Topic 2 Bio

• organic compounds

  compounds that contain carbon and are found in living things

  
  

  exceptions include: carbides (CaC2) carbonates (CO3) oxides of carbon CO" and cyanides CN
• Metabolism + types

  metabolism is the web of all enzyme catalysed reactions in a cell or an organism. Metabolic reactions provide a source of energy and enable the synthesis of new materials

  
  

  Anabolism (Building)

  synthesis of complex molecules from simple ones, and it requires energy

  
  

  Catabolism (Destroyer)

  breaking down complex molecules into simple ones, releases energy when bonds are broken
• Theory of vitalism


  organisms are composed of organic compounds that could only be synthesised by living organisms due to a vital force which they possess
• falsification of theory of vitalism

  in 1828 Fredrik Woehler synthesised urea using silver isocyanate and ammonium chloride

  
  

  demonstrated that organic compounds could be synthesised without a "vital principle"
• what are sone carbon compounds?

  carbohydrates:composed of C,H,Ois a source of energy + short term energy storage

  Lipidsnon-polar, hydrophobic molecules. They are long term energy storage

  Nucleic Acids:composed on nucleotide chains

  Proteins:involved in catalysis
• monomers of carbon compounds

  
• water electronegativity


  - oxygen is more electronegative than H, resulting in unequal electron distribution

  
  

  - makes water polar as it has a slight charge difference across its poles

  
• hydrogen bonding


  - the dipolarity of water allows hydrogen bonds to be formed between the positive H pole of one molecule and the negative pole of another

  
  

  - although hydrogen bonds is relatively weak, there are many of them per unit volume of water

  
• hydrophobic & hydrophilic interactions in water

  hydrophilic substances dissolve in water while hydrophobic substances join together

  IMPORTANCEdue to hydrophobic interactions phospholipids come together to form internal environments in water
• properties of water:

  specific heat capacity

  H-bounds restrict the movement of water molecules and therefore they need to be broken for water to charge the temperature

  
  

  - water has a high specific heat capacity

  
  

  - lot of energy needs to be used in order to break down the H-bonds

  
  

  IMPORTANCE:

  water temp remains relatively stable making it an excellent medium for living organisms as its thermally stable
• properties of water:

  Boiling point

  H-Bonds need to be broken before water turns into vapour

  
  

  - and due to its high specific heat capacity water has a high boiling point

  
  

  IMPORTANCE:

  water is liquid over a broad range of temp 0-100 C

  This makes water suitable for living organisms most of which are composed of a high % of water
• PROPERTIES OF WATER:

  Cohesion


  its the stability of two water molecules to bind together

  
  

  water is cohesive due to the H-Bonds between the molecules

  
  

  these cohesive properties also explain the waters high surface tension

  
  

  IMPORTANCE:

  the surface tension allows smaller organisms to travel across water. Cohesion also allows water to travel up the plants in xylem vessels as water molecules don't separate due the suction forces
• Adhesion


  the attraction of water molecules to other molecules

  
  

  waters dipolarity allows it to adhere to polar surfaces and hydrophilic

  
  

  IMPORTANCE:

  adhesive forces between water and cellulose in the cell walls of leaves result in water being drawn out of xylem vessels when leaves get dry. This also explains capillary action of water in xylem vessels.
• latent heat of vaporization

  when water evaporates H-bonds between molecules must be broken down requiring heat energy. And water has high latent heat of vaporization

  
  

  IMPORTANCE:

  makes water a good evaporative coolant

  
  

  example:

  the heat energy needed to evaporate water in sweat is taken from skin tissue, thus reducing the temp of the skin and the blood flowing through it when sweat evaporates
• solvent properties (name at least 4)

  due to its polarity water can dissociate substances composed of ions or polar molecules (NaCl) by weakening intramolecular forces

  
  

  - the slightly charged regions of water form hydration shells and dissolve them

  
  

  - this allows water to be called a universal solvent as it can dissolve a large number of substances

  
  

  IMPORTANCE:

  water is the medium for metabolic reactions
• properties of methane and water compared

  
• transport in blood plasma ( list 5 max)

  - Blood is composed of 55% plasma which is made up of mostly water.- The transport of substances in the bloodstream depends on their solubility

  INORGANIC SUBSTANCES- Ionic compounds, e.g. NaCl, are very soluble as they dissociate into ions.

  AMINO ACIDS- Solubility depends on R group

  GLUCOSE- Polar due to -OH group* and is therefore soluble

  OXYGEN- Non-polar yet its small size allows it to be dissolved in water in low conc.- At higher temp, the solubility of oxygen decreases- This problem is overcome with haemoglobin in RBC which has oxygen binding sites

  FATS & CHOLESTEROL- are both non-polar and... insoluble in water.- Instead, they're transported in lipoprotein complexes ↑- Hydrophilic portions of proteins, cholesterol, and phospholipids face outward & and shield internal hydrophobic components
• condensation + hydrolysis reaction

  Condensation:

  anabolic, requires ATP + enzyme, for example glucose + glucose = maltose + water

  
  

  Hydrolisis:

  catabolic, requirees enzyme, example: maltose + water --> glucose + glucose
• types of fatty acids

  Saturated fats:All carbon (C) in the chain is bonded to maximum hydrogen (H).They generally originate from animal sources, for example, fats.

