Chapter 3: Carbon Compounds in Cells
Chapter 3 in pdf
Introduction
- Climate change is occurring quickly as the earth warms. CO2 levels in the air are rising.
- Carbon is the main molecule in living organisms. It forms chains and rings to create the structure for many molecules.
Properties of Organic Compounds
- Organics are carbon based chains and rings. CO2 is not considered organic.
- Carbon can bond with 4 other atoms in 4 different directions. Carbon can form 3-D structures.
- Molecules behave as functional groups. Functional groups are the reactive part of the molecule.
- Hydroxyl alcohols, sugars
- Aldehyde sugars
- Keton sugars
- Amino amino acids, proteins
- Phosphate ATP, DNA, RNA
- Building Molecules (types of reactions)
- Functional group transfer: Grp. Moves from one molecule to another.
- Electron transfer: electrons move from one molecule to another. Electron donation.
- Rearrangement: Bonds move within the molecule by electron or atom movement.
- Condensation: -H or –OH groups are removed connecting 2 molecules in 1, plus H2O.
- Cleavage: H2O is split and the –H and –OH groups are added separating 1 molecule into 2 molecules.
- Carbohydrates (energy source; C, H, O atoms; …ose)
- Simple sugars: Monosaccharide
Has at least 1 –OH group plus an aldehyde or ketone with a carbon ring or chain.
- Oligosaccharides: short chains with a few condensation bonds. Sucrose is 1 glucose plus 1 fructose.
- Complex Carbohydrates (Polysaccharides)
- Long chains of branching or spiral carbohydrates. 100’s to 1000’s of sugars long.
- Starches, cellulose, and Glycogens are examples of complex carbohydrates.
- Plants store energy as starch molecules. Animals store energy as glycogen in the liver and muscle tissues. Cellulose builds plant cell walls.
- Chitin is a strong polysaccharide containing N atoms also. Chitin is found in the exoskeletons of arthropods and cell walls of fungi.
- Lipids: most are non-polar hydrocarbons such as fats, phospholipids, sterols, and waxes.
- Fats and fatty acids
- Fat is three fatty acids attached to a glycerol hydrocarbon chain with a carboxyl end.
- Unsaturated fat has some double or triple bonds, often oil at room temp.
- Saturated fat has all single bonds holding as many H as possible (saturated with H). Often solid at room temp. And less healthy.
- Energy yield per gram is over twice as much as carbohydrates. High energy per weight.
- Uses include energy storage, insulation, hives, and water proofing feathers and fur.
- Phospholipids
- Glycerol backbone plus 2 fatty acids chains and 1 phosphate group.
- Used in forming cell membranes.
- Sterols
- Sterols are lipids without fatty acids.
- The carbon backbone is made of 4 carbon rings.
- Cholesterol is the most common sterol and is used to form cell membranes. Other common sterols include Estrogen, Testosterone, Vit. D, and Bile Salts.
- Waxes
- A glycerol molecule plus fatty acid chains and long alcohol chains
- Cutin covers most above ground plant parts with a waxy coating.
- In animals, waxes protect feathers and fur.
- Hives are built of wax
- Amino Acids and Primary protein structure
- Uses
- All enzymes are proteins, and catalysts
- All animal structures are built of protein.
- Transport proteins help move molecules across membranes.
- General Amino Acid Structure
The 20 types of amino acids differ at the R grp. Site.
- Protein Primary Structure
- Proteins are chains of amino acids which fold into 3-D shapes.
- The primary structure is the order of the amino acids.
- The order of DNA determines the order of the amino acids.
DNA -------Þ RNA -------Þ a.a.
- The shape and function of the protein a rise from the primary structure.
3-D Structure of Proteins
- Second level Structure
- H bonds form between the carboxyl groups
and the amino groups
- H bonds give rise to either of 2 shapes:
- Coil shape (a helix)
- Flat pleat shape (ß pleated sheet)
- 3rd level Structure
More folding occurs because of the interactions between the R groups from other amino acids.
- 4th level Structure
- Interactions between separate amino acid chains, polypeptide chains.
- For example hemoglobin has 4 amino acid chains in each molecule.
- Disulfide bridge bonds often form between two sulfur atoms.
- Protein combinations
- Glycoproteins: cell surface proteins with sugars attached. Receptor molecules on the cell membrane.
- Lipoproteins: Blood proteins with lipids attached. Help carry lipids in the blood
- Denaturing Proteins
- pH changes will change the H bonds and change the folded shape of the protein, changing the function.
- Temperature can change the folding pattern by breaking the weaker bonds.
Common and famous Organic Pesticides
History of Pesticides
Sulfur: 500 b.c.
Toxic Metals: up to 1920
Tobacco (nicotine): 1600 to current
1995: 1.25 billion pounds of pesticide are used in the US each year.
Commonly Used or Famous
Atrazine (glycophosphate, “Round Up”)
DDT: 2 to 15 years to break down the insecticide, enters the food chain.
Malathion (insecticide, organophosphate)
1-12 weeks to break down
US accounts for 1/2 of the worlds pesticide use.
Nucleotides
Used in metabolism, coenzymes
- ATP
- cell energy storage
- end product of cellular respiration
- energy is released by losing a phosphate group
- NAD+, FAD+
- H carriers in cellular respiration.
Nucleic Acids (RNA, DNA)
Carries information in protein synthesis and stores the information for the primary structure of proteins.
DNA
- heredity
- 4 different bases: A, T, C, G
- Double stranded helix structure (A-T, C-G)
- Replicates (copies) before cell division
- Used as a template to make RNA
- RNA
- Protein synthesis
- 4 different bases (A, U, C, G)
- Single strand structure
- Carries the information for the primary protein structure from the nucleus to the ribosome.
- A template to make proteins.