Topic 1 Molecules, Transport and Health Flashcards
Why water is a polar molecule?
Because the electrons are held closer to the oxygen atom than to the hydrogen atoms
Why water has a relatively high boiling and melting point compared with other substances that have molecules of a similar size.
Because it takes a lot of energy to break all the hydrogen bonds
Where are hydrogen bond important?
In protein structure and in the structure and functioning of DNA
What does cohesive mean? (water is cohesive)
This means that the forces between the molecules stick together. This is important for the movement of water from the roots to the leaves of plants.
What does adhesive mean? (water is adhesive)
They are attracted to other different molecules. This is important in plant transport and in surface tension
Why water is slow to absorb and release heat?
it has specific heat capacity
Because hydrogen bonds between molecules need a lot of energy to separate them
Why water has a very high surface tension?
Because the attraction between the water molecules, including hydrogen bonds, is greater that the attraction between water molecules and the air.
What is dipole?
The separation of charge in a molecule when electrons in covalent bonds are not evenly shared
What is polar molecule?
A molecule containing a dipole
What is dissociation?
Splitting of a molecule into smaller molecules, atoms, or ions, especially by a reversible process
What are hydrogen bonds?
Weak electrostatic intermolecular bonds formed between polar molecules containing at least one hydrogen atom
What is monomer?
A small molecule that is a single unit of a larger molecule (Polymer)
What is polymer?
A long-chain molecule made up of many smaller, repeating monomers joined by chemical bonds
What is macromolecule?
A very large molecule ( often formed by polymerisation)
What are carbohydrates?
Carbohydrates are important in cells as an energy storage in animals and form an important part of cell wall in plants
What are the best known carbohydrates?
Sugars and starch
What is glucose?
A hexose sugar and it is used as a fuel by the cells of our bodies.
What does the basic structure of carbohydrates consist of?
Consists of carbon, hydrogen and oxygen
What are the main groups of carbohydrates?
Monosaccharides, disaccharides and polysaccharides
What are monosaccharides?
They are simple sugars
What are triose sugars?
A sugar with three carbon atoms
Important in mitochondria, where respiration process breaks down glucose into triose sugars.
What are pentose sugars?
A sugar with five carbon atoms
Ribose and Deoxyribose are important in the nucleic acids DNA and RNA, which make up the genetic material.
What are hexose sugars?
A sugar with six carbon atoms.
Best known monosaccharides, often taste sweet and include glucose, galactose and fructose.
What are isomers?
Molecules that have the same chemical formula, but different molecular structures.
What is disaccharide?
A sugar made up of two monosaccharides joined by glycosidic bonds
What is condensation reaction?
A reaction in which molecules of water is removed from reacting molecules as a bond is formed between them
How does disaccharide form?
Two monosaccharides join in a condensation reaction and glycosidic bond is formed between them.
How sucrose is made?
By joining glucose and fructose
How lactose is made?
By joining glucose and galactose
How maltose is made?
By joining two glucose
What are the three common disaccharides?
Sucrose, lactose, maltose
What are the most complex carbohydrates?
Polysaccharides
What is polysaccharide?
A polymer consisting of long chains of monosaccharides joined by glycosidic bonds
What are oligosaccharides?
Molecules with between 3 and 10 sugar units
How does glycosidic bond is split between two glucose units?
By hydrolysis
What is hydrolysis?
A reaction in which bonds are broken by addition of a molecule of water.
What is ATP?
The molecule that acts as a universal energy supply molecule in all cells.
What is the structure of polysaccharides?
Their structure make them ideal as energy storage molecules within a cell:
They form very compact molecules (take up little space)
They are physically and chemically inactive (do not interfere with other functions of the cell)
They are not very soluble in water, (so no effect on water potential within a cell and cause no osmosis water movements)