BIOL 111 Lab Exercise 3

« previous | Thursday, September 16, 2010 | next »

Lab Slides

Biomolecules

Most of this information is covered in Chapter 5→.

Any molecule that naturally occurs in living cells

• Essential to cell functions; form basic parts of tissues.
• Carbon skeleton. Also includes H, O, N, P, and S
• In addition to below, biomolecules include vitamins, hormones, phosphates, nucleotides, and nucleic acids

Saccharides (Carbohydrates)

Made of Carbon ring structure with hydrogen and hydroxides; Hydrophilic

Key functions:

1. Supply carbon for synthesis of other biomolecules
2. Form structural components in cells and tissues
3. Provide fuel for cell metabolism
4. Storage of glucose for later metabolic use

Three Types:

monosaccharides

• characterized by aldehyde (H–C=O) or internal ketone (C=O) carbonyl group
• identified with Benedict's reagent Cu⁺, which reacts with =O bond to form CuO

disaccharides

• 2 monosaccharides bonded by glycosidic bond formed by dehydration synthesis ; breaking this bond is called hydrolysis
• identifiable with Benedict's only if molecule has free aldehyde/ketone group

dietary polysaccharides (starches)

• long chains of glucose (fuel) molecules
• amylose is one strand; amylopectin has branched chains

amylose has spiral shape that reacts with I₃^– ion in Lugol's, which causes the blue-black color.

Lipids (Fats)

Functions:

1. Store oodles of energy
2. Provide environment to break down (metabolize) fat soluble vitamins
3. Required for growth and development
4. Insulates cells from outside (phospholipid bilayer / plasma membrane)
5. Protects organs

Characterized by hydrophilic "head" with hydrophobic nonpolar fatty acid "tails".

Tails bound to head via ester linkages: dehydration synthesis between OH in carboxyl in fatty acid and OH hydroxyl in the glycerol

saturated fatty acid

unbranched hydrocarbon chain formed with only single bonds

unsaturated fatty acid

unbranched hydrocarbon chain that contains one or more double bond between carbon atoms, creating a kink or bend in the chain

triglycerides

• Glycerol head and three fatty acid tails
• Highest energy per gram storage ratio out of all molecules
• Fats are solid at room temperature whereas oils are liquid.
• Normally lited as saturated fats on food labels
  • Trans fats formed by adding Hydrogen atoms to unsaturated fatty acids in vegetable oils; also increase risk of heart disease and heart attack

phospholipids

• Glycerol head, two fatty acid tails, and hydrophilic phosphate "hat" on top of head
• Main unit of cell membranes
• phospholipid — phosphate = diglyceride
• diglycerides listed as polyunsaturated fats on food labels; ← THESE FATS ARE ACTUALLY GOOD FOR YOU!

sterols

• Cholesterol derivatives: 4 carbon rings attached to hydrocarbon chain; very hydrophobic
• Important component of cell membranes
• Stored in endocrine organs (adrenals, thyroid, ovaries, testes, etc.) as steroid hormones
• Used in liver to form bile compounds that help in digestion

• Minimize dietary intake since cholesterol is synthesized naturally.
• Transported through body by lipoproteins: low density lipoprotein cholesterol (LDL-C) is bad, high density lipoprotein cholesterol (HDL-C) is good.

Types of lipids can be separated by thin-layer chromatography.

R_f

$R_{f}={\frac {\text{distance moved by pigment}}{\text{distance from origin to solvent front}}}$

Peptides (Proteins)

folded chains of amino acids.

• majority are enzymes that catalyze reactions
• structural or mechanical functions
• transport (like how hemoglobin transports O₂)
• cell signaling (hormones), Immune responses (immunoglobulins), cell adhesion (clotting factors), cell reproduction (mitosis)
• store nutrients in eggs and blood (albumin), and milk (casein)

Amino Acids

• building blocks of proteins
• central α-carbon with 4 groups: Amino group, carboxyl group, H atom, and R group
• Aminos join through dehydration synthesis called peptide bond: OH in Carboxyl bonds to H in Amino
• dipeptide (2 amino acids); tripeptide (3 amino acids); polypeptide (4+ amino acids)

Structure

1. primary: order of amino acids
2. secondary: unique pleated/coiled structure formed by hydrogen bonds
3. tertiary: bonds between R groups
4. quaternary: relationship of multiple peptide chains in complex proteins: most are globular, but structural proteins are fibrous

Chemical Tests

All are qualitative:

Test	Tests For	Color Before	Color After	Positive Control	Negative Control
Bennedicts	Reducing Sugars	Pale Blue	Blue = none Green = low Brown = intermediate Orange/Red= high	Glucose Solution	Distilled Water
Lugol's	Starch	Yellow	Blue-black	Potato	Distilled Water
Sudan IV	Lipids	Light Red	Red stained oil droplets	Any oil	Distilled Water
Biuret	Peptide Bonds	Very pale blue	Violet	Milk	Distilled Water
Ninhydrin	Free Amino Acids	No Color	Purple or Yellow (dry)	Amino acid methionine	Distilled Water

BMR

Calculated BMR = 24 kcal/kg/day × weight in kg. = kcal/day

Adjusted BMR: +30% sedentary; +60%-70% for 2 hrs exercise daily; +100% for several hrs of heavy exercise

My BMR

$160\,{\text{lbs}}\times {\frac {1\,{\text{kg}}}{2.2\,{\text{lbs}}}}\times {\frac {24\,{\text{kcal/day}}}{1\,{\text{kg}}}}\times 1.60\dots 1.70\,{\text{active}}=2793\dots 2967\,{\text{kcal/day}}$