Unit 1 Study Guide
Unit 1 Study Guide CELL-1010-01
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This 13 page Study Guide was uploaded by Samantha R on Sunday March 27, 2016. The Study Guide belongs to CELL-1010-01 at Tulane University taught by Vijayaraghavan, Meenakshi in Fall 2015. Since its upload, it has received 37 views. For similar materials see Intro to Cell & Molec Biology in Business at Tulane University.
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Date Created: 03/27/16
Chapter 1: Introduction to Biology Tuesday, February 9, 2017:29 PM Principles of Biology 1. Cells & Organization ○ Must consists of 1+ cells Cell: A macromolecule that has a source of information that is membrane bound (separating it from other cell contents) 2. Energy Use & Metabolism ○ Must possess the capacity to extract & utilize energy ○ Metabolism: Chemical reactions involved in the breakdown & synthesis of cellular molecules Catabolism: Process of breaking down energy Anabolism: Process of making energy ○ Autotroph vs Heterotroph Autotroph □ Chemoautotroph: Obtain energy via chemical reactions (oxidation) of inorganic compounds. □ Photoautotroph:Obtain energy via photosynthesis (light) & can use CO 2s principle source of carbon Heterotrophs □ Utilizes cellular respiration (Type of metabolism) 3. Response to Environmental Changes 4. Regulation & Homeostasis 7 CHARACTERISTICS OF LIFE 5. Growth & Development ○ How would you observe growth & development in a unicellular organism? *Increase in density 6. Reproduction ○ DNA allows genes to be passed on (heritability) ○ Reproduction is required to sustain life 7. Biological Evolution ○ Variation is the raw material for evolution ○ The more you are exposed to something the more you develop an ability 8. All Species are Related (Evolution) ○ Genome: Complete genetic composition of organism ○ Proteome: Protein composition of organism 9. Structure Determines Function ○ Analogous vs Homologous Structures 10. Emergent Properties & Interactions ○ Emergent Properties: New structures/functions that emerge from interactions with ecosystem Levels of Organization Diversity & Unity • Evolutionary History ○ Vertical Descent with Mutation Mutations → Kept by natural selection ○ Horizontal Gene Transfer Exchange of genetic information between differentspecies • Unity (Evolutionary Conservation) ○ All modern forms of life display a common set of characteristics Unit 1 Study Guide Page 1 ○ Horizontal Gene Transfer Exchange of genetic information between differentspecies • Unity (Evolutionary Conservation) ○ All modern forms of life display a common set of characteristics CLASSIFICATION ○ Prokaryotes & Eukaryotes Prokaryotes (Bacteria & Archaea) □ Unicellular Eukaryotes (Eukarya) □ Complex cells, multi cellular (some are unicellular) □ Nucleus (enclosed by a nuclear membrane) □ Cellular organelles are enclosed by membranes □ What do they have in common with Prokaryotes? --- Contain nucleotides in DNA □ 4 Kingdoms 1. Protista 2. Fungi ◊ Extracellular digestion ◊ Chitonous/Chitinous Wall 3. Plantae ◊ Photosynthesis ◊ Cellulose Wall 4. Animalia ◊ Cell Wall Genomes & Proteomes • Genome: The complete genetic makeup of an organism ○ Genomics: Techniques used to analyze DNA sequences in genomes • Proteome: The complete complement of proteins that a cell or organism can make ○ Proteomics: Techniques used to analyze the proteome of a single species and the comparison of proteomes of different species • The genome carries the information to make its proteome Biology as a Science • Hypothesis vs Theory ○ Hypothesis Proposed explanation for a natural phenomenon based on previous observations Predictions that can be shown to be correct or incorrect ○ Theory Broad explanation of some aspect of the natural world that is substantiated by a large body of evidence Allows us to make many predictions NEEDS CONSISTENCY & WIDE APPLICABILITY ○ Both can never be proven • Reasoning ○ Inductive Reasoning: Specific observati→nsGeneral conclusions Adding new information ○ Deductive Reasoning: General principl→s Specific results