3.1 Biological elements (2.1.2) Flashcards
Cells are the building blocks of all living organisms. What smaller components are they made up of?
Molecules
What are different types of atoms called?
Elements
How are different elements distinguished?
By the number of protons in their atomic nuclei.
All living things are made primarily from four key elements. What are these?
Carbon (C), Hydrogen (H), Oxygen (O), and Nitrogen (N).
What are 2 elements that also have important roles in the biochemistry of cells?
Phosphorus (P) and Sulfur (S)
Describe how a covalent bond occurs
A covalent bond occurs when two non-metal atoms share a pair of electrons. The electrons used to form bonds are unpaired and present in the outer orbitals of the atoms.
What is an atom or molecule in which the total number of electrons is not equal to the total number of protons called?
An ion
What is an atom/molecule called when it loses electrons?
Cation
What is an atom/molecule called when it gains electrons?
Anion
What happens in ionic bonds?
In ionic bonds, one atom in the pair donates an electron and the other receives it. This forms positive and negative ions that are held together by the attraction of the opposite charges.
What are ions in solutions called?
Electrolytes
What are calcium ions necessary for? (2)
- Nerve impulse transmission
- Muscle contraction
What are sodium ions necessary for? (2)
- Nerve impulse transmission
- Kidney function
What are potassium ions necessary for? (2)
- Nerve impulse transmission
- Stomatal opening
What are hydrogen ions necessary for? (2)
- Catalysis of reactions
- pH determination
Name 5 cations with useful roles
- Calcium ions
- Sodium ions
- Potassium ions
- Hydrogen ions
- Ammonium ions
Name 5 anions with useful roles
- Nitrate ions
- Hydrogen carbonate ions
- Chloride ions
- Phosphate ions
- Hydroxide ions
What are nitrate ions necessary for?
Nitrogen supply to plants for amino acid and protein formation
What are hydrogen carbonate ions necessary for?
Maintenance of blood pH
What are chloride ions necessary for?
Balance positive charge of sodium and potassium ions in cells
What are phosphate ions necessary for? (3)
- Cell membrane formation
- Nucleic acid and ATP formation
- Bone formation
What are hydroxide ions necessary for? (2)
- Catalysis of reactions
- pH determination
What 3 elements are present in carbohydrates?
Carbon, Hydrogen and Oxygen
What 3 elements are present in lipids?
Carbon, Hydrogen and Oxygen
What 5 elements are present in proteins?
Carbon, Hydrogen, Oxygen, Nitrogen and Sulfur
What 5 elements are present in nucleic acids?
Carbon, Hydrogen, Oxygen, Nitrogen and Phosphorus
What is a condensation reaction?
A reaction occurs when two molecules are joined together with the removal of water.
What is a hydrogen bond?
A weak interaction that can occur wherever molecules contain a slightly negatively charged atom bonded to a slightly positively charged hydrogen atom.
What is a hydrolysis reaction?
A reaction in which two molecules are split apart with the addition of water
What are condensation and hydrolysis reactions responsible for in living things?
Condensation and hydrolysis reactions are responsible for linking and splitting apart biological molecules in living things.
What are two monomers that are joined together called?
A dimer
In condensation reactions, what happens to the -OH groups of each molecule?
H20 is added in hydrolysis and H20 is removed in condensation.
Which biological molecule doesn’t form polymers like the rest?
Lipids
Describe what atoms water consists of and how they are bonded
Water consists of two hydrogen atoms, each covalently bonded to the oxygen atom.
Describe why water molecules are polar
The oxygen atom has a greater number of positive protons in its nucleus; this exerts a stronger attraction for the shared electrons. This means the oxygen atom becomes slightly negative, and the hydrogen atoms become slightly positive. When this happens, we say the molecule is polar.
What does having many hydrogen bonds help to do?
Stabilise the structure of the molecules
