M2 Biological Molecules Flashcards
Role of calcium ions (Ca 2+)
Nerve impulse transmission
Muscle contraction
Role of sodium ions (Na 2+)
Nerve impulse transmission
Kidney function
Role of potassium ions (K +)
Nerve impulse transmission
Stomata opening
Role of hydrogen ions (H +)
Catalysis of reactions
pH determination
Role of ammonium ions (NH4 +)
Production of nítrate ions by bacteria
Role of nitrate ions (NO3 -)
Nitrogen supply to plants for amino acrid and protein formation
Role of hydrogen carbonate ions (HCO3 -)
Maintenance of blood pH
Role of chloride ions (Cl-)
Balance positive charge of sodium and potassium ions in cells
Role of phosphate ions (PO4 3-)
Cell membrane formation
Nucleic acid and ATP formation
Bone formation
Role of hydroxide ions (OH-)
Catalysis of reactions
pH determination
What elements make up carbohydrates?
Carbon, hydrogen and oxygen
Usually in ratio C x (H2O) x
What elements make up lipids?
Carbon, hydrogen and oxygen
What elements make up proteins?
Carbon, hydrogen, oxygen, nitrogen and sulfur
What elements make up nucleic acids?
Carbon, hydrogen, oxygen, nitrogen and phosphorus
Describe polymers
Biological molecules are often polymers
Polymers are long-chain molecules made by the linking of multiple individual molecules called monomers in a repeating pattern
Describe the structure of water
A molecule of water is one atom of oxygen, joined to two atoms of hydrogen shared by electrons
The shared negative hydrogen electrons are pulled towards the oxygen atom, the other side of each hydrogen atom is left with a slight positive charge
The unshared negative electrons on the oxygen atom give it a slight negative charge
This makes water a polar molecule - it has a partial negative charge on one side and a partial positive charge on the other
The slightly negatively charged oxygen atoms attract the slightly positively charged hydrogen atoms of other water molecules
This attraction is called hydrogen bonding
Why does water have a high specific heat capacity?
Hydrogen bonds between water molecules can absorb a lot of energy, so water has a high specific heat capacity as it takes a lot of energy to heat up
Therefore water doesn’t experience rapid temperature changes
This makes water a good habitat for organisms such as fish, as the temperature does not very providing a consistent habitat
Water also helps buffer temperature changes during chemical reactions in prokaryotic and eukaryotic cells
Why is ice less dense than liquid water?
Below 4° Celsius water molecules are held further apart in ice as each water molecule forms four hydrogen bonds to other water molecules making a lattice shape
This makes ice less dense than liquid water, meaning that it floats
This means ice forms on the top of ponds and lakes, forming an insulating layer above the water below
This allows aquatic organisms to survive freezing temperatures, and their whole habitat does not freeze
Why is water cohesive?
Cohesion is the attraction between molecules of the same type. Water molecules are cohesive as they are polar molecules.
Water has cohesive properties, it moves as one mass as the molecules are attracted to each other.
This allows plants to draw water up through their roots in the transpiration stream.
This also makes water an efficient transport median within living things. Adhesion occurs between water molecules and other polar molecules and surfaces resulting in water exhibiting a capillary action, allowing water to rise up a narrow tube against gravity.
Water molecules are more strongly cohesive to each other than they are to air, resulting in water having a ‘skin’ of surface tension, which supports small insects such as pond skaters.
Why is water a good solvent?
Because it is a polar molecule, water acts as a solvent in which many of the solutes in an organism can be dissolved.
The positive end of the water molecule will be attracted to the negative ion, and the negative end of a water molecule will be attracted to the positive ion. The ions will be totally surrounded by water molecules and will dissolve.
Water acts as a medium for chemical reactions and helps transport dissolved compounds into and out of cells.
What are proteins made up from?
Amino acids are monomers in proteins
A dipeptide is formed when two amino acids join together
A polypeptide is formed when more than two amino acids join together
Proteins are made up of one or more polypeptides
What is the general structure of an amino acid
R
|
H2N - C - COOH
|
H
Describe the synthesis of peptides
Amino acids join when the amine and carboxylic acid groups connected to the central carbon atom react
The hydroxyl in the carboxylic acid group of one amino acid reacts with a hydrogen in the amine group of another amino acid
A peptide bond is formed between the amino acids and water is produced (condensation reaction) resulting in a dipeptide
Describe the primary structure of proteins
- The number, type and sequence of amino acids that make up this linear chain together with the peptide bonds that hold them together.
- Different proteins have different primary structures. The particular amino acids in the sequence will influence how te polypeptide folds to give the proteins final shape, which determines its function. The only bonds in the primary structure are peptide bonds.
Describe the secondary structure of proteins
The arrangement of the atoms that form the backbone or linear chain of the protein.
The amino acid chain can coil into an alpha helix, or form a beta pleated sheet.
The helix and beta pleated sheet shapes are secondary structures of proteins.
Describe the alpha helix secondary structure of proteins
The amino acid chain coils into a right-handed helix and hydrogen bonds form between oxygen and hydrogen atoms that have been brought into close proximity.
These hydrogen bonds help to stabilise this secondary structure.