DISCOVERING THE CELL Chapter 4. Discovering the Cell Robert Hooke – Simplistic microscope to...
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Transcript of DISCOVERING THE CELL Chapter 4. Discovering the Cell Robert Hooke – Simplistic microscope to...
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– 1st to observe and describe bacteria
• Termed ‘animalcules’• Contemporaries in the late 1600’s
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
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
Electron Microscope (EM)
Scanning (SEM)
• Details of cell surfaces, 3D image
• Uses a beam of electrons = higher resolution• Can’t be used on living cells
Transmission (TEM)• Details of internal cell
structures
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
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
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
Prokaryotic Cells• Nucleoid region• Chromosome/DNA (see
previous)• Cell membrane• Cell wall (peptidoglycan)• Capsule (glycocalyx)• Cytoplasm• Ribosomes (antibiotic functions• Pili• Flagellum/cilia
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
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
Endoplasmic Reticulum (ER)
• Smooth ER– No ribosomes– Lipid synthesis– Carbohydrate
synthesis• Rough ER– Ribosomes attached• Protein and rRNA• Free or attached
– Synthesize proteins
Golgi Apparatus (Body)
• Package and process proteins & lipids– “Warehouse & finishing factory”
• Polarity– Receives vesicles from ER– Produces finished vesicle
products
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
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
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