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Journal 2/19 • Vocab quiz & Vocab in your own words DUE Friday • Chemistry of Biology worksheet must be finished & in your binder by TODAY • Enzyme reading DUE Wednesday 1. What is an organelle? Give some examples. AGENDA: 1. Finish presentations (if we have any left) 2. Notes on cell organelle structure & function Structure and Function of the Cell What is a cell? The smallest unit that can perform all of life’s processes All living things are made of cells FUN FACTS Your body has over 200 different specialized cell types! The adult human body is made up of about 60-90 trillion cells!!! If you lined up all the cells in a human body end-toend, you could actually circle the earth 41/2 times! Some interesting animal cells Stained red & white blood cells, 3D WBC & RBC, brain cells structure of a neuron, epithelial cells embryonic stem cells Some kinds of plant cells: •Plant cells undergoing cell division. Root tip plant cells •Chloroplasts seen in plant cells Bacterial cells bacteria cells (much smaller than plant/animal cells) In this chapter: Section 1 The History of Cell Biology Section 2 Introduction to Cells Section 3 Cell Organelles and Features Section 4 Unique Features of Plant Cells I. History of Cell Biology People did not know about cells before the microscope was invented. How are living & non-living things different? The discovery of the cell was an important step in answering this question. 1st person to see & name cells In 1665, Englishman, Robert Hooke, first saw & named "cells" while he was using a new instrument called a "microscope." He cut thin slices from cork, looked under a microscope, saw tiny box-like shapes. These tiny boxes reminded him of the small rooms that monks lived in called "cells". Illustration of cork by R. Hooke Anton Van Leeuwenhoek The cork cells Hooke saw were actually the remains of dead plant cells. Leeuwenhoek (1632-1723) (Dutch) was actually the first man to observe live cells. Using microscopes he made, was the first to observe sperm, bacteria, & RBCs. Observations laid the foundations for bacteriology and microbiology. Other Scientists 1838 Matthias Schleiden –concluded that all plants were composed of cells. 1839 Theodor Schwann concluded all animals were made of cells. 1855 Rudolf Virchow reasoned that cells come from only other cells Together made “Cell Theory” Cell Theory (be able to state these 3 parts!) All living things are made of cells. May be unicellular or multicellular. Cells are the smallest basic unit of structure and function in an organism A cell is the smallest unit of matter that can carry on all the processes of life. Cells come only from other cells. Timeline cell research: 1. What are the 3 parts of cell theory? 2. What instrument was necessary before the cell theory could be developed? Image : http://www.schools.utah.gov/curr/science/sciber00/7th/cells/sciber/timeline.htm II. Introduction to Cells Cell Diversity Cells are not all alike. Differences in: Size Shape Function Internal organization Cell Shapes How does each cell’s shape reflect its function? Cells – a variety of Shapes. The largest cells~ eggs -A few types of cells are large enough to be seen by the unaided eye. -Human Female Egg is the largest cell in the human body, -can be seen without the aid of a microscope. ~“dot” made by sharp pencil) -Eggs of Birds & Frogs are large cells -Largest of known cells is the ostrich egg. Other interesting cell sizes Outer layer of the placenta is one undivided sheet of cytoplasm with thousands of cell nuclei-- the entire membranes enclosing the baby. A muscle fiber is actually one very long and wide cell with many nuclei--perhaps 1/10 of a mm wide and several centimeters long. More about cell sizes Plant cells do not show such great variability in size are all less than 1/50 of a mm in diameter. Bacteria are the smallest cells Smallest known cells A bacteria called mycoplasm. Viruses Are very very small but are not cells & not considered to be alive Cell Size is limited -by a cell’s surface area–to-volume ratio. Why Cell Size is Limited a. Surface area to volume ratio Oxygen, Nutrients, etc. must enter cells. If a cell grows too large- these things cannot enter cell quickly enough for cell needs. b. Also-The Nucleus can only control a limited amount of cytoplasm. Surface area and volume of cubes Flat, Long cells A way to get around limitations of surface area is to make the cell long and thin or skinny and flat. Examples: Shape of skin cells- flat- suited to covering the body. Used by many protists & certain cells in your body such as nerve cells and muscle cells, both of which are long and skinny. MORE EXAMPLES of cell shapes White blood cells (WBC’s) can CHANGE shape- to engulf invading bacteria **Phagocytosis- to engulf and digest microorganisms and cellular debris B. The three basic parts of a cell plasma membrane cytoplasm nucleus Plasma Membrane (or cell membrane) Cell’s outer boundary, covers a cell’s surface and acts as a barrier between the inside and the outside of a cell. Cytoplasm The region of the cell that is within the plasma membrane and that includes the fluid, the cytoskeleton, and all of the organelles except the nucleus. Nucleus a membrane-bound organelle that contains a cell’s DNA. C. 2 Types of Cells 1. Prokaryotic cells – NO ORGANELLES, NO NUCLEUS!!! (bacterial cells) 2. Eukaryotic cells The nucleus is the hallmark of eukaryotic cells; the very term eukaryotic means having a "true nucleus". (all other cells- protists, fungi, plant & animals) http://www.beyondbooks.com/lif71/images/00046824.jpg Summary – Differences- Prokaryotic & Eukaryotic Cells Prokaryotic Cells Eukaryotic cells small cells (< 5 mm) larger cells (> 10 mm) always unicellular often multicellular no nucleus or any membranebound organelles always have nucleus and other membrane-bound organelles DNA is circular, without proteins DNA is linear and associated with proteins to form chromatin ribosomes are small (70S) ribosomes