Using previous knowledge • Scientific Method 1. Observations made 2. Hypothesis 3. Experiment 4. Analyze Data 5. Reject/Accept Hypothesis Unit 1 Study Guide Page 2 Chapter 2: Chemical Basis of Life I (Atoms, Molecules, & Water) Tuesday, February 9, 20168:39 PM Atoms • Matter: Anything that contains mass & occupies space • Atoms Smallest functional units of matter that form all chemical substances and that cannot be further broken down into other substances by ordinary chemical or physical means. Each specific type of atom is a chemical element • All living organisms are a collection of atoms and molecules. • 3 Subatomic Particles Protons: positive, found in nucleus, same number as electrons # of Protons = Atomic # Neutrons: neutral, found in nucleus, number can vary Electrons: negative, found in orbitals, same number as protons • Entire atom has no net electric charge • Orbitals Each orbital can hold only 2 electrons S orbitals are spherical P orbitals are propeller or dumbbell shaped ○ Atoms with progressively more electrons have orbitals within electron shells that are at greater and greater distances from the center of the nucleus 1st shell (1s) □ 1 spherical orbital (1s) □ Holds 2 electrons 2nd shell (2s & 2p) □ 1 spherical orbital (2s) & 3 dumbbell-shaped orbitals (2p) □ Can hold 8 electrons 2e from (2s) & 6e from (2p) Periodic Table • Organized by atomic number • Rows correspond to number of electron shells • Columns indicate the number of valence electrons ○ Same # of valence electrons = similar chemical bonding properties • Octet Rule ○ Inert atoms have outer level filled. (STABILITY) ○ Reactive atoms do not have outer level filled. ○ For many atoms, the outer shell fills with 8 electrons Except Hydrogen (2e in outer shell) • Units ○ Mass vs Weight Mass is the amount of substance □ Atomic mass of an atom refers to the sum of the masses of protons and neutrons. MEASURED IN DALTONS (1 dalton = 1/12 of the mass of carbon) Protons and neutrons are more than 1,800x the mass of an electron Weight is that amount & its interaction with gravity ○ Moles 1 mole of an element = 6.022 10 atoms (Avogrado's #) • Isotopes ○ Multiple forms of an element that differ in the number of neutrons. ○ Same chemical properties ○ Different atomic mass • Hydrogen, oxygen, carbon, and nitrogen ○ Typically make up about 95% of the atoms in living organisms Hydrogen & oxygen occur primarily in water Nitrogen is found in proteins Carbon is the building block of all living matter Unit 1 Study Guide Page 3 Carbon is the building block of all living matter ○ Mineral elements - less than 1% ○ Trace elements - less than 0.01% Essential for normal growth and function Chemical Bonds & Molecules • Molecule: 2+ atoms • Compound: Molecule of 2+ elements • 3 Types of Bonds ○ Covalent Atoms share a pair of electrons Strongest of all chemical bonds (stable) □ Shared electrons behave as if the belong to each atom Single, double, & triple covalent bonds can occur Polar Covalent Bond: 2 atoms with different electronegativities form a covalent bond □ Electronegativity: An atom's ability to attract electrons & bond with another atom □ Shared electrons more likely to be in outershell of more electronegative atom □ POLAR MOLECULES Oxygen is more electronegativein this bond Nonpolar Covalent Bond: Between atoms with similar electronegativity ○ Hydrogen ALSO A POLAR COVALENT BOND Weak polar covalent bond Occurs when a hydrogen atom from one polar molecule is attracted to an electronegative atom in another polar molecule. Collectively strong, individually weak (form/break easily) □ Holds DNA strands together (strong) □ Substrate & enzyme bonding (weak) Enzymes facilitate & catalyze chemical reactions HOLDS DNA STRANDS Van Der Waals Forces □ Arise from random orbiting of electrons ○ Ionic Ion: atom/molecule with electronic charge (loses/gains electrons) Occurs from a cation & anion bonding □ Cation + □ Anion - • Molecules May Change Shapes ○ Covalent molecules are flexible Bonds form at fixed angles but they can still rotate on a sort of axis ○ Free Radicals: A