Biology

• Water

  Consists of two slightly positive hydrogen atoms covalently bonded to one slightly negative oxygen atom, making it a dipole molecule
• Water

  • Electrically neutral
  • Molecules can easily bond with each other (cohesion)
  • Excellent solvent
• Types of carbohydrates

  • Monosaccharides (one unit, e.g. glucose)
  • Disaccharides (two units, e.g. sucrose, lactose)
  • Polysaccharides (more than two units, e.g. starch, glycogen, cellulose)
• Drawing glucose structure

  1. Label the 6 carbons

  2. Remember OH and H placements (alpha vs beta)
• Condensation reaction

  When molecules combine, a water molecule is lost
• Glycosidic bond

  Bond formed between sugars when water is lost in a condensation reaction
• Sucrose

  • Disaccharide used for transport instead of glucose
  • More complex and energy efficient
  • Less reactive than glucose
• Polysaccharides

  • Consist of thousands of sugar monomers linked by glycosidic bonds
  • Form long chains or compact spirals
  • Mostly insoluble, must be hydrolyzed before absorption
• Main polysaccharides

  • Starch
  • Glycogen
  • Cellulose
• Starch

  High energy polysaccharide consisting of amylose (linear) and amylopectin (branched)
• Amylose

  Chain of alpha glucose molecules linked by alpha-1,4 glycosidic bonds
• Amylopectin

  Has alpha-1,4 and alpha-1,6 glycosidic bonds, resulting in branching
• Cellulose

  • Polysaccharide of beta glucose molecules linked by beta-1,4 glycosidic bonds
  • Forms linear chains linked by hydrogen bonds, making it insoluble and structurally strong
• Triglycerides

  • Consist of three fatty acids bonded to a glycerol molecule
  • Insoluble and hydrophobic
• Amino acids

  • Monomers of polypeptides and proteins
  • Used for cellular growth, repair, and forming molecules like enzymes and hormones
• Amino acid structure

  Carbon bonded to hydrogen, amino group (NH2), carboxyl group (COOH), and a variable R group
• Types of amino acids

  • 20 different, differentiated by R group
• Peptide bond formation

  Between carbon of one amino acid and nitrogen of another, with water molecule lost
• Protein structures

  • Primary (sequence of amino acids)
  • Secondary (hydrogen-bonded shapes like alpha helix and beta sheet)
  • Tertiary (multiple linked secondary structures)
  • Quaternary (multiple secondary and tertiary structures)
• Collagen

  Fibrous protein used for structural support, consists of three polypeptide chains in a triple helix
• Food tests

  • Reducing sugars (Benedict's test, brick red precipitate)
  • Non-reducing sugars (need acid hydrolysis first)
  • Starch (iodine test, blue-black color)
  • Proteins (biuret test, purple-lilac color)
  • Lipids (emulsion test, milky white layer)
• Animal cell organelles

  • Cytoplasm
  • Mitochondria
  • Cell membrane
  • Nucleus
  • Rough ER
  • Smooth ER
  • Golgi apparatus
  • Lysosomes
  • Centrioles
• Nucleus

  Contains chromosomes made of DNA and regulates organelle activity
• Plant cell organelles

  • Cytoplasm
  • Mitochondria
  • Cell membrane
  • Cell wall
  • Nucleus
  • Chloroplasts
  • Vacuole
  • Endoplasmic reticulum
  • Golgi apparatus
• Endosymbiotic theory

  Proposes that mitochondria and chloroplasts were once independent prokaryotes that were engulfed by larger host cells, providing energy production and photosynthesis capabilities
• Evidence for endosymbiotic theory

  • Mitochondria and chloroplasts have own circular DNA and ribosomes similar to prokaryotes
  • They divide by binary fission like prokaryotes
  • Their inner membranes have prokaryotic structures, outer membranes have eukaryotic structures
• Plant root structure

  • Epidermis (water absorption)
  • Cortex (water transport)
  • Endodermis (waterproof layer)
  • Vascular bundle (xylem and phloem)
• Plant stem structure

  • Vascular bundles (xylem and phloem)
  • Cambium (secondary growth)
  • Sclerenchyma (support)
  • Collenchyma (support)
  • Pith (parenchyma cells)
• Phospholipid

  Consists of a hydrophilic phosphate head and two hydrophobic fatty acid tails, forming a bilayer in cell membranes
• Fluid mosaic model of cell membrane

  • Phospholipid bilayer with embedded intrinsic and extrinsic proteins
  • Allows selective permeability of the membrane
• Fluid mosaic model

  Double layer of phospholipid with hydrophilic phosphate heads facing outward and hydrophobic fatty acid tails facing inward, containing intrinsic and extrinsic proteins
• Components of the fluid mosaic model

  • Phospholipid bilayer
  • Intrinsic proteins
  • Extrinsic proteins
  • Cholesterol
  • Glycolipids
  • Glycoproteins
• Intrinsic proteins

  • Span the entire width of the phospholipid bilayer
• Extrinsic proteins

  • Do not span the phospholipid bilayer, are on the periphery
• Phospholipid bilayer is hydrophobic in the inner section, making it difficult for water and polar molecules to diffuse through</b>
• Diffusion

  Net movement of molecules from regions of higher to lower concentration, a passive process that does not require ATP
• Simple diffusion

  Allows small, non-polar molecules like oxygen and carbon dioxide to move in and out of the cell through the phospholipid bilayer
• Facilitated diffusion

  Requires transmembrane proteins or intrinsic proteins to allow the passage of larger polar molecules like glucose and RNA
• Simple diffusion

  Directly proportional relationship between substance concentration and diffusion rate, slow but steady increase
• Facilitated diffusion

  Rate of diffusion plateaus when all protein channels are occupied, reaches Vmax