Stress Response Flashcards
Why does aggregation occur?
When the unfolded proteins cannot renature, the hydrophobic amino acids are exposed to water. Hence, they will form random bonds with other unfolded protein, forming clumps
How does heat cause denaturation and aggregation to occur?
As temperature increases, the molecular movement will also increase. Hence, leading to broken bonds and loss of 3D structure in proteins. If proteins cannot renature, it will undergo aggregation and form clumps
Why is the protein structure critical for protein function (enzyme)
Enzymes rely on their molecular shape to carry out functions
The substrate must correctly fit the active site, for the enzyme to function and for products to be formed.
When enzymes are denatured, it will lose its active site, substrate cannot bind to the enzyme and no products will be formed
Why is the protein structure critical for protein function (RNA polymerase)
RNA polymerase is needed to initiate transcription so that protein synthesis can occur
When RNA polymerase denatures, it will no longer be able to bind to the promoter region of the DNA and transcription cannot occur. Therefore, no protein would be made
What are the covalent bonds present?
Peptide bonds (in primary structure) Disulfide bonds (in tertiary and quaternary structure)
What are the non-covalent bonds present?
Hydrogen bonds
van der Waals forces
Hydrophobic interactions
Electrostatic interactions
How does the increase in temperature affect the cells
The biomolecules will lose their function, life processes will not be able to proceed and cells will experience cellular stress which may kill them.
How do cells respond to heat stress?
During heat stress, HSP binds to the denatured protein, releasing HSF. HSF gets phosphorylated and binds to HSE and upregulated HSP gene expression
Under normal conditions, is HSP still produced?
HSP is also produced under normal conditions as they are involved in folding newly synthesized proteins. Without them, the proteins might get misfolded.
However, HSP will bind to HSF, inactivating HSF and HSP will not be produced in excess.
What is the function of HSP25 and HSP70?
HSP25: bind to denatured proteins and stabilize them, hence preventing aggregation
HSP70: helps to re-fold denatured proteins to make functional proteins, this process requires energy from ATP