are large (80S) no cytoskeleton always has a cytoskeleton cell division is by binary fission cell division is by mitosis or meiosis reproduction is always asexual reproduction is asexual or sexual D. Cellular Organization Remember- organization levels: Atom-molecule-organelle-cell In multicellular eukaryotes, cells further organize into: - tissues - organs - organ systems - organisms. III. Cell Organelles and Features 1. Plasma membrane 2. Nucleus 3. Mitochondria 4. Ribosomes 5. Endoplasmic Reticulum (rough & smooth) 6. Golgi Apparatus 7. Vesicles 8. Cytoskeleton Parts of the Eukaryotic Cell 1. Plasma Membranesemi-permeable structure consisting mainly of phospholipids & proteins. The Plasma Membrane - fluid mosaic model - a double layer of phospholipid molecules & proteins - acts as a barrier, - keeping foreign entities out the cell and its contents (like cytoplasm) firmly inside the cell. -selectively permeable -allows only selected materials to pass in and out of a cell. Phospholipids in a cell membrane note: the Hydrophilic phosphate “head” the Hydrophobic lipid “tail” Proteins in membranes; help to MOVE Materials IN/OUT of the Cell. Membranes are FLUID- consistency of oil. “Fluid Mosaic Model” What is an Organelle? STRUCTURES THAT CARRY OUT SPECIFIC FUNCTIONS IN A EUKARYOTIC CELL. 2. NUCLEUS Large Organelle near the Center of the cell Contains genetic info in the DNA Nucleolus- ribosome synthesis Nuclear Pores- small holes through nuclear membrane to allow things like RNA to enter & leave nucleus The nucleus directs the cell’s activities and stores DNA. •Nucleolus - The is the place where DNA is concentrated when it is in the process of making ribosomal RNA. •Nuclear Envelope –The nucleus is surrounded by a double membrane 3. Mitochondria “POWER HOUSE” of the cell -Main function is the conversion of the potential energy of food molecules into ATP. (Adenosine Triphosphate) -Mitochondria structure: • • • • an outer membrane an inner membrane encloses a fluid-filled matrix the inner membrane is elaborately folded with cristae projecting into the matrix. has 5–10 circular molecules of DNA 4. RIBOSOMES -Ribosomes are the site of PROTEIN SYNTHESIS 5. ENDOPLASMIC RETICULUM (ER) -system of membranous tubules and sacs that connect the Nuclear Envelope to the Cell -Its like anIntracellular Highway, a path along which molecules move from one part of the cell to another. Poisons, waste, & toxic chemicals are made harmless. -SMOOTH ER (no ribosomes) –steroid synthesis -ROUGH ER (has ribosomes) - protein synthesis Other organelles 6. Golgi Apparatus- processing/packaging of secretions 7. Vesicles, including lysosomes (digestive enzymes) and peroxisomes (detoxification enzymes), are classified by their contents. 8. Cytoskeleton maintains shape of the cell made of protein fibers that help cells move includes microtubules, microfilaments, and intermediate filaments. Cilia & Flagella – assist in movement Centrioles consist of two short cylinders of microtubules at right angles to each other and are involved in cell division. 3 Differences between animal and plant cells Plants cells have most of the same organelles but will also have: 1. Cell Walls- made of cellulose 2. Vacuoles- fluid filled organelles for storage 3. Plastids (example: Chloroplasts) Have 2 membranes (like mitochondria) Have own DNA Some plastids function is storage Chloroplasts- absorb light for photosynthesis More about PLASTIDS Are in only in plants Organelles that-MAKE OR STORE FOOD. CHLOROPLAST converts SUNLIGHT, CARBON DIOXIDE, AND WATER INTO SUGARS. This process is called PHOTOSYNTHESIS. *Inside chloroplasts -THYLAKOIDS Membranes – are where Photosynthesis occurs. Endosymbiosis Theory that eukaryotic cell organelles like mitochondria and chloroplasts are derived from prokaryotic cells that were living inside larger prokaryotic cells. Evidence for: organelles have circular DNA, like bacteria cells. organelles have double membranes,(like a single-membrane cell had been engulfed by a larger cell.) Symbiotic relationship. (work together -energy/protection) Cells are organized Colonial organizations In unicellular organisms- collections of genetically identical cells that live together in a closely connected group- example: VOLVOX- a colonial algae In a Unicellular Organism, one cell carries out all of the functions of life. In a Multicellular Organism, cells are Specialized to perform one or a few functions. Because of cell specialization, the cells of Multicellular Organisms depend on other cells in the organism for their survival. In Multicellular organisms- form hierarchy of organization cell- tissue - organ - organ system- organism Cellular Level: The smallest unit of life capable of carrying out all the functions of living things. Tissue Level: A group of cells that performs a specific function in an organism form the TISSUE. Organ Level: Several different types of tissue that function together for a specific purpose form an ORGAN. Organ System Level: Several organs working together to perform a function make up an ORGAN SYSTEM. Cells Specialization Examples: Nerve cells to operate as part of the nervous system to send messages back and forth via the brain at the centre of the nerve system. Skin cells for waterproof protection and protection against pathogens in the open air environment. More specialized examples: Muscle cells are long and smooth in structure and their elastic nature allows these cells to perform flexible movements, just as they do in our own body's. Some white blood cells contain powerful digestive enzymes to eliminate pathogens by breaking them down to the molecular level. Plants also have Tissue and Organs, Dermal Tissue System forms the outer layer of a plant. Ground Tissue System makes up the bulk of roots and stems Vascular Tissue transports water and food throughout the plant. Xylem tubes to transport water & provide structural support for the plant. Phloem tubes transport sugars & other molecules The FOUR Plant Organs ROOTS STEMS LEAVES FLOWERS