Unit 1.2 - Proteins Flashcards
What is the proteome?
The entire set of proteins expressed as the genome
Why is the proteome larger than the genome?
Because more than one protein can be produced from a single gene due to alternative RNA splicing
Name two factors that can affect the set of proteins
Cellular stress and metabolic activity
What are the genes that do not code for proteins called?
Non-coding RNA genes
What is the role of the Golgi Apparatus?
Transport and modification of proteins
What are lysosomes?
Membrane-bound organelles that digest proteins
What is the difference between the smooth and rough ER?
The rough ER has ribosomes on its surface while the smooth ER lacks ribosomes
Where are lipids synthesised?
The smooth ER
What is a signal sequence?
A short stretch of amino acids at one end of the polypeptide
What do vesicles move along to get to other membranes?
Microtubules
What is proteolytic cleavage?
Another type of post-translational modification
What two proteins require proteolytic cleavage to become active?
Digestive enzymes and insulin
Describe a ‘“basic” amino acid R group.
- Positively charged
- Amine group (NH₂)
Describe an ‘“acidic” amino acid R group
- Negatively charged
- Hydrophilic
- Carboxylic acid group (COOH)
Describe a ‘“hydrophobic” amino acid R group
- Non-polar
- Hydrocarbon group (CH₃)
Describe a ‘“polar” amino acid R group
- Hydrophilic
- Carbonyl (C=O), hydroxyl (OH) or amine (NH) groups
What is the primary structure?
The sequence in which the amino acids are joined to make a protein during synthesis
What makes a secondary structure?
Hydrogen bonding along the backbone.
Describe an alpha helix
- Formed by twisting the polypeptide chain into a helix
- Stabilised with hydrogen bonding
Describe a beta-pleated sheet
- Arranged in rows
- Stabilised with hydrogen bonding
Describe turns
Reverse the direction of the polypeptide chain
What stabilises a tertiary structure?
Interactions between R-groups
Describe a disulfide bridge
Covalent bonds between R-groups
Describe ionic bonds
Between positive and negative residues
Describe electrostatic interactions
Van der Waals
What are interactions of R groups influenced by?
Temperature and pH
Where do allosteric interactions take place?
Spatially distant parts of a protein
Describe cooperativity
The binding of a substrate in one active site that can alter the affinity of other sites
What effect do temperature and pH have on oxygen delivery and affinity of haemoglobin for oxygen
- An increase in oxygen delivery
- A decrease in affinity of haemoglobin for oxygen
What changes in temperature and pH affect haemoglobin?
An increase in temperature and a decrease in pH
