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Name the properties of water
Cohesive, Adhesive, Thermal, Solvent
Why is water solvent?
Due to polarity, water molecules can separate other polar molecules easily
Why does water have the property of cohesion?
It is due to hydrogen bonds forming between water molecules as a result of polarity (i.e. weak forces of attraction of oxygen and hydrogen atoms)
Why does water have the property of adhesion?
It is due to dipolarity, molecules adhere to polar to hydrophillic surfaces (i.e. atoms in xylem)
What are the thermal properties of water?
High specific heat capacity
Why does water have these thermal properties?
Due to STRONG hydrogen bonds, water has high melting and boiling point
What are the benefits of water having a high specific heat capacity?
It remains a constant temperature, fluctuating very little from the mean. This means, that it makes a good habitat for organisms that reside within the sea, ocean or rivers
What are the benefits of water having a high latent heat of vaporization?
It makes a good coolant, as vaporization allows heat to be taken away from body in sweat
What is an example of cohesion benefiting an organism?
Pulling forces can allow water to be transported to areas of a tree above the ground, through the xylem
What is an example of adhesion benefiting an organism?
Adhesive force between water and cellulose wall allows water to be transported from xylem to cell to keep cell wall moist and primed for gas exchange (also applicable to alveoli)
What is an example of the solvent properties of water benefiting an organism?
It allows for blood withing animals to act as a medium of transportation.
Which substances are carried by their blood, and how?
NaCl, ionic compound so dissolves easily into plasma as ions Na and Cl
Glucose and amino acids are polar so water molecules can easily break weak intramolecular molecular forces them to be dissolved in the plasma
Oxygen is non-polar, so must be combined with hemoglobin in erythrocytes to be transported
Metabolism
web of all enzyme-catalysed reactions in a cell or organism
Where does metabolism occur?
Cytoplasm, mitochondria, choloplasts
Anabolism
synthesis of polymers from monomers
Catabolism
breaking down of polymers to form monomers
Hydrolysis reaction
E.g. two amino acids form a dipeptide, linked by a peptide bond and one molecule of water
Condensation reaction
E.g. The peptide bond breaks in a dipeptide and an OH and H atoms saturate bonds forming two amino acids
Polypeptide
amino acid
Polysaccharide
monosaccharide (carbohydrate)
lipids
monoglycerides and fatty acids
nucleic acid
nucleotides
Urea
nitrogenous waste produced by break down of polypeptides
What is significant about urea?
It was synthesized in a laboratory falsifying the theory of Vitalism, instead suggesting organic molecules did not have a 'vital force' and instead are not fundamentally different to inorganic molecules
How do the cohesive properties of water explain its surface tension?
The hydrogen bonding between water molecules allows the liquid to resist low levels of external force (surface tension)
The high surface tension of water makes it sufficiently dense for certain smaller organisms to move along its surface
How do the adhesive properties of water explain capillary action?
Attraction to charged or polar surfaces (e.g. glass) allows water to flow in opposition of gravitational forces (capillary action)
This capillary action is necessary to allow water to be transported up plant stems via a transpiration stream
Organic compound
a compound that contains carbon and is found in living things
Why is carbon the basis for organic life?
it can form four covalent bonds allowing a diversity of stable compounds to exist
What are the main classes of carbon compounds?
Carbohydrates, lipids, nucleic acids, proteins
What is a carbohydrate composed of?
C,H and O atoms in a common ratio - (CH2O)n
What is a lipid?
Non-polar, hydrophobic molecule comes in variety of forms - simple, complex or derived
What is the function of carbohydrates?
a source of energy (and as a short-term energy storage option) and also as
a recognition molecule (glycoproteins) and as
a structural component (part of DNA / RNA)
What is the function of lipids?
component of cell membrane (phospholipid, cholestrol)
long term energy store (fats, oils)
signalling molecule
What is a nucleic acid?
DNA and RNA
What is the function of nucleic acids?
To form genetic material, DNA - master code for protein assembly, RNA - manufactures protein
Proteins are composed of which atoms?
C, H, O, N
What is the role of proteins?
Major regulatory molecules involved in catalysis (enzymes)
structural molecules
role in cellular signalling
Describe the structure of an amino acid
Amine: NH2
Carboxyl: COOH
Variable R group
Hydrogen atom: H
Describe the structure of a nucleotide
Phosphate group: 3(O)-P=O
Pentose sugar
Nitrogenous base
How are glycerol and fatty acids joined to make triglycerides?
ester linkages
How are monosaccharides joined to form polysaccharides?
glycosidic linkages
How are amino acids joined to form polypeptide chains?
peptide bonds
How are nucleotides joined to form polynucleotide chains?
phosphodiester bonds
What are the polymers of glucose?
glycogen, cellulose and starch
Name two reasons for metabolism
They provide a source of energy for cellular processes (growth, reproduction, etc.)
They enable the synthesis and assimilation of new materials for use within the cell
Name three examples of monosaccharides
glucose, galactose, fructose
Name three examples of disaccharides
lactose, maltose and sucrose
Name three examples of polysaccharides
cellulose, glycogen and starch
What is the function of monosaccharides?
immediate energy source
What is the function of disaccharides?
transport
What is the function of polysaccharides?
long-term energy store, cell structure or cell recognition
What is the structure of cellulose?
linear molecule composed of ฮฒ-glucose subunits (bound in a 1-4 arrangement)
What is the function of cellulose?
structural polysaccharide found in cell wall of plants, cannot easily be digested by most animals due to lacking specific enzyme
What is the structure of starch?
energy storage composed of ฮฑ-glucose subunits (bound in a 1-4 arrangement) exists in one of two forms - amylose or amylopectin
Distinguish between amylose and amylopectin in terms of structure and function.
Amylose - linear (helical) molecule: harder to digest and less soluble but takes up less space (preferred storage form in plants)
Amylopectin - branched (contains additional 1-6 linkages)
What is the structure of glycogen?
energy store composed of ฮฑ-glucose subunits linked together by both 1-4 linkages and 1-6 linkages (branching)
It is similar to amylopectin, but more highly branched (every 20 compared to 10)
Fatty acids that possess no double bonds are...
saturated
Fatty acids with double bonds are...
unsaturated
Structure of unsaturated fatty acids
Bent (double bond)
Structure of saturated fatty acids
Linear
Types of fatty acid
saturated, monounsaturated (one double bond), polyunsaturated (several double bonds)
Distinguish between cis and trans unsaturated isomers
Cis: The hydrogen atoms attached to the carbon double bond are on the same side
Trans: The hydrogen atoms attached to the carbon double bond are on different sides
Which isomer of unsaturated fatty acid is not naturally occurring?
Trans, produced by industrial process of hydrogenation to maintain linear structure and thus remains solid at room temperature
Note 
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