Chemical Elements And Biological Compounds Flashcards
(36 cards)
Inorganic ions are also called what?
Electrolytes or minerals
What cellular processes are inorganic ions important in?
Muscle contraction
Nervous coordination
Maintaining osmotic pressure in cells and blood
4 examples of inorganic ions?
Magnesium
Iron
Phosphate ions
Calcium
Explain water
Water is a medium for metabolic reactions and an important constituent of cells me being 65-95% of the mass of many plants and animals. About 70% of each individual human is water.
The water molecule is a dipole, meaning it has a positively charged end (hydrogen) and a negatively charged end (oxygen), but no overall charge.
A molecule with separated changed is called ‘polar’. The charges are very small and are written as d+ and d-, to distinguish them from full charges (- +).
Hydrogen bonds can form between the d+ on a hydrogen atom on one molecule and the d- on an oxygen atom of another, hydrogen bonds are weak, but collectively are very difficult to break which gives water a wide range of physical properties vital to life
The properties of water?
It's a solvent It is a metabolite It has High specific heat capacity It has High latent heat of vaporisation Cohesion High surface tension High density Transparent
Explain the property of water (solvent)
Living organisms obtain their key elements from aqueous solution. Water is an excellent solvent. Because water molecules are dipoles, they attract charged particles, such as ions, and other polar molecules, such as glucose. These then dissolve in water, so chemical reactions take place in solution. Water acts a transport medium.
E.g. In animals, plasma transports dissolved substances and in plants, water transports minerals in the xylem, and sucrose and amino acids in the phloem. Non-polar molecules, such as lipids, do not dissolve in water
Explain the property of water ( metabolite )
Water is a metabolite: water is used in many biochemical reactions as a reactant
E.g. With carbon dioxide to produce glucose in photosynthesis.
Many reactions in the body involve hydrolysis, where water splits into a molecule. E.g. Maltose + water —> glucose + glucose
In condensation reactions, water is a product. E.g. Glucose + fructose —-> sucrose + water
Explain waters Hugh specific heat capacity
This means a large amount of heat is needed to raise its temperature. This is because the hydrogen bonds between water molecules restrict their movement, resisting an increase in kinetic energy and therefore, resisting an increase in temperature.
This prevents large fluctuations in water temperature, which is important in keeping aquatic habitats stable, so that organisms do not have to adapt to extremes of temperature. It allows enzymes within cells to work efficiently.
Explain waters high latent heat of vaporisation
This means a lot of heat energy is needed to change it from a liquid to a vapour. This is important for example in temperature control, where heat is used to vaporise water from sweat on the skin or from a leafs surface. As the water evaporates, the body cools.
Explain waters property, cohesion
Water molecules attract each other forming other hydrogen bonds. Individually these are weak but,because there are many of them, the molecules stick together in a lattice. This sticking together is called cohesion. It allows columns of water to be drawn up xylem vessels in plants
Explain waters high surface tension
At ordinary temperatures water has the highest surface tension of any liquid except Mercury. In a pond, cohesion between water molecules at the surface produces surface tension so that the body of an insect, such as the pond skater, is supported.
Explain waters high density
Water is denser than air and, as a habitat for aquatic organisms, provides support and buoyancy. Water has a maximum density at 4*C. Ice is less dense than liquid water, because the hydrogen bonds hold the molecules further apart than they are in liquid. So ice floats on water. It is a good insulator and prevents large bodies of water losing heat and freezing completely, so organisms beneath it survive
Explain waters transparency
Water is transparent, allowing light to pass through. This lets aquatic plants photosynthesise effectively
What are carbohydrates?
Organic compounds containing the elements carbon, hydrogen and oxygen
What is the basic unit of a carbohydrate?
A monosaccharide
What do two monosaccharides combine to form?
A disaccharide.
Many monosaccharide molecules combine to form a polysaccharide
What is a monosaccharide?
- general formula
- names determined by?
- example
Small organic molecules and are the building blocks for the larger carbohydrates. Monosaccharides have the general formula (CH2O)n and their names are determined by the number of carbon atoms (n) in the molecule. A triode sugar has three carbon atoms; a pentose has five and a hexose has 6.
Glucose is a hexose sugar. The carbon atoms of a hexose are labelled 1-6
What formula do all hexose sugars share?
C6H12O6, but they differ in their molecular structure .
What happens to the carbon atoms of monosaccharides when the sugar is dissolved in water?
The carbon atoms make a ring and they can alter their binding to make straight chains,with the rings and chains in equilibrium
How many isomers does glucose have?
2
What are the isomers of glucose?
Alpha and beta , based on the positions of an OH and a H.
These different forms result in biological differences when they form polymers, such as starch and cellulose.
Monosaccharides have many functions and can act as:
A source of energy in respiration. Carbon - hydrogen and carbon - carbon bonds are broken to release energy, which is transferred to make adenosine triphosphate (ATP)
Building blocks for larger molecules. Glucose, for example, is used to make the polysaccharides starch,glycogen and cellulose.
Intermediates in reactions, e.g. Trioses, are intermediates in the reactions of respiration and photosynthesis.
Constituents of nucleotides, e.g. Deoxyribose in DNA , ribose in RNA, ATP and ADP
What are disaccharides?
Composed of two monosaccharide units bonded together with the formation of a glycosidic bond and the elimination of water. This is an example of a condensation reaction.
How to test for presence of sugars?
Equal volumes of Benedicts reagent and the solution being tested are heated to at least 70*C. If a reducing sugar, such as glucose, is present, the solution will turn from blue through green, yellow and orange and finally brick-red precipitate forms.
These sugars donate an electron to reduce copper (II) ions in copper sulfate, to red copper (I) oxide.
Some disaccharides, such as sucrose, are non reducing sugars and give a negative result, I.e. The solution remains blue. Sucrose can only be detected if it is broken down to its constituent monosaccharides, for example by heating with hydrochloric acid. Benedicts reagent needs alkaline conditions to work, so alkali is added, Benedicts reagent is then added and heated as before, if the solution now turns red then a non reducing sugar was initially present
