A1CC1 Chapter 1 - Chemical elements and biological compounds Flashcards
What roles are inorganic ions required for? (Give 2)
Muscular contraction
Nervous Coordination
What are inorganic ions also known as?
Electrolytes
What are the 4 important inorganic ions?
Magnesium, Iron, Calcium, Phosphate.
What is Magnesium Ion (Mg2+) used for and what process is it involved in?
Constituent of Chlorophyll. Photosynthesis.
What is is Iron Ion (Fe2+) used for and what process is it involved in?
Constituent of Haemoglobin. Transport of Oxygen.
What is Calcium Ion (Ca2+) used for?
Structural component of bones and teeth. (Phosphate also required here)
What is Phosphate Ion (Po4 3+) Ion used for?
Needed for making nucleotides including ATP. Also a constitent part of phospholipids in cell membranes.
What gives water its important properties?
Water is dipolar (Both positive and negative charge). Hence, Hydrogen Bonds can form easily between water molecules. Although Hydrogen Bonds on their own are weak, many of them together make the overall molecule to be difficult to break.
What are water’s important properties? (7)
- Solvent
- High Specific Heat Capacity
- High latent heat of vaporisation
- Metabolite
- Cohesion
- High Density
- Transparent
Explain where these 7 properties are used for water:
1. Solvent
2. High Specific Heat Capacity
3. High latent heat of vaporisation
4. Metabolite
5. Cohesion
6. High Density
7. Transparent
- In biochemical reactions Eg: Hydrolysis and Condensation.
- Large fluctuations of temperature are prevented due to the large number of hydrogen bonds. This property is used in aquatic environments to allow for them to be thermally stable.
- Cooling mechanism since a lot of energy is required to vaporise water. Eg: Sweating in mammals.
- In biochemical reactions and as a reactant in photosynthesis.
- Xylem vessels of trees. This is because water molecules attract eachother meaning they can form hydrogen bonds between eachother. This creates surface tension.
- Ice floats meaning it can act as an insulator preventing the water underneath from freezing completely, protecting the aquatic habitat.
- Allows light to pass through, allowing aquatic plants to photosynthesise.
What are Carbohydrates made up of?
Carbon, Hydrogen and Oxygen
What do Carbohydrates act as? (4)
- Building blocks for more complex molecules, eg: ribose (which forms a constituent molecule of RNA)
- Sources of energy eg: Glucose.
- Energy storage molecules. eg: glycogen and starch.
- Structural support. eg: cellulose and chitin.
Are monosaccharides soluble in water?
Yes.
Are monosaccharides sweet tasting?
Yes.
What is the general formula for Monosaccharides?
(CH2O)n where n is between 3 and 6.
What is the importance of a triose sugar?
Respiration pathways.
What is the importance of pentose sugars?
Important constituents of RNA and DNA (ribose and deoxyribose)
How does glucose exist?
As two isomers;
alpha glucose and beta glucose
What is an isomer (in biology)
Substances that have the same formula but different structure.
What is the difference in structure between alpha and beta glucose?
Alpha Glucose has the hydroxyl group (OH) facing down
Beta Glucose has the hydroxyl group facing up.
What is a disaccharide?
A molecule formed by joining two monosaccharides together.
How do disaccharides form? (Type of reaction and bond formed)
Condensation reaction.
Glycosidic Bond is formed.
How do you breakdown disaccharides (a glycosidic bond)?
Hydrolysis (chemical addition of water)
How to form the disaccharide ‘Maltose’? and state its biological role.
Glucose + Glucose. Germination of seeds.
How to form the disaccharide ‘Sucrose’? and state its biological role.
Glucose + Fructose. Transport in phloem of flowering plants.
How to form the disaccharide ‘Lactose’? and state its biological role.
Glucose + Galactose. Mammalian Milk.
How to test for the presence of reducing sugars?
- Add Benedict’s Reagent.
- Strongly heat in boiling water bath.
- If positive then blue –> green –> orange –> brick-red precipitate.
What can we test as a reducing sugar?
All monosaccharides and some disaccharides (eg maltose and lactose)
How to test for non-reducing sugars?
- Heat with Hydrochloric Acid, then neutralise by adding alkali slowly until fizzing stops.
- Add Benedict’s Reagent and strongly heat as before.
- If solution changes from blue –> red then non-reducing sugar is present.
What is a polysaccharide?
A polymer formed by many monosaccharides joined together.
Why are polysaccharides good energy storage molecules?
- Unable to diffuse out of the cell.
- Compact shape
- Insoluble in water , hence no affect on water potential meaning no osmotic effect.
- Easily hydrolysed into constituent monosaccharides which can be used in respiration with the exception of cellulose, which is difficult to digest due to its fibrous structure.
What is Starch and where is it found?
Starch is the main energy store in plants, found in starch grains which are seen in most plant cells and in chloroplasts.
What is starch made up of?
Starch is many alpha glucose molecules bonded together and consists of two polymers. Amylose and Amylopectin.
What is Amylose (apart from the monomer in starch)?
Amylose is linear (unbranched) glycosidic bonds forming between the first Carbon atom (C1) and the fourth Carbon (C4). These are referred to as 1-4 Glycosidic Bonds. This is repeated forming a straight chain, which then coils into a single helix.
What is Amylopectin (apart from the other monomer in starch)?
Amylopectin is a branched molecule and fits inside amylose. It contains both 1-4 Glycosidic Bonds and 1-6 Glycosidic Bonds. When there is a 1-6 Glycosidic Bond formed, this is a side branch.
What makes Amylopectin good for energy release?
Because Amylopectin is highly branched is has more exposes ends that can be hydrolysed meaning a more rapid release of glucose.
How to test for the presence of starch?