molecule/compound containing an atom with a single unpaired electron in its outer shell. (O2-, OH, NO) Formation: radiation or toxins Effects: Rupture of cell membrane, genotoxin (damages genetic material) □ If you have one free radical it can create more free radicals □ Harmful effects – killing healthy cells (occurs active) □ Beneficial aspects – destroy infective agents; (ex. Hydrogen peroxide) Assimilating food containing antioxidants Can be charged or neutral • Chemical Reaction ○ Occurs when 1+ substances are changed into other substances Breaking old bonds & forming new bonds ○ All eventually reach chemical equilibrium ○ Require energy source ○ Often require catalyst (enzymes) Properties of Water • Aqueous Solution (water is solvent) • Hydrophilic ○ Ionic & polar covalent molecules • Hydrophobic Unit 1 Study Guide Page 4 • Aqueous Solution (water is solvent) • Hydrophilic ○ Ionic & polar covalent molecules • Hydrophobic ○ Molecules composed of primarily hydrogen & carbon (nonpolar bonds) They will dissolve in nonpolar solvents • Amphipathic Molecule: Have both polar or ionized regions @ 1+ sites & nonpolar regions at other sites ○ May form micelles in water Polar (hydrophilic) regions at the surface of the micelle & nonpolar (hydrophobic) ends are oriented toward the interior of the micelle' ○ May form bilayers (consist of 2 hydrophilic layers) • Solutions ○ Concentration (solute mass/solution volume -- g/L) ○ Molarity (solute moles/1 L water -- mol/L) • Water in 3 States of Matter ○ Stable as a liquid ○ High heat of vaporization & fusion ○ High specific heat Specific Heat: Amount of heat energy required to raise 1 gram of substance by 1°C) Allows for water to maintain stable temperatures in large bodies ○ Living organisms have evolved to function best within a range of temperatures consistent with the liquid phase of water. • Colligative Properties of Water ○ Colligative Properties: Depend on the total # of dissolved solutes not @ 1°C ○ Addition of solutes to water lowers its freezing point below 0°C and raises its boiling point above 100°C • Not just a solvent ○ Water has many important functions in living organisms Participates in chemical reactions □ Hydrolysis or dehydration (type of condensation reaction) Provides force or support Remove toxic waste components Evaporative cooling (sweating) Cohesion -water droplets attract each other) Adhesion -water is attracted to & adheres to charged surfaces it can bond to) Acids & Bases • Pure water has the ability to ionize to a very small extent into hydrogen ions (H+) and hydroxide ions (OH-) • In pure water: + - -7 -7 -14 [H ][OH ] = [10 M][10 M] = 10 M • Acids are molecules that release hydrogen ions in solution ○ A strong acid releases more H+ than a weak acid • Bases lower the H+ concentration ○ Some release OH- ○ Others bind H+ • pH ○ pH = - log10 [H+] ○ Acidic solutions are pH 6 or below ○ pH 7 is neutral ○ Alkaline solutions are pH 8 or above ○ The pH of a solution can affect: The shapes and functions of molecules The rates of many chemical reactions The ability of two molecules to bind to each other The ability of ions or molecules to dissolve in water • Buffers ○ Organisms usually tolerate only small changes in pH ○ Buffers help to keep a constant pH ○ An acid-base buffer system can shift to generate or release H+ to adjust for changes in pH Unit 1 Study Guide Page 5 changes in pH Unit 1 Study Guide Page 6 Chapter 3: Basis of Life II (Organic Molecules) Wednesday, February 10, 20164:29 PM Organic Chemistry • Organic Molecules contain carbon • Carbon ○ 4 Valence Electrons ○ Forms polar or nonpolar bonds Ex) Nonpolar Hydrocarbons ○ Small atom → Short Bond → Strong Bonds • Functional Groups: Groups of atoms with special chemical features that are functionally important ○ Always exhibits the same properties in all molecules ○ Examples: Amino -NH 2 Amino Acids (Proteins) Carboxyl -COOH Amino & Fatty Acids Hydroxyl -OH Steroids, Alcohol, Carbohydrates ○ Methyl -CH3 Attached to DNA, Proteins, & Carbohydrates 2 Phosphate -PO -4 Nucleic Acids, ATP, Phospholipids - Sulfate -SO4 Attached to Lipids, Proteins, & Carbohydrates • Isomers: 2 Structures with an identical molecular formula but different structures & characteristics ○ Structural Isomers: Contain same atoms but in different bonding relationships ○ Stereoisomers: Identical bonding relationships, but different spatial positioning of atoms. Geometric Isomers: Positioning around double bond □ CIS = same side (next to each other) □ TRANS = opposite side Enantiomers: Mirror image of another molecule Organic Molecules & Organic Molecules • Monomers are small molecules that link together to form polymers ○ Macromolecules are often polymers • Condensation Reaction: When 2+ molecules combine with the loss of a small molecule ○ Dehydration Reaction: 2+ molecules combine to form a larger molecule & a water molecule (the water molecule is removed after this occurs) Removes OH & H • Hydrolysis Reaction: Polymer is broken down into monomers; water molecule is added back for each monomer released) ○ Breaks a covalent bond via adding OH & H (hydrolytic cleavage) *BOTH OF THESE ARE CATALYZED BY ENZYMES* ~4 Types of Organic (Macro)molecules~ • Carbohydrates ○ Composed of Carbon, Hydrogen, & Oxygen (1:2:1 Ratio) ○ Most carbons are linked to a hydrogen & hydroxyl group ○ Glycosidic covalent bond ○ Good for energy storage C-H bonds release energy during oxidation ○ Ex) Sugars Monosaccharides: Monomer sugars □ Glyceraldehyde 3-Carbons (Simplest) □ Pentoses: Ribose & Deoxyribose Part of RNA & DNA molecules □ Hexose: Glucose Water-soluble Glucose Isomers: ◊ Structural: Glucose & Fructose ◊ Stereoisomers Geometric: α- & β- Enantiomers: D- & L- Disaccharides: Carbohydrates composed of 2 monosaccharides □ Joined by dehydration or condensation □ Broken apart by hydrolysis □ Ex) Sucrose □ Transport Disaccharides Humans: Transport glucose as monosaccharide Plants: Transform glucose into a disaccharide transport form. Polysaccharides: Many monosaccharides linked together to form long polymers □ Examples: Unit 1 Study Guide Page 7 □ Examples: Energy Storage: ◊ Starch (plants) ◊ Glycogen (animals) Structural Role: ◊ Cellulose (plants) --cell wall ◊ Chitin (insects & fungi) --cell wall & exoskeleton ◊ Glycosaminoglycans (animals) --cartilage • Lipids ○ Composed of predominantly hydrogen & carbon ○ Triglycerides: Glycerol bonded to 3 fatty acids TRYGLYCERIDE Joined by dehydration or condensation Broken apart by hydrolysis Nonpolar = Hydrophilic Fatty Acid: Chain of carbon & hydrogen with a carboxyl group at one end Glycerol: 3-carbon molecule with a hydroxyl group bonded to each carbon Each hydroxyl group is linked to the carboxyl group (via dehydration) Fatty Acids □ Saturated: all carbons are linked by single covalent bonds Tend to be solid @ room temp. □ Unsaturated: contain 1+ double bonds Monounsaturated: 1 double bond Polyunsaturated: 2+ double bonds Tend to be liquid @ room temp Fats are important for energy storage PHOSPHOLIPID □ Holds 2x as much energy as starch/glycogen Fats can be structural □ Providing cushioning & insulation ○ Phospholipids: 2 fatty acids & a phosphate group Amphipathic Molecule (contains polar & nonpolar regions) □ Phosphate group = Polar (hydrophilic) Often a nitrogen containing, polar group attached @ head □ Fatty Acid = Nonpolar (hydrophobic) ○ Steroids: 4 interconnected rings of carbon atoms Not very water-soluble Ex) Cholesterol, Estrogen, Testosterone □ Cholesterol can be converted to other steroids by modifying side groups ○ Waxes: 1+ hydrocarbons, long fatty acid structure, & a hydrocarbon chain Nonpolar (hydrophobic) □ Barrier to water loss Forms structural elements (EX: Bees wax/honeycomb) ○ Terpenes: Long chain of lipids • Proteins ○ Composed of carbon, hydrogen, oxygen, nitrogen, & small amounts of other elements (notably sulfur) ○ Proteins are made up of Amino Acid Monomers Amino Acid: α-carbon linked to: amino group, carboxyl group, hydrogen, & a side chain □ Side Chain (R Group) determines structure & function □ N-Terminus: Amino group end □ C-Terminus: Carboxyl end *Carboxyl is always on the right & amino on the left Types of