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Unit II: The Cell. All organisms are made of cells, the organism’s basic unit of structure and function. Size range of cells. How We Study Cells. Microscopes - light microscope - electron microscope (TEM/SEM). A Panoramic View of the Cell. Prokaryotic Eukaryotic
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Unit II: The Cell All organisms are made of cells, the organism’s basic unit of structure and function.
How We Study Cells Microscopes - light microscope - electron microscope (TEM/SEM)
A Panoramic View of the Cell Prokaryotic Eukaryotic +only in bacteria/archaebacteria Protists, Fungi, Plantae, Animalia +no true nucleus/nuclear envelope true membrane-bound nucleus +genetic material in nucleoid region genetic material in nucleus +no organelles many organelles
Animal vs. Plant Cell • Unique to Plant Cells: • - cell wall • - large central vacuole • Chloroplasts • Plasmodesmata • Unique to Animal Cells: • Centrioles • Lysosomes • - flagella and/or cilia
The Nucleus and Ribosomes Nucleus - enclosed by nuclear envelope - contains most of the genes that control the entire cell + DNA organized with proteins into chromatin - nucleolus Nuclear lamina – protein filaments that give structure to the inner nuclear membrane
The Nucleus and Ribosomes (con’t) Ribosomes - build proteins - RNA/protein complexes - free/bound
The Endomembrane System • Includes: • nuclear envelope • Endoplasmic reticulum • Golgi apparatus • Lysosomes • Vacuoles • Plasma membrane*
Endomembrane System (con’t) • Endoplasmic reticulum • manufactures membranes • two distinct regions • + smooth ER • - synthesis of lipids • - carbohydrate metabolism • - detoxify drugs/poisons • - stores calcium ions • + rough ER • - manufacture proteins for • secretion • - membrane production
Endomembrane System (con’t) • Golgi apparatus • finishes, sorts, and ships cell products • two poles • + cis face • + trans face Enzymes in the Golgi modify products of the ER in stages as they move through the Golgi stack from cis to trans face.
Endomembrane System (con’t) • Lysosomes – contain hydrolytic enzymes • digestive compartments • + intracellular digestion • + recycle cell material • + program cell destruction (apoptosis)
Endomembrane System (con’t) • Vacuoles • function in cell maintenance • + food vacuole • + contractile vacuole • + central vacuole (pictured) • - tonoplast
Other Membranous Organelles • Peroxisomes • consume oxygen for • metabolism • + contain specialized • teams of enzymes • - peroxide-producing • oxidases and catalase • RH2 + O2 -oxidase-> R + H2O2 • 2H2O2 -catalase-> 2H2O + O2
Mitochondria and Chloroplasts • energy transformers of cells • + double membranes • + contain ribosomes/DNA • Mitochondrial DNA is only passed on • by mom
The Cytoskeleton • Cytoskeleton • provides structural support • for motility and regulation • + network of fibers • - microtubules • - microfilaments • - intermediate filaments
Centrosomes • Found in animal & plant cells • Produce microtubules during cell reproduction • Animal cells contain centrioles which contain 9 sets of 3 microtubules
F L A G E L L A C I L IA
Cell Surfaces and Junctions • Cell Walls (1° & 2°) • cellulose fibers • Plasmodesmata • Middle lamella • Made of pectin • (sticky polysaccharide) • Pectin holds cell walls • together like concrete
Cell Surfaces and Junctions • ECM (Extra Cellular Matrix) • meshwork of macromolecules outside plasma membrane • + mostly glycoproteins (Collagen & proteoglycan) • + support/anchorage (Fibronectin & integrin)
Cell Surfaces and Junctions Tight junctions – prevent fluid from moving between cell layers in a tissue Desmosomes – anchor adjacent cells Gap junctions – allows the movement of cytoplasm, ions, sugars, amino acids from one cell to the next
Membrane Structure and Function Collagen proteoglycan Fibronectin
Membrane Structure and Function (con’t) • Plasma Membrane • boundary that separates living cell from • its non-living surroundings • + 8 nm thick • + selectively permeable • + unique structure relates to function
Phospholipid Glycerol Fatty Acid Chains Amphipathic molecule – has hydrophilic & hydrophobic regions
Membrane Structure and Function (con’t) • Fluid Mosaic Model • The Fluid Quality of Membranes • + held together by hydrophobic interactions • - lipids/proteins drift about laterally • + unsaturated hydrocarbon tails • - maintain fluidity at low temperatures • + cholesterol • - stabilizes the membrane • restrains movement at high temp. • hinders close packing at low temp.
Membrane Structure and Function (con’t) • Fluid Mosaic Model • Membranes as Mosaics • + membrane is collage of proteins • - integral proteins • transmembrane • - peripheral proteins • appendages
Membrane Structure and Function (con’t) • Functions of Membrane Proteins • Transport • Enzymatic Activity • Signal Transduction • Intercellular joining • Cell-cell recognition • Attachment to the cytoskeleton and ECM