أسئلة المحاضرة الـ 13 بيو (قبل التعديل)

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Questions and Answers

What primarily remains unaffected during the denaturation of proteins?

Quaternary structure

Tertiary structure

Secondary structure

Primary structure (correct)

Which of the following agents is least likely to cause protein denaturation?

Organic solvents

High pressure

70% alcohol solution

Mild soap (correct)

What is a common result of protein denaturation?

Loss of biological activity (correct)

Stabilization of protein structure

Formation of disulfide bonds

Increased enzymatic activity

Which physical agent is explicitly mentioned as causing denaturation?

UV light Signup and view all the answers

Which of the following is a biological consequence of protein denaturation?

Unfolding of protein structure Signup and view all the answers

What is the primary role of chaperones in protein folding?

They assist in the correct folding of proteins and prevent aggregation. Signup and view all the answers

Which of the following is NOT a consequence of protein misfolding?

Enhanced protein solubility. Signup and view all the answers

What triggers the formation of amyloidosis?

Abnormal proteolytic cleavage leading to β pleated sheet structures. Signup and view all the answers

Which family of proteins is known as molecular chaperones?

Hsp 60 family. Signup and view all the answers

How do hydrophobic interactions contribute to protein stability?

By burying hydrophobic amino acids inside the protein structure. Signup and view all the answers

What is the function of the Hsp 70 family of proteins?

They assist in the proper folding of polypeptides. Signup and view all the answers

What is a characteristic feature of the proteins implicated in Alzheimer's disease?

Presence of amyloid beta and tau proteins. Signup and view all the answers

Which process is critical for reducing the unstable interactions of misfolded proteins?

Hydrophobic interactions that reduce surface area. Signup and view all the answers

Which of the following best describes the primary structure of a protein during denaturation?

The peptide bonds remain intact. Signup and view all the answers

Which physical agent is capable of causing protein denaturation?

High pressure Signup and view all the answers

What is a chemical result of exposure to acid gastric juices on proteins?

Denaturation of proteins Signup and view all the answers

What effect does a 70% alcohol solution have on bacterial cells?

Denatures proteins and inactivates enzymes Signup and view all the answers

What is a consequence of protein aggregation during misfolding?

Loss of antigen-antibody reactions Signup and view all the answers

What primarily aids in maintaining the structural stability of proteins during folding?

Hydrophobic interactions Signup and view all the answers

What role do chaperonins, such as GroEL/Hsp 60, play in protein folding?

They assist in correct folding pathways. Signup and view all the answers

What can result from gene mutations affecting proteins?

An altered protein structure Signup and view all the answers

Which of the following diseases is associated with the accumulation of misfolded protein aggregates?

Amyloidosis Signup and view all the answers

What type of protein aggregates are commonly seen in Alzheimer's disease?

Fibrillar protein assemblies Signup and view all the answers

How do proteins manage to avoid aggregation during the folding process?

Through the action of molecular chaperones Signup and view all the answers

What is a consequence of proteolytic cleavage of certain proteins?

Formation of amyloid-like fibrils Signup and view all the answers

What is the primary function of Hsp 70 family of proteins?

To assist in proper protein folding Signup and view all the answers

Study Notes

Biochemistry: Protein Folding

Protein folding is a physical and dynamic process.
Polypeptides fold into a 3-dimensional conformation for proper function.
Spontaneous folding is aided by hydrophobic interactions, burying hydrophobic amino acids within the protein structure.
Hydrophobic interactions keep proteins stable and biologically active, reducing surface area.
Chaperones (heat shock proteins) assist in correct folding and prevent aggregation.
Chaperones help proteins fold into functional structures.
Chaperones, specifically Hsp 70 and GroEL/Hsp 60, are crucial for proper protein folding.
Hsp stands for heat shock protein

Protein Misfolding

Protein misfolding can result from spontaneous processes or gene mutations.
Abnormal proteolytic cleavage can lead to misfolding.
Partially or improperly folded proteins may interact with chaperones.
Misfolded proteins form insoluble aggregates.
Accumulation of misfolded protein aggregates leads to diseases like Alzheimer's, Parkinson's, and Type II diabetes.
Diseases associated with misfolded proteins include Alzheimer's disease (amyloid beta and tau), Parkinson's disease (alpha-synuclein), and Type II diabetes (amylin).

Protein Denaturation

Denaturation disrupts secondary, tertiary, and quaternary protein structure.
Primary structure and peptide bonds remain unchanged.
Physical agents like heat, UV light, ultrasound, high pressure, and violent shaking denature proteins.
Chemical agents like strong acids, strong alkalies, organic solvents, and heavy metal salts also denature proteins.
Denaturation has applications in sterilization and disinfection.
Denaturation leads to loss of protein activity, antigen-antibody reaction, and easier digestion.
Medical supplies and instruments are sterilized using heat to denature proteins.
Acidic gastric juices denature proteins to break down food.
Alcohol (70%) is used as a disinfectant, penetrating bacterial cell walls and denaturing proteins and enzymes.
Denaturation affects a protein's ability to perform its function.
Denaturation results in unfolding of the protein molecule and the destruction of some subsidiary hydrogen bonds.
Exposure of some groups like SH (cysteine) is possible during denaturation.

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