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This 26 page Class Notes was uploaded by Meagan Notetaker on Friday September 9, 2016. The Class Notes belongs to bisc 160 at University of Mississippi taught by SYMULA, REBECCA E in Fall 2016. Since its upload, it has received 7 views.
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Date Created: 09/09/16
Biology 160 Contact: firstname.lastname@example.org Biology Resource Center: 309 Shoemaker, Mrs. Lewis Supplemental Instruction: Taylor Ferris, Jack Mason, Breeley Sellier, Cal Wilkerson Chapter 1: Sections 1.1, 1.2, 1.3 08/22 A. Biology is the study of living things Components of life o Common components: carbohydrates, fatty acids, nucleic acids, amino acids o Made up of cells o Convert environmental molecules to biological molecules o Extract energy from the energy from the environment to do work o Contain genetic information and use it to reproduce sexually or asexually o Maintain homeostasis o Grow/Develop o Respond to environment o Adaptation (evolution in population) o Movement (pollen, seeds, limbs) Biodiversity o The reason why many species emerged and currently survive Unifying themes o Concepts and ideas that apply to everything (processes) To study Biology, we use observations to build hypotheses o Qualitative observations, quantification of observations o Frog experiments Poison frogs produce compounds that cause paralysis in vertebrates Poison frogs are vertebrates WHY DO THEY NOT PARALYZE THEMSELVES? 08/24 Objectives: o Explain the biological significance of understanding chemistry o Describe the properties of atoms that influence molecules o Explain how electrons determine chemical bonds and molecule shape o Identify and describe the formation and types of bonds found in biological molecules B. Biology uses the Scientific Method o Observations, questions, hypotheses, predictions. o Goal: Falsify null hypotheses Controlled or comparative o Statistical tests Some principles apply to all living things (know this semester) o Life arose from non-life o Cells are the basic unit of life and can specialize o Cells use nutrients for energy and building structures o Information is stored in a common genetic language (DNA) o Populations of organisms evolve o All life shares a common evolutionary history o Living organisms regulate their internal environment o Living organisms interact C. All Living things consist of cells Cells are the basic unit of life o Unicellular vs. multicellular Can live independently are a single cell Start single then go through mitosis o Similar characteristics o Make up tissues/organs Cell Theory (CH. 5) o Chemical composition o Water-based o Genetic material copied, passed on o Cells come from pre-existing cells When life appeared first on earth, one single cell existed (common ancestor) D. All life shares a common evolutionary history Phylogeny illustrates relationships o Common ancestry o Shared features Splits indicate changes First organism started common characteristics o Key components: Common ancestor (where two nodes meet) Descendants E. Natural selection generated some key adaptations Chemical evolution Cellular structure of the common ancestor o Cell membrane Photosynthesis was critical o Created ozone layer, allowed animals to move on to land, aerobic respiring life flourishes Compartmentalization (endosymbiosis) multicellularity o Nucleus, organelles o Bacterial cells taken in and specialize Fossil record F. Natural selection generates diversity All life shares a common evolutionary history o Phylogeny o Diversification through natural selection Successful phenotypes perpetuate = evolution/adaptation Unsuccessful phenotypes die out (depend on environment) Living things interact with each other and the environment o Communities (interspecies), populations (intraspecies), ecosystems (+ abiotic) o Cell-to-cell communication Nerves o Biodiversity Biology is organized at different levels Atoms to organisms, Organisms to ecosystems Chapter 2: 2.1-2.2 08/24 Biology is the study of living things o Molecule interactions o Whole organisms A. Properties of molecules influence living things Molecules are made up of atoms Molecules vary in size Molecules have three dimensional shape o Shape matters for function Molecules have specific chemical properties o Determine how they interact B. Atoms have a general structure Protons (+1), neutrons (no charge), electrons (-1) o Electrons orbit proton/neutron nucleus Dalton is the mass of one