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Biomolecules of Life Carbohydrates Carbohydrates include sugars and the polymers of sugars. The monomers of carbohydrates are monosaccharides, or simple sugars. Carbohydrate polymers are called polysaccharides. Monosaccharide Polysaccharide Carbohydrates are made of CHO: carbon, hydrogen, and oxygen. Monosaccharide Polysaccharide Monosaccharides have molecular formulas that are usually multiples of CH2O. Glucose (C6H12O6) is the most common monosaccharide. Glucose Polysaccharides have storage and structural roles. The structure and function of a polysaccharide are determined by its sugar monomers and the positions of glycosidic linkages (the bonds that hold polymers together). Starch, a storage polysaccharide of plants, is constructed of monomers of (alpha) glucose. Plants store starch within chloroplasts and other plastids. glucose Starch, made from 1-4 glycosidic linkages Glycogen, a storage polysaccharide in animals, is made from highly branched chains of glucose . Glycogen is stored mainly in liver and muscle cells. Cellulose is a polysaccharide that is a major component of plant cell walls. Cellulose is a polymer of glucose, and is not digestible by animals. glucose Cellulose, made from 1-4 glycosidic linkages Starch vs. Cellulose Starch, made from 1-4 glycosidic linkages Cellulose, made from 1-4 glycosidic linkages Chitin, a structural polysaccharide, is found in the exoskeleton of arthropods and the cell walls of many fungi. Directionality influences structure and function of polymers. An example is the directionality of DNA that determines the direction in which complementary nucleotides are added during DNA synthesis. Directionality influences structure and function of polymers. Think of directionality like the “head” and “feet” of a person- you have specific ends. Molecules have specific ends, too, and some have special names. The type of bonds between monosaccharides determines their relative orientation in a carbohydrate. This then determines the secondary structure of the carbohydrate. Beyond this, there is no special directionality to know about. So, carbohydrates are mainly for: quick energy, storage, and structure. Monomers include things like glucose, fructose, galactose. Polymers include starch, chitin, glycogen, cellulose. Carbohydrates • Stop and review the information to make sure you have it all before moving on! Proteins Proteins are derived from polypeptides, which are polymers built from the same set of 20 amino acids (protein monomers). Proteins are made of CHON: - Carbon - Hydrogen - Oxygen - Nitrogen *They can have other elements too, depending on what their R-groups are made of (more on that soon). In proteins, the specific order of amino acid monomers in a polypeptide interacts with the environment to determine the overall shape of the protein. An amino acid monomer contains an amino group, a carboxyl group, and an R group attached to a central carbon. (I would probably draw this in your notes…) Amino Group Carboxyl Group The main part of the amino acid is shared between all 20 kinds. However, the “R group” is what makes each amino acid unique. Amino Acids with Electrically Charged Side Chains Aspartic acid Glutamic acid Lysine Arginine Histidine Amino acids differ in their properties due to differences in their R groups, also called side chains. (p79) Amino Acids with Electrically Charged Side Chains Aspartic acid Glutamic acid Lysine Arginine Histidine As amino acids link up, a polypeptide chain forms. This is what is known as the primary structure of the protein. (There are 4 levels of protein structure. This is the first. See pg.82 for more info). In any given protein, some amino acids in the polypeptide chain will interact and form hydrogen bonds. This is called the secondary structure of the protein. Typical secondary structures are a coil called an helix and a folded structure called a pleated sheet. (pg 82) pleated sheet helix Tertiary structure (the 3rd level of how a protein folds) is determined by interactions between R groups/side chains. These interactions include hydrogen bonds, ionic bonds, hydrophobic interactions, and van der Waals interactions. Strong covalent bonds called disulfide bridges may reinforce the protein’s structure. Quaternary structure results when two or more polypeptide chains form one macromolecule. A functional protein consists of one or more polypeptides twisted, folded, and coiled into a unique shape. After reading this and checking out the book, does protein folding still confuse you? Then watch the first video and take a look at the second animation. https://www.youtube.com/watch?v=qBRFIMcxZNM http://www.stolaf.edu/people/giannini/flashanimat /proteins/protein%20structure.swf Amino acids are linked by peptide bonds. Peptide bonds form from condensation, or dehydration synthesis, reactions. Proteins have an amino end and a carboxyl end. Proteins have many functions- almost too many to list. They do everything from transport molecules in organisms, speed up reactions (enzymes), form body structures (like hair and nails), and much more. We will learn a ton more about proteins this year. Some examples: Collagen is a fibrous protein consisting of three polypeptides coiled like a rope. Some examples: Hemoglobin is a globular protein consisting of four polypeptides: two alpha and two