Cells Structural and functional units of living organisms
Eukaryotic ( true nucleus ) vs. Prokaryotic ( before nucleus ) cells Proks
Eukaryotic ( true nucleus ) vs. Prokaryotic ( before nucleus ) cells Proks - nucleoid is not separated from cytoplasm by a membrane Euks -
Eukaryotic ( true nucleus ) vs. Prokaryotic ( before nucleus ) cells Proks - nucleoid is not separated from cytoplasm by a membrane Euks - nuclear material is enclosed in a double membrane - nuclear envelope
Prokaryotic vs. Eukaryotic Cells
Prokaryotic vs. Eukaryotic Cells Changes from Proks to Euks: (1) DNA size and compactions (2) Cell size and organization (3) Early euk cells were endosymbiotic
Prokaryotic vs. Eukaryotic Cells Changes from Proks to Euks: (1) Euks have more DNA than proks so cells needed better ways to fold the DNA compactly into complexes (using proteins) so that the DNA was divided equally between daughter cells at cell division, complexes = chromosomes (chromatin) (2) Euk cells larger so needed a better system of intracellular membranes, so development of double membrane around DNA (nucleus); membrane separated nuclear process of RNA synthesis from cytoplasmic process of protein synthesis (3) Early euk cells, which were unable to perform photosynthesis or aerobic metabolism, enveloped aerobic /photosynthetic bacteria to form endosymbiotic species, some aerobic bacteria became mitochondria and some chloroplasts
Development of Eukaryotic Cells
Prokaryotic (bacterial) Cell
Prokaryotic Cells Two groups: Archaebacteria recently discovered live in extreme environments (salt lakes, hot springs, deep in ocean) Eubacteria most common well-studied (Escherichia coli/e. coli) inhabit soil, surface water, organisms
Eukaryotic Cell Animal cell Plant cell
Plasma membrane Eukaryotic Cell
Plasma membrane Eukaryotic Cell
Eukaryotic Cell Endoplasmic Reticulum (ER) Membrane-enclosed compartments Extends through cytoplasm Flattened branches = cisternae Smooth ER (lipid biosynthesis, drug metabolism) Rough ER (LOTS OF PROTEIN SYNTHESIS) -
Eukaryotic Cell Endoplasmic Reticulum (ER) Membrane-enclosed compartments Extends through cytoplasm Flattened branches = cisternae Smooth ER (lipid biosynthesis, drug metabolism) - Ribosome free Rough ER (LOTS OF PROTEIN SYNTHESIS) - Ribosomes attached ALSO free ribosomes - synthesize proteins that will remain in cytosol
Eukaryotic Cell Golgi Complex Membrane-enclosed compartments Extends through cytoplasm Flattened branches = cisternae Site of Types of Modifications
Eukaryotic Cell Golgi Complex Membrane-enclosed compartments Extends through cytoplasm Flattened branches = cisternae Site of processing, packaging and targeting of proteins Modifications - sulfate, carbohydrate, lipids, etc. Modification tags protein for its destination
Eukaryotic Cell Lysosomes Animal cells only Contain enzymes that digest Enzymes kept inside by membrane Lysosome ph - Enzymes within lysosome act best at ph
Eukaryotic Cell Lysosomes Animal cells only Contain enzymes that digest proteins, polysaccharides, nucleic acids, lipids Enzymes kept inside by membrane Lysosome ph - ATP-fueled proton pump keeps ph in lysosome at ~5.0 rather than 7.0 (in cytosol) Enzymes within lysosome act best at lower ph
Eukaryotic Cell Peroxisomes Purpose - Example: H 2 O 2 Catalase 2H 2 O 2 --> 2H 2 O + O 2
Eukaryotic Cell Peroxisomes Purpose - take up reactive chemical species that could otherwise damage cell machinery Example: H 2 O 2 Catalase 2H 2 O 2 --> 2H 2 O + O 2 Catalase at high concentration in peroxisome
Eukaryotic Cell Nucleus Contains cellular DNA (some DNA in mitochondria and chloroplast)
Nucleus Chromosomes = 2 chromatids Eukaryotic Cell Chromatin mass = 50% DNA, 50% histones DNA of single human chromosome forms ~1,000,000 nucleosomes
Eukaryotic Cell Most cells (somatic cells) have 2 copies of each chromosome Gametes, germline cells (egg and sperm) have only 1 copy of each chromosome
Mitochondria Eukaryotic Cell Diameter of ~1 µm (bacterial cells) 100s-1000 per cell Metabolic cells have more mitochondria Matrix has lots of enzymes and metabolic intermediates Have their own DNA, RNA and ribosomes Descendants of aerobic bacteria??
Eukaryotic Cell Cytoskeleton Meshwork through cytoplasm Provides structure and organization to cytoplasm and shape to cell
Viruses = Parasites of Cell Viruses Replicate themselves in host cells Contain DNA or RNA surrounded by a capsid (protective coat) Outside host cell, virus is nonliving particle (virion) Inside host cell, virus is parasite Uses host cells machinery to make more virus particles Turnip yellow mosaic virus (spheres) Tobacco mosaic virus (cylinders) Bacteriophage T4 HIV Poliovirus
Skeletal muscle cell Red blood cells Secretory cells of pancreas Sperm cells Human embryo at 2-cell stage