Foundations of <a href="/keyword/biological-science/" >biological science</a> I (BioSci 150) C Cells... Structure and Function It is the cell that is alive! Therefore... study cells to study life. Foundations of <a href="/keyword/biological-science/" >biological science</a> I (BioSci 150) C A typical bacterium Prokaryotes lack organelles (internal membrane-bound structures) and have few or no internal membranes 1.0 mM Foundations of <a href="/keyword/biological-science/" >biological science</a> I (BioSci 150) C Generalized animal cell Nuclear envelope Nucleolus Chromatin Rough endoplasmic reticulum Centrioles Lysosome Ribosomes Smooth endoplasmic reticulum Gogli apparatus Peroxisome Mitochondrion Cytoskeletal element Cell membrane (Plasma membrane) 10 mM Centrioles are only found in animal cells. Figure 7.6a Foundations of <a href="/keyword/biological-science/" >biological science</a> I (BioSci 150) C Generalized plant cell Nuclear envelope Nucleolus Chromatin Rough endoplasmic reticulum Ribosomes Smooth endoplasmic reticulum Gogli apparatus Central vacuole Cell wall Chloroplast Peroxisome Plasmodesmata permit cell-cell contact Mitochondrion Cytoskeletal element 10 mM Cell membrane (Plasma membrane) Circled structures are only found in plant cells. Figure7.6b Foundations of <a href="/keyword/biological-science/" >biological science</a> I (BioSci 150) C Cell Sizes On average, prokaryotic cells are 1/10th the diameter of eukaryotic cells, and 1/1000th the volume. Organelle membranes increase the overall cellular membrane surface area, and serve to divide the cells labors. The membranes of organelles are semipermeable barriers to the exchange of molecules and particles with the cytoplasm. Foundations of <a href="/keyword/biological-science/" >biological science</a> I (BioSci 150) We study cells by breaking them open, separating their internal parts and asking what they do Differential Centrifugation: C Fig. 7.20b In pellet: nuclei mitochondria, chloroplasts, other... ribosomes Foundations of <a href="/keyword/biological-science/" >biological science</a> I (BioSci 150) Ribosomes: the smallest structure in the cell ...a protein synthesis machine that translates a nucleotide sequence in messenger RNA (mRNA) into an amino acid sequence (a polypeptide) eukaryotic and prokaryotic ribosomes are similar C polypeptide large subunit mRNA small subunit All cells have ,,em! Foundations of <a href="/keyword/biological-science/" >biological science</a> I (BioSci 150) The nucleus: the largest structure in a cell Cross-sectional view of nuclear envelope Nuclear pore C Surface view of nuclear envelope Cytoplasm chromatin in nucleus Inner membrane <a href="/keyword/outer-membrane/" >outer membrane</a> chromatin in nucleus Nuclear matrix Inner membrane Nuclear envelope <a href="/keyword/outer-membrane/" >outer membrane</a> Cytoplasm Nuclear pore complex Foundations of <a href="/keyword/biological-science/" >biological science</a> I (BioSci 150) C premise: If proteins are only made in the cytoplasm, premise: and, if proteins are found in the nucleus Then, proteins enter the nucleus after synthesis. A deduction... but how? 1. NUCLEOPLASMIN ...can be shown to enter the nucleus: Core &quot;Tails&quot; Label Nucleoplasmin in nucleus An argument: ? 1. Nucleoplasmin is a protein composed of a core and several &quot;tails.&quot; 2. Attach radioactive label. 3. Inject into cytoplasm of cell. 4. Wait, then locate labeled nucleoplasmin. 