47 Questions
What is the purpose of posttranslational modifications of proteins?
To convert proteins to a functional form
Where does trimming of proteins occur?
In the endoplasmic reticulum (ER) or Golgi apparatus
What is the function of ubiquitination on a target protein?
Marks the protein for degradation
What is the process that adds a phosphate to serine, threonine, or tyrosine residues?
Phosphorylation
Which process covalently links the sulfur atoms of two different cysteine residues?
Disulfide bond formation
Which type of covalent attachment attaches a sugar to a protein?
Glycosylation
When do cotranslational modifications of proteins occur?
During translation in the cytoplasm
Where are DNA polymerases targeted for proper function?
Nucleus
What process adds a methyl group, usually at lysine or arginine residues?
Methylation
What determines whether a protein will undergo posttranslational modification?
The amino acid sequence and 3D conformation of the protein
In protein targeting, where are insulin molecules typically directed for secretion?
Plasma membrane
Which proteins are examples of those that undergo trimming?
Insulin, collagen
Which cellular compartment do receptors target for proper function?
Plasma membrane
What kind of proteins require the assistance of chaperones for proper folding?
All newly synthesized proteins
What can accumulation of misfolded proteins into aggregates lead to?
'Serious diseases'
What is the main importance of posttranslational modifications of proteins?
Conversion to a functional form
How does the cell determine which proteins need to undergo posttranslational modifications?
Amino acid sequence and 3D conformation of the protein
Which type of covalent attachment adds a sugar to a protein?
Glycosylation
What is the function of ubiquitination on a target protein?
Marks the protein for degradation
Where does trimming of proteins occur?
RER or Golgi
What kind of proteins typically require trimming?
Insulin, collagen
What does covalent addition of one or more chemical groups to a protein include?
Glycosylation, ubiquitination, acetylation
Which process involves the addition of a methyl group, usually at lysine or arginine residues?
Methylation
What type of covalent attachment attaches a sugar to a protein?
Glycosylation
Where are DNA polymerases targeted for proper function?
Nucleus
What kind of proteins require the assistance of chaperones for proper folding?
Misfolded proteins
Which cellular compartment do receptors target for proper function?
Plasma membrane
What is the function of Sodium chloride in the cell lysis solution?
To osmotically shock the cells by causing a sudden and rapid change in the movement of solutes across the cellular membrane
What is the role of Proteinase K in the cell lysis solution?
To digest histone and other proteins that bind to DNA and mediate its packaging inside the nucleus
What is the function of Tris-HCL in the cell lysis solution?
To maintain the pH optimum for proteinase K activity
What is the function of Ethylene diamine tetra acetic acid (EDTA) in the cell lysis solution?
To inhibit the function of nucleases and consequently the destruction of DNA
What is the purpose of combining Phenol: Chloroform: Isoamyl alcohol (25:24:1) in the purification step?
To promote the partitioning of proteins and lipids into the organic phase leaving isolated DNA in the aqueous phase
What is involved in the first common principle shared by all different DNA extraction protocols?
Lysis of cell membranes
What is NOT a component of cell lysis solution for DNA extraction?
Protein-nucleic acid complex
What is NOT a function of sodium dodecyl Sulfate (SDS) in cell lysis solution?
Mediating packaging of DNA inside the nucleus
What is NOT an essential ingredient for cell lysis?
Protein-nucleic acid complex
What does EDTA do to prevent DNA destruction during cell lysis?
It inhibits nucleases by chelating metal ions that act as cofactors
What is the purpose of DNA extraction in a biological sample?
To isolate DNA from other macromolecules for further investigations
Where is genomic DNA located in eukaryotic cells?
In the nucleus
What is the role of histone proteins in relation to DNA?
They mediate the coiling of DNA into a compact structure
In which type of investigations is DNA extraction particularly useful?
Forensics investigations
What are the main components that need to be separated from DNA during the extraction process?
Proteins, RNA, and lipids
What is the structure of DNA?
Double helix composed of two separate strands
What does DNA contain that provides instructions for an organism's development and reproduction?
Nucleotides
What is the function of DNA polymerases?
To synthesize new DNA strands using existing ones as templates
Why is it necessary for DNA to be tightly packed within the nucleus of eukaryotic cells?
To store large amounts of genetic information in a small space
What do scientists typically use extracted DNA for in medicine and science?
For further investigations and applications in various fields like medicine and science
Test your knowledge on the importance of posttranslational modifications in protein processing and targeting, including cotranslational modifications and the impact on protein function, subcellular localization, and secretion.
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