proton and one neutron Atoms are neutral, have mass C. Elements are composed of the same atom Carbon, Nitrogen, Oxygen, Phosphorus (DNA, RNA), Sulfur, Hydrogen make up 98% of living organism mass o C-6 ; N-7; O-8, P- 15, H-1 o KNOW THESE: atomic number/chemical symbol Present in small amounts in organisms: Na, Mg, K, Ca, Mn, Fe, Co, Cu, Zn, Si, Cl Elements differ by the number of protons o Atomic number (number of protons) o Chemical symbol o Atomic mass vs. Mass Number MN: number of protons plus number of neutrons Number of Neutrons can vary AM: proportional average of atomic mass Isotopes have different numbers of neutrons o Hydrogen (0n), Deuterium (1n), Tritium (2n) o Used for many things: Carbon dating Live close to ocean= different oxygen, heavy Oxygen evaporates faster by ocean (heavier 02 breathed in) Bone composed of this Oxygen Can tell where Dinosaurs lived based on enamel’s Oxygen Radioisotopes are unstable isotopes that lose parts of the atom o Radiation: alpha (He nucleus), beta (electron), gamma (rays) o Can change elements if proton lost o Can be incorporated in the body and parts affected give off radiation o Used often as a measure Electrons are organized around the nucleus o Shells contain orbitals o Most shells contain 8 electrons o Orbitals can hold up to 2 electrons The Bohr Model is a simplification of electron organization o Electron pairs occupy the same orbital o When shells aren’t full they form bonds Chapter 2: 2.4 08/26 Objectives: Identify and describe the formation and types of bonds found in biological molecules Explain electronegativity and its biological importance Describe unique characteristics of water, especially the significance of hydrogen bonds Use concepts of acids, bases and buffers A. Electron shells determine atom reactivity Number of electrons determines reactivity o Reactive atom: when it doesn’t have a full valence shell o Inert: full valence shell (Nobel gases) Molecules form by interactions of electrons o Reactive atoms aim to fill valence shells Stabilize by interacting with other atom’s electrons Make a molecule by forming bonds Single, double, triple o Energy o C O H 2 2 4 o Interactions=bonds Generate stable molecules Take energy to made, release energy when broken B. Chemical bonds link atoms in a molecules o Covalent bond (shared electrons) o Ionic bonds (donated electrons) o Weak(er) bonds Van der Wall Chemical bonds are represented different ways o Bohr models (valence shells overlap with electrons) o Structural formulas o Ball-and-stick model o Space-filling model C. Atoms share electrons in covalent bonds o Electrons shared between two atoms o Ring shows range where atoms might be o Electrons move towards atom when bond formed o Covalent bonds result in stability o Valence shell is full o Bond strength is the energy it takes to break a bond Covalent bonds have orientation, length o If the same two atoms are covalently bonded They are equal in length They are at the same angle Most molecules have a Carbon component o This gives a molecules 3D shape Tetrahedron usually results with Carbon SHAPE DICTATES FUNTION IN BIOLOGY Electrons are not always shared equally o Electronegativity Oxygen has a stronger pull on electrons, hydrogen has less pull Oxygen becomes more negative, hydrogen becomes more positive POLAR BOND o Polar bonds One side is more negative than the other Electronegativity is a characteristic of an atom (Pauling scale) o More able to pull electrons away Electronegativity of a bond determines molecules polarity o Electronegativities: Oxygen = 3.5 Carbon = 2.5 Hydrogen = 2.1 Nitrogen = 3.0 o Subtract electronegativities to determine polarity o Polar: o Non-Polar o C-O o C-C o H-O o C-H o N-H o C-N Ionic bonds form by stealing electrons o Electronegative EXTREMES! Na: .9 Cl: 3.0 Create cations (+) and anions (-) o Oxidation-reduction (Redox). LEO says GER OXIDATION IS LOST, REDUCTION IS GAIN Important because they release energy—don’t have to use ATP (more energy than ATP) o Bonds form from resulting attraction Ionic bonds interact with polar molecules o Ions are attracted to poles of water* o Na gives off positive charge and interacts with negative end of water, Cl gives off negative charge and interacts with positive end o Ions dissociate and interact with water o Crucial interaction in cells Hydrogen bonds are due to bond polarity o Within or between molecules Hydrogen on one molecule interact with Oxygen on other molecules o Sides of protein and interact