Cell Biology Exam 1 Notes
Cell Biology Exam 1 Notes BIOL 231
University of Louisiana at Lafayette
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This 16 page Study Guide was uploaded by Karen Notetaker on Monday February 1, 2016. The Study Guide belongs to BIOL 231 at University of Louisiana at Lafayette taught by Patricia Mire-Watson in Spring 2016. Since its upload, it has received 82 views. For similar materials see Cell and Molecular Biology in Biological Sciences at University of Louisiana at Lafayette.
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Date Created: 02/01/16
Exam 1 Material Chapter 1 - Cells are so small (microscopic), but so complex and do so much. - Much of cell biology is unknown. - Cell sizes varies (At least 0.5 100μm) - Smallest visible length with the naked eye: about 1mm(1000μm) - Cell shapes range from Simple, Complex and Dynamic. o Simple: Round/Oval; Ex: Plant Cells o Complex: Have a lot of protrusions; Ex: Neurons, Paramecium with cilia: o Dynamic: Able to be changed; Ex: White Blood Cells that crawl by changing their shape: - Cell functions are specialized (show division of labor). Ex: Neuron transmitting electrical signals/WBC’s fighting infection through phagocytosis. Both cells/different functions - Common function: Cells are the basic units of life: FIG. 1-2 Replication, Transcription and Translation - To produce different functions, structure must be different - **Structure determines function** - Structure is made via proteins made from translation (RNAProtein) - All cells use transcription and translation. - Transcription = DNA RNA o All DNA is made of same bases - Translation – RNA Proteins o All proteins are made of same amino acids - Viruses ≠ cells because they are NONLIVING o Unable to do transcription/translation without help - Basic Chemistry in Cells = Same fundamental molecules & mechanisms for making these molecules o Due to this, it is believed that all cells share a common ancestor - How can we have same molecules but diverse forms? o Evolution - Evolution = Change over time: o Mutation = Type of evolution that results from changes in DNA: DNA has certain code for certain individuals. DNA replication normally results in perfect copies: Ex: AAGCGC AAGCGC DNA replication may be flawed resulting in a mutation: Ex: AAGCGC AAGGCG Mutated DNA codes for the wrong RNA, which then codes for the wrong proteins. Wrong proteins = wrong shape = wrong function - Cells have been around for 3.8 billion years - Cells pass on genetic info via DNA replication followed by division - Mutations also occur via radiation and adaptation - Natural Selection = Type of adaptation; Mutations already exist; Individuals better adapted will live on and pass down DNA; Enhances evolution: o AKA Survival of the Fittest - Same molecules, different forms? How? o Mutations (Changes in DNA) Mutated DNA Mutated RNAMutated ProteinsImproper folding/structureImproper function. Cells replicate DNA prior to division. - Mutated DNA can lead to different traits - Cells same DNA, different DNA? (Skin cells vs. Cardiac cells) o Skin cells for protection, Cardiac for muscle contraction: Both have same DNA due to mitosis, different gene expression through differentiation. o Differentiation – Certain genes expressed, others not; selective gene expression (Just because a cell HAS the DNA, does not mean it will USE all of it): Ex: Different cell types in multicellular organism with same genome (DNA)/different proteome(Proteins): - Genome – Total DNA in a cell: - Proteome – Total Proteins in a cell: o Makes one cell type different from another o Are different in each cell type (epitheleal, cardiac, respiratory, etc) TABLE 1-1 Discoveries in Cell Structures - Cell biology discoveries are based on new technological devthopment - 17 Century (1600’s) o Light microscope Hooke First to discover and name “cells” Discovered dead cells in pieces of cork o Cork comes from plants What he actually discovered was the places that living cells USED to be Named “cell” because it resembled the cells of a beehive Developed his own light microscope that allowed magnification to see smaller objects Leeuwenhoek First to see live cells (Protozoa and Bacteria) Protozoa = Protists Mostly saw single-celled organisms Called them “animalcules” because he thought they were tiny animals that moved around Obtained samples by scraping his teeth then observing under a microscope - 19 Century (1800’s) o Microscopes improve o More affordable/available o Able to see more o Developed better methods of grinding lenses to make them better Brown Discovered a common large construct in different types of cells that became known as the nucleus Cells were thought to be composed of a nucleus and water/chemicals because they couldn’t see the organelles in the cytoplasm Schleiden Botanist Discovered plant cells by looking at different pieces of plant material and noticing that there were cells in every kind of material Schwann Zoologist Discovered animal cells by looking at different pieces of animal material and noticing that there were cells in every th kthd of material - 19 & Early 20 Century (1800’s to 1950’s) o Discoveries include: Organelles, Cell Division, and Inner Structures of Cell Organelle – “Little Organ”; Structures that carry out a particular function just like an organ in the body Cell Division found through studying a variety of live