Intro to Cells Key Concept: Cells are the basic unit of life. Introduction to Cells Cells are the basic units of organisms Cells can only be observed under microscope Basic types of cells: 1 Animal Cell Plant Cell Bacterial Cell 2 Cell Theory Scientists who contributed to cell theory The cell theory grew out of the work of many scientists and improvements in the microscope. 3 principles of the Cell Theory: 1. The cell is the basic unit of life. 2. All living things are made of cells. 3. All cells are made from other living cells. 3 Hooke: first to identify cells & name them Leeuwenhoek: developed better lenses for microscope Schleiden: said that plants were made of cells Schwann: said that animals were made of cells Virchow: said that all cells come from other living cells (all cells reproduce) 4 All Cells: There are 2 types of cells: Microscopic Enclosed by a membrane Filled with cytoplasm Have DNA cell membrane 1. Prokaryotic Cells 2. Eukaryotic Cells cytoplasm Bacterium (colored SEM; magnification 8800x) 5 6 1
Cells May be Prokaryotic or Eukaryotic Prokaryotes include bacteria & lack a nucleus or membrane-bound structures called organelles ( Pro = no ) Eukaryotes include most other cells & have a nucleus and membrane-bound organelles ( Euk has a nuk ) Prokaryotes (bacteria) No nucleus or organelles Has a Cell membrane & cell wall Contain ribosomes (no membrane) to make proteins in their cytoplasm 7 8 Two Main Types of Eukaryotic Cells Number of Cells Organisms may be: Unicellular composed of one cell (prok & euk) Multicellularcomposed of many cells that are organized (euk only) Plant Cell Animal Cell 9 10 Eukaryotic Cell Basic Structure of a Cell Contain 3 basic cell structures: Cell Membrane Nucleus Cytoplasm with organelles 11 12 2
Cell membrane Outer covering of cell Made of protein and phospholipids Selectively permeable--- 13 Nucleus Controls the normal activities of the cell Bound by a nuclear membrane (function?) Contains chromosomes Each cell has fixed number of chromosomes that carry genes that give the cell its characteristics 14 Nucleolus Cytoplasm Jelly-like substance enclosed by cell membrane Provides a medium for chemical reactions to take place Inside the nucleus; makes ribosomes 15 16 Very small size Organelles Can only be observed under a microscope Have specific functions Found throughout cytoplasm Organelles Found in ALL Eukaryotic Cells Examples of Organelles include: Endoplasmic reticulum, Ribosomes, Nucleolus, Golgi Bodies, Lysosomes, Mitochondria, Vacuoles, Chloroplasts, 17 18 3
Endoplasmic Reticulum: internal membrane system ( highway ) Smooth ER lacks ribosomes & makes lipids & carbohydrates Rough ER has ribosomes on its surface which make proteins to EXPORT Ribosomes Make proteins to be used inside the cell, while others leave the cell Some are attached to the Rough ER while others float freely in the cytoplasm 19 20 Golgi Bodies Lysosome Process, Sort, & Deliver proteins digests & gets rid of wastes or foreign materials like bacteria/viruses; recycles worn-out cell parts (Modifies/Packages/Transports) 21 22 *not found in plant cells* VESICLES Small sacs that transport materials from place to place Mitochondrion ( mitochondria ) *Rod shape *Site of Cellular respiration *has its own DNA 24 4
Mitochondria *Burn sugars to produce energy (ATP) *Active cells like muscles have more mitochondria Vacuoles Used to store food and water There are many, small vacuoles in animals cells only; only one large one in plant cells 25 26 Cytoskeleton Framework/structure of cell Movement of parts of cell 2 parts: Microtubules thick tubes; make up centrioles Microfilaments thin tubes; make up cilia & flagella Special Cell Structures Cilia short, hair-like projections; used for movement (locomotion) Flagella long, whip-like projection; moves organism/cell in one direction 27 28 Organelles found in PLANT cells only Chloroplast Contain the green pigment chlorophyll Converts light energy into chemical energy (glucose) Process called photosynthesis 29 30 5
Vacuole Plant Cell Have a large central vacuole Stores sugars, proteins, minerals, wastes, & pigments Cell wall Protects Gives shape to cell Made of cellulose Plant Cell Strong and rigid Found in plant, fungi, and bacteria Freely permeable 31 32 Organelles found in ANIMAL cells only vacuole cytoplasm nucleus mitochondrion Animal cell No cell wall or chloroplast Stores glycogen in the cytoplasm for food energy 33 glycogen granule cell membrane 34 Animal Cell Organelles Different kinds of plant cells Help cell divide Near the nucleus Paired structures Onion Epidermal Cells root hair Guard Cells 35 Root Hair Cell 36 6
Different kinds of animal cells Similarities between plant cells and animal cells white blood cell Both have a cell membrane surrounding the cytoplasm red blood cell Amoeba Both eukaryotic cheek cells sperm muscle cell nerve cell Paramecium 37 38 Differences between plant cells and animal cells Differences between Plant Cells and Animal Cells Animal cells Plant cells Animal cells Plant cells Relatively smaller in size Irregular shape No cell wall Relatively larger in size Regular shape Cell wall present Vacuole small or absent Glycogen as food storage Centrioles present Large central vacuole Starch as food storage Centrioles absent 39 40 Cell Song Video https://www.youtube.com/watch/?v=rabkb5as 2Zg Animal Cell Diagram LETTER NAME OF ORGANELLE A CELL MEMBRANE B CYTOPLASM C NUCLEUS D NUCLEOLUS G RIBOSOMES H MITOCHONDRIA I NUCLEAR ENVELOPE OR MEMBRANE J1 ROUGH ENDOPLASMIC RETICULUM J2 SMOOTH ENDOPLASMIC RETICULUM K GOLGI APPARATUS L LYSOSOME 7
Plant Cell Diagram LETTER NAME OF ORGANELLE A CELL WALL C CYTOPLASM E RIBOSOME F1 ROUGH ENDOPLASMIC RETICULUM F2 SMOOTH ENDOPLASMIC RETICULUM G MITOCHONDRIA H CHLOROPLAST M GOLGI APPARATUS N NUCLEUS J CENTRAL VACUOLE B CELL MEMBRANE 8