Biology Notes BIO 311C
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This 22 page Class Notes was uploaded by Nhi Notetaker on Wednesday September 14, 2016. The Class Notes belongs to BIO 311C at University of Texas at Austin taught by Dr. Debra Hansen in Fall 2016. Since its upload, it has received 6 views. For similar materials see Intro to biological sciences in Biology at University of Texas at Austin.
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What is Karma?
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Date Created: 09/14/16
Spontaneous generation (abiogenesis) is a supposed process where life forms emerge systematically from other than parents, a nonliving matter. Compared to nonliving, living things have more structure/complexity Metabolism (chemical interaction with environment) Growth/reproduction Properties of living things Order Energy processing Evolutionary adaptation growth/development Response to environment Regulation Adaptation Biological Hierarchy biological systems are structured at many interrelated levels; at every level, structure is related to function Levels of Biological Organization 1. Biosphere all life on Earth and all the places where life exist: land, water, atmosphere 2. Ecosystemall living things in area, all nonliving things in environment; soil, water, atmospheric gases, light 3. Communitiesarray of organisms in ecosystem; trees, animals, mushrooms, microorganisms, etc. (set of populations) 4. Populationsall individuals of a species in area 5. Organismsindividual living things 6. Organ and Organ Systemsbody part that carries out a particular function in body; complex organisms have organ systems, each a team of organs that cooperate in a larger functions. Organs made of multiple tissues. 7. Tissuesgroup of cells that work together to perform specialized function 8. Cellslife’s fundamental unit of structure and function; single cell performs all structures of life, multiple cell have divisions of labor among specialized cells 9. OrganellesFundamental components presents in cells 10. Moleculeschemical structure of two or more atoms Emergent Properties are due to arrangement and interactions of parts as complexity increases ● Reductionismisolates components of living systems, lack significant properties that emerge at higher levels of organization ● Systems biologythe exploration of a biological system by analyzing interactions among its parts What are emergent properties? Properties that are in complex systems, that wasn’t there in individual components. For example, the properties of water molecules that were not present in individual hydrogen and oxygen molecules. Ex) Wood can be cut into a long pole, and it is strong. Straw is long, thin, and flexible. Wood and straw have particular properties due to the cells that make them. Separately, neither wood or straw helps you clean. When put into a particular organization of a broom, they can be used to sweep a floor. "Sweeping ability" is an emergent property of a broom that wood and straw do not have. 3 Domains of Life: Bacteria, Archaea, Eukarya ● Bacteria and Archaea are prokaryotic. ● Eukarya includes three kingdoms Plantae, Fungi, and Animalia, each distinguished by their modes of nutrition. ● Plantae produces their own sugars by photosynthesis ● Fungi absorbs dissolved nutrients from surroundings ● Animalia obtain food by eating and digesting ● Protistssingle celled eukaryotes Atoms and Molecules ● atom – building block of all molecules ● molecule – two or more atoms connected with a strong bond ● proton – positivelycharged particle found in the nucleus of an atom ● neutron – noncharged particle found in the nucleus of an atom ● electron – negativelycharged particle that orbits around an atom in a cloud ● ion – a charged atom with a different number of electrons than the uncharged form ● anion – an ion with more electrons than the uncharged form (negativelycharged) ● cation – an ion with fewer electrons than than the uncharged form (positivelycharged) ● valence electron – electron in the outer shell, possibly available to participate in bonds ● electronegativity – attraction of electrons toward an atom’s nucleus Bonds and Interactions ● covalent bond – connection formed when two atoms share electrons ● polar covalent bond – type of covalent bond resulting from unequal sharing of