with each other Important for shape of the function (tertiary bonds) ESSENTIAL IN BIOLOGY o Weak bonds o Negative charge and a positive charge on H atom Polar and nonpolar molecules dislike each other o A: Hydrophilic Van der Waals forces (weak) Interaction between negative and positive on water (any polar interactions) o Hydrophobic interactions Nonpolar (C-H bonds) Not attracted to each other and aggregate together away from water Chemical reactions change or add bonds o Reactants o Products o Energy change Either invest or release energy o Redox reaction: reduction-oxidation Most biological reactions happen in water o 71% of earth’s surface o 60-75% of animal body o 90-98% of a cactus Water’s covalent bonds are polar o Hydrogen bonds form with Itself Highly polar, water tension Other polar molecules Water has special properties o Ice floats (hydrogen bonds that do not break apart) Space out and become less dense o Hydrogen bonds constantly form and break as liquid o No hydrogen bonds in vapor o Heat capacity (high specific heat) Heat of vaporization: heat to point of gas, hard to break bonds Atmospheric variatior Hydrogen bonds cause surface tension Hydrogen bonds between water molecules o Cohesion: when two molecules of same type stick together Bubbles, droplets of water o Detergents or surfactants o o Chapter 3: 3.1, 3.2 o 08/29 o Explain how there can be a variety in carbon atoms Describe the features of biological macromolecules Describe the basic structure of amino acids Introduce the different levels of protein structure o Water is the “solvent” for life o Solution, solute Dissolved molecules in water: solution Solute: what is dissolved o Aqueous o Water soluble Can dissolve o Moles A mole is the number of molecules o I mole of Oxygen = 6.02 X 10 molecules of Same for all moles Avogadro’s number o Molar solution: 1 mole of something in a liter of water Aqueous solutions are water based o Solution, solute o Aqueous o Concentrations are low Micromolar Aqueous solutions vary in proton concentration o Concentrations of protons matter Measuring pH of a solution HCl H + Cl o Dissociation + o Acids release H +protons) o Bases accept H o Acids/bases vary in strength pH is measured on a logarithmic scale o 10 fold differences o Negative logarithm + o Small pH = large number of H o Acids / bases vary in strength o pH can alter homeostasis Stomach acid o Buffers minimize pH change Maintain homeostasis Water is a weak acid and a weak base o Can donate or accept ions o Donate: Hydroxide o Accept: Hydronium Number of each kind is equal Constant exchange o Can go back and forth (reversible) Carbon compounds are required in living things o Six electrons = 4 bonds o Single, double, and triple bonds o Straight, branched, ringed Carbon compound structure is abbreviated o Hydrogens are implied Functional groups influence molecular properties o Small groups of atoms Interact with other molecules Tend to be reactive o Different properties Allow them to interact with other things o Many in a single molecule o Hydroxyl: groups form Hydrogen bonds with water o Aldehydes are REACTIVE energy-releasing (carbonyl) DOUBLE BONDED OXYGEN causes reactivity Double bond at the end o Ketones are polar, important in energy reactions (carbonyl) Double oxygen bond in the middle Carbonyl: carbon double bonded oxygen o Carboxyl are acidic OH makes it a carboxyl Often are charged o Amino groups are basic KNOW THE “N” BASE o Phosphate groups are negatively charged USED in DNA and RNA Energy released from them o Sulfyhydryl groups can form covalent bonds Building protein structures is import o Methyl groups (not really “functional”) are non-polar low reactivity Three Hydrogens G a t h e r together and away from water Isomers have atoms arranged differently o Isomers: structural (straight vs. branched), optical (atoms are mirror images) o Same chemical formula o ISOMERS: SHAPE DETERMINES FUNCTION Molecule structure determines function o Example: poison frog toxin o Sodium channel Protein that interacts with poison frog toxin Biological molecules are made and broken o Macromolecules- order of abundance: proteins (polypeptides), nucleic acids, carbohydrates (polysaccharides), lipids KNOW MONOMERS o Condensation o o o Chapter 3: 3.2, 3.3 o 08/31 o Describe the features of biological macromolecules Describe the basic structure of amino acids Explain the different levels of protein structure Describe the structure and function of carbohydrates and their building