1.2 Proteins Flashcards
Define the term proteome
The entire set of proteins expressed by a genome
Why is the proteome larger than the number of genes in a cell?
Post translational modification and alternative RNA splicing.
State 3 functions of non-coding RNAs.
rRNA, tRNA and microRNA
Explain why the proteome changes within a cell.
Metabolic activity, cellular stress or disease.
Why do cells have a system of internal membranes?
To increase surface area for chemical reactions to happen.
Where are cytosolic proteins made?
The cytoplasm.
State the function of smooth ER
Lipid synthesis.
State the function of the lysosome.
An organelle that contains a variety of hydrolyses that digest proteins, lipids and carbohydrates.
Where are the signal sequences within the cell and what is their function?
A short stretch of amino acid that determines the location of the protein.
State the type of bond that holds amino acids together.
Peptide bond.
Discuss the chemical nature of a basic amino acid.
Positively charged r-group, and hydrophilic in nature.
Discuss the chemical nature of an acidic amino acid.
Negativley charged r-group, and hydrophilic in nature.
Discuss the chemical nature of a polar amino acid.
Polar in nature (hydroxyl group), and hydrophilic in nature.
Discuss the chemical nature of a non-polar amino acid.
Non-polar in nature (Hydrocarbon), and hydrophobic in nature.
Describe the bonding of a primary protein structure.
Held together by a peptide bond.
Describe the bonding of a secondary protein structure.
Secondary structures are either; a helix or a beta sheeted plate.
a helix are held together by a hydrogen at every four amino acids. beta sheeted plate is when different parts of the polypeptide chain run alongside each other
Describe the bonding of a tertiary protein structure.
Tertiary structures include disulphide bridges that exist between r-groups which contain sulphur.
Describe the bonding of a quaternary protein structure.
Quaternary protein structures include two or more polypeptide subunits , creating a more complex protein. E.g haemoglobin.
Name the bond that exists in a disulphide bridge.
Covalent bond.
State the main difference between the quaternary structure and tertiary structure.
The number of subunits.
Discuss the effect of temperature on r-group interactions.
High temperatures will break the polypeptide chain.
Discuss the effect of pH on r-group interactions.
Ionic interactions are lost.
Describe a ligand.
A molecule that can bind to a protein.
Describe the three examples of ligand binding.
Enzymes, receptors and histones.
State the effect of a ligand biding to a protein.
Conformational changes.
What is allosteric regulation.
The biding of modulators at spatially distinct sites.
What are positive and negative regulators.
Positive regulators increase a proteins affinity for a molecule, where as negative regulator decreases a proteins affinity for a molecule.
Discuss positive and negative modulation of ATCase.
ATP functions as a positive modulator, where as CTP functions as a negative modulator.
Name bonds that stabilise the tertiary protein structure.
London dispersion, ionic and hydrogen.
Define co-operativity.
Co-operativity is when the binding of a ligand to one sub-unit increases the affinity of the remaining units for the ligand.
Discuss co-operativity in haemoglobin.
The binding of oxygen to one subunit increases affinity for oxygen in the remaining subunits.