  Unsaturated fats:Contain one or more double bonds between carbon atoms.Monounsaturated fats have one double bond.Polyunsaturated fats have two or more double bonds.They usually come from plant sources, like oils.
• unsaturated fatty acid structural isomers

  
• examples of fats ( at least 4 examples)

  Polysaturated cis fats

  —> omega 3

  —> walnuts, sunflower seeds etc

  
  

  Monusaturated cis fats

  —> plant based oils

  
  

  Saturated fats

  —> butter, eggs

  —> palm oil

  
  

  Trans fats (processed)

  —> cookies, fries, cakes
• fatty acid diagram


  Generalised form:

  CH3 - (CH2)n - COOH

  
• glycerol diagram


  C3H8O3

  
• Triglyceride formation drawing

  
• Types of lipids


  Triglycerides:

  —> three fatty acids + one glycerol

  —> fats and oils

  
  

  Phospholipids

  —> two fatty acids + phosphate group + one glycerol

  
  

  Steroids:

  —> have a similar structure of 4 fused rings

  —> cholesterol and estrogen
• Uses of lipids


  —> Thermal insulation

  —> buoyancy aid

  —> waterproofing hair and feathers

  —> shock absorbance for soft organs

  —> phospholipid in the membranes
• Lipid health risks (claim) blood cholesterol levels
• Evidence for/against lipid health claim

  high cholesterol levels in the bloods [lead to the narrowing of arteries (arteriosclerosis) high levels of Low-density lipoproteins (lead to the development of plaques (atherosclerosis) (liver -> body) if coronary arteries are blocked, CHD will result. (coronary heart disease) Saturated Fats increase LDL levels. Claim made that these fats increase the risk of CHD (raise cholesterol) Cis (unsaturated) fats increase HDL levels, lowering blood cholesterol levels (blood -> liver) claim made that these fats decrease the risk of CHD trans fats increase LDL levels and decrease HDL levels claim made that these fats increase the risk of CHD (significantly raise cholesterol levels)
• Examples of carbohydrates


  Cn(H2O)nMONOSACCHARIDES (immediate energysource)—> Glucose, galactose, fructose—> Hexose (6- carbon)

  DISACCHARIDES - (function as transport form)—> Maltose (glucose + glucose)—> Sucrose (glucose + fructose)—> Lactose (glucose + galactose)

  POLYSACCHARIDES: (energy storage + cell structure)STORAGE—-> Plants —> starch—-> Animals — glycogenSTRUCTURE—-> Plants —> cellulose—-> Animals —> chitin
• Maltose condensation reaction

  
• Polysaccharides


  Cellulose (4)Structural polysaccharide found in the cell

  wall of plants

  
  

  - is an unbranched linear polymer of

  β-glucose bound in a 1,4 arrangement

  
  

  - glucose units alternate (up, down, up, down);

  making the polymer linear.

  
  

  - Cellulose molecules are arranged parallel

  to each other with H-bonds,

  providing tensile strength to plant cell walls.
• Polysaccharides


  Starch (4)- energy storage polysaccharide found in plants

  - is a polymer of a-glucose and exsists in two forms:

  
  

  —> [Amylose] has only 1,4 linkages and is helical in shape.

  Harder to digest and less soluble, but takes up less space so is the preferred form of storage in plants.

  
  

  —> [Amylopectin] has 1,4 and 1,6 linkages, making it branched every ~20 subunits.

  
  

  Starch is hydrophilic but too large to be soluble, allowing plants to store glucose in a form that doesn't cause osmotic problems.

  
  

  —> branched strcutre allows glucose to be loaded/unloaded more rapidly
• Polysaccharides


  Glycogen (4)- energy storage polysaccharide formed by animals and some fungi

  —> it is a branched polymer of α-glucose

  
  

  -> has 1,4 and 1,6 linkages, making it branched every ~10 subunits

  —> is insoluble, allowing animal cells to store a large amount of energy without causing osmotic problems
• Comparing polysaccharides

  
• Energy storage; lipids VS carbs (6+5)

  For Lipids:Long-term storageRelease 2× more energy than carbohydrates in cellular respirationDon't associate with water, whereas carbohydrates do (1g glycogen → 2g water)Being 6× more efficient than carbohydratesAdds less to body mass which is important for active animalsOxidation releases more metabolic water than carbohydrates which is important for desert animals

  For Carbohydrates:Short-term storageEasy to release energy (useful for high-demand activities)Have more effect on osmotic pressureUsed for both aerobic and anaerobic respiration, whereas lipids are only used for aerobic respiration (O2 needed)Easier to transport (they're soluble)
• BMI


  body mass index

  —> mass(kg)/height in m^2

  
• Faults in BMI calculation (4)

  - Can't be used on kids who have growth spurts

  - Assumes all weight is bad fat (Some is heavy bones/muscles)

  - Not valid for pregnant women or athletes with atypical muscle/fat ratios

  - Disregards genetics in different cultures (e.g., shorter Asians)
• amino acid structure


  There are 20 different amino acids which are universal to all living organisms

  
  

  —> except for a further two, that are extra variations

  
• Polypeptide condensation reaction

  
• Polypeptides (4)


  - Unbranched chain of amino acids joined together on the ribosome

  - 1 gene codes for one polypeptide (typically)

  - The number, order, and sequence of amino acids in a polypeptide is found in the genes (sequence of bases in DNA)

  - A protein consists of one or more polypeptides linked together