cells; first dividing cells found under microscope Microscopes still improving allowing more people to look into cells th - Mid 20 Century (1950) o Electron microscope developed Have a higher resolution to magnify to a larger extent and still resolve the structures clearly. Allowing to see much smaller structures in cells enclosed in membranes (Cytoplasm, Cell membrane, Cytoskeleton, etc) Disadvantage: Long process to prep cells (About 2 weeks) o Cytoplasm view changes to include structures in cytoplasm (not empty space, but instead, very dense) FIG 1-8A - 1960’s o Confocal microscope Refers to the ability to collect light from single focal point in a cell Quick process that can be viewed the same day Used to see structures inside cells that have been labeled by fluorescent dyes Fluorescent molecules are used to label internal structures and molecules in cells o They absorb light of one wavelength, and emit another o Different colored dyes use to label different structures allow viewing of internal processes without having to prepare the cell for electron microscopy - 1990’s o Discovery of Green Fluorescent Protein (GFP) There are other colors now Label expressed proteins in living cells Can monitor gene expression Now know what protein codes for GFP Can put that gene into cells, attached to a gene for another protein so they are expressed together, and it will make a protein that fluoresces green and tell when expressed. o GFP discovered in Jellyfish - Modern Cell Theory 1) All living organisms are made of 1 or more cells. 2) All cells come from preexisting cells by cell division. PANEL 1-1 - Forms of Microscopy o Light Microscopy White light travels through glass lenses that bend and focus it toward the specimen and magnify image. Resolution limited to 0.2 μm by wavelength May be used to see dead or live cells, but may have a difficult time seeing them due to transparency. Brightfield (BF) – Good to see colored cells such as Euglena because of natural pigmentation (natural contrast) Phase Contrast (PC) – Best to see live cells Dark Field (DF) – Also good to see live cells; Black background, white image: PC and DF add contrast and allow to see cells that otherwise would be transparent (such as animal cells) Doesn’t kill the cell, at least not at first o Epiflouresence Light source comes from above Wavelengths selected by filter; dyes absorb that light’s (excitation) wavelength and emit another (emission) Second filter filters out light to show the emitted light Variation of the Light microscope o Confocal Laser; single wavelength Cells must be dead or they kill them High energy and very focused light Pinhole detects emitted light from specific area Better for seeing inside cell Clearer picture than Epiflourescense Doesn’t collect out of focus light - Electron o Uses beam of electron instead of light and uses electro magnets instead of glass lenses to bend/focus electrons o Must be metal-coated dead/highly processed o Increased resolution Flavors: 1)Transmission Electron Microscopy (TEM) Thin sliced 2D internal structure 2 nm resolution 2)Scanning Electron Microscopy (SEM) Whole specimen 3D surface 3-20 nm resolution - 2 Major Types of Cells: 1) Prokaryotic – “Before Nucleus”; Have no membrane-bound organelles, includes no nucleus: Still cells (Have DNA, proteins, ribosomes, a membrane and can reproduce) o Ribosomes play a role in making proteins Simple in structure (no organelles, etc) Single-celled organisms that typically live in chains or clusters o Can still survive on their own (reproduce on their own) Initially grouped together as Bacteria Can be in a variety of places Can use different sources for energy Differ greatly from each other with their genetics and other biochemical properties Have been divided into 2 groups: 1) Eubacteria – “True” Bacteria 2) Archaea – Extremophiles Love extreme environments (Thermal vents, Artic, etc) 2) Eukaryotic – “True Nucleus”; Have membrane- bound organelles; have a membrane-bound nucleus: - Single-celled type organisms = Protists(Euglena, Paramecium, Amoeba) - Eukaryotes much more complex than Prokaryotes - Yeast, which is a Fungus (eukaryote), is a single-celled organism. o Most eukaryotes are normally multicellular however Everything inside cell and outside nucleus = Cytoplasm consisting of cytosol (water/chemicals) and organelles: - Cytoplasm has molecules, ions, chemical rxns taking place, organelles, free ribosomes and cytoskeleton. - Organelles in Eukaryotic cells: o Nucleus Location of DNA housing True nucleus due to nuclear envelope surrounding it Envelope, not membrane, because it’s folded over to form a double membrane which allows transport of molecules in and out through pores o “Endo”membrane system (Plasma Membrane- outside of cell) Plasma membrane could have pieces separated to become integrated into the membrane of other structures in the cell (during import/export of materials) Plasma membrane forms “bubble” called a vesicle to transport material through cell Vesicles can fuse with membranes of structures in cell including the ER and the Golgi. Semi-permeable Allows certain things to travel in and out of cell PM exchanges material with extracellular fluid Also receives signals from environment (other cells, etc) o Mitochondria Makes ATP through cellular respiration through chemiosmosis ATP synthase uses gradient Also contains DNA Similar size and structure