Basic Structure of a Cell copyright cmassengale 1 Characteristics of organisms? 1. Made of CELLS 2. REPRODUCE (species) 3. Maintain HOMEOSTASIS 4. GROW and DEVELOP 5. EXCHANGE materials with surroundings (water, wastes, gases) 6. RESPOND to environment 7. ORGANIZED 8. Require ENERGY (food) copyright cmassengale 2 CELL THEORY • All living things are made of cells • Cells are the basic unit of structure and function in an organism • Cells come from the reproduction of existing cells copyright cmassengale 3 CELL SIZE Typical cells range from 5 – 50 micrometers (microns) in diameter copyright cmassengale 4 First to View Cells • In 1665, Robert Hooke used a microscope to examine a thin slice of cork (dead plant cell walls) • What he saw looked like small boxes copyright cmassengale 5 Cell Size and Types • Cells, the basic units of organisms, can only be observed under microscope • Three Basic types of cells include: Animal Cell Plant Cell copyright cmassengale Bacterial Cell 6 ENDOSYMBIOTIC THEORY • some organelles within cells were at one time free living cells themselves • organelles with their own DNA • Chloroplast and Mitochondria copyright cmassengale 7 Number of Cells Although ALL living things are made of cells, organisms may be: • Unicellular – composed of one cell • Multicellular- composed of many cells that may organize into tissues, etc. bacteria butterfly copyright cmassengale 8 Multicellular Organisms • Cells in multicellular organisms often specialize (take on different shapes & functions) copyright cmassengale 9 All Cells – are surrounded by a barrier called a cell membrane. – contain DNA. Bacteria Animal cell copyright cmassengale 10 Prokaryotes • Simplest type of cell • Nucleoid region contains the DNA • Surrounded by cell membrane & cell wall (peptidoglycan) • ribosomes in their cytoplasm to make proteins • Includes bacteria copyright cmassengale 11 Eukaryotes • More complex type of cells • HAVE a nucleus and membrane-bound organelles • Cytoplasm with organelles • Includes protists, fungi, • plants, and animals • “You are Eukaryotes” copyright cmassengale 12 Two Main Types of Eukaryotic Cells Plant Cell copyright cmassengale Animal Cell 13 Organelles • • • • • Little organs Very small (Microscopic) Perform various functions for a cell Found in the cytoplasm May or may not be membrane-bound copyright cmassengale 14 Animal Cell Organelles Ribosome (attached) Ribosome (free) Nucleolus Nucleus Cell Membrane Nuclear envelope Mitochondrion Smooth endoplasmic reticulum Rough endoplasmic reticulum Centrioles Golgi apparatus copyright cmassengale 15 Plant Cell Organelles copyright cmassengale 16 Cell or Plasma Membrane • Composed of double layer of phospholipids and proteins • Surrounds outside of ALL cells • Controls what enters or leaves the cell • Living layer Outside of cell Proteins Carbohydrate chains Cell membrane Inside of cell (cytoplasm) Protein channel copyright cmassengale Lipid bilayer 17 Cell Wall • Nonliving layer • Supports and protects cell • • • • Cell wall Made 0f; cellulose in plants peptidoglycan in bacteria chitin in Fungi copyright cmassengale 18 Cytoplasm • Jelly-like substance • Provides a medium for chemical reactions to take place • Contains organelles • Found in ALL cells copyright cmassengale cytoplasm 19 • • • • Nucleus Control center Contains the DNA Has a nuclear membrane with pores Has a fixed number of chromosomes that carry genes • Genes control cell characteristics copyright cmassengale 20 Inside the Nucleus The genetic material (DNA) is found DNA is spread out And appears as CHROMATIN in non-dividing cells DNA is condensed & wrapped around proteins forming as CHROMOSOMES in dividing cells copyright cmassengale 21 Nucleolus • Inside nucleus • Disappears when cell divides • Makes ribosomes that make proteins copyright cmassengale 22 Ribosomes • “Protein factories” for cell • Join amino acids to make proteins • Process called protein synthesis copyright cmassengale 23 Cytoskeleton • Helps cell maintain cell shape • Also help move organelles around • Made of proteins • Microfilaments are threadlike Microtubules are tubelike MICROTUBULES MICROFILAMENTS copyright cmassengale 24 • • • • Centrioles Found only in animal cells Paired structures Made of bundle of microtubules Appear during cell division forming mitotic spindle • Help to pull chromosome pairs apart to opposite ends of the cell copyright cmassengale 25 Mitochondria • “Powerhouse” of the cell • Generate cellular energy (ATP) • active cells like muscle cells have MORE mitochondria • In both plants & animal cells • Surrounded by a DOUBLE membrane • Folded inner membrane -CRISTAE • Has its own DNA copyright cmassengale 26 What do mitochondria do? “Power plant” of the cell Respiration: Burns glucose to release energy (ATP) Stores energy as ATP copyright cmassengale 27 Endoplasmic Reticulum - ER • Network of hollow membrane tubules • Connects to nuclear envelope & cell membrane • Functions in Synthesis of cell products & Transport Two kinds of ER ---ROUGH & SMOOTH copyright cmassengale 28 Rough Endoplasmic Reticulum (ER) • Has ribosomes on its surface • Makes proteins for EXPORT out of cell copyright cmassengale 29 Smooth Endoplasmic Reticulum • Smooth ER lacks ribosomes on its surface • Is attached to the ends of rough ER • Makes cell products that are USED INSIDE the cell copyright cmassengale 30 Golgi Bodies Look like a stack of pancakes Modify, sort, & package molecules from ER for storage OR transport out of cell copyright cmassengale 31 Lysosomes • Contain digestive enzymes • Break down food, bacteria, and worn out cell parts for cells • Programmed for cell death (AUTOLYSIS) • Lyse (break open) & release enzymes to break down & recycle cell parts) copyright cmassengale 32 Cilia & Flagella • for cell movement • Cilia are shorter and more numerous on cells Flagella are longer and fewer copyright cmassengale 33 • • • • Vacuoles Fluid filled sacks for storage Small or absent in animal cells Plant cells have a large Central Vacuole No vacuoles in bacterial cells copyright cmassengale 34 • • • • • Chloroplasts Found in plants Photosynthesis – food making process Contains its own DNA Contains enzymes & pigments for Photosynthesis Never in animal or bacterial cells copyright cmassengale 35 Chloroplasts • Surrounded by DOUBLE membrane • Outer membrane smooth • Inner membrane modified into sacs called Thylakoids • Thylakoids in stacks called Grana & interconnected • Stroma – gel like material surrounding thylakoids copyright cmassengale 36