unit 2 Flashcards
vitalism theory
early idea that organic compounds could only be produced in living cells
falsification of the vitalism theory
Friedrich Wohler (German scientist) mixed two inorganic substances (cyanic acid and ammonium) and obtained urea, an organic molecule.
carbon atoms
- The molecules used by living organisms are based on carbon
- Each carbon atoms forms 4 covalent bonds = allows great diversity of compounds to exist
- Is the strongest type of bond between atoms = stable molecules = can form large molecules
- H = 1 bond
- O = 2 bonds
- N = 3 bonds
organic vs inorganic compounds
organic = compounds that are found in living organisms and contain carbon.
inorganic = compounds that don’t contain carbon
types of carbon compounds
carbohydrates
lipids
proteins
nucleic acids
carbohydrates
- can be:
monosaccharides (glucose, galactose & fructose)
disaccharides (maltose, lactose & sucrose)
polysaccharides (starch, glycogen & cellulose) - contain C, H & O
- used for energy or structural purposes
- general formula = (CH2O)n
proteins
- contain C, H, O and N (sometimes S)
- large organic compounds made of A.A arranged into one or more linear chains
- proteins are distinguished by their “R” groups.
e.g. enzymes & antibodies
lipids
- contain C, H and O
- group of organic molecules that are insoluble in water but soluble in non-polar organic solvents
e.g. triglycerides, phospholipids, and steroids
nucleic acids
- contains C, H, O, N and P
- composed of smaller units called nucleotides
- Nucleotides: Base, sugar and phosphate groups covalently bonded together
- if sugar is ribose = RNA;
if sugar is deoxyribose = DNA
what is metabolism?
- the web off all enzyme-catalyzed reactions in a cell or organism
can be anabolism (making) or catabolism (breaking)
what is anabolism?
- the synthesis of complex molecules from simpler molecules including the formation of macromolecules from monomers.
- by condensation reactions.
- water is produced
- energy is required
- enzymes are needed to catalyze the reaction
give 2 examples of condensation reactions
- protein synthesis = condensation of amino acids to form a polypeptide:
amino acid + amino acid —-> dipeptide + water - formation of a disaccharide:
glucose + glucose —-> maltose + water
(monosaccharides) (disaccharide)
what is catabolism?
- the breakdown of complex molecules into simpler molecules including the breakdown of macromolecules into monomers.
- by hydrolysis
- water is required
- energy is released
- enzymes are needed to catalyze the reaction
give 2 examples of hydrolysis reactions
- . hydrolysis of a disaccharide (lactose) to 2 monosaccharides (glucose & galactose):
lactose + water —–> galactose + glucose - hydrolysis of a triglyceride to glycerol and 3 fatty acids
triglyceride + 3 water molecules —-> glycerol + 3 fatty acids
properties of H2O: high specific heat capacity
a considerable amount of energy is needed to increase its temperature, due to the strength of the hydrogen bonds which are not easily broken.
this is why the temperature of water tends to remain relatively stable.
Benefit to living organisms: It is beneficial for aquatic animals as they use water as a habitat.
properties of H2O: high latent heat of vaporization
water absorbs a great deal of heat to evaporate, due to the H bonds.
Benefit to living organisms: water acts as an excellent coolant; the evaporation of water (sweat/transpiration) cools body surfaces.
properties of H2O: adhesive
water is adhesive, as it can form an attraction to unlike molecules.
e.g. when water molecules are attracted to cellulose molecules by hydrogen bonding
Benefit to living organisms:
- water exhibits adhesion to the inside of the vascular tubes in plants, which are partially made of cellulose
- allows the water to be pulled up and move against gravity
properties of H2O: transparent
allows light to pass through for photosynthesis
hydrophilic substances
- hydrophilic = “water loving”
- include all substances that dissolve in water; polar substances
- examples: charged ions such as Na+/ polar substances such as glucose and fructose
hydrophobic
- hydrophobic means “water fearing”
- include all substances that are insoluble in water; non polar substances.
- examples: non polar molecules such as lipids
formation of a polysaccharide examples
in plants, many glucose molecules combine through condensation reactions to form the polysaccharide starch
in animals, many glucose molecules combine through condensation reactions to form the polysaccharide glycogen
structure & function of starch
- consists of 2 types of molecules:
1. amylose which is linear (a straight chain of α-D glucose molecules)
2. amylopectin which is branched (a branched chain of α-D glucose molecules) - the bonds are α-1-4 glycosidic bonds
- the -OH groups from the glucose molecules are always pointed down, causing starch to have a curved appearance.
- too large to be soluble in water at room temperature
- function: store glucose in plants.
saturated fatty acids
- single C-C bonds
- saturated with hydrogen
- no double bonds
- solid at room temperature
- found in animals
cis - unsaturated fatty acids
- hydrogen atoms on the same side of the C=C double bond.
- has a twist at the double bond. This causes the fatty acid to pack more closely and lower its melting point.
- liquid at room temp
- naturally found.
trans - unsaturated fatty acids
- hydrogen atoms on the opposite side of the C=C double bond.
- has no twist at the double bond
- has a higher melting point
- solid at room temperature.
- artificially made
what are the 4 levels of proteins?
- primary = the sequence of AA within the protein
- secondary = repetitive shapes of either a helix or a pleated sheet (e.g. spider silk)
- tertiary = 3d folding pattern of a protein due to side chain interactions - globular shape
- quaternary = 2 or more polypeptides combined to make a single functional protein (e.g. haemoglobin)
(proteins) what is the function of collagen
- structural
- fibrous, rope-like protein
- main protein component of connective tissue, which is abundant in skin, tendons & ligaments
(proteins) what is the function of immunoglobulin
- defense / immunity
- recognizes antigens as part of immune response
- Y shaped proteins produced by B cells
what are enzymes?
- 3d globular proteins
- act as catalysts; speed up chemical reactions.
- have an active site to which the specific substrate binds.
what is the active site of an enzyme?
- the region where a specific substrate binds to an enzyme
what is effect of temp on enzyme activity?
- as temp /\ so does the kinetic energy of substrates & enzymes = more collisions between them = increased rate of reaction
- optimum temp = max rate of reaction
- beyond optimum temp = enzymes loses it’s shape = cannot fit to substrate = denatured
what is lactase
the enzyme that hydrolyses lactose (di) into glucose and galactose (mono) that are easily absorbed by the gut.
what is lactose intolerance?
inability to fully digest lactose due to lack of lactase
how is lactose-free milk produced?
- the milk is treated with the enzyme lactase which breaks lactose down into galactose and glucose
- the lactase is immobilised
- milk is then repeatedly passed over immobilised enzyme, becoming lactose free
what are nucleotides made of?
- a phosphate group
- a pentose sugar (ribose in RNA, deoxyribose in DNA)
- a nitrogenous base - A,G,C,T (U replaces T in RNA)
what are the 5 nitrogenous bases?
- Adenine
- Guanine
- Cytosine
- Thymine
- Uracil
what is the structure of a strand of DNA?
- nucleotides are linked into strands via condensation reaction
- covalent bonds are made between phosphate of 1 nucleotide and the pentose sugar of the next
- phosphate group attached to 5’C of sugar joins with the hydroxyl group attached to 3’C of sugar = phosphodiester bond + water
what is DNA replication?
- the process by which cells double the quantity of DNA to prepare for division
- occurs during S-phase of the cell cycle
- semi-conservative as both DNA molecules are formed from an old strand & a new one
- depends on complementary base pairing
- 2 molecules involved: DNA replication enzymes & free floating nucleotides