blocks Pre-read 3.4, 4.1 for Friday o Macromolecules are made and broken Condensation reaction o Take out a water molecule and link the molecules o Each unit is a monomer, linked are polymers Hydrolysis (Hydro-split)ing reaction o Water is added in and the molecule is broken apart into monomers Macromolecules are grouped into four categories o Nucleic acids, carbohydrates, proteins, lipids Macromolecules vary in molecular properties o Functional groups: is it polar, non polar, charged o Polarity o Charge o How do you denature a protein? Heat, acid (full of charged protons) Break apart hydrogen bonds between O—H o o Proteins Proteins have a variety of roles o Enzymes o Defense (anti-bodies) o Hormones, regulatory o Receptors o Storage o Structural o Transport Ion channels o Genetic regulation Amino acids (MONOMER) are the building blacks of Proteins o N—C—C : back bone of amino acid o R is the side chain which bonds to the alpha carbon o There are 20 different amino acids Carboxylic acid- donates a proton (H movies to the amino group) R groups vary in properties Charged hydrophilic Polar hydrophilic “Special” Non-polar hydrophobic Say which category an amino acid belongs to o Identify polar/non polar or charged Charge will always interact with water because water is polar o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o o Amino acids are joined by peptide linkage o (+H_3N) N terminus, C terminus (COO-) Polypeptides are formed by joining many amino acids o Covalent bonds between C=O and N o Sequence order (R side chains) o C—O , negative, H—N is Positive; alternating charges on polypeptide Proteins have 4 levels of organization o Primary, secondary, tertiary, quaternary o Peptide linkage= primary Secondary structure forms between amino and carboxyl groups o They fold in on each other o Carboxylic acid and amino acids have hydrogen bonds together o Held together by hydrogen bonds o Form an alpha helix or a beta pleated sheet Tertiary structure forms between side-chains (R groups) o Hydrogen bonds (charged) o Hydrophobic interactions (van der Waals) o Ionic bonds o Di-Sulfide bridges if covalent bonds COVALENT BONDS (stable) o o o o o o o o o o o o o o o o Disulfide bridges are covalent bonds between cysteine side chains o Organization of disulfide bridges = texture of hair, breaking them changes structure o Cysteine has sulfur Quaternary structure forms between separate polypeptides o Hydrogen bonds o Hydrophobic interactions o Van der Waals o Ionic bonds o Disulfide bridges SHAPE AND CHEMISTRY INFLUENCE FUNCTION o Ionic interactions (charged side-chains/ R groups_ o Hydrophobic interactions o Hydrogen bonds o Disulfide bridges give flexibility (disulfide bridges = yoga) Weak interactions polypeptides make membrane channels flexible (SEE SLIDE) o Regulate ion travel in the cell (need flexibility/ strength) o Alpha helix form between amino/carboxyl—secondary o Tertiary causes folding, quaternary = 4 units o Membrane channel = funnel o ALL HAVE prim and sec., some have tert., not all have quad. o o Chapters 3, 4: 3.4, 4.1, 4.2 o 09/02 o Describe the structure and function of carbohydrates and their building blocks Describe the structure, function, and diversity of lipids Describe the structure and function of nucleic acids Outline the requirements for the origin of macromolecules o o Carbohydrates: Monosaccharaides = monomer Carbohydrates are made up of MONOSACCHARAIDES (simple sugars) o Storage, transport, energy, carbon skeleton (break down carbon into chains and use them to build amino acids etc.) o ALL different shapes o Always follow one formula: only carbon, hydrogen, and oxygen Same number of carbons and oxygens, double hydrogens Usually hydroxyl and aldehyde o Glucose can be straight or alpha/beta glucose (some forms are easier to break up than others) Alpha: hydroxyl below Beta: hydroxyl below o Dark black line= 3D Monosaccharaides can vary in the number of carbons Monosaccharaides are joined by glycosidic linkages o Condensation reactions (release H O)2 o Alpha: link points under o Beta: link points above o Shapes differ o Diversity in carbohydrates Polysaccharides can be branched or in chains o Cellulose forms a linear molecules: can be stacked, packed tightly Hard to break bonds Influence (water) interactions o Glycogen/starch: starch is branched, glycogen is highly branched Cannot be packed as tightly SUGAR storage molecules in animals Carbohydrates can be modified with different functional groups (figure 3.1) o