- Iodine Test.
- If positive then orange to blue-black colour change.
Why is the iodine test impractical to test for the concentration of starch present?
As temperature changes, so does the concentration of the colour meaning it is not a consistent result as there are two independant variables stemming from the same result.
What is Glycogen?
The main storage product in animals and very similar to amylopectin. The only difference is that Glycogen is even more branched than amylopectin.
What is Cellulose?
A structural polysaccharide.
Where is Cellulose found?
Plant cell walls.
What makes up Cellulose?
Many beta-glucose units bonded together with adjacent glucose molecules rotaed by 180 degrees forming long straight parallel chains that are cross-linked by hydrogen bonds.
What happens when these straight parallel chains become so tightly cross-linked?
They form bundles called microfibrils.
What are many microfibrils arranged together called?
Fibrils.
What are properties of Cellulose? (2)
- Very strong due to hydrogen and glycosidic bonds.
- Freely permeable due to gaps in cellulose fibres in plant cell walls.
What is Chitin?
A structural polysaccharide found in the exoskeleton of insects and cell walls of fungi.
Why is chitin found in the exoskeleton and cell walls of these species?
It has the properties of strong, lightweight and waterproof.
What makes up Cellulose molecules?
Many long parallel chains of beta-glucose molecules (with acetylamine group too) all cross-linked to eachother by hydrogen bonds forming microfibrils due to adjacent glucose molecules being rotated 180 degrees similar to cellulose.
What are lipids?
Non-polar compounds that are hence insoluble in water.
What are lipids made up of?
Carbon, Hydrogen and Oxygen.
The ratio of Hydrogen here is much more carbohydrates.
The ratio of Oxygen here is much less than carbohydrates.
What is a triglyceride?
A glycerol molecule and three fatty acids.
What type of reaction forms a Triglyceride?
Condensation Reaction.
What type of bond is formed in a Triglyceride?
Ester Bond.
What is this ester bond between?
The glycerol and fatty acids.
What is a saturated fatty acid?
A fatty acid without any C=C double bonds (apart from the carboxylic acid functional group)
What is an unsaturated fatty acid?
A fatty acid with at least one C=C double bond.
Saturated vs Unsaturated fatty acids (mention health impacts)
Saturated:
Causes Coronary heart disease
Increase in LDL which causes harm to health.
Unsaturated:
Increase in HDL which carries harmful fats away to the liver for disposal.
What are waxes and why are they useful?
Waxes are a type of lipid that melts at temperatures above 45C. They perform a waterproofing role in both animals and plants. Eg: Leaf Cuticle.
What are the roles of lipids? (5)
- Energy Reserve.
- Thermal Insulation.
- Protection.
- Metabolic Water.
- Waterproofing.E
Explain these five roles for lipids.
- Energy Reserve = Lipids contain more Carbon-Hydrogen bonds than carbonhydrates. Therefore, excellent energy reserves because one gram of fat when oxidised yields approximately twice as much energy as the same mass of carbohydrate.
- Thermal Insulation = Stored under the skin acting as insulator against heat loss.
- Protection = Fat is stored around delicate internal organs like the kidneys to protect against physical damage.
- Triglycerides produce a lot of metabolic water when oxidised. This is important in desert animals such as the kangaroo rat.
- Waterproofing = Fats are insoluble in water and important for land organisms like insects where the waxy cuticle reduces water loss.
What is a phospholipid?
A special type of lipid where one fatty acid tail is replaced with a phosphate group.
What does this mean for the structure of the phospholipid?
It means it is soluble in water because one end is hydrophobic and the other is hydrophillic. The glycerol and phosphate group are polar and able to dissolve in water.
What is the definition of Hydrophobic?
Cannot interact with water due to the lack of any charge on the molecule.
What is the definition of Hydrophillic?
Can interact with water due to the presence of charge on the molecule.
What is the test for fats and oils?
The lipid emulsion test:
1. Dissolve in organic solvent (ethanol)
2. Shake with equal amount of water.
3. Causes lipids to fall out of solution as they are insoluble in water.
4. If positive then cloudy white precipitate is formed.
What are proteins made up of?
Amino Acids.
What groups specifically make up proteins?
Amino Group, Carboxyl Group and R Group (R is different in every amino acid)
How is a peptide bond formed?
The condensation reaction between two amino acids results in a peptide bond and the resulting molecule to be a dipeptide.
What long chains are proteins made up of?
Polypeptide chains (many amino acids joined together)
What is the primary structure of a protein?
The order of amino acids in a polypeptide chain. Determined by the DNA sequence on one strand of the DNA molecule.
What is the secondary structure of a protein?
The folding of the primary structure into a 3D shape which is held together by Hydrogen Bonds. This creates two distinct shapes, the alpha helix and beta pleated sheet.
What is the tertiary structure of a protein?
The further folding of the alpha helix into a more compact shape, which is held together with disulphide, ionic, hydrogen bond and hydrophobic interactions. It gives globular proteins such as enzymes their shape.
What is the quaternary structure of a protein?
The combination of two or more polypeptide chains in tertiary form. Eg: Haemoglobin.
What is a fibrous protein?
Perform structural functions. They are strong and insoluble in water. Eg: Keratin in hair or Collagen to support tendons. A single fibre consists of three polypeptide chains twisted around eachother like a rope. These chains are linked by cross-bridges, making a stable molecule.
What is a globular protein?
Proteins that perform a variety of functions. Eg: Enzymes, antibodies, plasma proteins and some hormones like insulin. These are very compact and folded as spherical molecules. They are soluble in water.
What is the test for proteins?
The Biuret Test.
1. Add Biuret Reagent to sample.
2. Blue to Purple means positive for proteins.
