Unit 1 (1.1) Flashcards
1. Chemical elements are joined together to form biological compounds
Name the four key inorganic ions in living organisms
Magnesium Mg2+
Iron Fe2+
Phosphate PO43-
Calcium Ca2+
Role of Magnesium (Mg2+)
Required for chlorophyll for photosynthesis
Role of Iron (Fe2+)
Found in haemoglobin, required for transport of oxygen
Role of Phosphate (PO43-)
For nucleotides and phospholipids, required for the phospholipid bilayer of cell membranes . And used to produce ADP and ATP
Role of Calcium (Ca2+)
Required for bones, teeth and cell walls in plants. Used to strengthen the tissues.
Why is water a polar molecule
O is more electro negative than H, O attracts the electron density in the covalent bond more strongly, forming O delta-, H delta +
Hydrogen Bonding
Weak intermolecular forces of attraction form between O and H (dotted line) on a adjacent molecule.
Properties of water
Organic Solvent
Transparent
High Density
High Surface Tension
High Specific Heat Capacity
High Latent Heat of Vaporisation
Why is high specific heat capacity important for organisms?
The water acts as a temperature buffer enabling endotherms to resist fluctuations in core temperature and maintain optimum enzyme activity. (Requires a lot of energy to increase temperature)
Why does water have high surface tension
Due to the ordered arrangement and cohesion of molecules at the surface of water
Why is high surface tension important?
Allows small insects to walk on water, and enables transport of water and nutrients through plan cells and small blood vessels.
Why is High latent heat of vaporisation important?
When water evaporates it leaves a cooling effect , this is important for homeostasis
Why is water transparent?
Allow light to pass through
Why is water an organic solvent?
It dissolves ionic substances, enables chemical reactions to take place within cells , the transport of materials in the plasma and removal of metabolic waste.
What is glucose
A hexose monosaccharide
Draw A and B Glucose
..
Name of bond when two monosaccharides react
Glycosidic Bond
What is a Disaccharide
Formed by condensation of two monosaccharides forming a glycosidic bond
Name 3 Disaccharides and their Monosaccharide components
Sucrose- (Glucose and Fructose)
Lactose- (Galactose and Glucose)
Maltose-(A Glucose and A Glucose)
What is a Polysaccharide?
Polymer of monosaccharides formed by many condensation reactions
Name some Polysaccharides
Starch
Chitin
Glycogen
Cellulose
Starch Function and Structure
Energy storage in plants,
Polymer that comes in two forms (amylose and amylopectin)
Glycogen Function and Structure
Energy storage in animals, highly branched enabling the rapid hydrolysis of glucose molecules
Structure and Function of Cellulose
Main component of cell walls in plants , linear polysaccharide, alternate glucose molecules rotated 180* allowing hydrogen bonds between parallel chains, forming microfibrils
Structure and Function of Chitin
Found in exoskeletons of insects, crustaceans as well as fungal cell walls. alternate glucose molecules rotated 180* allowing hydrogen bonds between parallel chains, forming microfibrils
How is a triglyceride formed?
One molecule of glycerol forms ester bonds with three fatty acids via condensation reactions.
What is a phospholipid?
A type of lipid formed by the condensation of one molecule of glycerol , two molecules of fatty acid and a phosphate group.
Relate the structure of phospholipids to their function
Glycerol backbone attached to two hydrophobic fatty acid tails and one hydrophilic polar phosphate head. Forms phospholipid bilayer in water.
What is a saturated fat?
They have no C=C bonds and are solid at room temperature due to strong intermolecular forces
What is an unsaturated fat?
Have one or more C=C bonds, and are liquid at room temperature dure to weak intermolecular forces
What is low density lipoprotein (LDL)
Combination of triglycerides from saturated fats and protein, it blocks receptor sites, reducing cholesterol absorption.
How does it contribute to risk of cardiovascular disease?
The high blood cholesterol levels caused by LDL’s leads to formation of atherosclerosis plaques
What is Glycine?
An amino acid, a compound that the body uses to create protein
Draw and Label Glycine
..
Name the bond formed when two amino acids react
Peptide bond
How are polypeptides formed?
Many amino acid monomers join together in condensation reactions forming peptide bonds
Primary protein structure
The individual sequence of amino acids in a protein
Secondary Protein structure
Interactions of the amino acids in the polypeptide chain resulting in a helices or b pleated sheets. Hydrogen bonds hold the arrangements in place.
Tertiary protein structure
Folding of a protein to make a three dimensional structure, held in place by various interactions and bonds: Disulphide, Ionic, and Hydrogen bonds. Hydrophobic interactions
Quaternary Protein structure
Interactions of more than one polypeptide chain , may involve addition of prosthetic groups
How do fibrous proteins relate to their structure?
long polypeptide chains, folded in parallel. Little tertiary/quaternary structure for strength. This makes them insoluble and good for structural roles.
How do globular proteins relate to their structure?
Spherical, compact, and highly folded, hydrophilic R groups face outwards, hydrophobic R groups face inwards therefore they are water soluble. Metabolic roles, eg. enzymes
What is a reducing sugar?
It can react as a reducing agent as it has a free aldehyde or ketone functional group.
What is a non reducing sugar?
It does not have a free aldehyde or ketone functional group so it cannot act as a reducing agent
Benedict’s test for reducing sugars
- Add equal volume of the sample being tested and Benedict’s reagent
- Heat the mixture in an electric water bath at 100* for 5 mins
3.Observe the colour of the precipitate formed
Positive result for reducing sugars
Change from green to yellow to orange to brown to brick red depending on the quantity of reducing sugar present
Benedict’s test for non reducing sugars
- Negative test for reducing sugar
- Hydrolyse non-reducing sugars with an
equal volume of dilute HCl - Heat in a boiling water bath for 5mins
- Add NaHC03 to neutralise the acid
- Re-test resulting solution with Benedict’s
reagent - Observe the colour of the precipitate formed
Positive result for non-reducing sugars
Colour change from green to yellow to orange to brown to brick-red depending on quantity on non-reducing sugar present.
Biuret test for proteins
- Add an equal volume of of the sample to
be tested and NaOH - Add a few drops of dilute copper (II)
sulphate solution - Mix gently and record any observations
Positive result of biuret test
colour change from pale blue to purple
Iodine-potassium test for starch
- Add iodine-Kl solution
- Colour change from orange to blue-black in presence of starch
Emulsion test for fats and oils
- Add ethanol to the sample and shake
- Allow the mixture to settle
- Add an equal volume of water
- Record any observations
Positive result of emulsion test
white, cloudy emulsion forms
