Chemistry of life - Review Notes
Organic Chemistry – the element carbon provides the chemical backbone of all living things. Carbon has the ability to loose or gain 4 electrons making it neither a strong electron donor or electron acceptor. This ability to share electrons allows carbon to share electrons with many elements. Over 2 000 000 different carbon compounds have been identified.
Molecules are considered organic if they contain the element carbon in their structure. Frequently organic molecules also contain hydrogen, oxygen and nitrogen too. Organic molecules are handy, as their bonds can be broken down within cells for energy. Organic molecules can also easily be linked to other larger molecules to build macromolecules (large molecules) that are required for life.
Compounds that don’t contain the carbon are considered to be inorganic molecules. Carbon dioxide is an exception, it is considered to be inorganic.
4 main chemicals of life (MACROMOLECULES): Micromolecules Universal Solvent
1. Carbohydrates 1. Vitamins and minerals 1. Water
2. Proteins
3. Lipids
4. Nucleic Acids
7 Important functions of Water:
1. It is abundant in the cell
2. It is a carrier for molecules across the cell membrane (osmosis)
3. It is a lubricant between organs, tissues and individual cells.
4. Liquid over a wide range of temperatures
5. Protects the cell from temperature changes as it changes temperatures slowly
6. Floats when freezes, expands when solid
7. Clings together, enabline turgor pressure in plants from roots to shoots.
Metabolism is the name for all the chemical reactions that occur in your body. Approximately 200, 000 chemical reactions occur daily within one single cell. Catabolic and anabolic reactions are two types of reactions that occur inside the cells. Catabollic reactions occur when large chemicals are broken down into smaller components. Specifically we studied hydrolysis the addition of water molecules to large sugar molecules that breaks large sugars into their smaller counterparts. Another type of metabollic reaction that occurs in the cells is anabolic reactions. In an anbolic reaction, complex chemicals are built from smaller components. We did this in the jujube lab, in adding two glucose molecules through the elimination of water in a process called dehydration synthesis.
Carbohydrates:
Ø Most important source of energy – total energy gain is 4 Calories/gram
Ø Carbohydrates are built from sugar molecules (you can identify a sugar by ending in “ose”).
Ø Normally the ratio of Carbon to hydrogen and oxygen in a carbohydrate molecule is 1:2:1 (e.g. glucose C6H12O6).
Ø Some famous sugars include: Glucose (found in human blood -#1 brain food), Fructose (plant sugar), and deoxyribose (the sugar portion of DNA), Cellulose (a polysaccharide that makes up plant walls- commonly known as ruffage or fiber).
Ø You can classify carbohydrates according to the number of sugar units they contain:
o Monosaccharides – simple sugars – 1 ring – e.g. glucose and fructose (very sweet).
o Disaccharides – 2 ringed sugars – e.g. sucrose (white table sugar from glucose and fructose), maltose (we built this in the jujube lab – found in nature from seeds of germinating plants), lactose (milk sugar made from one glucose and one galactose molecule). All disaccharides are formed from dehydration synthesis!
o Polysaccharides are carbohydrates fromed by the union of many monosaccharide subunits. E.g. starch (built from many plant glucose molecules). We saw starch in the microscope lab looking at the leucoplasts in potatos (remember they were purple when mixed with the iodine). Plants store their energy as starch. Glycogen is stored in animal cells and is often refered to as animal starch. Glycogen is made up of 16 to 24 glucose molecules. The liver converts glycogen into glucose units for energy.
Lipids:
Ø Commonly known as “fat” – total energy gain 9 Calories/gram.
Ø Foods – fish, olive oil, red meat, nuts.
Ø Lipids are made up of two portions a glycerol head and fatty acid tails.
Ø Lipids can also go through dehydrations synthesis and hydrolsis.
Ø Functions: Lipids help cushion organs and cells; carry vitamins A, D, E and K, help build hormones and other important chemicals in the body, and they insulate your core from the cold (blubber).