electrons ● nonpolar covalent bond – type of covalent bond resulting from equal sharing of electrons ● ionic bond – attraction between atoms that have opposite charges ● hydrogen bond – attraction between a partially positivelycharged hydrogen atom and another partially negativelycharged atom ● partial charge – unequal distribution of electrons caused by a polar covalent bond ● hydrophobic interaction – aggregation of nonpolar molecules in water or other aqueous environment ● van der Waals interaction – small repulsions and attractions between atoms caused by fluctuations in the electron cloud Water Properties ● surface tension – organized layer of water molecules where water meets air ● cohesion – the tendency of water molecules to stick to each other ● adhesion – the tendency of water molecules to stick to other polar molecules ● specific heat – the amount of energy required to raise a given volume of a substance by one degree Celsius ● lattice – the structure formed by water molecules as they cool to form a solid ● density – the number of molecules in a given space Acids and Bases ● acid – a substance that increases the concentration of protons in a solution ● base – a substance that decreases the concentration of protons in a solution ● pH – a numerical scale that indicates how acidic or basic a solution is relative to water ● buffer – a molecule that can donate or absorb protons to stabilize the pH of a solution ● buffer range – the section of the pH scale in which a particular buffer can function Preparing Solutions ● concentration – the ratio of substance per volume of solution ● molarity – the number of moles of a substance per liter of liquid ● stock – a concentrated solution used to make other, less concentrated solutions Organic Molecules ● hydroxyl – a functional group made of one oxygen and one hydrogen ● carbonyl – a functional group made of a single doublebonded oxygen ● carboxyl – a functional group made of a doublebonded oxygen, one singlebonded oxygen, and a hydrogen ● amino – a functional group containing nitrogen and hydrogen ● phosphate – a functional group containing phosphorus and oxygen ● methyl – a functional group containing carbon and hydrogen ● carbon skeleton – a carbon and hydrogen structure to which functional groups are attached ● functional group – portion of a molecule with defined chemical properties ● isomer – alternate form of a molecule, differing in shape but not chemical composition. ● structural isomer – isomer resulting from changes to the overall bonding pattern of a molecule ● geometric isomer – isomer resulting from changes next to a double bond; bonding pattern remains the same in both isomers but spatial orientation is different ● optical isomer – isomer resulting from changes next to an asymmetric carbon; isomers are mirror images of each other Atoms with incomplete valence shells can interact with certain other atoms where its partner complete its shell by either transferring or sharing valence electrons. Covalent Bonds sharing of a pair of valence electrons by two atoms. Two or more atoms held together by covalent bonds are molecules. An atom’s valence is its bonding capacity; usually equals the number of unpaired electrons required to complete its outermost shell. Electronegativity is the attraction of an atom’s nucleus to its electrons of a covalent bond. The more electronegative an atom is, the more strongly it pulls shared electrons towards itself. Nonpolar covalent bonds occurs between two atoms of the same element because they have the same electronegativity, so both sides are balanced. Polar covalent bonds happen when an atom is bonded to a more electronegative atom, the electrons of the bond are not shared equally, resulting in a slightly positive and slightly negative side. Ionic Bonds two atoms are so unequal in attraction for valence electrons that the more electronegative atom strips an electron away from the less electronegative atom, causing a positively charged ion (cation) and a negatively charged ion (anion). Because of these opposite charges, cations and anions attract each other resulting in a ionic bond. Ionic compounds do not consist of molecules. Not as strong as covalent bonds in an aqueous solution because it dissolves. Weak Chemical Bonds: Hydrogen Bonds when a hydrogen atom is covalently bonded to an electronegative