beta chains. Important to know: Most proteins probably go through several states on their way to a stable structure. Chaperonins are protein molecules that assist the proper folding of other proteins. Important to know: This loss of a protein’s native structure is called denaturation.A denatured protein is biologically inactive. This can be caused by the things listed in the table. Proteins are affected by changes in: • • • • pH Salt concentration Temperature Other environmental Before moving on… • Compare carbohydrates and proteins. – How are their structures different? – How are their functions different? Nucleic Acids In nucleic acids (polymers), biological information is encoded in sequences of monomers called nucleotides. Nucleic acids consist of CHONP: carbon, hydrogen, oxygen, nitrogen, and phosphorous. Each nucleotide has the following structural components: • a five-carbon sugar • a phosphate group • a nitrogen base Deoxyribose sugar is in DNA and ribose sugar is in RNA. The polymers of nucleic acids (called “nucleic acids,” ooo, fancy!) consist of DNA and RNA. Nucleic acids carry genetic information, which is used to assemble proteins. The bonds that connect nucleotides are called phosphodiester bonds. Phosphodiester bonds form by condensation reactions. Directionality: nucleic acids have a 5’ end and a 3’ end. We will talk more about which is which later on. DNA and RNA differ in function and differ slightly in structure. These structural differences account for the differing functions. • • • • DNA Deoxyribose sugar Thymine Shape: double helix Code for genetic information • • • • RNA Ribose sugar Uracil Shape: single strand Copy DNA so protein can be made Lipids Lipids are the one class of large biological molecules that do not form polymers. They are mostly made of carbon and hydrogen. The most biologically important lipids are fats, phospholipids, and steroids. In general, lipids are nonpolar, having little or no affinity for water. Lipids are hydrophobic because they consist mostly of hydrocarbons (they are mostly C and H), which form nonpolar covalent bonds. Fats are constructed from two types of smaller molecules: glycerol and fatty acids. Fatty acids are bonded to the glycerol molecule by ester bonds. The formation of ester linkages is a dehydration synthesis reaction. Differences in saturation determine the structure and function of lipids. Saturated fatty acids have the maximum number of hydrogen atoms possible and no double bonds. (solid at room temp- can pack close) Unsaturated fatty acids have one or more double bonds. This results in a bent structure. (liquid at room temp- “kink”- can’t pack) Trans fats (hydrogenated oils)- unsaturated fats that have been synthetically converted to saturated fats by adding hydrogen. These kinds of lipids are great for long-term energy storage (they provide more energy per gram, when compared to the other biomolecules). They are also great for insulation. Phospholipids have polar regions that interact with other polar molecules such as water. They also have nonpolar regions that do not interact with water. Phospholipids are found in cell membranes and help serve as barriers to keep things in or out of cells. Steroid lipids include cholesterol, steroid hormones (derived from cholesterol), and bile salts. Cholesterol (seen below) is important in cell membranes and helps keep them fluid. Note its ring-shaped structure. Steroid hormones are derived from cholesterol. In humans, sex hormones like testosterone and estrogen are steroid hormones. Steroid hormones are special because they are able to pass through the cell membrane and get inside a cell (most other chemical messengers cannot do this). Bile salts, also cholesterol-derived, are used to help digest lipids in the body. Wrap up! • Remember, if you have questions/confusions, you have options. – Try to find your answers in the book. It’s giant but it’s actually a really good resource. See if you can answer things yourself. – If the book fails you, try to find your answers online. You have a plethora of resources available to you through Google and YouTube…more than I ever had in school. Lucky you! – Finally, you can always jot your ponderings down! Ask in class! If you are confused, someone else probably is too. Asking helps everyone, not just yourself. You can even ask “extension” questions if you just want to know more about something. And finally… • Remember, how much you learn (and how well you do on the final test) is ultimately up to you. • How can you ensure learning? Immerse yourself in content. Review often. • Here’s an example…seek out videos. Bozeman and Crash Course are always fantastic. See next slide. And finally… • There’s a GREAT Crash Course video on this topic. I’m not going to require it, but honestly, it would be a really good idea for you to watch it. Why? – The more ways you reinforce the topic, the more likely you are to transfer it to long-term memory. – You might pick up something from him that you didn’t from me. – Yeah, it looks long, but the “meat” of the video doesn’t really start until 3:43. Can you spare ~10 minutes? – And besides…he’s hilarious, so it’s worth it. I can’t watch one of these videos without cracking up! And finally (again)… • There are “test yourself” questions that you can use to see if you’re “getting it.” Go back to my dropbox folder and open PPT 6.