Redox reactions o Add functional groups o o Lipids Lipids (fats) have a variety of functions o Fats and oils (energy storage) o Phospholipids (cell membranes) o Carotenoid/ chlorophylls (energy capture) Carrots and tomatoes orange color Vitamin building blocks o Steroids (hormones and vitamins) Estrogen/testosterone Signal molecules o Stored fat (thermal insulation) o Lipid coat (electrical insulation) Neurons, transmit faster o Oil or wax (water repelling) Protective layer on skin Lipids contain many non-polar hydrocarbons o Are they water-soluble? No o No single monomer Triglycerides (simple lipids) are synthesized by condensation — always join by hydroxyl group (figure 3.20) o ESTER LINKAGE- joins Trigly. o Fatty acids and glycerol o Hydrolysis releases energy by breaking ester bonds from triglycerides o REMOVE TREE WATERS = Triglyceride At room temperature, “fats” are solid, “oils” are liquids o Triglycerides Triglycerides can saturated or unsaturated o Double or single bonds Saturated: single bonds, straight chain Double bond puts bend in carbon chain (unsaturated) Phospholipids form biological membranes o Hydrophilic head (positive), phosphate (negative), hydrophobic tail Heads face out towards water, tails congregate together SURFACTANTS have polar head, non polar tails o o Chapter 5: 5.1-5.2 o 09/07 o Describe the structure and function of nucleic acids Explain why cells are the fundamental unit of living things Describe the features that make up a prokaryotic cell Describe the features found in all eukaryotic cells Summary on Blackboard o Lipids have a variety of biological jobs o Hormones are messenger molecules Sterols (cholesterol produces lipid based hormones) o Waxes are protective and structural Fatty acid – ester linkage – alcohol o o Nucleic Acids Nucleic acids code for biological “information” o Central Dogma DNA relates to RNA, RNA relates to polypeptides (proteins) o DNA o RNA o Protein = information Nucleotides are the building blocks of nucleic acids o Nucleotides: Nitrogenous base 5 Bases: o Pyrimidine: single ring Cytosine, thymine, uracil o Purines: double ring Adenine, Guanine Sugar (deoxyribose, ribose) Phosphate Nucleoside = sugar and base Becomes nucleotide There are other important nucleotides o Signaling molecules Cyclic AMP—cAMP o Energy sources ATP- break off phosphate to release energy (P—O is polar) o Information Transfer Nucleotides are joined between the sugar and phosphate groups o 5’ carbon and 3’ carbon connected Last carbon outside of the ring with Phosphate = 5’ Base always on 1’ 2’ can change 3’ always has a hydroxyl o Phosphodiester bond Form two ester bonds (C—O) o Hs are on the Phosphate DNA and RNA differ by the nucleotide sugar o Ribonucleotides: Sugars-ribose RNA Hydroxyl group on the 2’ sugar o Deoxyribonucleotides: Sugar-deoxyribose DNA Has an H on the 7’ carbon DNA and RNA differ by the types of nucleotide bases o RNA (Uracil) o DNA (Thymine) has a methyl group DNA and RNA differ by the number of strands o Hydrogen bonds: C—G triple bond ; A—T double bond : polar bonds o DNA = double strand o RNA = single strand Hydrogen bonds cause it to fold RNA folding makes complex 3D shape o Complementary base pairs o Hydrogen bonds Make structures o Imperfect pairing DNA carries information in a double helix o DNA sequence = order of bases TCAGCA vs. CCAGCA o Complementary base pairing o Replication Happens before cell division Whole molecule o Transcription (making proteins) Happens all the time; does not need replication to happen Translation is independent of replication Gene o Function of DNA/Replication: store and pass on information (repair/replace); o Review macromolecules = be sure to identify ********** o o Chapter 5 Cells are the fundamental unit of life o All living things are composed of cells o All cells come from pre-existing cells Surface area to volume ration (SA:Vol) limits cell size o For a single 1mm X 1mm 2 SA: 6 sides X 1 mm L X 1mm W X 1 mm = 6 mm3 Vol: 1 mm L x 1 mmW x 1 mm D = 1 mm SA: Vol = 6:1 o As cube grows, SA is different than Vol o Surface area allows for materials to be transported into and out of the cell; low SA= high exchange with the environment o SA = cell’s best friend o o 09/09 Explain why cells are the fundamental unit of living things Describe the features that make up a prokaryotic cell Describe the features found in all eukaryotic cells Chapters 5 Section 5.3-5.4 Pre-read chapter 6 o All cells have a plasma membrane o PHOSPHOLIPID BILAYER: Hydrophilic heads, hydrophobic fatty acid tails o Fluid mosaic o Selectively permeable (some things can be allowed in) o Infolding o Internal environment Separate environment for reactions o Communication o Attachment All cells have ribosomes o Not all identical o Sizes differ Bacteria have different sized ribosomes than people o Make proteins o Made of rRNA, some proteins interact with the rRNA o Free vs. Bound (attached to surfaces) Bound to the Endoplasmic reticulum Cells are either prokaryotic or eukaryotic o Three domains: Bacteria, Archae, Eukarya o Prokaryotes: Bacteria, Archae Pro-before before-nucleus o Eukaryotes: Eukarya (plants, animals, fungi, protists) Eu- true (true-nucleus) o Presence or absence of nuclei o Prokaryotes do not have MEMBRANE BOUND organelles o PROKARYOTES What are the features of Prokaryotic cells? o Nucleoid: circular DNA o Capsule: protective coat o Cytoplasm o Ribosomes o Flagellum o Plasma membrane o Cell wall: outer membrane (absent in some bacteria), peptidoglycan o Have to be organized Perform chemical reactions GO through mitosis Prokaryotes have internal membranes o Make compartments by folding o Isolate reactions, chemical compounds, force reactions to happen in certain parts of the cell Prokaryotes have a variety of cell walls o Bacteria: Peptidoglycan (thick vs. thin (or absent)) o Archae: Pseudo-peptidoglycan o No cell wall o Can have two membranes with peptidoglycan between Prokaryotes have unique flagella o Propeller-like o Protein rotates causes spinning Prokaryotes have pili o Protein projections Long and come from the outside o Adherence o “Sex” Different pili type Exchange DNA SIZE is a HUGE difference between eukaryotes and prokaryotes because… o EUKARYOTES Eukaryotic cells have compartments o Organelles/membranes o Nucleus o Mitochondrion o ER and Golgi o Lysosomes o Chloroplasts o Concentrate reactions, increases surface area (more room for reactions to occur) What features are found in all eukaryotes o Features change based on function The nucleus is one defining feature of eukaryotes o Nuclear pores: allow access o DNA and associated proteins o Site of transcription o RNA leaves membrane to the cytoplasm where translation occurs at the ribosomes (rRNA) Separates translation o Nucleolus Assembly of ribosomes occurs o IMPORTANT- nuclear envelope (outer/inner membrane) is directly connected to the inside of the ER The nucleus holds DNA and its proteins o Chromatin Condensed, Associated with proteins, tightly wrapped o Chromosomes Linear o Nuclear lamina Proteins that organize chromosomes Ribosomes are made in the nucleus used in the cytoplasm o Assembled in nucleolus and used in cytoplasm o Made of rRNA and protein o Protein synthesis Either made in cytoplasm or at ER The endomembrane system consists of several organelles o Plasma membrane o Nuclear membrane o ER RER Ribosomes bound to it, proteins made and put in to the ER SER Modification (add sugars to proteins) Make lipids, steroids (lots of smooth ER for testosterone) Package and send to Golgi o Golgi Concentrate proteins for secretion Ensure carbohydrates are added Make polysaccharides (for cell wall) Put proteins in the membrane o Lysosomes The Golgu orocesses proteins and aids in secretion o Cisternae Flattened sacs, two sides (cis, trans) Where modification occurs o Cis Close to the ER Receive membrane bound package goes to cisternae o Trans Opposite side of ER o Vesicle Small compartment The Lysosomes are derived from the Golgi o Many hydrolysis reactions o Gets rid of faulty or old organelles o Primary vs. secondary Primary: before fusion Secondary: after fusion with phagosome o Digestive enzymes o Autophagy o Phagocytes White blood cells Form membrane o ONLY IN NON PLANTS The mitochondria transform energy to ATP o Make ATP from molecules o Fuel molecules o Double membrane, with high internal folded Endosymbiosis—though to come from a prokaryote o Outer membrane, inner membrane o Cristae (folds) o Matrix Inner area o Isolate cellular respiration Chloroplasts transform light into sugar o Makes glucose, mitochondria break down the glucose o Plastid o Internal membrane system o Thylakoid (individual membrane), granum (stack of membranes) o Stroma- space between the membranes o Other plastids: leukoplasts, chromoplasts o o 09/12 Explain why membranes are described as fluid mosaics Explain the various functions of cell membranes Describe how molecules move actively across membranes Explain other processes that require