Amino Acids & Their R GROUP: Type R Group Nonpolar CH 2r CH 3 Polar Uncharged -O o2 -H Charged Acids or Bases Aromatic Aromatic Carbon Ring Special-Function Particular Position & Function ○ Joined by dehydration or condensation Peptide Bond (between carboxyl & amino group) Forms Polypeptides: Proteins made up of 1+ polypeptides ○ Broken apart by hydrolysis ○ Protein Structure (4 Progressive Levels) i. Primary □ Linear sequence of amino acids □ Sequence is determined by genes ii. Secondary Unit 1 Study Guide Page 8 i. Primary □ Linear sequence of amino acids □ Sequence is determined by genes ii. Secondary □ Spiral (α helix) & Pleated sheet (β sheet) Key determinants in protein's characteristics □ Motif: Random coiled regions (super secondary structures) Shape is specific & important to function □ Irregular or repeating □ Chemical & physical interactions cause folding iii. Tertiary □ 3-D shape of one coiled polypeptide iv. Quaternary □ 2+ polypeptides binded to each other to form a functional protein □ Protein Subunits: Individual polypeptide chains Form Multimeric Proteins (consist of 2+ polypeptides) ○ 5 Factors Promoting Protein Folding: i. Hydrogen Bonds (collectively strong & stable) ii. Ionic Bonds (Polar interactions) iii. Hydrophobic Effects (nonpolar, likely in center of protein) iv. Van der Waals Forces (attractive forces @ specific distance) v. Disulfide Bridges (covalent bond b/w 2 cysteine side chains) *1-4 are protein-protein interactions* ○ Proteins Contain Functional Domains Within Their Structures Domains: Portions of proteins with distinct structures & function • Nucleic Acids ○ Responsible for the storage, expression, & transmission of genetic information ○ 2 Classes: DNA □ Store genetic information coded in the sequence of their monomer building blocks (nucleotides) RNA □ Involved in decoding this information into instructions for linking together a specific sequence of amino acids to form a polypeptide chain ○ Structure: Phosphate group, 5-Carbon sugar (ribose or deoxyribose), & a single or double ring of carbon & nitrogen (base) □ Sugar-Phosphate backbone ○ DNA vs RNA DNA RNA Deoxyribose Ribose Thymine (T) Uracil (U) Adenine (A), Guanine (G), Adenine (A), Guanine (G), & Cytosine (C) & Cytosine (C) Double Helix (2 Strands) 1 Strand 1 Form Several Forms (mRNA, rRNA, etc.) Unit 1 Study Guide Page 9 Chapter 4: General Features of Cells Wednesday, February 10, 2019:00 PM Cell Theory • All living things are composed of 1+ cells • Cells are the smallest units of living organisms • New cells come only from pre-existing cells via cell division Microscopy • Magnification: Ratio between size of image produced & its actual size • Resolution: Ability to observe 2 adjacent objects as distinct from one another (clarity) • Contrast: How different one structure looks from another ○ Can be enhanced using dyes • Light Microscope ○ Resolution: 0.2 μm ○ Confocal Microscope gives best focus & resolution among light microscopes • Electron Microscope ○ Resolution: 2 nm ○ Transmission Electron Microscopy Thin slices stained with heavy metals Some electrons scattered, others pass through to form an image BEST FOCUS & RESOLUTION OF ALL MICROSCOPES ○ Scanning Electron Microscopy Sample coated with heavy metal Beam scans surface to make 3D image Cell Characteristics Prokaryotic Eukaryotic • DNA Nucleus Cytoplasm Ribosomes Nucleoid Region Nucleus (Lack nuclear membrane) Unicellular Uni/Multicellular Archaea & Bacteria Eukarya Bacteria Cell • Plasma Membrane: Barrier • Cytoplasm: Contained inside plasma membrane • Nucleoid: Region where genetic material is found (DNA) • Ribosomes: Involved in protein synthesis • Plasmid: Genetic structure that replicates independently of DNA ○ Help with antibiotic resistance ○ Usually non-virulent (can be broken down by antibodies) • Cell Wall: Support & protection (peptidoglycan) • Glycocalyx: Traps water, protection ○ Capsule - may help evade immune system, protects from antibodies ○ Predominately carbohydrate ○ Allows cell to adhere to the surface via moisture • Pili: Attachment • Flagella: Locomotion ○ Made up of protein (flagellin) • Folds increase surface are→ increase amount of proteins & pigments on plasma membrane → enabling special functions (ex: photosynthesis) Eukaryotic Cell • DNA housed in nucleus • Compartmentalization • Organelles: Sub-cellular structure/membrane-bound compartment with unique structure & function • Shape, size, & organization vary • DOESN'T HAVE: Chloroplasts & Cell Wall Unit 1 Study Guide Page 10 • DOESN'T HAVE: Chloroplasts & Cell Wall Proteome Determines the Characteristics of a Cell • Identical DNA in different cells but different proteomes • The proteome of a cell determines its structure & function • Influence on Cell's Proteome: ○ Gene Regulation ○ Amount (persistence & concentration) of protein ○ Different amino acid composition/sequence of a particular protein ○ Protein Modification Cytosol • Outside organelles but inside plasma membrane • Cytoplasm includes EVERYTHING inside plasma membrane (cytosol, endomembrane system, organelles) • Metabolism ○ Cytosol is the central coordinating region for many metabolic activities ○ Catabolism: Breakdown of a molecule into smaller components (glycolysis) ○ Anabolism: Synthesis of cellular molecules & macromolecules Translation: Process of polypeptide synthesis □ Information within a gene is ultimately translated into the sequence of amino acids in a polypeptide □ Ribosome: Site of Synthesis □ tRNA: Brings amino acids MICROTUBULES INTERMEDIATE FILAMENTS ACTIN FILAMENTS □ mRNA: Information to make a polypeptide • Cytoskeleton: Network of 3 types of protein filaments 1. Microtubules Long, Hollow, Cylindrical Dynamic Stability: Can grow & shorten 2. Intermediate Filaments Twisted, rope-like *Within centrosomeare centrioles 3. Actin Filaments Long, Thin fibers • Motor Proteins: Category of cellular proteins that use ATP as a source of energy to promote movement ○ 3 Domains: Head, Hinge, Tail ○ 3 Different Kinds of Movements WITH CYTOSKELETON Protein moves the cargo from one location to another Protein remains in place & causes filament to move Attempting to walk (both motor protein & filament restricted in their movement) exerts a force that causes the filament to bend • Flagella & Cilia Unit 1 Study Guide Page 11 Protein moves the cargo from one location to another Protein remains in place & causes filament to move Attempting to walk (both motor protein & filament restricted in their movement) exerts a force that causes the filament to bend • Flagella & Cilia ○ Share same internal structure Axoneme: Contains microtubules, dynein, & linking proteins ○ Movement involves the propagation of a bend, which begins at the base of Axoneme the structure & proceeds toward the tip Dynein Arm Linking Protein Plasma Central Membrane Microtubule Endomembrane System • Endomembrane System: Network of membranes enclosing the nucleus, endoplasmic reticulum, golgi apparatus, lysosomes, vacuoles, & plasma membraneal Triplet Body Microtubule • May be directly connected to each other or pass materials via vesicles Nuclear Envelope • Nuclear Envelope: Double-Membrane structure enclosing nucleus • Outer membrane of nuclear envelope is continuous with the ER • Nuclear pores provide passage ways • Nuclear Matrix: ` ○ Nuclear Lamina: Composed of intermediate filaments that line the inner nuclear membrane. ○ Internal Nuclear Matrix: connected to lamina & fills interior of nucleus • Nucleus: Protection, organization, & expression of genetic material • Chromatin = Relaxed Chromosomes (DNA) • Nucleolus: Assembly of ribosomes occurs here Endoplasmic Reticulum • Endoplasmic Reticulum: Network of membranes that form flattened, fluid-filled tubules or cisternae • Encloses a single compartment called the ER Lumen • Rough ER ○ Studded with ribosomes ○ Involved in protein synthesis & sorting ○ Glycosylation: attachment of carbohydrates to proteins & lipids • Smooth ER ○ Detoxification ○ Carbohydrate metabolism ○ Calcium balance ○ Synthesis & modification of lipids Golgi Apparatus • Stack of flattened, membrane-bounded compartments ○ Not continuous with ER • Vesicles transport