The Discovery of Cells PDF

The Discovery of Cells 1585 ○ The first compound microscope is made by Janssen (two lenses) 1660’s ○ Lenses improve ○ First cells seen by Hooke (“cells”)and van Leeuwenhoek (pond water) The Discovery of Cells 1838 ○ Cell Theory from Schwaan and...

The Discovery of Cells 1585 ○ The first compound microscope is made by Janssen (two lenses) 1660’s ○ Lenses improve ○ First cells seen by Hooke (“cells”)and van Leeuwenhoek (pond water) The Discovery of Cells 1838 ○ Cell Theory from Schwaan and Schleiden The Discovery of Cells 1939 ○ Electron microscope invented - can magnify up to 50 million times! light microscope → scanning electron microscope → transmission electron microscope The Discovery of Cells 1943 ○ The first computer was invented The Discovery of Cells 1952 ○ Henrietta Lacks’s cells become the HeLa cell line 1953 Structure of DNA was discovered 1981 ○ Transgenic mice and fruit flies become available The Discovery of Cells The Cell Theory states that: 1. All organisms are composed of one or more cells. 2. The cell is the basic unit of organization in all organisms. 3. All cells come from pre-existing cells  Cell Types There are two basic cell types 1. Prokaryotes: Cells that lack a nucleus and membrane-bound organelles (Kingdoms: Eubacteria and Archeabacteria)  Cell Types There are two basic cell types: 2. Eukaryotes: Contain a nucleus and membrane- bound organelles Kingdoms: Protista, Fungi, Plantae, Animalia Cell Types Why do cells have organelles? Organelles are structures within cells that lets many chemical reactions happen simultaneously - compartmentalization Prokaryotes Cell Membrane ○ All cells are surrounded by a membrane ○ Thin, flexible barrier ○ Lets things in and out to promote homeostasis (selective permeability) Prokaryotes Cell Membrane ○ Composed of a phospholipid bilayer: a doubled layered sheet of 2 lipids Proteins are embedded in this layer Prokaryotes Model is called the fluid mosaic model because the lipid bilayers and proteins (pieced together like a mosaic) move like fluid and yet create a barrier against the outside environment Prokaryotes Outside of cell (water) Cell Membrane hydrophilic ○ Composed of a Phosphat phospholipid e+ bilayer: a doubled glycerol layered sheet of 2 Fatty hydrophobic lipids acids Inside of cell (water) Prokaryotes Cytoplasm ○ Area of the cell that fills in all the other space ○ It is about 80 percent water and also contains dissolved salts, fatty acids, sugars, amino acids, and proteins such as enzymes. Prokaryotes Nucleoid ○ Area in the cytoplasm that contains the DNA ○ Not surrounded by a membrane Prokaryotes Ribosomes ○ Produce proteins (protein synthesis) ○ Found in the cytoplasm ○ Like a small machine in a factory Cell Types Reminder: There are two basic cell types 1. Prokaryotes: Cells that lack internal membrane-bound structures 2. Eukaryotes: Contain membrane-bound structures Eukaryotes Nucleus - The nucleus contains almost all the cell’s DNA - surrounded by a double membrane. - contains the DNA Eukaryotes Endoplasmic Reticulum ○ Internal membrane where proteins are made Eukaryotes Endoplasmic Reticulum 2 types: ○ Rough ER: has ribosomes on it, makes proteins that will leave the cell ○ Smooth ER: has no ribosomes Eukaryotes Golgi Apparatus ○ Organelle that edits, sorts and delivers proteins to their destination ○ Tags proteins (and lipids) so the cell knows where to send them Eukaryotes Lysosomes ○ Small organelles filled with enzymes ○ Janitors of the cell- they break down molecules the cell doesn’t need anymore Eukaryotes Vacuoles ○ One large vacuole in plants. ○ Many small vacuoles in animals. ○ Used for storage of water, salts, proteins… ○ Fluid-filled sac Eukaryotes Mitochondria ○ Powerhouse of the cell! ○ Food molecules (glucose) are broken down to make energy. This is called cell respiration. Eukaryotes Chloroplast ○ In plants and some algae ○ Transforms sunlight and CO2 to food for plants (photosynthesis!) ○ Filled with chlorophyll to capture light Eukaryotes Cell Wall ○ Plants, fungi, and most bacteria have a cell wall ○ Made of cellulose in plants  **** HONORS SLIDE**** Eukaryotes Cytoskeleton ○ Network of fibrous tubes that give support and helps the cell keep its shape. ○ Microtubules and microfilaments. Eukaryotes Flagella/Cilia ○ Used for mobility ○ Cilia: short, hair-like projections from the cell membrane. ○ Flagella - whip like tail flagell a Eukaryotes Size and Shape ○ Plant have rectangular and fixed shapes Eukaryotes Size and Shape ○ Animals have round or irregular shapes Unicellular vs. Multicellular organism Unicellular organism: single celled organism Ex. bacteria, some protists  Unicellular vs. Multicellular organism Multicellular organism: organisms made of many cells ○ Cells must communicate and cooperate ○ Cell specialization: cells develop in an organism in different ways to perform different tasks Ex. Cells that make up our blood Levels of Organization Why is this important? When we’re sick, our immune system deals with invaders by engulfing them with their membrane We depend on transport across a membrane to take up nutrients in our gut Movement Across a Membrane Concentration: mass of solute per volume of solvent ○ What would units of concentration be? Concentration gradient: the difference in concentration of a substance from one location to another Equilibrium: when the concentration of the solute is the same all over Diffusion Passive Transport Diffusion: particles move from an area of high concentration to an area of low concentration Substances diffuse across membrane without energy Osmosis Passive Transport Osmosis: diffusion of water through a selectively permeable membrane *this is a type of diffusion!* Isotonic: same solute concentration Hypertonic: solute outside is higher (then water is _____) Hypotonic: solute outside is lower (then water is ______) Osmosis Osmotic pressure: pressure exerted by the movement of water in or out of the cell Facilitated Diffusion Passive Transport Facilitated diffusion: when protein channels in the membrane “help” molecules pass through No energy needed Active Transport Active transport: uses energy to move molecules from low to high concentration Proteins act as pumps to move molecules ○ Example: sodium/potassium pump Active Transport Endocytosis: process of taking material INTO the cell through pockets in the membrane Honors add in: ○ Phagocytosis: cell eating, engulfs material ○ Pinocytosis: cell drinking, using water to transport material Active Transport Exocytosis: when large amounts of material are RELEASED from the cell ○ EXocytosis → EXit