Advanced Cell Bio Chapter 1
Advanced Cell Bio Chapter 1 BCMB 311
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This 0 page Class Notes was uploaded by Izabella Nill Gomez on Sunday January 24, 2016. The Class Notes belongs to BCMB 311 at University of Tennessee - Knoxville taught by Dr. Barry Bruce, Dr. J. Park in Spring 2016. Since its upload, it has received 14 views.
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Date Created: 01/24/16
Advanced Cell Biology Notes Chapter 1 Cells small membrane enclosed units lled with an aqueous solution of chemicals and the ability to create copies of themselves simplest forms of life Cell Biology study of cells and their structure function behavior Ces vary in shape and size and chemical requirements but have similar basic chemistry internally Genetic information inside cells is carried in DNA molecules In every cell DNA polymer chains are made from the same set of monomers nucleotides Information is encoded in DNA and transcribed to RNA which is translated to proteincentra dogma The appearance and behavior of a cell is dictated by its protein molecules which serve as structured supports chemical catalysts Proteins are built from amino acids all organisms use the same set of 20 amino acids to make proteins Amino acids are linked in different sequences for a different 3D shape conformation Protein is a single functional unit of architecture and functional properties in a cell How a cell organizes this machinery Cells function as aggregates tissues Properties above and beyond individual properties Common features of all cells Cell expansion and cell division Protein composition affects polarization of cell walls and connected membranes all surfaces are slightly different Viruses are chemical zombies inert and inactive outside host cells but can exert malign control over a cell once they can gain entry Mutations in a cell can create offspring that are malignant benign or bene cial Principles of genetic change and selection applied repeatedly over billions of cell generations are the basis of evolutionprocess by which living species become gradually modi ed and adapted to their environment in more sophisticated ways Evolution offers a compelling explanation as to why present day cells are similar in fundamentals all inherited genetic instructions come from the same common ancestor The ancestral cell existed between 35 and 38 billion years ago developed into different types of cells through the long process of mutation and selection A cell39s genomethe entire sequence of nucleotides in an organism39s DNA provides genetic program that instructs the cell how to behave For cells of plant and animal embryos the genome directs growth and development of an adult organism with hundreds of different cell types Can be varied developed during embryonic growth from one fertilized egg cell Different cells express different genes depending on the internal state and cues from surroundings Cells were made visible in the 17th century when the microscope was invented Light microscopes use visible light to illuminate specimens and allowed biologists to see the structure that underpins living things Electron microscopes 1930s use beams of electrons to be the source of illumination Extended the ability to see details of cells Using the light microscope Robert Hooke identi ed the rst cells The birth of cell biology occurred after 2 publications Schleiden in 1838 and Schwann in 1839 Documented the results of systematic investigation of plant and animal tissues with light microscopes The cell theory was eventually developed Louis Pasteur then con rmed that cells do not arise spontaneously but originate from other cells The theory of evolution by Charles Darwin explained divergence and similarities of different organisms In a section of tissue divided into thousands of small cells compacted or separated by extracellular matrix made of protein bers in a polysaccharide gel Each cell is about 520 I m in diameter The inside of the cell is transparent mostly colorlessseen by staining cells or using optical techniques Inside the cell the nucleus is in the middle The cytoplasm surrounding is transparent Fluorescence microscopes use sophisticated methods electron image processing 0 see uorescently labeled cell components in ner detail can push limits to identify even a ribosome which is a large macromolecular complex that is composed of proteins and RNA molecules Electron microscopy has the highest resolutionmagni cation Tissue must be xed preserved by solution supported by embedding in resinwax sectioned into thin slices and stained before viewed Cell components can then be organized into organellessubstructures with specialized functions Plasma membrane is separate cell interior from exterior environment Membranes surrounding organelles are internal Transmission electron microscopy can look at thin sections of tissue transmitting beams of electrons through the sample Scanning electron microscopy scatters electrons off the surface of the sample to look at surface detail of cells None of these can visualize individual atoms of the biological molecules use Xray crystallography Bacteria have the simplest structure of all cells Essentially contain no organelles no nucleus Eukaryotes are organisms that contain a nucleus Prokaryotes do not have Prokarya often have a tough coat on the cell wall surrounding the plasma membrane which encloses single compartment with cytoplasm and DNA Most live as singlecelled organisms although chainsclusters can form Chemically most diverse and inventive of cells Exploit many different habitats Organelles are subcomponents within the eukaryotic cell contain 2 double membranes When cells engulf bacteria vesicles and lysosomes consume via a hydrolytic process Mitochondria are thought to have evolved from aerobic bacteria that lived inside of anaerobic eukaryotes Almost any carboncontaining source is used for nutrient even C02 inorganic Some prokaryotes can perform photosynthesis others derive energy from chemical reactivity of inorganic substances in the environment Other living things depend on the organic compounds that these cells generate from inorganic materials Plants using photosynthesis also depend on bacteria to capture N2 from the atmosphere Chloroplasts evolved from photosynthetic bacteria that once found a home inside of a plant ancestor 2 domains of prokarya bacteria and archaea Archaea are found in extreme inhospitable habitats resembling from primitive Earth Eukaryotes are generally bigger more elaborate than bacteria and archaea The nucleus is usually the most prominent organelle enclosed within two membranes that form a nuclear envelope Contains more molecules of DNAong