2. What allows a nucleus to recognize nucleoplasmin? Foundations of <a href="/keyword/biological-science/" >biological science</a> I (BioSci 150) C Hypothesis: a specific part of the protein is required for nuclear transport. nuclear localization signal Foundations of <a href="/keyword/biological-science/" >biological science</a> I (BioSci 150) C Large particles (like ribosomal subunits) and large molecules actually do move in and/or out of the nucleus through pores: Nucleus Nucleus Cytoplasm Cytoplasm Micro-injected particles move through pores Foundations of <a href="/keyword/biological-science/" >biological science</a> I (BioSci 150) Macromolecules and ribosomal subunits move in and out of nucleus DNA mRNA DNA archives instructions RNA is a copy of the instructions C Ribosome Some proteins enter nucleus and assist with copying DNA or making RNAs mRNA RNA instructions are used to make proteins Proteins are shipped to specific locations in the cell Protein Foundations of <a href="/keyword/biological-science/" >biological science</a> I (BioSci 150) C Rough endoplasmic reticulum (RER), Golgi vesicles and the <a href="/keyword/outer-membrane/" >outer membrane</a> of the nuclear envelope are part of a cellular endomembrane system... Foundations of <a href="/keyword/biological-science/" >biological science</a> I (BioSci 150) C Rough endoplasmic reticulum (RER) Synthesis of ,,packaged or secreted proteins ...part of endomembrane system Foundations of <a href="/keyword/biological-science/" >biological science</a> I (BioSci 150) C Golgi Vesicles Part of endomembrane system... Foundations of <a href="/keyword/biological-science/" >biological science</a> I (BioSci 150) C nucleus RER Golgi vesicles secretion cis face trans face Secreted &amp; other ,,packaged proteins move through parts of the endomembrane system. Lysosome Foundations of <a href="/keyword/biological-science/" >biological science</a> I (BioSci 150) C Lysosome: a bag of digestive enzymes that catalyze the hydrolysis of DNA, RNA, proteins, CHOs, fats, etc. Lysosomes function during the digestion of bacteria by white blood cells (phagocytes), and in tissue remodeling that occurs during development, wound healing, metamorphosis, etc. Foundations of <a href="/keyword/biological-science/" >biological science</a> I (BioSci 150) C Directing the traffic of secretory and lysosomal proteins: Proteins destined for secretion or packaging in lysosomes have a specific amino acid sequence address label... Foundations of <a href="/keyword/biological-science/" >biological science</a> I (BioSci 150) C NH2 Other functions of the RER and Golgi vesicles include the addition of sugars to proteins to make glycoproteins. carbohydrate group COOH Foundations of <a href="/keyword/biological-science/" >biological science</a> I (BioSci 150) smooth endoplasmic reticulum (SER) (no ribosomes attached) C In liver &amp; other cells, detoxification Foundations of <a href="/keyword/biological-science/" >biological science</a> I (BioSci 150) C Mitochondria: the site of respiration and most ATP synthesis in cells <a href="/keyword/outer-membrane/" >outer membrane</a> Intermembrane space Inner membrane Matrix Cristae 424 nm DNA (in the matrix) Figure 7.16 Note the inner and <a href="/keyword/outer-membrane/" >outer membrane</a> s and the increased surface area of the cristae Foundations of <a href="/keyword/biological-science/" >biological science</a> I (BioSci 150) C Chloroplasts the site of photosynthesis in green plants. green because they contain chlorophyll. like mitochondria, have inner &amp; <a href="/keyword/outer-membrane/" >outer membrane</a> s. thylakoid membranes contain enzymes to reduce CO2. Figure 7.17 Granum <a href="/keyword/outer-membrane/" >outer membrane</a> Inner membrane DNA Thylakoids Stroma Foundations of <a href="/keyword/biological-science/" >biological science</a> I (BioSci 150) C The endosymbiotic theory: mitochondria and chloroplasts were free-living bacteria and cyanobacteria ,,eaten but not digested by early eukaryotic cells. The symbiosis evolved into a non-parasitic relationship benefiting the host and perhaps the endosybiont as well. Foundations of <a href="/keyword/biological-science/" >biological science</a> I (BioSci 150) C Evidence for the endosymbiotic theory: Mitochondria &amp; chloroplasts dimensions are similar to those of bacterial and cyanobacteria, respectively. The