membrane proteins o THere are other organelles with many functions o Peroxisomes o Glyoxysomes (plants) Found only in plants Break down starches and lipids Break down storage molecules Vacuoles (plants, protists) o Store color compounds o Store toxic materials o Used for structure, adding water to the plants o Contractile vacuoles release water Cytoskeleton provides cell structure and movement o Cell support, shape o Organelle position o Cell movement o Anchoring cells Microfilaments influence cell movement and shape o Made of strands of protein (actin) often interact with strands of other proteins o Cytoplasmic streaming o Shape stabilizing o Single, bundles, or networks o Muscle contraction and relaxation Intermediate filaments anchor organelles and maintain rigidity o Made up fibrous proteins organized into tough, ropelike assemblages that stabilizes a cell’s structure and help maintain its shape o Karatin- hair, nails: provide structure for cells o Desmosomes Link adjacent cells tightly but permit materials to move around them in intercellular space Microtubules form an internal skeleton o Long hollow cylinders made up of many molecules of the protein tubulin. o Consist of dimers (alpha and beta) o Tubulin o Hollow tube o Organizing center o Cilia/flagella o Can be temporary or permanent Motor proteins interact with the cytoskeleton o Proteins in cell that interact with ATP o ATP causes shape of motor protein to change o Dynein (protein) ATP changes its shape and it shifts o Nexin (protein) Anchors microtubules ATP causes nexin to bend Motor proteins move organelles o Kinesin Holds on the vesicle and walks along the microtubule (ATP) o Walking Extracellular matrix is made up of fibers in a gel-like medium o Plant cell wall Cellulose Support and provide protection to cell Limit volume Has to break down matrix to grow Barrier to infection Cell growth o Animal cell Collagen, proteoglycans (sugars with amino groups) Hold together tissues Cell recognition Framework for skin, bond, cartilage Cell membranes are mostly lipids o Lipids o Cholesterol (lipid) Part of the inner membrane (non polar) o Proteins- o Carbohydrates Glycoprotein Glycolipid Modified lipids with sugars attached, interact with the polar parts of the membrane Membranes are made of phospholipids o Are weak molecular forces like hydrogen bonds permanent? o Can they move? Yes, highly fluid o What cell structures make them? Endoplasmic reticulum makes them, vesicle transports the cells, fuse with the membrane Fluidity of membranes vary o Saturated vs. unsaturated fatty acids Saturated makes the membrane less fluid Unsaturated increases fluidity o Cholesterol (embedded) Increases cell fluidity Tails less tightly packed Membrane fluidity varies with temperature o Want membrane more fluid: in colder temperature o Want membrane less fluid: in hotter temperatures o Internal temperature determined by habitat o Poikilothermic, ectothermic Temperature changes with the environment o Prediction: membrane lipids of cold-adapted animals will have more unsaturated phospholipids o Muscles are more cold tolerant than oyster (die at high temperature) o Oysters are less cold tolerant than muscles (die at low temperatures) Membrane fluidity varies with temperature o Hibernating animals change more, endotherms do not change much Proteins can be embedded in membranes o Peripheral membrane proteins Stay in the head and protrude outside the cell o Integral membrane proteins Most in the tails (non polar), stick out one side o Trans-membrane protein From the outside to the inside through the membrane Hydrophilic on the outside, hydrophobic on the inside o Position dictates job o Can interact with carbohydrates Carbohydrates can be embedded in membranes o Have specific jobs based on structure, have more than one type of monomer o Cell recognition sites Specific tag, unique, identifiable o Cell adhesion o Glycolipids and glycoproteins Membranes are fluid mosaics o Many small parts (mosaic) o Weak molecular forces hold them together Membranes have several functions o Compartmentalization and organization o Energy transformation Converting chemical bonds into ATP Sunlight into sugars o Cell recognition and adhesion o Signaling/ communication Recognize other cells o Membrane transport Membranes can link cells together o Cell recognition Sponges- Glycoproteins are so specific they allow membrane to reform o Cell adhesion o Specificity o o
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