materials between stacks • 3 Overlapping Functions ○ Secretion, Processing, & Protein sorting • Proteolysis: Enzymes (proteases) make cuts in polypeptides. ○ Turns them into functional hormones Lysosomes • Contain acid hydrolases that perform hydrolysis ○ Different types of acid hydrolases ○ Break down proteins, carbohydrates, nucleic acids, & lipids • Autophagy: Recycle worn-out organelles via endocytosis (engulf like phagocytosis) Vacuoles • Function extremely varied ○ Central Vacuoles (Plants): Storage & support ○ Contractile Vacuoles (Protists): Maintaining water balance ○ Phagocytic Vacuoles (Protists & White Blood Cells): Degradation FORMATION OF PEROXISOMES Peroxisomes • Relatively small • Catalyze certain chemical reactions ○ Typically those that break down molecules by removing hydrogen or adding oxygen ○ Reaction byproduct is hydrogen peroxid→ broken down to water & oxygen Plasma Membrane • Boundary between the cell & the extracellular environment • Membrane transport in & out of cell ○ Selectively permeable • Cell signaling using receptors • Cell adhesion (proteins) Semiautonomous Organelles • Can grow & divide to reproduce themselves • Depend on other parts of the cell for internal components • Mitochondria ○ Makes ATP ○ Synthesis, modification, & breakdown of cellular molecules ○ Generate heat in brown fat cells Unit 1 Study Guide Page 12 • Depend on other parts of the cell for internal components • Mitochondria ○ Makes ATP ○ Synthesis, modification, & breakdown of cellular molecules ○ Generate heat in brown fat cells ○ Have DNA ○ Divide via binary fission • Chloroplasts ○ Photosynthesis ○ In nearly all plants & algae ○ Outer, Inter, & Inner membrane Thylakoid Membrane: Forms flattened tubules that stack to form a granum ○ Types of Plastids: Chloroplasts: Photosynthesis, green pigment (plants) Chromoplasts: Store yellow, orange, & red pigments (flowers & fruits) Amyloplasts: Colorless, store starch in roots ENDOSYMBIOSIS THEORY • Purple Bacteria evolved mitochondria • Cyanobacteria evolved chloroplasts Protein Sorting • Proteins have sorting signals ○ Located within their amino acid sequence ○ Function: Direct them to correct locations) IF PROTEIN HAS NO SORTING SIGNAL 1. Cytosolic Proteinremains in Cytosol & is synthesized there IF PROTEIN HAS ER SIGNAL SEQUENCE --ER Retention Signal Present 1. ER Signal Sequence = sends them to the ER 2. Signal Recognition Particles i. SRP recognizes ER Signal Sequence ii. Pause translation iii. Binds to SRP receptor (in ER membrane) iv. Docks ribosome v. SRP is released vi. Translation continues --ER Retention Signal not Present 1. ER Signal Sequence = sends them to the ER 2. Cotranslational Sorting: Transporting protein from →RGolgi i. Protein binds to ER membrane cargo receptor ii. Proteins loaded into vesicle Vesicle has: □ Proteins binded to cargo receptors (inside) □ Coat Proteins: Aid in formation (outside) □ V-Snares: Will bind with T-Snare receptors on Golgi to deliver proteins (outside) iii. Vesicle released from ER Coat proteins shed iv. Transports from ER→ Golgi i. V-Snares bind to Golgi T-Snares ii. Proteins delivered Golgi Retention Signal Present Golgi Retention Signal NOT Present 3.Retention Signa→ Remain in Golgi 3.Protein transports from Go→gi ○Lysosomes ○ Secretory Vesicle ○Vacuoles ○ Plasma Membrane PROTEIN HAS OTHER SORTING SIGNAL --(Ex: Directed to Mitochondria) *Post-Translation (can go to mitochondria, nucleus, peroxisomes, & chloroplasts) 1. A protein destined for mitochondria is first made in the cytosol ○ Protein has amino acid sequence @ N-Terminus (matrix targeting sequence) ○ Proteins called chaperones keep it in an unfolded state 2. Matrix targeting sequence binds to receptor in outer membrane of mitochondria ○ Recognizes matrix targeting sequence 3. Protein is released into channel i. It can move through because it isn't folded (due to chaperone) 4. Protein arrives @ matrix 5. Protein is threaded into the matrix ○ Chaperones released 6. Protein folds into 3D structure Unit 1 Study Guide Page 13
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