Bio-1 crash course

• 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
• Functions of water


  • Temperature regulation due to specific heat capacity and ability to evaporate easily
  • Universal solvent due to positive and negative charges that can attract other molecules or ions
  • Allows mass flow/bulk flow due to cohesion and surface tension
  • Reactivity used in hydrolysis reactions and assists in buffers
• Carbohydrates


  Organic molecules containing carbon, hydrogen and oxygen
• 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)
• Glucose


  C6H12O6, a hexose monosaccharide
• Ribose


  C5H10O5, a pentose monosaccharide
• Condensation reaction


  Many molecules combine, a molecule of water is lost
• Glycosidic bond


  Bond formed between sugars when a water molecule is lost
• Sucrose is used for transport instead of glucose because it is more complex and less reactive
• Polysaccharides


  • Can consist of thousands of sugar monomers
  • 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 and amylopectin
• Amylose


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


  Consists of alpha-1-4 glycosidic bonds with alpha-1-6 branches
• Glycogen is similar to starch but has more branches, acting as an energy reserve in animals
• Cellulose


  Comprises thousands of beta glucose molecules linked by beta-1-4 glycosidic bonds, forming a linear structure
• Cellulose


  • Linear chains linked and stacked by hydrogen bonds, making them extremely strong and insoluble
• 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 and repair, form enzymes and hormones
• Structure of amino acid

  Carbon bonded to hydrogen, amino group (NH2), carboxyl group (COOH), and a residue group (R)
• There are 20 different types of amino acids, differentiated by their R groups
• Peptide bond formation


  Formed between the carbon of one amino acid and the nitrogen of another, with a water molecule lost
• Protein structures


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


  • Collagen, keratin, elastin
• Globular proteins


  • Enzymes, insulin, hemoglobin
• Collagen


  Fibrous protein used for structural support, consists of three polypeptide chains in a triple helix
• Reducing and non-reducing sugar tests


  1. Add Benedict's solution, heat in water bath - brick red precipitate for reducing sugars, green for trace

  2. For non-reducing sugars, need to break glycosidic bond with dilute HCl first
• Starch test


  Add iodine solution - blue-black colour indicates presence of starch
• Protein test


  Add reagent - purple/lilac colour indicates presence of protein
• Lipid test


  Add ethanol, then water - milky white emulsion indicates presence of lipids
• Differences between light and electron microscopes

  • Electron microscopes have higher magnification and resolution
  • Light microscopes use visible light, electron microscopes use electron beams
  • Electron microscopes require samples to be fixed and stained
• Functions of cell organelles

  • Cytoplasm - site of chemical reactions, maintains cell shape
  • Mitochondria - site of ATP production
  • Cell membrane - regulates entry and exit of materials
  • Nucleus - stores genetic material, regulates organelle activity
  • Rough ER - site of protein synthesis
  • Smooth ER - site of lipid synthesis
  • Golgi apparatus - transports proteins
  • Lysosomes - contain enzymes to break down waste
  • Centrioles - produce microtubules for cell division
• Nucleolus contains ribosomal RNA (rRNA) which helps with protein synthesis
• Differences between animal and plant cells

  • Plant cells have cell walls made of cellulose, animal cells do not
  • Plant cells have chloroplasts for photosynthesis, animal cells do not
  • Plant cells have large central vacuoles, animal cells have smaller vacuoles
  • Plant cells lack centrioles, animal cells have centrioles
• Differences between prokaryotic and eukaryotic cells

  • Prokaryotes have no nucleus, eukaryotes have a nucleus
  • Prokaryotes have smaller 70S ribosomes, eukaryotes have larger 80S ribosomes
  • Prokaryotes have no membrane-bound organelles, eukaryotes have membrane-bound organelles
  • Prokaryotes are smaller (5-10 micrometers), eukaryotes are larger (up to 100 micrometers)
  • Prokaryotes have cell walls made of peptidoglycan, plant eukaryotic cells have cellulose cell walls
• Endosymbiotic theory


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

  • Mitochondria and chloroplasts have their own circular DNA
  • They have their own 70S ribosomes like prokaryotes
  • They are similar in size to many prokaryotes
  • They divide by binary fission like prokaryotes
  • Their inner membranes have prokaryotic structures
• Parts of a plant root

  • Epidermis - allows water absorption
  • Cortex - moves water to the center
  • Endodermis - waterproof layer with casparian strips
  • Vascular bundle - contains xylem and phloem
• Parts of a plant stem

  • Vascular bundles - contain xylem and phloem
  • Cambium - responsible for secondary growth
  • Sclerenchyma - dead cells for support
  • Collenchyma - living cells for support
  • Pith - contains parenchyma cells