Lesson 1: The Cell PDF

THE CELL JAYNEL E. BARZO LEARNING OUTCOMES 1) Trace the beginnings of the discovery of the cell and the development of cell theory 2) Differentiate prokaryotic & eukaryotic cells 3) Identify the parts of a cell & describe the function of each part 4) Describe the different organelles in foun...

THE CELL JAYNEL E. BARZO LEARNING OUTCOMES 1) Trace the beginnings of the discovery of the cell and the development of cell theory 2) Differentiate prokaryotic & eukaryotic cells 3) Identify the parts of a cell & describe the function of each part 4) Describe the different organelles in found plant and animal cells DISCOVERY OF CELLS Robert Hooke (1635-1703)  coined the term “cell” responsible for the start of cytology Antonie Van Leeuwenhoek (1632-1723)  discovered bacteria and other microscopic organisms in rainwater Robert Brown (1773-1858)  discovered the nuclei within cells Felix Dujardin  noted that all living things contain a thick jelly fluid called “sarcode” Matthias Schleiden (1804-1881) and Theodor Schwann (1810-1882)  introduced the concept that all plants and animals are made up of cells Johannes Purkinje (1787-1869)  coined “protoplasm” to refer to the living matter of the cell Rudolf Virchow (1821-1902)  found that cells divide to form new cells; “omnis cellula e cellula” or cells come from preexisting cells CELL THEORY 1) All organisms are composed of one or more cells. 2) The cell is the basic unit of structure and function of all organisms. 3) All cells arise only from pre-existing cells. CELL THEORY  The three statements that comprise the cell theory tell you that the cell is the basic structural, functional, and reproductive unit of all organisms. CELL THEORY  An adult human is estimated to have at least 70 to 100 trillion cells divided into about 200 different tissues. CELL DIVERSITY  Not all cells are alike. Cells within the same organism show diversity in size, shape, and internal organization.  Some organisms contain only one cell (unicellular). Other organisms are made up of many cells (multicellular). Unicellular Multicellular CELL SIZE  A few types of cells are large enough to be seen by the unaided eye. CELL SIZE  Most cells are small for two main reasons: a) The cell’s nucleus can only control a certain volume of active cytoplasm. b) Cells are limited in size by their surface area to volume ratio. CELL SIZE  A group of small cells has a relatively larger surface area than a single large cell of the same volume. CELL SHAPE  Cells come in a variety of shapes – depending on their function. INTERNAL ORGANIZATION  Cells contain a variety of internal structures called organelles.  PROKARYOTIC CELL EUKARYOTIC CELL Example Protoctista, fungi, animals, Bacteria Organisms plants Typical Size ~ 1-10 m ~ 10-100 m Real nucleus with nuclear Nucleus Type No nucleus or nuclear body envelope DNA Circular (ccc DNA) Linear (chromosomal DNA) Ribosomes 70S 80S  PROKARYOTIC CELL EUKARYOTIC CELL Cytoplasmic Highly structured by membranes Very few structures Structure and a cytoskeleton Movement Flagellae/cilia (flagellin) Flagellae/cilia (tubulin) Mitochondria None 1-100 (except RBC’s) Chloroplasts None In algae and plants Cell Division Binary fission Mitosis and Meiosis ▪complex barrier that functions like a gate ▪fluid mosaic of proteins in a phospholipid bilayer ▪selectively permeable phosphate head ▪polar ▪hydrophilic two fatty acid tails ▪nonpolar ▪hydrophobic Fluid Mosaic Model Cytosol ▪everything within the cell membrane except the nucleus ▪contains cytosol, jelly- like mixture where organelles are found Cytosol + Organelles = Cytoplasm  ▪contains the genetic material, DNA, in the form of chromatin Nucleus ▪considered as the control center of the cell ▪Nucleolus = ribosome synthesis & assembly ▪Nuclear envelope = double membrane with pores ▪Nucleoplasm = semifluid medium inside the nucleus ▪sites of aerobic respiration and ATP production ▪considered as the powerhouse of the cell ▪ATP is the energy currency of the cell ▪Outer Membrane = selectively permeable boundary between mitochondria & cytosol ▪Inner Membrane = has many long folds called cristae used during ATP synthesis ▪semi-autonomous since they have their own DNA ▪arise only when existing ones grow and divide ▪site of protein synthesis ▪cells’ most common organelle ▪found in the cytoplasm, rough ER, chloroplasts, and mitochondria (found in chloroplasts (found in rough ER) and mitochondria) Polysome = groups of 80S ribosome working together ▪system of membranous tubules and sacs ▪act as an internal transport system ▪abundant secretory cells and liver cells Rough ER ▪studded with 80S ribosomes ▪allows mRNA transport to the ribosomes Smooth ER ▪preparation for protein secretion ▪site of steroid & lipid synthesis ▪system of membranes made of flattened sacs called cisternae ▪processing, packaging, and secreting organelle ▪modify & export proteins ▪small spherical organelle with hydrolytic enzymes ▪site of protein and food digestion ▪formed from pieces of Golgi apparatus ▪internal framework that maintains the shape and structure of the cell ▪helps the cell to move ▪ Microfilaments (contractile, made of actin) ▪ Microtubules (rigid and hollow tubes, made of tubulin) ▪ Intermediate filaments (ropelike, fibrous polypeptide) ▪two bundles of microtubules placed at right angle ▪forms the spindle fibers used during cell division ▪Cilia are short, and numerous and hair-like. ▪Flagella are longer, fewer and whip-like. ▪assist in cell movement and moving substance PLANT CELLS Plant cells have three additional structures not found in animal cells: ❖Cellulose cell walls ❖Chloroplasts (and other plastids) ❖Central vacuole  freely permeable (porous) and does not regulate the movement of molecules into and out of the plant cell  rigid and provides support and protection  found also in fungi such as mushrooms and yeast (but made up of chitin) a) Primary (cellulose) cell wall forms between middle lamella & cell membrane enlarges as more cellulose is added b) Secondary (lignified) cell wall forms only in woody tissue (mainly xylem) when cells reaches full size stronger and waterproof Primary cell wall increases the extensibility of the cell wall during expansion (cell growth). Secondary cell wall provides mechanical support and aids in water transportation.  large membrane-bound sac  serves as a storage area (organic molecules and inorganic ions)  store waste in insoluble form and may contain poison to deter animals  may be found in other organisms  sites of photosynthesis  encloses thylakoids which contain chlorophyll  contain cccDNA and 70S ribosomes  semi-autonomous organelles  other plastids store reddish-orange pigments