polymers with genetic information of the organism Chromosomes are compact versions of this information before the cell divides Mitochondria are present in almost all eukaryotic cells among the most conspicuous organelles in the cytoplasm Seem to be wormshaped structures with branching networks Individual mitochondria is enclosed in 2 separate membraneswith inner membrane formed into folds that project into interior of organelles Mitochondria are generators of chemical energy for the cell by harnessing energy from oxidation of food molecules like sugars to produce ATP to power cell activities Because mitochondria consumes oxygen and produces C02 in the course of the activity it39s called cellular respirationbreathing on a cellular level Without it organisms would be unable to use oxygen to extract the energy they need form food molecules Mitochondria contain their own DNA information to divide in two resembling bacteria Chloroplasts are large green organelles found only in the cells of plants and algae More complex than mitochondria possess internal stacks of membranes with pigment chlorophyll Carry out photosynthesistrapping energy of the sunlight in chlorophyll molecules in the process Photosynthesis is the fundamental metabolismmost farreaching energy source is solar radiation Chloroplasts release oxygen as a byproduct Plant cells can store the sugar for use and oxidize in mitochondria Chloroplasts have their own DNA In plant cells they have water transporters that stores in vacuole that has hydrostatic pressure that lls up but continues to keep a certain shape in leaves thanks to cellulose microfibersresists Turgor pressure The cell wall chloroplasts vacuole Golgi move around in plant cells Plastidspasticity in form and functionpigmentation granulespigments are accumulated from chloroplasts Chlorophyll membranes are packaged in discs grana in chloroplasts Thylakoids are where photosynthesis proteins are Photosynthesis is membrane process Chloroplasts and mitochondria were once considered prokarya Compartmentalization is the hallmark of eukarya 1 place for DNA many places for proteinsstamped with zipcode to correct organelleif traf cked causes problems like in Alzheimer s The ER is an irregular maze of interconnected spaces enclosed by a membrane site where most cellmembrane components as well as materials destined for export are made Enlarged in cells that specialize in secretion of proteins and contiguous with the nuclear envelopecontents are regulated Assembly site for many parts of the cell secretion proteins lipids transportation site Made on ribosomes attached to the ER Stacks of attened membraneenclosed sacks are Golgi apparatus which modi es and packs molecules made in ER for transportation The Golgi is attached by the Golgi matrix glue Specialized is vesicularization formed by pinching off No mixing of contents fusion is as precise as ssion Cis Golgi faces the ER trans Golgi faces away towards membranefunctionally distinct compartments Lysosomes are small irregular shaped organelles in which intracellular digestion occurs breaking down unwanted molecules by recycling or excreting from cells Peroxisomes are small membraneenclosed vesicles that provide a safe environment for a variety of reactions in which H05 Hydrogen Peroxide is used to inactivate toxic molecules Continual exchange of materials takes place between the ER Golgi lysosome and the outside of the cell mediated by transport vesicles that pinch from membrane of one organelle and fuse with another like tiny soup bubbles making big ones Endocytosis carries products from outside the cell exocytosis takes out The cytosol is part of the cytoplasm is not contained within intracellular membranes the largest single compartmentbehaves like waterbased cells Eukaryotic cells cytosol crisscrossed by long ne laments Filaments anchored to one end to the plasma membrane or radiate out from a central site adjacent to the nucleus cytoskeletoncomposed of actin laments abundant in muscle cells microtubules form hollow tubes are the thickest help align chromosomes in replication Intermediate laments which strengthen the cellgives shape ability to move strength The cytoskeleton39s function in cell division is most ancientseparates internal components into 2 daughter cells during cell division The cytosol is a dynamic jungle of protein ropes are continually strung together and taken apart Motor proteins use ATP to move along these cables carrying organellesproteins through the cytoplasm Large and small molecules that ll the free space are swept by thermal motion According to a theory ancestral eukaryotes were predators that fed by capturing other cells Requires large size exible membrane and a cytoskeleton to help the cell move and eat The nuclear envelope could have developed to keep DNA function in a physicalchemical lifestyle Most likely engulfed freeliving bacteria Partnership endued with oxygenrich levels Protozoans are freeliving motile microorganisms that prey on other cells Ex Didinium Swims at high speed by beating its ciia releases darts from the snout to paralyze then attaches and swallows Protozoans can be photosynthetic carnivorous motile or sedentary They can be intricate and versatile Model organisms contribute to our knowledge of biology through scienti c research and expand our understanding of how cells work Ecoi is a small rodshaped cell that normally lives in the gut of vertebrates This model organism has taught the fundamental mechanisms of life Yeast is a simple eukaryote singlecelled fungus with a rigid cell wall immobile with mitochondria but no chloroplasts Carries out basic task of eukaryotes Arabodopsis is a model plant a small weed that gives insight into the development and physiology of crop plants and evolution of other species Plants animals and fungi diverged 15 billion years ago and bacteria archaea eukarya 3 billion years ago Multicellular animals account for the majority of all named species of organisms and the majority are insects and Drosophila is used to study genetics and modes of inheritance Valuable model for studying human development and disease The nematode is also studied for developmental processes that occur in other organisms Ex known apoptosis programmed cell death by which surplus cells are disposed ofspecia for cancer research Zebra sh vertebratetransparent for the rst 2 weeks of life are also studied for developmental processes The mouse is also used to study mammalian genetics developmental immunology ce bioogyfor human disease At the molecular level evolutionary change is slow Evolutionary conservatism provides the foundation on which the study of molecular biology is built
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