1. DISCOVERING THE CELL Chapter 4

2. Discovering the Cell Robert Hooke – Simplistic microscope to examine cork – Referred to compartments as ‘cellulae’ Origin for today’s term cell Antoni Van Leeuwenhoek – Invented many simplistic microscopes – 1 st to observe and describe bacteria Termed ‘animalcules’ Contemporaries in the late 1600’s

3. Cell Theory All living things are composed of cells – Schleiden and Schwann – 1 to many billions with different functions Smallest unit to demonstrate properties of life New cells are only formed from existing cells – Virchow – Mitosis and meiosis

4. Compound Light Microscope Visible light is refracted (bent) through glass lenses Apparent size seen is magnification Clarity to discern 2 points as distinct is resolution – HD TV’s, DVD players, and Blue-Ray players

5. Electron Microscope (EM) S canning (SEM) Details of cell s urfaces, 3D image Uses a beam of electrons = higher resolution Can’t be used on living cells Transmission (TEM) Details of internal cell structures

6. Limits on Cell Size Communication time b/w inside and outside Interaction of with environment – Ratio of surface area to volume Larger volume needs more nutrients = more wastes More surface area speeds mov’t of ‘stuff’ – Volume increases faster than surface area with growth Cell so big transport can’t keep up Effects shapes and body plans too

7. Cellular Classification Prokaryotes – NO nucleus (nucleoid region) – NO membrane bound organelles – Single, circular DNA – Smaller, less complex – E.g. bacteria and archaea Eukaryotes – Nucleus – Membrane bound organelles – DNA arranged on multiple chromosomes – Larger, more complex – E.g. protists, fungi, plants, and animals

8. The Basic Cell Plasma membrane – Phospholipid bilayer – Regulates mov’t in and out Cytoplasm – Fills cell – Contains organelles and surrounding substances DNA – Genetic material – Location varies in cell types Ribosomes – Synthesize proteins – Composition varies in cell types

9. Prokaryotic Cells Nucleoid region Chromosome/DNA (see previous) Cell membrane Cell wall (peptidoglycan) Capsule (glycocalyx) Cytoplasm Ribosomes (antibiotic functions Pili Flagellum/cilia

10. Eukaryotic Cells Most living organisms – Protists – Fungi – Plants – Animals Organelles allow compartmentalizing – Different areas carrying on reactions independently of rest of cell Endomembrane system connects – Nuclear membrane  rough ER  smooth ER  golgi apparatus  lysosomes/vacuoles  plasma membrane

11. Nucleus Control center Nucleolus – Constructs ribosomes Chromatin – All DNA in cell – Organized into chromosomes – 6 Feet of DNA in one nucleus!!! Nuclear envelope/membrane – Regulates transport of molecules – Receptors for signaling – Nuclear pores Allow communication with cytoplasm

12. Endoplasmic Reticulum (ER) Smooth ER – No ribosomes – Lipid synthesis – Carbohydrate synthesis Rough ER – Ribosomes attached Protein and rRNA Free or attached – Synthesize proteins

13. Golgi Apparatus (Body) Package and process proteins & lipids – “Warehouse & finishing factory” Polarity – Receives vesicles from ER – Produces finished vesicle products

14. Cellular Production Vesicles are sacs containing enzymes – Lysosomes Intracellular digestion Destroy bacteria in white blood cells Breaks down damaged organelles – Peroxisomes Break down fatty acids & proteins Detoxify alcohol & other toxic substances Vacuoles are large storage vesicles – Varies between eukaryotic cells Food vacuoles Contractile vacuoles  protists Central vacuoles  plants

15. Cellular Energy Mitochondria  eukaryotic cells – Site of cellular respiration Forms ATP (energy) from carbohydrates – Similar to bacteria  have their own DNA & ribosomes – Double membrane, matrix, cristae Chloroplast  plants and algae – Site of photosynthesis Forms sugars from sunlight – Double membrane, thylakoids, grana, stroma Theorized as both results of endosymbiosis

16. Cytoskeleton Protein fibers that extend throughout the cytoplasm Microfilaments – Supports shape and allows change Intermediate filaments – Reinforce shape and anchors organelles Microtubules – Produce movement Cilia, flagella, and pseudopodia – Assembled by centrioles

17. Eukaryotic Cell Types Animal Cells Plant Cells