to chloroplasts from plant cells Both have 2 membranes and a lot of in- folding making a membrane inside the cell Chloroplasts also contain DNA o Endoplasmic Reticulum 2 Flavors: 1) Rough ER o Has ribosomes on surface Involved in proteins o Plays a role in protein synthesis o Makes the protein portion of membrane 2) Smooth ER o Makes lipid portion of membrane Can be of plasma membrane of cell or other organelles o Ribosomes Also called “Protein Factories” because that is where the cell makes them. Some are attached to ER Make proteins to be part of the membrane or secreted from cell Free ribosomes make free proteins(enzymes) to help with rxns in cell o Golgi Folded Packaging/modifying molecules for transport Receives molecules through vesicles, then sends molecules through a system of cisternae(membrane folds) After packaging is complete, molecule is released from other side by a vesicle and transported o Lysosomes and Peroxisomes Both involved in rxns breaking things down in a contained environment If was not contained, the products released could cause a problem for cell Peroxisome o Like a vesicle with material in it o Runs rxns containing H 2 2 Releases free radicals that could possibly steal electrons from other molecules Lysosome o Contains enzymes for cellular digestion o Cytoskeleton Filaments that are collectively providing support, internal organization, motility, and the shape of the cell Separated by width, not length Length can vary greatly 3 Types of Cytoskeleton filaments: Dynamic cytoskeleton filaments(can change their length: 1) Actin filaments 7 nm Aka microfilaments 2)Microtubules 20 nm in diameter ***Both are used in dynamic processes such as change in shape and movement of cell or cellular components Stable/Scaffold cytoskeleton filaments(structural support): 3) Intermediate 14 nm in length More permanent in cell Different types - Eukaryotic cells arose from PREDATORY Prokaryotic cells o Good predators have: Way to isolate what it takes in (membrane) Bigger size Speed o Evidence: Eukaryotic cells are bigger than prokaryotic cells Eukaryotic cells have cytoskeleton allows for faster and more dynamic motion Eukaryotic nuclear envelope also for protection - Mitochondria and Chloroplasts both have DNA, something needed for independence. o They can also independently divide. o Believed that they were once free-living prokaryotes that at some point were engulfed by bigger cells, but were not digested. Adaptation: Mitochondria make ATP for cells through cellular respiration Adaptation: Chloroplasts engulfed and able to create energy through photosynthesis - Endosymbionts: Mutual help: Chapter 2 - Cellular components in a bacterial cell: o Water – 70% o Polymers(Macromolecules) – 26% Proteins, Nucleic Acids, Lipids, etc o Monomers – 3% Amino Acids, Nucleotides, Fatty Acids, etc o Ions - Water o Polar molecule H is partially +, O is partially – Polar covalent bond hold an H O 2olecule together sharing electrons(O has greater electronegativity, receiving more electrons) Electronegativity – The strength of the pull on valence electrons by an element: Gives water its unique characteristics; suits it well to be the solvent for most reactions o Liquid at room temperature Unique because most substances are gases at room temp Due to hydrogen bonding that holds the H O 2 molecules together: Attraction btw/ one H(+)molecule to another molecule. o Due to opposite charges. o Solid water = less dense than at liquid state o High specific heat – heat needed to change temp by 1 degree C o Surface tension and Capillary Action o Surface tension – Cohesiveness to each other More cohesion than adhesion o Capillary Action – Adhesion to small diameter tubes Seen in trees o Single water molecule can form 4 H bonds. Stability depends on state of water Fewest = Gas o Because lots of kinetic energy Intermediate = Liquid Strongest = Solid Each H bond takes up space, but liquid allows the H bonds to be closer than solid and gas, leading to liquid being more dense than solid o Ability to form H bonds with other H O2molecules, but also with other molecules that are polar as well They exchange/pass a proton called ionization Can occur when something with polar covalent bonds is dissolved in water Can be called an Acid-Base reaction o Acid with hydroxyl group(polar) in water, proton moves over to the water molecule forming a Hydronium ion o The concentration of Hydronium ions in a solution is measured by the pH scale o More Hydronium ions, lower pH number (more acidic) o pH scale = 0-14 Neutral = 7 Acid = 0 - 6.9 (more Hydronium ions) Base = 7.1 – 14 Pure water has a concentration of - 7ydronium ions is 10 (where the 7 comes from) pH plays a part in a lot of the properties of molecules in cells as well as what chemical rxns take place in cells o Polar molecules like other polar molecules Also like charged particles Substances that like water = Hydrophillic Such as polar molecules, ionic molecules, and amphipathic molecules Substances that hate water = Hydrophobic Substance that likes/hates water = Amphipathic o Water polarity allows interactions of charged particles - 4 Types of Monomers: o Amino Acids Proteins o Monosaccharides Polyssacharides Monosaccharides 3 Carbon = Trioses 5 Carbon = Pentose o Deoxyribose 6 Carbons = Hexose o Nucleotides Nucleic Acids o Fatty Acids Lipids
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