atom, the hydrogen atom has a partial positive charge that lets it become attracted to a different electronegative atom nearby, this attraction is called a hydrogen bond. Van der Waals(london dispersions) individually weak and only happens when molecules are close together. Electrons in nonpolar covalent bonds have positively and negatively charged regions because electrons are not always evenly distributed so it attracts other positively and negatively charged regions and stick to one another. Emergent Properties of Water that is Important to Life: Cohesion hydrogen bonds hold the substance together collectively. Contributes to transport of water against gravity in plants. As water evaporates from a leaf, hydrogen bonds cause water molecules leaving the veins to pull on molecules farther down. Adhesion, clinging of molecules to one another, helps move water up by hydrogen bonds from water and the molecules of the cell. Surface tension measure of how difficult it is to break the surface of a liquid. Water has a high surface tension because of hydrogen bonds. Moderation of Temperature water moderated air by absorbing heat from warmer air and releasing stored heat to cooler air. Thermal energy is the kinetic energy associated with random movement of atoms, depending on the matter’s volume. Temperature is a measure of energy that is the average of kinetic energy of molecules regardless of volume. Whenever two objects of different temperature are brought together, thermal energy passes from the warmer to the cooler until it’s the same temperature. (Ice cube cools a drink from absorbing thermal energy as it melts) Heat is thermal energy in transfer from one body of matter to the other. Specific Heat is a measure of how well a substance resists changing its temperature when it releases or absorbs heat. High specific heat of water tends to stabilize ocean temperatures suitable for marine life. (1g to change temp by 1 degree C) Heat must be absorbed to break bonds; heat is released when bonds form. Molecules of liquid stay close together until it moves fast enough to overcome these attractions, becoming vapor or gas. Heat of Vaporization (1g to convert from liquid to gas) water has high heat of vaporization, hydrogen bonds must be broken before molecules can turn from liquid to gas. As liquid evaporates, the surface of the liquid that remains behind cools down. Evaporative cooling occurs because the molecules with the most kinetic energy are more likely to leave as a gas, leaving behind molecules with less kinetic energy therefore is cooler (decrease in temperature) Sweat: as the water “hottest” molecules evaporate, it cools down the body by absorbing heat. The sweat left behind is the cooler molecules. Ice Floats on Water: Water expands as it solidifies, becoming less dense. Water expands as it warms and contracts as it cools. But when it starts to freeze, more molecules move too slowly to break hydrogen bonds, causing it to lock in a crystalline lattice, which is a stable structure. Then when ice absorbs enough heat for its temperature to rise again, hydrogen bonds between the molecules are disrupted and the crystal structure breaks and the ice melts. This allows ice to insulate liquid water below it in oceans, ponds, and lakes, preventing it from freezing and allowing life to exist. If ice sank, more ice would form on the bottom of the ocean, preventing life forms from surviving. Water is a versatile solvent: Solutionhomogeneous mixture of two or more substances Solvent dissolving agent Solute substance that is dissolved in Water molecules can dissolve other molecules if they are polar on the surface. For example, NaCl is put into water. Oxygen regions of water are negatively charged and attracted to Sodium cations, while hydrogen regions of water are positively charged and are attracted to chloride anions. So the water molecules surrounds the individual sodium and chloride ions, separating and shielding them from one another. Important to cell membranes as a gatekeeper. Hydrophilic is a substance that has an affinity for water, molecules so large doesn’t have to dissolve, like cotton, or adhesion of water to help water move up a plant’s walls. Hydrophobic substances that do not have an affinity for water, nonionic and nonpolar repels water, like vegetable oils. Acids and Bases: A hydrogen bond, a