Found a site w/ good pictures http://www.chemistar.com/Biology/organicmolecules.html
- Provide energy (9 cal/gram compared to carbs & proteints at 4cal/gram)
- Provide structure (ex. cell membranes)
- Some are hormones. (ex. estrogen, testosterone)
Contain C, H, O
Sources – Fats, oils, waxes, phospholipids (part of cell membranes), steroids.
Fats are a subgroup of Triglycerides – a typical triglyceride molecule is found in oils (plants) & fats (animals).
ex. 1 glycerol + 3 fatty acids = 1 triglyceride (ester bond- connects glycerol to fatty acids)
Subgroups of Lipids…
Saturated: maximum # of Hydrogen attached to each carbon. (no double bonds between Carbon atoms)
Monounsaturated: has only one double bond in the chain. Therefore, fewer Hydrogens & a kink in the chain. (Oleic Acid)
Polyunsaturated:2 + double bonds in the chain. Also, has less Hydrogen & more kinks in the chain. (Linoleic Acid)
1 glycerol + 2 fatty acids + 1 phosphate group + 1 organic functional group = phospholipid
Phosphate groups – Interacts with water; because the phosphate head is polar.
Fatty acid ‘legs’ – Non-polar, do not interact with water and align themselves together to be protected from the water while exposing the phosphate groups to the water.
- Contain 4 fused rings
- Include cholesterol (found in cell membranes of animals)
- Involved in cell communications (ex. hormones)
- Catalysts for chemical RXNs (enzymes)
Contains C, H, N, O (S)
- R-group: Glutamine; Serine
Polypeptides (Polymers): 2+ amino acids linked together.
- Peptide Bonds- Protein covalent bonds
- DNA provides the instructions to make (LARGE CHAINS) proteins; they are made inside the cell linking one amino acid to another.
- Each protein has a unique combination of amino acids
- 20 different types of amino acids formed in living things.
Levels of Protein Structure:
- Primary – The specific order of amino acids in a polypeptide chain.
- Secondary – Hydrogen bonds form between the carboxyl groups & amino groups. This stage forms β -pleated sheets & α-helices throughout the polypeptides.
- Tertiary – Additional bonding occurs involving R-groups to make simpe proteins (one peptide chain) functional.
- Quaternary – Additional bonding occurs between more than one polypeptide chain to make functional protein (complex)
Ex. of importance of primary structure:
- Prion that causes Scrapie (sheep) : Alanine is substituted for valine and #136 resulting in a mis-fold of proteins.
- Sickle Cell Disease (humans): Valine gets substituted for glutamate @ # 6 in hemoglobin. Valine does not interact well w/ water causing it to crystalize and form a deformed cell.
Protein Denaturation – The loss of tertiary or quaternary structure, resulting in a loss of function. Causes are high heat, alcohol, some metals and/or acids.
Extra Credit: Smith Lemli Opitz Syndrome – an autosomal recessive metabolic and developmental congenital disorder that causes the inability to correctly produce or synthesize cholesterol due to a low occurrence of the 7-DHC reductase enzyme.
Only a few of the symptoms:
- Small head size (microcephaly)
- Mental retardation
- Learning disabilities and behavioral problems
- Malformations of the heart, lungs, kidneys, gastrointestinal tract, and genitalia
- Low muscle tone (hypotonia)
Q: Is my bacteria gram positive or gram negative?
Purple colored cells = gram positive
- Gram Positive Cells – have thick peptidoglycan (multiple layers) that contains teichoic acid
Pink colored cells = gram negative
- Gram Negative Cells – Thin peptidoglycan (few layers) with outer membrane that contains lipopolysaccharides (toxic to mammalian cells)
Can be used to identify Gram-Positive vs. Gram-Negative cells. Potassium Hydroxide causes Gram – Negative cells to lyse (busrt), releasing a viscous liquid. (It will be ‘snotty-like’) Gram-positive cells do not lyse when mixed with KOH, so the liquid remains thin/non-viscous.
Acid Fast Stain
Q: Does the unknown bacteria have mycolic acid (was like substance) in its cell walls?
A: Use an acid fast stain.
Note: Mycolic acid is only found in gram positive cells, but not all gram positive cells have mycolic acid.