organaisms &amp; organelles have similar size circular DNA molecules. The organelles replicate &amp; transcribe their genes and translate mRNAs with their own ribosomes. Foundations of <a href="/keyword/biological-science/" >biological science</a> I (BioSci 150) Structures of the Cytoskeleton microfilaments Fig 7.32 C intermediate filaments microtubules Foundations of <a href="/keyword/biological-science/" >biological science</a> I (BioSci 150) The Mammalian Cell Cytoskeleton seen by Immunofluorescence Microscopy Fluorescence micrograph showing mesh-like distribution of intermediate filaments C Fluorescence micrograph showing distribution of microfilaments along axes of movement Fig 7.33a,b Cytoskeleton components help maintain cell shape Foundations of <a href="/keyword/biological-science/" >biological science</a> I (BioSci 150) C Motor proteins Kinesin &quot;walks&quot; along a microtubule track Transport vesicle ATP Kinesin ADP+Pi ATP ADP+Pi Microtubule Cell motility involves cytoskeleton components... e.g., neuronal transport of neurotransmitters Figure 7.37b Foundations of <a href="/keyword/biological-science/" >biological science</a> I (BioSci 150) C The Roles of Cytoskeletal Filaments Microfilaments: motility (e.g., muscle) &amp; structure Intermediate filaments: structure Microtubules: structure &amp; motility (e.g., vesicle transport, cilia, flagella, mitotic spindle...) Foundations of <a href="/keyword/biological-science/" >biological science</a> I (BioSci 150) C Protozoa with typical cilia and flagella: Cilia Figure 7.38 Flagella Foundations of <a href="/keyword/biological-science/" >biological science</a> I (BioSci 150) C The structure of eukaryotic cilia &amp; flagella: axoneme Cell membrane Central pair Outer doublet Dynein Bridge Spoke Figure 7.39a, b Typical &quot;9 + 2&quot; arrangement of microtubules Foundations of <a href="/keyword/biological-science/" >biological science</a> I (BioSci 150) C Sliding microtubules cause cilia and flagella to bend: Like Figure 7.4 Foundations of <a href="/keyword/biological-science/" >biological science</a> I (BioSci 150) C Cell-Cell Interactions Cell surface structures allow: Cell-cell recognition Cell-cell attachment Cell-cell communication Foundations of <a href="/keyword/biological-science/" >biological science</a> I (BioSci 150) C The cell surface: out CHOs on glycoproteins integral mp peripheral mp in Figure 8.1 Foundations of <a href="/keyword/biological-science/" >biological science</a> I (BioSci 150) C The ECM Serves to attach cells to surfaces (e.g., epithelial cells that line your intestines). promotes cellcell interactions (to form tissues and organs). Foundations of <a href="/keyword/biological-science/" >biological science</a> I (BioSci 150) C Cell Junctions e.g., intestinal epithelial cells microvilli tight junctions water-tight seal desmosomes like a rivet gap junctions communication via ion flow Foundations of <a href="/keyword/biological-science/" >biological science</a> I (BioSci 150) C Some cell-cell signals enter the cell and bind to an intracellular hormone receptor protein to cause a response... Foundations of <a href="/keyword/biological-science/" >biological science</a> I (BioSci 150) C ...but other cell-cell signals cant cross the plasma membrane. These molecules bind to cell-surface hormone receptor proteins. e.g., adrenalin e.g., insulin receptor receptorkinase ATP ADP G-protein ATP ADP kinases... AT AD There are two types of signal transduction... G-proteindependent enzyme 2nd messenger activates kinases kinases activate proteins in phosphorylation cascades cell responses Foundations of <a href="/keyword/biological-science/" >biological science</a> I (BioSci 150) C In fact, protein phosphorylation is a general mechanism cells use to regulate their activities. Foundations of <a href="/keyword/biological-science/" >biological science</a> I (BioSci 150) C End of Power Point Presentation