* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download File - Mrs. LeCompte
Survey
Document related concepts
Microtubule wikipedia , lookup
SNARE (protein) wikipedia , lookup
Cell culture wikipedia , lookup
Cell encapsulation wikipedia , lookup
Cellular differentiation wikipedia , lookup
Cell growth wikipedia , lookup
Extracellular matrix wikipedia , lookup
Cell nucleus wikipedia , lookup
Cytoplasmic streaming wikipedia , lookup
Organ-on-a-chip wikipedia , lookup
Signal transduction wikipedia , lookup
Cytokinesis wikipedia , lookup
Cell membrane wikipedia , lookup
Transcript
4-2 Notes THE ENDOMEMBRANE SYSTEM Membranes are interrelated directly through physical contact or indirectly through vesicles Vesicles = Membrane-enclosed sacs that are pinched-off portions of membranes moving from the site of one membrane to another. Includes: Nuclear envelope, Endoplasmic reticulum, Golgi apparatus, Lysosomes, Vacuoles, and Plasma membrane. 3) ENDOPLASMIC RETICULUM (ER) – extensive membranous network of tubules and sacs (cisternae) Two Types: o Smooth ER Participates in the synthesis of lipids, phospholipids and steroids Detoxification drugs and poisons o Rough ER studded with ribosomes continuous with outer membrane of the nuclear envelope Make secretory proteins and membrane, often in the following process: (“secreted”) Ribosomes attached to rough ER make secretory proteins. ↓ Growing polypeptide is threaded through ER membrane into the lumen or cisternal space. ↓ Protein folded into its native conformation ↓ Functional/Carbohydrate Groups are added ↓ Protein departs in a transport vesicle pinched off from ER 4) GOLGI APPARATUS = Organelle made of stacked, flattened membranous sacs that modifies, stores and packages products of the endoplasmic reticulum. Vesicles may transport macromolecules between the Golgi and other cell structures Modifies proteins by adding: carbohydrate/sugar or phosphate groups Labels products for secretion. 5) LYSOSOMES = membrane-enclosed bag of hydrolytic enzymes that digest all major classes of macromolecules (lipases, carbohydrases, proteases, and nucleases). Functions o Intracellular digestion Ex. Phagocytosis = cellular process of ingestion. o Recycle cell’s own organic material Monomers are released o Programmed cell death = Apoptosis Ex. Fingers and toes are formed that way in human embryos 6) VACUOLE = membrane-enclosed sac that is larger than a vesicle 3 types: o Food vacuole o Contractile vacuole = vacuole that pumps water from the cell o Central vacuole = Large vacuole found in most mature plant cells enclosed by a membrane called tonoplast Plays a role in plant growth by absorbing water and elongating the cell Stores organic compounds, inorganic ions, dangerous metabolic byproducts, pigments, and unpalatable (yucky!) compounds 7) PEROXISOMES = contain specialized enzymes to breakdown peroxide in nearly all eukaryotic cells 2 H2O2 2 H2O + O2 (bad) (good) MITOCHONDRIA AND CHLOROPLASTS ARE MAIN ENERGY TRANSFORMERS Enclosed by double membranes Are NOT part of endomembrane system Contain ribosomes and their own DNA that programs a portion of their protein synthesis Are Semi-autonomous organelles that grow and reproduce within the cell 8) MITOCHONDRIA = Organelles which are the sites of cellular respiration Makes ATP and is found in nearly all eukaryotic cells The more energy (ATP) needed = more mitochondria Parts include: o Smooth outer membrane o Convoluted (wavy) inner membrane o Intermembrane space o Mitochondrial matrix Contains enzymes that catalyze many metabolic steps of cellular respiration (i.e. the Krebs Cycle) 9) CHLOROPLASTS = sites of photosynthesis Parts include: o Intermembrane space o Thylakoids = Flattened membranous sacs inside the Chloroplast Thylakoids form a 3rd membrane system Thylakoid space = Space inside the thylakoid Chlorophyll is found in the thylakoid membranes. o Stroma = Viscous fluid outside the thylakoids 10) Cytoskeleton = A network of fibers throughout the cytoplasm that forms a dynamic framework for support and movement and regulation Gives mechanical support Helps maintain its shape Enables cell to change shape Directs cellular “traffic” – like organelle movement Transmits signals 3 types of fibers Microtubules (largest) Organized by the microtubule organizing center (MTOC) Functions Cellular support (reinforce cell shape) Tracks for organelle movement Separation of chromosomes during cell division Forms centrosomes and centrioles o Centriole = Pair of cylindrical structures located in the centrosome of in animal cells o Cilia and flagella = Locomotor organelles Cilia Flagella Occur in large numbers 1 or a few per cell Smaller Longer ULTRASTRUCTURE: Are extensions of plasma membrane Core is 9 doublets of microtubules arranged in a ring with 2 single microtubules in the center (9 + 2 pattern). Microfilaments (smallest ones) Formed from actin linked into long chains and wound into a helix Pinches an animal cell in two during cell division Elongation and contraction of pseudopodia during amoeboid movement Cytoplasmic Streaming (cyclosis) = Flowing of the entire cytoplasm around the space between the vacuole and plasma membrane in a plant cell. Intermediate Filaments (medium-sized) Constructed from keratin subunits Very strong *Both Microfilaments and Intermediate Filaments bear tension resist popping