Biology/Biochemistry Flashcards
What is a biomaterial?
A biomaterial is a non-viable material used in a medical device, intended to interact with biological systems.
What is biocompatibility?
The ability of a material to perform with an appropriate host response in a specific application.
Reliability/probability of success
r = 1-f
What is a hydrogen bond?
The attractive interaction of a hydrogen atom with an electronegative atom (e.g. nitrogen or oxygen) from another molecule or chemical group- must be covalently bonded
Strength of hydrogen bond
5-30 kJ/mole- stronger than the van der Waals interaction
What is a stereoisomer?
Stereoisomers are isomeric molecules that have the same molecular formula and sequence of bonded atoms, but with different 3D orientation in space. Structural isomers share the same molecular formula, but the bond connection and/or their order between different atoms/groups differs. In stereoisomers, the order and bond connections of the constituent atoms remains the same, but their orientations in space differ.
pH formula
pH = -log(10)[H+]
What is a zwitterion?
A zwitterion is a molecule with a positive and negative electrical charge on different atoms within the molecule. In some amino acids, zwitterions exist due to non-uniform distribution of ions at atoms/molecules. Zwitterion properties of an amino acid can be modulated by pH.
What is an L-isomer?
A stereoisomer that rotates polarised light left (laevorotatory). All proteins in all species are made up of the same set of 20 L-amino acids).
Hydrophobicity
Water unfriendly- contains a large number of CH2 or phenyl (benzene C6H6) rings groups
Hydrophilicity
Water friendly- contains a large number of OH, COOH, NH2 or any group which can carry charge (polar molecules)
Aldehyde
Has a C=O group at the end of the molecule
Ketone
Has a C=O group at some other point along the chain
Three main physiological functions of lipids
1) Building blocks of phospholipids and glycolipids that are important in biological membranes
2) Derivatives serve as hormones and intracellular messengers
3) Fuel storage
Describe the formation of peptide by amino acids and identify the pepetide bond
Two amino acids bond together by a peptide bond. Water will be released during this process.
Describe the structure of haemoglobin
Haemoglobin consists of 2 alpha and 2 beta chains containing a Haem group. In an alpha-helix, the protein chain is coiled like a loosely coiled spring. In a beta-pleated sheet, the chains are folded so that they lie alongside each other.
What holds a protein into its tertiary structure?
The tertiary structure of a protein is held together by interactions between the side chains- the “R” groups. There are several ways this can happen.
Primary structure
The sequence of amino acids in a protein is called the primary structure. The peptide bonds lie in the same plane and define the polypeptide backbone.
Secondary structure
The secondary structure is governed by the rotations, or folding of the polypeptide chains. The two most common types of folding are the alpha helix and the beta pleated sheet.
Tertiary structure
Refers to the 3D structure of an amino acid or protein. The folded structure is maintained by electrostatic interactions, H-bonding and in some cases sulphide links. For a protein in water, its 3D structure is determined by the hydrophobicity/hydrophilicity of the amino acids.
Quarternary structure
Refers to the spatial arrangement of chains of a protein relative to one another (like haemoglobin, which has a number of polypeptide chains). The chains are held together by van der Waals forces.
Describe the common pathway of blood clotting
Active X-factor from either intrinsic or extrinsic pathways triggers the reaction from prothrombin to thrombin. Thrombin then triggers the reaction for fibrinogen to turn into fibrin (loose) and fibrin (tight).
Acute Inflammation
Relatively short duration (minutes- days). Main characteristics are exudation (accumulation) of fluid and plasma proteins which cause swelling (oedema) and migration of white blood cells called neutrophils.
Chronic Inflammation
Generally characterised by the presence of a second class of white blood cells, macrophages, monocytes and lymphocytes. New blood vessels and connective tissues start to proliferate.
