Transcript Cell Wall
The Cell Cell Theory • 1-All living things are made of cells • 2-Cells are the basic unit of life • 3-All cells come from preexisting cells Scientists • • • • • Hooke Leeuwenhoek Schleiden Schwann Virchow Microscopes • Light microscope- resolves to about .2 um – magnification • Electron microscope- resolves to about .2 nm – – – – Scanning (SEM)-cell surfaces Transmission(TEM)-Internal contents **what is the disdavantage? (note the newer STM, scanning tunneling, enables 3-D images and can be used w/ living) Cell Size Limit • Cells must divide when volume exceeds surface area (Mader text: p. 59; Glencoe text: section 9.1) • Cells vary in size from about 1 um (bacteria) to about 1m (sciatic neuron-nerve cell) Prokaryotic Cells • Lack membrane bound nucleus • DNA found in nucleoid region • Like many eukaryotic cells, these cells have cell walls, plasma membranes, flagella and ribosomes • Unlike eukaryotic cells, they may have a capsule and pili The prokaryotic cell Cellular Organelles Nucleus • • • • controls all functioning of the cell “Brain” of the cell contains the hereditary information of DNA DNA holds the coded instructions for making proteins and other important molecules • Nucleus is important because making proteins is one of the main functions of the cell • Chromatin is the granular material seen within the nucleus (DNA bound to protein) 2. Nucleolus: dark regions within the nucleus a. produces ribosome's B. In animal & plant cells 3. Ribosomes: organelle that carries out protein synthesis/interprets code from RNA. Made of rRNA and protein •Can be attached to ER or floating •In plants & animal cells Cell Wall • Found in plants, algae, fungi, and almost all prokaryotes. Not in animals • Made from carbohydrates (cellulose in plant cells) • Provides support, protection and excessive uptake of H2O • Outside the cell membrane. Cell Membrane • Thin flexible barrier around the cell. • Selectively permeable. Made of – – – – lipid bilayer proteins carbohydrate chains Scattered cholesterol Endoplasmic Reticulum • Endoplasmic Reticulum • Rough ER – Membranous maze connected to nuclear envelope • Covered in ribosomes • Makes proteins and cell membrane • Smooth ER – no ribosomes present – Also a membranous maze – Lipid synthesis – Detoxifies harmful substances – Cells in liver have a lot of smooth ER Golgi Apparatus • Center of manufacturing, processing, packaging and shipping • Enzymes here attach carbohydrates and lipids to proteins • After the ER makes the proteins, they move into the Golgi Apparatus where they are modified • From the Golgi Apparatus , modified proteins are moved to their destinations Lysosomes • Small organelle filled with hydrolytic enzymes that cell uses to digest macromolecules. Important in phagocytosis • Acidic interior (pH-5) • Also functions to break down lipids, carbohydrates and proteins from food into particles that could be utilized by the rest of the cell • Debris removal of worn out organelles Vacuoles • Membrane bound sacs • Temporary storage areas for food water, enzymes and waste • Special types – Contactile –pumps out excess water in single celled water dwelling organisms (ex-aquatic protists, such as protozoans) – Central- large vacuole found in plants used for water storage Chloroplasts • • • • Plant cells Shaped like lenses Double membrane Use energy from sunlight to make energy-rich food molecules in a process known as photosynthesis Light energy + 6H2O + 6CO2 ----- C6H12O6 + 6O2 Mitochondria • Organelles that release energy from stored food molecules-Cellular respiration • Power house of the cell; ATP is made here • Energy released from the mitochondria is used by the cell for growth, development and movement 6O2 + C6H12O6 --------6CO2 + 6H20 +Energy Centrioles • Organelles made of microtubules and are involved in cell division • Animal cells only Peroxisomes • Specialized compartment bound by single membrane • Similar to lysosomes (contains enzymes) • Generation and degradation of H202 (hydrogen peroxide) to protect cell from it’s toxic effects Cytoskeleton • Microfilaments thinnest, made of protein, help cells change shape • Intermediate fibers Varied,rope-like, tension bearing • Microtubules Largest, anchorage and movement Role of Cytoskeleton • Extensions of plasma membrane – Cilia – Flagella – Both have 9 +2 microtubule arrangement except at base, which has 9 triplets-Basal Body • Identical in structure to centriole Cytoplasm • Everything between the plasma membrane and the nuclear envelope • Semifluid (cytosol) with organelles suspended in it • Protoplasm=cytoplasm+nucleoplasm (inside nucleus) Cell Junctions • See Handout and/or book • Plant cells – Plasmodesmata- junctions between plant cells (walls) • Animal cells ~Tight junctions ~Anchoring junctions (desmosomes) ~Communicating (Gap) *Know exp of each! Definitions • Cytology • Histology • Cytosol