hydrogen atom might shift one molecule to another, transferring a hydrogen ion (H+), leaving behind a hydroxide ion (OH) and binding to a hydronium ion (H3O+). When acids dissolves in water they donate a H+ to the solution, increasing the hydrogen ion concentration. Acidic solutions have more H+ than OH. A base reduces the H+ concentration: By accepting hydrogen ions (ex. NH3 attracts H+ from solution, resulting in NH4+) By dissociating to form hydroxide ions, which combine with hydrogen ions and form water (ex. NaOH dissociates into Na+ and OH) PH scale At any aqueous solution at 25 degrees celsius, [H+][OH] = 10^14 014, 0 is more acidic, 14 is more basic. Buffers allow biological fluids to maintain constant PH despite additions of acids or bases, minimizing concentrations of H+ and OH by accepting hydrogen ions when there is excess of donating hydrogen ions when they have been depleted. Most buffers contain a weak acid and its corresponding base. Carbon can bond to various other atoms, including O, N, and H. Carbon can also bond to other carbon atoms, forming skeletons of organic compounds. Shapes is important to its function. Carbon has emergent properties that result from the properties of their functional groups. Variation in Carbon Skeleton: Hydrocarbons are organic molecules consisting of only carbon and hydrogen. Usually hydrophobic compounds because majority of their bonds are relatively nonpolar carbon to hydrogen linkages. Hydrocarbons can undergo reactions that release a lot of energy. Isomers are compounds with the same numbers of atoms on each element but with different structures, thus different properties. Structural isomers differ in covalent arrangement of their atoms. Cistrans isomers (geometric) differ in arrangement about a double bond. Cis isomer have the two atom attached to double bonded carbons are on the same side. Trans isomer have the two atoms attached to double bonded carbons on opposite sides. Enantiomers are isomers that are mirror images of each other that differ in shape because of an asymmetric carbon, one that is attached to four different atoms. The four groups can be arranged around the asymmetric carbon in two different ways that are like mirror images, like difference between left hands and right hands, allowing it to bind to specific molecules. Functional Groups: chemical groups directly involved in chemical reactions, each has certain properties like shape and charge. Hydroxyl group(OH) Is polar due to electronegative oxygen, forms hydrogen bonds with water, help dissolve compounds like sugars. Name: Alcohol. Ex. Ethanol Carbonyl group Sugars with ketone are called ketoes (ex. Acetone), with aldehydes are called aldoses (ex. Propanol). Name: ketone (carbonyl group is within carbon skeleton) or aldehyde (carbonyl group is at the end of a carbon skeleton) Carboxyl group (COOH) Acts like an acid (can donate H+) b/c covalent bond b/w oxygen and hydrogen is so polar. Name: Carboxylic Acid or organic acid. Ex. acetic acid Amino group (NH2) Acts as base, can pick up H+ from surrounding solution. Name: Amine. Ex. Glycine Sulfhydryl group(SH) Two SH groups can react, forming a crosslink that helps stabilize protein structure. Name: Thiol. Ex. Cysteine Phosphate group (OPO3^2) Contributes negative charge (when positioned inside a chain of phosphates, 2 when at the end). When attached, gives a molecule the ability to react with water, releasing energy. Name: Organic Phosphate. Ex. glycerol phosphate Methyl group (CH3) Affects expressions of genes when on DNA or on protein bound to DNA. Affects the shape and function of male and female sex hormones. Name: Methylated compound. Ex. 5Methyl cytosine http://chemistry.elmhurst.edu/vchembook/213organicfcgp.html Vocabulary Carbohydrates: ● monosaccharide – sugar made of only one monomer ● disaccharide – sugar made of two monomers ● polysaccharide – sugar made of many monomers ● cellulose – polysaccharide used for structure by plants ● starch – polysaccharide used for storage by plants ● amylose – unbranched starch ● amylopectin – branched starch ● glycogen – polysaccharide used for storage in humans ● Alpha 14 glycosidic linkage – covalent bond found in glycogen and starch ● Beta 14 glycosidic linkage – covalent bond found in cellulose ● Alpha 16 glycosidic linkage – a branch point in glycogen and amylopectin ● glucose – a hexose and an aldose ● fructose – a hexose and a ketose ● sucrose – a disaccharide made of glucose and fructose ● lactose – a disaccharide made of glucose and galactose ● maltose – a disaccharide made of two glucose monomers ● ribose – a pentose and an aldose ● deoxyribose – a pentose with one fewer hydroxyl group than ribose Lipids: ● hydrocarbon – molecule made of only carbon and hydrogen ● saturated hydrocarbon – hydrocarbon with no double bonds and the maximum number of hydrogens ● unsaturated hydrocarbon – hydrocarbon with one or more double bonds and less than the maximum number of hydrogens ● fatty acid – hydrocarbon with a carboxyl group on the end ● glycerol – a three carbon molecule which serves as a framework for lipids ● phospholipid – lipid made of two fatty acids, a glycerol, and a hydrophilic head ● triglyceride – lipid made of three fatty acids and a glycerol ● fat – a common term for triglycerides ● sterols – class of molecules featuring four fused carbon rings ● cholesterol – sterol found in membranes ● hydrophilic – chemical property meaning “can interact with water” ● hydrophobic – chemical property meaning “cannot interact with water” ● amphipathic – chemical property meaning “can interact with both water and hydrophobic molecules” Amino Acids: ● amino acid – an organic molecule that is the building block of proteins ● polypeptide – a chain of many amino acids linked together ● peptide bond – the covalent bond linking two amino acids ● alpha helix – a spiral shape stabilized by hydrogen bonding ● betapleated sheet – a structure in which the polypeptide chain folds back and forth; stabilized by hydrogen bonding ● disulfide bridges – a covalent bond formed between the sulfurs of cysteine monomers ● chaperonin – a protein molecule that assists in the proper folding of other proteins ● primary structure – the specific sequence of amino acids in a polypeptide ● secondary structure – the threedimensional shape of a polypeptide as determined by coiling or folding due to hydrogen bond formation between components of the polypeptide backbone ● tertiary structure – the threedimensional shape of a polypeptide as determined by interactions of the side chains involved in various bonds ● quaternary structure – the shape of a multisubunit protein ● denaturation – the process by which a protein becomes biologically inactive by losing its native shape Nucleic Acids: ● nucleic acids – complex biomolecules composed of nucleotides that store cellular information in the form of a code; e.g.: RNA and DNA ● nucleotide – subunit of nucleic acids, formed from a 5carbon sugar covalently bonded to a nitrogenous base (nucleoside) and a phosphate group ● nitrogenous bases – nitrogencontaining ring structure, purines and pyrimidines ● pyrimidines – cytosine, thymine, uracil (C & T in DNA, C & U in RNA) ● purines – adenine and guanine (in DNA AND RNA) ● nucleoside – nitrogenous base linked to the 1′ carbon of sugar ● phosphodiester linkages – bonds that connect nucleotides in DNA and RNA ● ribose – a pentose (and an aldose) sugar, found in RNA ● deoxyribose – a pentose that is missing one hydroxyl group Carbon from Big Bang is inorganic Through food, organism ingest plants that uses photosynthesis to change it to organic carbon. Animals eats something that eats something that eats plants and so on and so on. Organic compounds made of carbon: Carbohydrates, proteins, lipids, nucleic acids Functional Groups common groupings with predictable characteristics. HydroxylOH Alcohols, sugars, proteins, and nucleic acids Carbonyl CO At the end, aldehyde: middle, ketone. Present in sugars, proteins and nucleic acid. Carboxyl COOH, COO Fatty acids, amino acids, proteins Amine NH2, NH3+ Amino acids, proteins, and nucleic acids Sulfhydryl SH Most reactive, proteins Phosphate PO42 Phospholipids, nucleic acids MethylCH3 Lipids, proteins, nucleic acid NH2 or NH3 acts as bases because lone pairs on the nitrogen atom accepts protonsby decreasing concentration of H+. Ex. Carboxylic acid. Two oxygens are electronegative, so one of the hydrogen might give itself up completely ,donating an H+ ion, making it an acid. Level 14: monomeric, macromolecules, supramolecular complexes, organelles and cell Carbohydrates, proteins, and nucleic acids are chainlike molecules called polymers, long molecules consisting of many