CELLS
…a sense of scale…..
Single-cellular Organism Made of just one cell
Multi-celluar Organism Made of many cells working together
Cell Types There are two major types of cells –Prokaryotic Cells Pro=Before Karyon=Kernel or nucleus –Eukaryotic Cells Eu=New Karyon=Kernel or nucleus
Cell Types Prokaryote Smaller Less Complex No nucleus No organelles with membranes Bacteria Eukaryote Larger More Complex Has a nucleus Organelles with membranes Plants, Animals, Fungi, Protists
Discovery of Cells
Hans and Zacharias Janssen (1590) Made the First compound light microscope
Robert Hooke (1663) Looked at a piece of cork and called what he saw “cells”
Anton van Leeuwenhoek (1674) First to observe living cells
Theodor Schwann (1838) All animals are made of cells Matthias Schlieden (1838) All plants are made of cells Together they said all living things are made of cells
Rudolf Virchow (1855) Stated that Cells can only come from pre- existing cells
Cell Theory 1.All organisms are composed of one or more cells. 2.The cell is the basic unit of structure and organization of organisms. 3.All cells come from pre- existing cells.
Cell Structure
Organelles: structures inside cells that are specialized to perform specific tasks (eukaryotic) cells are divided into 2 major parts: the nucleus & the cytoplasm (everything outside the nucleus)
Nucleus: contains almost all the cells’ DNA (the instructions for making the molecules of life) Nuclear Envelope: the membrane surrounding the nucleus Nuclear Pores: portals for materials to go in & out of the nucleus ribosomes Nucleolus: dense region of nucleus (which is made of RNA and protein) where ribosomes are made Chromatin: strands of DNA bound to protein-condenses into compact Chromosomes only when the cell divides
Ribosomes: the cellular “factories” that assemble proteins
Endoplasmic Reticulum: where membranes & other cell “products” are assembled Rough ER- contains ribosomes / Smooth ER- no ribosomes
Golgi Apparatus: modifies, sorts, & “packages” proteins made in the ER for storage in the cell or “export” Products get “shipped” from the ER & the Golgi apparatus in Transport Vesicles
Lysosomes: organelles filled with enzymes that break down food molecules into smaller molecules that the cell can use
Lysosomes are important in developing embryos to “kill” off unneeded cells by breaking open & spilling their contents inside cells Lysosomes also break down old, worn-out cells, which is why they are called the “suicide sacks” of the cell.
Vacuoles: saclike structures that store materials for the cell (like H 2 O) …the pressure created by water in a plant’s central vacuole helps keep plants upright
Mitochondria: convert the chemical energy in food into compounds that are easier for the cell to use Mitochondria have their own DNA. Another interesting fact is that you inherit them ONLY from your mother!
Chloroplasts: use energy from sunlight to convert H 2 O & CO 2 into glucose (& O 2 ) by photosynthesis
Cytoskeleton: a network of protein filaments that helps give a cell its shape.
There are 3 main types of fibers in the cyto- skeleton: 1)Microfilaments: made of the protein actin, they help cells change shape & help muscles contract 2) Intermediate Filaments: have ropelike structure-function to resist tension & stretching & anchoring certain organelles. These are made of various types of proteins. 3) Microtubules: straight, hollow tubes made of protein tubulin. -reinforce cell shape -act as tracks along which some organelles move -build cilia & flagella
Your white blood cells can “crawl” around by the assembling & disassembling of microfilaments bacteria
Cilia & Flagella: Both are arrangements of microtubules extending from some cells, either to move the cell or move things around the cell Cilia are generally shorter & more numerous than flagella
Compare and Contrast Plant cells & Animal Cells: Cytoplasm Cell Membrane LARGE vacuoles Chloroplast Cell Wall Rectangle shaped Small Vacuoles or NONE. *Centrioles & Lysosomes Round shaped Nucleus & Nuclear Membrane Plant CellsAnimal Cells