Transcript Cells
Structure and Function The Inner Life of a Cell Historical Development 1665 Robert Hooke, an English scientist, saw box-like structures in cork. He thought they looked like the rooms Monks lived in. He called them “cells”. Historical Development 1674 Anton von Leeuwenhoek, a Dutch lens maker, made a powerful single lens microscope. He looked at a drop of pond water. He saw living cells he called “animalcules”. Historical Development 1838 Matthias Schleiden, a German botanist, said all plants are made of cells. Historical Development 1839 Theodor Schwann, a German zoologist, said animals are made of cells. Historical Development 1855 Rudolf Virchow, a German physiologist, said cells come from existing cells. Cell Theory The contributions of these scientists and others led to the development of the cells theory. 1. All living things are made of cells. 2. Cells are the basic units of structure and function in living things. 3. New cells come from existing cells. Cell Theory Of course there are exceptions….. Where did the first cells come from? What about viruses? And organelles that have their own DNA, like mitochondria and chloroplasts? Two Types of Cells Prokaryotes “first cells” Small and simple DNA not housed in a nucleus Lack most organelles bacteria Two Types of Cells Eukaryotes “true cells” Larger and more complex DNA housed in a nucleus Many organelles Everything but bacteria! Protists, fungi, plants, animals The Origin of Cells Section 7-2 Division of Labor A cell is made up of many parts with different functions that work together. Similarly, the parts of a computer work together to carry out different functions. Section 7-2 Nucleolus Nucleus Ribosome (attached) Nuclear envelope Ribosome (free) Cell Membrane Mitochondrion Smooth endoplasmic reticulum Rough endoplasmic reticulum Centrioles Golgi apparatus Animal Cell Eukaryotic Cell Structure A cell is like a factory………….. Nucleus Control center Houses DNA Undividing cell = chromatin Dividing cell = chromosomes Nucleolus – “little nucleus”; makes ribosome parts Nuclear envelope – pores allow materials in and out Cytoplasm Division of labor…………. Organelles! Ribosomes Protein factories Two subunits – large and small Made of the nucleic acid RNA and protein Found attached to the ER or free in the cytoplasm Endoplasmic Reticulum Internal membrane system Rough has ribosomes on the surface Makes & transports proteins Smooth has no ribosomes Makes membrane lipids & detoxifies chemicals Liver cells have lots of smooth ER Golgi Apparatus Stacks of flattened membrane disks Modifies, sorts and packages proteins for storage or secretion Gland cells have lots of golgi bodies Lysosomes Sacs of digestive enzymes Clean-up crew Digests worn out cell parts White blood cells have lots of lysosomes Vacuoles Fluid-filled sacs Storage of water, nutrients, wastes… Very large in plant cells Contractile vacuoles regulate water content of protists Mitochondria “Powerhouse” of the cell Converts energy stored in sugar to a form of energy usable by the cell = ATP Contains DNA and can replicate itself Uses oxygen Chloroplasts Site of photosynthesis Green pigment chlorophyll Converts light energy into the chemical bond energy of glucose Has DNA and can replicate itself Cytoskeleton Support and transport; maintains shape Made of protein filaments Microfilaments – movement Microtubules – shape, cell division Centrioles Cilia and flagella Section 7-2 Cell membrane Endoplasmic reticulum Microtubule Microfilament Ribosomes Mitochondrion Cell Boundaries Cell wall Outside the cell membrane in bacteria, fungi, algae and plant cells Support and protection Made of carbohydrate and protein fibers secreted by the cell membrane Plant cell walls are mainly cellulose, an indigestible fiber Cell Boundaries Cell membrane – Lipid bilayer with embedded proteins Selectively permeable – regulates what enters and leaves the cell Channel proteins allow materials to easily enter or leave the cell Marker proteins have carbohydrate chains that identify the cell The Structure of the Cell Membrane Section 7-3 Outside of cell Proteins Carbohydrate chains Cell membrane Inside of cell (cytoplasm) Protein channel Lipid bilayer Diffusion Diffusion – the movement of materials from areas of high concentration to areas of low concentration Does not require energy End result is equilibrium Small, neutral molecules diffuse in and out of cells Oxygen, carbon dioxide, water Diffusion Across a Membrane Facilitated Diffusion Channel proteins open up to allow larger molecules, like glucose, to easily pass into the cell. It still does not require energy. Facilitated Diffusion Section 7-3 Glucose molecules High Concentration Cell Membrane Low Concentration Protein channel Osmosis The diffusion of water through a selectively permeable membrane. Causes cells to shrink or swell. Plant cells depend upon the pressure exerted by a swollen vacuole against the cell wall to keep upright. This is known as turgor pressure. Osmosis Section 7-3 Active Transport Using energy to move materials into or out of a cell against the concentration gradient. Cell membrane proteins “pump” materials in or out. Nerve cells do this to prepare to carry a message. Protists do this to engulf food. Active Transport Section 7-3 Molecule to be carried Energy Molecule being carried Active Transport Active Transport The Diversity of Cellular Life Unicellular organisms Colonial organisms Multicellular organisms Unicellular Organisms Made of a single cell Most dominant life form on earth Some have highly specialized organelles Each cell must perform all life functions: Grow Respond to change Reproduce Transform energy Bacteria, protists, yeasts Colonial Organisms Unicellular organisms living together to benefit each other. Each cell is still autonomous, but may have a special job such as reproduction. Examples: sponges, algae Multicellular Organisms Made of many cells. Cells are specialized and must communicate and cooperate. The process of a cell developing a specialty is called differentiation. Examples of specialized cells: Red blood cells Muscle cells Leaf guard cells Nerve cells Levels of Organization In multicellular organisms: Organelles cells tissues organs organ systems organism Cell size Organelles You know……….. Ribosomes Vacuoles ER Chloroplasts Lysosomes Mitochondria Golgi bodies Nucleus Cells The unit of structure and function in living things. Muscle cells Bone cells Guard cells Xylem cells Salivary gland cells White blood cells Nerve cells Tissues A group of similar cells performing the same function Muscle tissue - contracts Epithelial tissue – lines and protects Nervous tissue – carries messages Connective tissue – connects different body parts Organs A group of different tissues working together to carry out a task. Heart – pumps blood Liver – detoxifies blood Kidney – filters blood Flower - reproduction Roots – absorbs water… Stomach – digests proteins Organ System A group of related organs working together to carry out a life process. Circulatory system – transport Digestive system – nutrition Excretory system – excretion Reproductive system - reproduction Organism You Me Pet Worm Mushroom Fern Oak tree Snake Fish