Transcript Carbon
Biochemistry Review Session #1 Properties of Water and Life Hydrogen Bonds Partial negative charge on Oxygen attracts partial positive charge on Hydrogen atoms Weak bonds, but very important in nature! Impacts most of water's properties Cohesion Water molecules stick to each other Water can be “pulled” as each molecule pulls on the molecule next to it Adhesion Water can also stick to other charged surfaces Important in our ability to move water, plants ability to take in water etc. Surface Tension Hydrogen bonds cause water to have a high surface tension or a surface that is hard to break Specific Heat Specific heat refers to the amount of heat it takes to raise 1g, 1°C Water has a very high specific heat It takes a lot of energy to change the temperature of water, because of Hbonds Spec. Heat Con. Water can moderate temperature Allows organisms to resist temperature change Essential to life Evaporative Cooling Water also has a high heat of vaporization Evaporating water consumes a lot of solar energy Sweat cools us off because the hottest molecules evaporate first Ice Floats This is unusual! Most solids are more dense than liquids The H-Bonds become locked Keeps the rest of lakes and rivers from freezing Warms the rest of the water Water is the Solvent of Life A solvent dissolves a solute Water dissolves almost any ionic or polar molecule Allows chemical reactions to occur in the body- allows us to break down food, separate molecules etc. Hydrophilia vs. Hydrophobia Hydrophilic= water loving, aka water soluble Hydrophobic (non-polar compounds)= won’t mix with water Water is Actually Undergoing a Chemical Reaction Or H2O OH- + H+ [OH] and [H] = 10-7 M Carbon-Based Molecules Aka Organic Molecules Almost everything besides water in our bodies is made from carbon! Proteins DNA Carbohydrates Fatty Acids Urea Carbon is the Building Block Wants to form 4 bonds Allows carbon to make lots of different molecules COHN Variation in Carbon Skeletons Carbon chains are the background of most macromolecules Hydrocarbons = only C and H atoms These molecules are hydrophobic Functional Groups What makes each molecule unique are the specific functional groups attached to the carbon chain Each group has a particular “behavior” Phosphate Hydroxyl Group Known as the alcohols Hydroxyl group is polar, can cause short chains to be hydrophilic Carboxyl Group O + R O- H+ Molecules containing carboxyl group are called carboxylic acids Acts as an acid, giving up its proton [H+] Essential part of amino acids Amino Group + H+ Known as amines Amino group acts as a base, accepting protons Essential part of amino acids Carboxyl and amino groups can bind to each other Amino Acids KNOW THIS STRUCTURE!!!! Sulfhydryl Group Similar to Hydroxyl group (notice location on periodic table) Involved in stabilizing proteins Phosphate Group Strongly negatively charged Very hydrophilic Extremely important in the transfer of energy! Found in DNA/RNA Macromolecules Polymers from Monomers Polymers Long chain of monomers Monomers are connected to each other by dehydration reactions (aka condensation) This takes energy and involves the removal of water Hydroxyl group from one molecule and H atom from another are removed, forming a water molecule Hydrolysis Macromolecules are split apart by water So we can make new polymers Also releases energy Carbohydrates Simple Sugars Disaccharides Polysaccharides Starch Glycogen Cellulose Chitin Sugars / Monosaccharides Molecular formula is multiple of CH2O ex. glucose C6H12O6 Used directly to generate usable energy Most Sugars form rings Can also be used to build more complex carbs Can also be used to build other molecules i.e. DNA, RNA, fats etc. Disaccharides Dehydration reactions connect 2 sugar molecules Forms 2 ring sugars such as lactose and sucrose Polysaccharides A few hundred to a few thousand sugar molecules linked together The type of sugar and the arrangement determine what kind of carbohydrate is made Starch Major energy storage unit in plants Potatoes, grain, corn etc. are heavy in starch Glycogen How animals, including humans, store sugar Different shape than starch, but same basic purpose We break down glycogen when we need fuel Cellulose (aka Dietary Fiber) Major component of plant cell walls We can’t digest cellulose, but it is important for healthy bowel movements Carb Review •The way organisms store sugars •Made of simple sugars, connected by dehydration reactions •Also important in plant cell walls Lipids – The Hydrophobic Macromolecules Only class of macromolecule that is not a polymer! Mostly hydrocarbons (hence the hydrophobia) Fat Glycerol, a 3carbon sugar with fatty acids attached Notice they are made by dehydration rxns C-H tail DOES NOT want to mix with water Saturated vs. Unsaturated Fat Saturated = all single bonds in the hydrocarbon tail Unsaturated = at least one double bond Kink in chain Straight chain Solid at room temperature Liquid at room temp Called oils Most animal fats Found in fish and plants (lard, butter) Purpose of both = ENERGY STORAGE, insulation etc. Phospholipids Similar to fats, except only 2 fatty acid tails One of the carbons is instead bonded to a phosphate group Phosphate head gives the molecule a polar, hydrophilic head Important in cell membranes Phospholipids Steroids Four fused carbon rings Cholesterol, many hormones No polar groups – this molecule is non-polar Proteins Important in nearly everything the cell does Structural support, storage, transport, signaling, movement, defense, enzymes etc. Tens of thousands of different proteins in the body Amino Acids are the Building Blocks All proteins are made of amino acids Amino acids contain an amino group, a carboxyl group, an H atom and a “variable group” The R group is the only thing that changes Peptide Bonds Amino acids are joined by dehydration reactions, creating polypeptides Bond formed is called a peptide bond Polypeptides Multiple amino acids joined together form a polypeptide. If the polypeptide is functional in the body, then it is considered a protein Protein may be made of several polypeptides Function Depends on Shape A functional protein is has a unique 3-d shape The amino acid sequence determines the shape Denaturing Proteins • When exposed to heat, acid/base or salts, proteins lose their shape • This is why heat kills many organisms, why people with fruit allergies can eat cooked fruit, etc. • Can regain shape More on Denaturing •Heat (energy) causes the atoms to move so much that they break apart •Acids, bases and salts are charged molecules and interrupt with bonding in the protein Nucleic Acids Store and transmit hereditary information Polymers of nucleotides DNA and RNA Nucleotides A nitrogen ring connected to a ribose (5-carbon) sugar connected to a phosphate group Sugar is ribose in RNA, and deoxyribose in DNA (only difference is a single oxygen atom on the 2nd carbon) DNA/RNA Backbone Nucleotides are bound together by dehydration reactions connecting the phosphate group of one nucleotide RNA!to the sugar of the next Is this DNA or RNA? Living Things Exchange Materials •All of these molecules require intake of energy and atoms/molecules •This requires a large surface area Reason Why Cells Are Small Other Examples of Increasing Surface Area •Alveoli in lungs help us take in more oxygen and get rid of more CO2 Other Examples Villi in the intestine help absorb more nutrients Other Examples •Root hairs help plants soak up more nutrients and water Nutrient Cycles •Energy flows into and out of Earth (not a cycle) •But the materials we need cycle in and out of living things •I.e. water, we drink it, pee it out, it evaporates, it rains, we drink it again etc. Carbon Cycle •Taken in during photosynthesis •Center of almost all molecules made in plant •Animals obtain by eating carbonbased foods Other Cycles Nitrogen Phosphorus •Taken in from soil by •Taken in from soil as well plants •Used in nucleic acids •Used to build and some lipids as well proteins and nucleic as things like ATP acids •Must be eaten by animals •Passed on to animals