Ø Phospholipids and triglycerides and waxes are three important groups of lipids.
Ø Phospholipids are the building blocks of the fluid mosaic model of the cell membrane. They have a phosphate/glycerol head that is polar and hydrophillic and two fatty acid tails that are hydrophobic.
Ø Triglycerides – are another type of lipid found in the body. These special lipid molecules are built from one glycerol and three fatty acids with the help of an enzyme.
Ø Lipids that are solid or semi-solid at room temperature are said to be saturated (loaded up with covalent bonds to H atoms). Butter, shortening and marbling in meat are all good examples of saturated fats. Saturated fats are very stable at room temperature.
Ø Lipids that are liquid at room temperature are said to be unsaturated (containing double bonds, or less H atoms). Oil is an example of an unsaturated fat. Unsaturated fats are easier to break down in the body than saturated fats. Hense the push for people to use vegetable or canola oil rather than butter while cooking.
Ø Waxes – are the third group of lipids. They are formed from long chains of fatty acids joining long-chain alcohol or carbon rings. Waxes are insoluble in water, and are used for water proofing plant leaves or animal feathers and fur.
Ø Fats & Diet – stable fats in the body (saturated fats) tend to stay put once ingested leading to plaque in the arteries and ultimately to health complications (e.g. stroke, cancer, high blood pressure, type two diabetes).
Ø Cholesterol – not all fat is bad. Cholesterol is required by the cell membrane and is also important for the production of hormones (specifically sex hormones – estrogen and testosterone). There are two different types of cholesterol in the blood HDL and LDL. HDL is the “good” cholesterol and LDL is the “bad” cholesterol.
Proteins:
Ø The most important macromolecule in the body. Their importance can not be underestimated! Proteins rule everything in biology! Total energy gain is 4 Calories/gram. (however, energy gain is not their main function).
Ø Proteins are essential for building, repair and maintenance of the cell.
Ø Made from carbon, hydrogen, oxygen, nitrogen and sulphur.
Ø Your body requries 20 amino acids, but can only produce 12!
o We must rely on digestion to gain the other amino acids we need.
o 20 different amino acid groups give rise to an infinite amount of proteins.
Ø Make up the cells in the muscles of our body, the nerves, skin and hair.
Ø Proteins are large molecules constructed of many amino acids. Proteins are the building blocks of cells.
Ø Again, dehydration synthesis and hydrolysis apply to this macronutrient.
Ø The bond that is formed from an acid group (COOH) and the amino group (NH2) is called a peptide bond. Because of this special bond, proteins are frequently called polypeptides (many peptide bonds).
Ø Antibodies – are specialized proteins that help defend against diseases.
Ø Enzymes – are specialized proteins that help speed up chemical reactions.
Ø Shapes – primary (linear), secondary (coiled), tertiary (bent-coiled) and quarternary (compact with a specific structure).
Ø You can unfold a protein (de-nature) by exposing the protein to heat, radiation or a change in pH. (i.e. frying an egg, baking a cake, UV exposure, x-rays).
Nucleic Acids:
Ø Building block of DNA and RNA.
Ø Made from carbon, oxygen, hydrogen, nitrogen and phosphorous. Nucleic acids are the molecules of heredity.
Ø Each nucleic acid contains a nucleotide.
Ø Nucleotides are made up of one 5 carbon sugar, a phosphate group (P) and a nitrogen base.
Ø DNA is made from double stranded molecules whose nucleotides are linked by sugar and phosphate groups.
Ø RNA is made from a single stranded molecule that contains uracil rather than the sugar thyamine found in DNA.
Ø Spreading the message: DNA is contained inside of the nucleus, whereas, RNA is made from a copy of DNA and travels outside of the nucleus via the nuclear pores to the cytoplasm. In the cytoplasm the RNA is read by a ribosome and is decoded into a protein.