Grade 12 Biology Notes

Topics: Adenosine triphosphate, Metabolism, Cellular respiration Pages: 10 (2462 words) Published: April 29, 2012
Biology notes for FST Project
*ADD SUMMARIES AT END OF CHAPTERS

UNIT 1

Macromolecules
* Large molecules sometimes composed of a large number of repeating subunits * Four major classes: Carbohydrates (made of simple sugar/glucose), Lipids (Glycerol and Fatty Acids), Proteins (Amino Acids) and Nucleic Acids (Nucleotides) * Condensation reaction/dehydration synthesis: a reaction that creates a covalent bond between two interacting subunits. Removal of H from one functional group and an OH from the other, and the H come together to form a water molecule (H2O). Anabolic process because it results in the construction of large molecules from smaller subunits * Hydrolysis reaction: a catabolic process in which a water molecule is used to break a covalent bond. AKA the opposite of condensation, where one H goes to one atom and the OH goes to the other * Enzymes are biological catalysts, and catalysts are chemicals that speed up chemical reactions without being consumed in the process

Carbohydrates
* Most common organic material among earth
* Produced by plants and algae through photosynthesis
* Used by organisms as sources of energy, as building materials, and as cell surface markers for cell-to-cell identification and communication * Carbon, hydrogen and oxygen in a 1:2:1 ratio (CH20)

* Monosaccharides (simple sugars), oligosaccharides, and polysaccharides * Monosaccharides can be distinguished by the carbonyl group they possess- aldehyde or ketone- and the number of atoms in their carbon backbone * Glyceraldehyde: 3 carbons (triose) with aldehyde group (R- CHO) * Ribose: 5 carbons, component of RNA

* Oligosaccharides are sugars containing two or three simple sugars attached by glycosidic linkages * These bonds are condensation reactions, and transports sugars from one part of the cell to another * Polysaccharides are monosaccharide polymers composed of several hundreds/thousands monosaccharides held together by glycosidic linkages * Used for energy storage ands structural support

* Starch and glycogen are for storage, cellulose and chitin are structural * Sometimes plants produce too much glucose than needed, so enzymes in the chloroplast link excess glucose molecules together to form starch (storage) * Starch is a mixture of two different polysaccharides, amylose and amylopectin

Lipids
* Hydrophobic molecules composed of carbon, hydrogen and oxygen * Fewer polar OH bonds and more non polar CH bonds than carbohydrates * They are insoluble in water but soluble in non polar substances * Lipids are used for storing energy, building membranes and other cell parts, and used as chemical signaling molecules * They can be divided into four families: fats, phospholipids, steroids and waxes * Triglycerides are forms of fat that carbohydrates (Excess) are stored in * Triglycerides have three fatty acids attached to one glycerol * A glycerol is a three carbon alcohol containing a hydroxyl (OH) group attached to each carbon * Fatty acids are long hydrocarbon chains containing a single carboxyl group (COOH) at one end * The OH from each carbon on the glycerol attached to the OH on the end of each fatty acid, creating a COC bond and H2O (COC linkage is an ester linkage) * Membranes of cells are composed of phospholipids, which are composed of a glycerol which is attached to two fatty acids and polar phosphate group * When in water, the phospholipids form a sphere called a micelle. The heads dissolve in the water and the tails mix together in the center of the sphere * Membranes also contain sterols/steroids, which are compact hydrophobic molecules containing four fused hydrocarbon rings and several functional groups * An example is cholesterol- in high concentrations and a diet high in saturated fats (single bonds between carbons) have been linked to the development of atherosclerosis (where plaque...
Continue Reading

Please join StudyMode to read the full document

You May Also Find These Documents Helpful

  • Unit One Grade 12 Biology Study Notes Essay
  • Essay about Biology Grade 12
  • Biology 12 Essay
  • grade 12 AP biology exam notes Essay
  • Grade 12 Biology Exam Essay
  • Grade 12 Biology Enzymes Essay
  • 9th grade biology notes Essay
  • BIology grade 11 notes Essay

Become a StudyMode Member

Sign Up - It's Free