Cells and proteins - 2 Flashcards
what is proteomics?
the study of an entire set of proteins expressed by the organism’s genome
what is a proteome?
set of proteins in an organism
why is a proteome larger than a genome?
since alternative RNA splicing and post translation modification means that one gene = many proteins
what is alternative RNA splicing?
different mRNA segments can be treated as introns or axons depending on the protein
name two types of post translation modification
- addition of a phosphate or carbohydrate
- cleavage
what is the structure of an amino acid?
- amide group
- R group
- carboxylic group
how do amino acids join together?
in a condensation reaction
what type of bonds form when amino acids join together?
peptide bonds
what is a chain of amino acids called?
a polypeptide
where are the N terminal?
where the NH2 group is
where is the C terminal?
where the carboxylic group is
what is the primary structure?
the order in which the amino acids are synthesised
what are the four classes of amino acids?
- acidic
- basic
- polar
- hydrophobic
describe an acidic amino acid
- negatively charged
- R group = carboxylic group
describe a basic amino acid
- positively charged
- R group = amide group
describe a polar amino acid
- slightly charged
- R group = OH group
describe a hydrophobic amino acid
- usually no charge
- R group = hydrocarbon
what is the secondary structure?
chain which forms either two structures in which hydrogen bonds keep the structure in place
what two types of secondary structures can be formed?
alpha helix or beta-pleated sheets
what are the two types of beta-pleated sheets?
anti-parallel sheets or parallel sheets
what gives a protein its 3D structure?
different types of bonding forming a tertiary structure
what types of bonding can form in a tertiary structure?
- hydrogen bonds
- ionic bonds
- hydrophobic
- van der Waals forces
- disulphide bridges
what is a quaternary structure?
proteins with many chains of polypeptides subunits connected together
what is a prosthetic group?
non-protein group which is strongly bound to a polypeptide unit
what can cause a protein to denature?
temperature and pH
what is an R-group?
variable group on an amino acid
what are the importances of R-groups on a protein?
- determines the structure of protein
- determines the location within a cell
- call allow bindings of ligands
what are cytoplasmic proteins?
soluble proteins that forms a globular structure with hydrophobic core
what makes cytoplasmic proteins soluble?
surface has a greater proportion of hydrophilic R groups
