Chapter 3- 3.1- Biological elements Flashcards
What are elements?
Different types of atoms are elements.
Elements re distinguished by the number of protons in their atomic nuclei. There are over a hundreds known elements in the universe but only a small percentage of these are present in the living world.
All living things are made up of four key elements- carbon (C), hydrogen (H), oxygen (O) and nitrogen (N).
In addition, phosphorous (P) and sulphur (S) also have important roles in the biochemistry of cells.
What is bonding?
Atoms connect with each other by forming bonds.
Atoms can bond to other atoms of the same element, or atoms of different elements, provided this follows the “bonding rules”.
When two or more atoms bond together the complex is called a molecule.
A covalent bond occurs when two atoms share a pair of electrons.
The electrons used to form bonds are unpaired and present in the outer orbitals of the atoms.
What are the simple rules that bonding follows?
Carbon atoms can form four bonds with other atoms.
Nitrogen atoms can form three bonds with other atoms.
Oxygen atoms can from two bonds with other atoms.
Hydrogen atoms can only form one bond with another atom.
What is an ion?
An atom or molecule in which the total number of electrons is not equal to the total number of protons is called an ion. If an atom or molecule loses one or more electrons it has a net positive charge and is known as a cation.
If an atom or molecule gains electrons, it has a net negative charge and is known as an anion.
In ionic bonds, one atom in the pair donates and electron and the other receives it. This forms positive and negative ions that are held together by the attraction of the opposite charges.
Ions in solution are called electrolytes.
What are some of the important roles of cations in living organisms?
Calcium ions are necessary for nerve impulse transmission and muscle contraction.
Sodium ions are necessary for nerve impulse transmission and kidney function.
Potassium ions are necessary for nerve impulse transmission and stomatal opening.
Hydrogen ions are necessary for catalysis of reactions and pH determination.
Ammonium ions are necessary for production of nitrate ions by bacteria.
What are the important roles of anions in living organisms?
Nitrate ions are necessary for nitrogen supply to plants for amino acid and protein function.
Hydrogen carbonate ions are necessary for maintenance of blood pH.
Chloride ions are necessary for balancing the positive charge of sodium and potassium ions in cells.
Phosphate ions are necessary for cell membrane formation, nucleic acid and ATP formation and bone formation.
Hydroxide ions are necessary for catalysis of reactions and pH determination.
What are some of the key biological molecules?
Carbohydrates- carbon, hydrogen, and oxygen, usually in the ratio C(x)(H(2)O)(x).
Lipids- carbon, hydrogen and oxygen.
Proteins- carbon, hydrogen, oxygen, nitrogen, and sulphur.
Nucleic aids- carbon, hydrogen, oxygen, nitrogen, and phosphorus.
What are polymers?
Biological molecules are often polymers.
Polymers are long-chain molecules made up by the linking of multiple individual molecules (called monomers) in a repeating pattern.
In carbohydrates the monomers are sugars (saccharides) and in proteins the monomers are amino acids.