similar building blocks(monomers) linked by covalent bonds. Dehydration reaction trading one covalent bond for another covalent bond. Releases water, or removes a water molecule. Allows monomers to connect through covalent bonds. Hydrolysis adding a water molecule, breaking a bond: H on one side, OH on other. Ex. digestion food in form of large polymers, various enzymes attack polymers, speeding up hydrolysis, released monomers absorbed through bloodstream Carbohydrates include sugars and polymers of sugars Monosaccharidesimple sugars Glucose, starch, galactose CH2Osimilar structures Carbonyl group (CO) different placement, multiple hydroxyl groups (OH) Diversity depends on spatial arrangement of their parts around asymmetric carbon Disaccharide double sugars, 2 monosaccharides joined by covalent bond maltose, sucrose, fructose, lactose Dehydration reaction glycosidic linkages Polysaccharides carbohydrates macromolecules, made of many sugar building blocks Storage Starch allows plants to store energy All “A” configuration, all monomers in same position Animals store glycogen Structural Cellulosecomponent of tough plant cell walls All “B” configuration, making every glucose monomer “upside down” with respect to its neighbors Almost all animals cannot digest, most cellulose digestion is in cells of symbiotic protists living in termite guts. Chitin carbohydrate used by arthropods Build exoskeletons Used by fungi in cell walls Similar to cellulose with “B” linkages Lipids(fats, phospholipids, steroids) All lipids are hydrophobic, nonpolar, don’t break down/dissolve from water molecules because of hydrocarbon regions Not big enough to be true polynomers or macromolecules Fats large molecules assembled by smaller molecules through dehydration Glycerol (alcohol, 3 carbons with hydroxyl) and fatty acids(long carbon skeleton with carboxyl group at the end) Hydrophobic because of hydrocarbon chains water molecules bond together and exclude the fats(ex. Vegetable oil separates from dressing) Triacylglycerol 3 fatty acids and glycerol by ester linkage(formed by dehydration between hydroxyl group and carboxyl group) Used as energy stored ATP molecules = “pocket change” Made by breaking down “fuel” like glucose Plants are immobile, can have bulky energy like starch, but animals carry energy with them so need compact energy like fat Fats are more compact compared to starch (that’s why animals use fats b/c they move) Fish have liquid fat while cows have solid fat. Cows uses fat for warmth. Fish fat is liquid in order to adjust to temperature and conditions, due to adding double bonds to fatty acids preventing it from, solidifying. Hydrogenation process converts unsaturated fats to saturated fats by adding hydrogen Hydrogen vegetable oils also creates unsaturated fats with trans double bonds. 1. Your body needs a certain amount of cholesterol that travels through blood with help of “lipoprotein” 2. Low density protein (LDL) carries cholesterol to your cells for use in cell membranes. High Density lipoproteins (HDL) finds excess cholesterol and return it to the liver 3. High LDL to HDL ratio will increase arterial plaque risk, leads to heart disease 4. Eating trans fat increases LDL to HDL ratio 5. Deposits called plaques develops in blood vessels, slow blood flow Saturated fats no double bonds between carbon atoms, “saturated with hydrogen” Most animals, allow fats to pack more tightly Ex. butter, solid at room temp Unsaturated one or more double bonds, fewer hydrogen atoms Most have cis double bonds, causes kinks why its liquid at room temp Ex. olive oil, fats of plants and fish Trans double bonds, contribute to heart problems Monounsaturated=one double bond Polyunsaturated= more than one double bond Both are “good” fats (not saturated or trans) but eating a lot of seed oil in large quantities is “bad for you” Phospholipids part of cell membranes “bilayers” Has two fatty acids attached to glycerol Two ends show different behaviors towards water, hydrocarbon tails are hydrophobic, but phosphate group form hydrophilic head with affinity for water Steroids carbon skeleton with four fused rings Most function as signalling hormones Cholesterol regulates futility in animal cell membrane Proteins made up of one or more polypeptides Enzymescatalysts speeds up reactions without being consumed Constructed by sets of