Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Biological molecules: • All are organic (based on carbon). • Monomers vs. polymers: – Monomers refer to the subunits that, when polymerized, make up a larger polymer. – Monomers may function on their own in some cases. Four types of biological molecules • Carbohydrates - refer to a large group of biochemicals which in nature include monomers and polymers. • Lipids - not considered as monomers/polymers like the others; they all have one PHYSICAL property in common. • Proteins - polymers of amino acids with versatile functions. • Nucleic acids - polymers of nucleotides, may be DNA or RNA. • Definition: contain carbon, hydrogen, and oxygen (carbo+hydrate), usually in the following ratio: [C(H20)]n Basic Building Blocks • Monosaccharides – Three types, each of which contains 6 carbon atoms: – glucose (most popular) – fructose – galactose Monosaccharides • Usually, they exist in nature as a "ring" form, after an ester linkage forms between the #1 carbon and the hydroxyl group of carbon #5 (in the case of monosaccharides with six carbons). Building on a theme • When two monosaccharides are joined together by dehydration synthesis (a glycosidic bond), a DISACCHARIDE results. • Disaccharides always contain glucose + one other monosaccharide: • Sucrose (common table sugar) = glucose + fructose • Lactose ("milk sugar") = glucose + galactose • Maltose = glucose + glucose Other monosaccharides • Some have five carbons, like ribose and deoxyribose, the sugars in the nucleotides of DNA and RNA (LATER) Polysaccharides • Usually consist of long chains of glucose or modified glucose monomers, linked by different types of glycosidic bonds and with different branching properties. • Starch - plant storage polysaccharide • Cellulose - plant structural polysaccharide (beta-1, 4 linkage that animals cannot in general digest) • Glycogen - animal storage polysaccharide • Chitin - makes up fungal cell walls and arthropod exoskeletons polymer of N-acetyl glucosamine (NAG) • Peptidoglycan - polymer of alternating NAG and NAM (N-acetyl muramic acid) subunits, most bacterial cell walls contain it Functions of Carbohydrates: • Mainly, to provide ENERGY for an organism • Structural components of cell walls • May be attached to proteins and function as antigens In nutrition, • Mono- and disaccharides are referred to as sugars, or simple carbohydrates. • Polysaccharides are referred to as complex carbohydrates. • Definition: biological molecules that are insoluble in water (they are hydrophobic, or non-polar) Basic Types • Triglycerides (fats and oils) • Phospholipids • Sterols Triglycerides • Fats are solid at room • Triglycerides are temperature, because formed when three they contain saturated FATTY ACIDS are fatty acids. joined to a molecule of the trialcohol glycerol • Oils tend to be liquid at room temperature, by dehydration because they possess at synthesis. least one point of unsaturation (C=C double bond). Saturated fatty acids Points of unsaturation (cause double bonds and "kinks" in the molecule) Phospholipids • Are very similar to triglycerides in chemistry: one of the fatty acids is replaced with a phosphate containing group. • This causes the molecule to have a "split personality", being partially hydrophobic and partially hydrophilic. Molecules like this are referred to as “amphipathic”. Sterols, or steroids • Are based on ring structures. • Cholesterol is the most popular steroid, although many hormones and other biological compounds are formed from cholesterol (testosterone, estrogen, cortisol, vitamin D). Functions of LIPIDS: • Triglycerides - long term energy storage, cushioning and insulation in multicellular organisms. • Phospholipids - structural basis of cell membranes and lipid-transporting lipoproteins (HDL's and LDL's). • Steroids - Cholesterol functions in the structure of cell membranes; others are hormones, etc. • Definition: long chains of subunits called AMINO ACIDS joined by PEPTIDE BONDS (dehydration synthesis again) • There are 20 different amino acids. • Each one contains a central carbon bound to an amino group, a carboxylic acid group, a hydrogen, and an R (variable) group. AMINO ACIDS Levels of protein structure • Primary - sequential order of amino acids in chains Levels of protein structure • Secondary - local hydrogen bonding interactions between amino and acid groups form structures such as the alpha-helix and the beta-pleated sheet. Continued • Tertiary - hydrogen • Quaternary bonds, electrostatic, Sometimes, folded and hydrophobic polypeptides interactions associate with each between R groups other to form a cause the molecule functional protein to fold up in three(e.g., hemoglobin, dimensional space. antibodies). Types of non-covalent interactions that create and maintain tertiary structure include: Hydrophobic interactions Hydrogen bonding (between R-groups) Ionic/electrostatic interactions Functions of PROTEINS are MANY!! • • • • Enzymes (catalyze chemical reactions) Hormones Antibodies Structural (mainly in animals - muscle tissue, connective tissue) • Famous proteins: hemoglobin, collagen, keratin, insulin • Membrane associated transporters…and more!! In nutrition, • We ingest proteins mainly to get amino acids for building our own proteins. • They do however contain calories, and any excess will be converted to fat. • In the process, they become deaminated, forming the metabolic waste urea, which is excreted in the urine. • Definition: long chains of subunits called NUCLEOTIDES joined by PHOSPHODIESTER BONDS. • There are two classes of nucleic acids depending upon which type of sugar they contain. The two classes are DNA and RNA. The nucleotide contains: • A five carbon sugar (ribose in RNA or deoxyribose in DNA); • A phosphate group; • A nitrogen containing base, of which there are four types in DNA. Continued • DNA bases: – Guanine – Cytosine – Adenine – Thymine • In RNA, thymine is replaced by uracil. Bonding RULES • DNA exists in nature as a double helix, with two nucleotide strands running antiparallel and joined by hydrogen bonding between the bases. • A binds with T (2 H-bonds). • G binds with C (3 H-bonds, stronger bond). • In RNA, A binds with U when applicable. Functions of NUCLEIC ACIDS • DNA makes up the genes, which contain genetic information. • RNA functions in various capacities in the process of protein synthesis (i.e., expression of the genetic information). • ATP, a triphosphate form of an RNA nucleotide, also functions as the major energy carrying molecule of the cell! Ribose