anchor organelles and maintain cell shape Microfilaments – Microfilaments, also called actin filaments, are the thinnest components and are found in muslces for contracting. • In muscle cells, thousands of actin filaments are arranged parallel to one another • Thicker filaments composed of myosin interact with the thinner actin fibers Cell Junctions Plasmodesmata – pores in the • cell walls between plant cells • Gap Junctions – pores in the membranes between animal cells** • Desmosomes – anchores that hold cells together** • Tight Junctions – tightly pressed cells to seal fluid out** Animal vs. Plant Animal Cells Plant Cells No cell wall Cell Wall No chloroplasts Chloroplasts Lysosomes Lysosomes (rarely) Scattered Vacuoles Large Central Vacuole