amino acids, tend to be basic (donates H+) Peptide bond(between amino acids) Primary structure specific sequence of amino acids Covalently bonded between C atom of a carboxyl group of an amino group to make a polypeptide Releases a molecule of H2O in process of condensation reaction Polypeptide, polymer of amino acids Center carbon connects with an amino group, carboxyl group, hydrogen atom, and variable group “R” Chaperonins are protein molecules that aid in the proper folding of molecules by keeping the new polypeptide segregated from disruptive chemical conditions in cytoplasmic environment while it folds spontaneously Complex that facilitates folding for a polypeptide, an aggregate of chaperone proteins Barrelshaped (with a lid). The Polypeptide “enters” the barrel, which provides correct space and chemical environment for protein to fold correctly. Chaperonins are upregulated by environmental stress If an amino acid is changed, it may not have the same interactions therefore its structure will be different, and hindering its function. Ex. sickle cell anemia; normal red blood cells has Glutamic acid which has a polar R group. While sickled cell has Valine which is non polar. Changing the primary structure doesn’t necessary change function evolutionary advantage Denaturation is when a protein loses its 3D structure and becomes nonfunctional due to exposure to chemical conditions that disrupt noncovalent bond Higher Temp excited electrons disrupt bonds (hbonds, covalent) Changing PH(acidic/basic) adding more H+ disrupt Hbond Add salt concentrationsalt=ions, affecting ionic bonds Levels of Protein Function: 1. Primary linear chain of amino acids, determined by inherited genetic info (covalently bonded) 2. Secondary regions stabilized by Hbonds b/w atoms of polypeptide backbone (helix or pleated sheet) 3. Tertiary 3D shape stabilized by side chain (R) interactions, determines function and specificity(folds, loops, turns), ionic bond, london dispersions, hydrogen bonds, hydrophobic interactions, disulfide bond, etc Ex. antibody and virus protein fits into each other 4. Quaternary two or more polypeptides interactions. Ex. hemogoblin Nucleic Acids polymers made of monomers called nucleotides DNA(deoxyribonucleic acid) and RNA (ribonucleic acid) enables living organisms to reproduce complex components DNA provides directions for its own replication and directs RNA synthesis RNA controls protein synthesis “gene expression” Proteins are required to implement genetic programs Site of protein synthesis is called a ribosome In eukaryotic cells, ribosome are between nucleus and plasma membrane (cytoplasm) and DNA stays in nucleus. mRNA used to convey instructions from nucleus to cytoplasm. Prokaryotic cells(lacks nuclei) use mRNA to convey message from DNA to ribosome Each gene along a DNA molecule directs synthesis of a mRNA (messenger), which directs production of polypeptides (DNA>RNA>protein) Nucleic Acids macromolecules or polymers called polynucleotides, each polynucleotide have monomers called nucleotides Nucleotides made up of 5carbon sugar(pentose), nitrogenous base, and one or more phosphate groups Nucleoside is the carbon sugar and nitrogenous base Nitrogenous bases: Pyrimidine 6 membered carbon ring and nitrogen atoms. Cytosine, thymine, uracil Purines6 membered carbon ring with 5 membered ring. Adenine and guanine Adenine, guanine, cytosine in DNA and RNA, Thymine only in DNA, Uracil only in RNA Sugars: DNA deoxyribose, lacks an oxygen atom on second carbon in ring RNA ribose Nucleotide: Attach phosphate group to 5’ carbon of sugar Linkages of nucleotides into polynucleotides are joined by phosphodiester linkages (phosphate group that links sugars of two nucleotides) One end has a phosphate attached to a 5’ carbon, other end has a hydroxyl group on a 3’ carbon Structures of DNA and RNA DNA molecules forms a double helix, two sugar phosphate backbones run opposite 5’ to 3’ directions from each other “antiparallel”, two strands held together by hydrogen bonds Adenine always pair with Thymine, Guanine with Cytosine When the cell divides, copies are distributed to daughter cells, making them genetically identical RNA molecules exists as single strands Base pairing allows it to take on 3D shape tRNA (transfer) brings amino acids to ribosome during polypeptide synthesis Adenine pairs with Uracil