本期內(nèi)容是 生物高分子實(shí)驗(yàn) 的基礎(chǔ)理論部分，實(shí)驗(yàn)手冊(cè)請(qǐng)看下期、實(shí)驗(yàn)?zāi)M請(qǐng)看下下期。本部分內(nèi)容來(lái)自 University of California, Berkeley - UC Berkeley Extension, 虛擬實(shí)驗(yàn)的內(nèi)容來(lái)自 Labster. 本部分內(nèi)容均不會(huì)標(biāo)記為為原創(chuàng)，但由于是UP主購(gòu)買(mǎi)的課程，因此不接受非授權(quán)的轉(zhuǎn)載，謝謝您的理解。

每一個(gè)生物基礎(chǔ)實(shí)驗(yàn)均會(huì)分為三部分：第一部分為實(shí)驗(yàn)的生物理論；第二部分為實(shí)驗(yàn)的指導(dǎo)手冊(cè)；第三部分為 Labster?的虛擬實(shí)驗(yàn)?zāi)M。第一部分的基本信息由 Ying Liu, Ph.D. 提供，第二部分的實(shí)驗(yàn)手冊(cè)來(lái)自 Labster, 第三部分的實(shí)驗(yàn)?zāi)M過(guò)程由UP主操作。

Lab 2 - Macromolecules:?Basic Information:

Molecules of Life:

????Biological macromolecules are large molecules made up of repeating units of sMaller molecules;

????These are also called organic molecules because they contain carbon and hydrogen;

????The four classes of biological macromolecules are: Carbohydrates, Proteins, Lipids, Nucleic Acids.

Dehydration and Hydrolysis Reactions

????Macromolecules are polymers, made of repeating units of building blocks called monomers;

????The synthesis of the polymers uses reaction called dehydration reaction, because the removal of water allows subunits (monomers) to link together into larger molecules;

????The breakdown of the polymers uses hydrolysis reaction because the addition of water breaks larger molecules into their subunits.

[1] Carbohydrates

????- Carbohydrates are made of C, H, and O, usually at the ratio of 1:2:1 (glucose: C6H12O6);

????- Function as short- and long-term energy storage;

????- Name generally end in ‘-ose’;

????- One monomer unit is called a monosaccharide;?

Glucose: the most common monosaccharide:

????????- End product of photosynthesis in plants;

????????- Metabolized by cells (cellular respiration) to produce ATP (a source of energy).

A disaccharide is formed when two monosaccharides are covalently bonded together (sucrose, lactose, etc.);

Glycosidic linkage: the covalent bond formed;

Polysaccharides (complex carbohydrates) are made of many carbon rings;

Starch is the storage form in plants (less branched);

Glycogen is the storage form in animals (highly branched);

Cellulose (fiber) is found in plant cell wall (structural support);

Chemical bonds in cellulose are different from those in starch, and we don’t have the enzymes to break it down;

Fiber passes through our body undigested.

Assays for Carbohydrates

????- I2KI test for starch: Starch (colorless) + I2KI (amber): turns blue-black when together;

????- Benedict’s test for reducing sugar: Benedict’s reagent (blue) turns green or orange / red if glucose is present.

Iodine Assay for Starch

????- Amylose in starch combines with iodine to give a blue-black color;

? ? - Iodine+iodide slide into helical structure of amylose;

????- Glucose does not have helix, no change in color with iodine;

? ??- Add several drops of Lugol’s until visibly yellow-amber.

Benedict’s Reagent Assay

????- Aldehyde or ketone group of simple sugar reduces blue Cu++ to Cu+ which precipitates as red copper oxide;

????- Color change to green/yellow/orange/red indicates reducing sugar;

????- Starch has few groups (only the glucose at the end of a chain of starch will have an exposed aldehyde functional group to react with Benedict's reagent), so no reaction;

????- Sucrose gives negative result.

[2] Proteins

????- Proteins are made of subunits called amino acids;

????- There are 20 amino acids in our cells;

????- Peptide bonds link the carboxyl group (COOH) of one amino acid to the amino group (NH2) of another amino acid;

????- Important for diverse functions in the body including hormones, enzymes, antibodies and transport.

????- The chains of amino acids linked by peptide bonds are called polypeptides, ranging from a few amino acids to hundreds of amino acids long;

????- Proteins fold into 3D structures (native state), which is essential for their function;

????- Loss of the 3D structure (denaturation) leads to loss of function.

Protein Structures:

Protein Functions:

????- Support: structural proteins such as keratin in our hair and nails, collagen in our skin, cytoskeleton;

????- Enzymes: molecules that catalyze reactions all over the body.

????- Transport channels: facilitate the movement of chemicals into and out of our cells;

????- Hormones: insulin and glucagon both regulate blood glucose level;

????- Antibodies: molecules important in the immune system;

Assay for Proteins

????- Biuret test: presence of proteins:

????- Dye reacts with the peptide bonds;

????- Copper (II) is reduced to copper (I), which forms a complex with the nitrogens and carbons of the peptide bonds in an alkaline solution.

[3]?Lipids

????- Lipids consist mostly of carbon and hydrogen, and do not dissolve in water;

????- Major functions of lipids include: Energy storage (Triglycerides), Cell membrane (Phospholipids), Hormones (steroids), etc.;

????- Their low water solubility is an absence of hydrophilic polar groups;

????- Building blocks: fatty acids.

Triglycerides: Fats and Oils

????- Triglyceride is composed of one molecule of glycerol and three molecules of fatty acids (16-18 carbon long);

????- Saturated fat has single bonds and is solid at room temperature;

????- Unsaturated fat contains double bond(s) and is liquid at room temperature.

????Fats (saturated) usually come from animals;

????????- Function for long-term energy storage, insulation from heat loss, and cushion for organs;

????Oils (unsaturated) usually come from plants.

????Artificial trans fats are created in an industrial process to make them more solid (extend shelf life) - Doughnuts, baked goods including cakes, pizza, cookies, and stick margarines.

Phospholipids

????- Phospholipids are the primary components of cellular membranes;

? ? - A phospholipid contains one molecules of glycerol, 2 fatty acids and a polar phosphate group;

????- It contains a polar head (hydrophilic) and two nonpolar tails (hydrophobic);

????- They form a lipid bilayer.

- When exposed to water, a single layer of phospholipids forms a micelle;

- 2 layers of phospholipids form lipid bilayer, the structure of cell membrane.

Steroids

????- Steroids are lipids that have a backbone of four fused rings

????- Cholesterol is an important biological molecule that plays a key role in cell membrane structure;

????- Estrogen and testosterone are sex hormones; Cholesterol is the basis of estrogen and testosterone.

Assay for Lipids

????- Brown Paper Bag Test: presence of lipids - Brown paper turns translucent in the presence of lipids (wait until it is dry!);

????- Sudan IV: fat soluble dye that stains lipid red.

This Lab:

Results:

感謝閱讀！下一期為實(shí)驗(yàn)手冊(cè) & 下下期將進(jìn)行 Labster 實(shí)驗(yàn)！