Biotechnology MCQ Quiz in मराठी - Objective Question with Answer for Biotechnology - मोफत PDF डाउनलोड करा

The correct answer is: 8000 bases

Explanation:

• Retroviruses are enveloped RNA viruses that use reverse transcription to convert their single-stranded RNA genome into double-stranded DNA, which integrates into the host genome.
• Engineered retroviruses (like lentiviral vectors) are commonly used in gene therapy to deliver genetic material. These vectors can accommodate and deliver up to 8,000 bases of single-stranded RNA.
• This capacity makes retroviruses suitable for introducing relatively large genes into host cells compared to other viral delivery systems.

The correct answer is: Proteome

Explanation:

• Proteome:

  • Refers to the complete set of proteins produced by an organism at a specific time under certain conditions. It reflects the functional output of the genome and varies depending on the cell type, developmental stage, and environmental factors.

• Why the other options are incorrect:

  1. Transcriptome: Refers to the complete set of RNA transcripts (including mRNA, rRNA, tRNA, etc.) produced by an organism at a particular time.
  2. Lipidome: Refers to the complete set of lipids (fats and related molecules) present in a cell or organism at a given time.
  3. Metagenome: Refers to the collective genome of microorganisms in an environmental sample.

The correct answer is: α-helices

Explanation:

• α-helices are the most common structure found in the portions of transmembrane proteins that span the lipid bilayer. These helices are hydrophobic in nature, allowing them to interact favorably with the hydrophobic core of the membrane. They can stabilize the protein structure within the membrane.

• β-sheets, while important in other regions of proteins, typically do not form the transmembrane regions because their structure is less favorable in the hydrophobic environment of the lipid bilayer.

• Turns and loops are often found in regions of proteins that are exposed to the aqueous environment, rather than in the membrane-spanning portions.

Key Points

• Membrane-spanning α-helices often contain hydrophobic amino acids, which interact with the fatty acid tails of the phospholipids, stabilizing the protein within the membrane.
• The number of transmembrane helices in a protein varies, with some proteins having a single helix and others having multiple helices forming a channel or pore.
• β-barrels, while less common, are found in the outer membranes of Gram-negative bacteria, mitochondria, and chloroplasts. They are made up of β-sheets arranged in a barrel-like structure.
• Transmembrane protein domains may also undergo conformational changes upon ligand binding or environmental changes, which is crucial for signal transduction and transport functions.
• Hydropathy plots are used to predict transmembrane segments by analyzing the hydrophobicity of amino acid sequences.
• Transmembrane proteins play key roles in processes like cell signaling, transport, and maintaining cell structure.

The correct option is: 2 .

Explanation:

• Endoplasmic reticulum: This statement is incorrect. HSP70 chaperones are typically found in the endoplasmic reticulum (ER), where they assist in the proper folding of nascent proteins and help prevent misfolding.

• Golgi bodies: This statement is correct. HSP70 chaperones are not typically associated with the Golgi apparatus. While the Golgi does play a role in protein processing and sorting, it does not primarily contain HSP70 chaperones, which are more involved in the folding and stabilization of proteins as they are synthesized.

• Nucleus: This statement is incorrect. HSP70 chaperones can be found in the nucleus, where they assist in the folding and maintenance of nuclear proteins and can also be involved in DNA repair processes.

• Mitochondria: This statement is incorrect. HSP70 chaperones are present in mitochondria, where they play a crucial role in the import and folding of mitochondrial proteins.

• Heat shock proteins (HSPs), including HSP70, are crucial for cellular stress responses, helping to ensure protein homeostasis. Their presence in various organelles reflects their importance in protecting cells from stress and assisting in the proper functioning of proteins.

The correct option is: 1.

Explanation:

• Mitochondria: These organelles are crucial in the initiation of apoptosis by releasing pro-apoptotic factors, such as cytochrome c, into the cytosol. This release activates caspases, leading to the execution of apoptosis. Mitochondria thus play a central role in the intrinsic pathway of apoptosis, responding to stress signals and cellular damage.

• Nucleus: While the nucleus is vital for cell regulation and houses the genetic material, it does not directly initiate apoptosis by releasing pro-apoptotic factors. However, it can be involved in the process by activating genes that promote apoptosis under certain conditions.

• Golgi apparatus: This organelle is primarily responsible for modifying, sorting, and packaging proteins and lipids for secretion or delivery to other organelles. It does not have a direct role in apoptosis or in releasing pro-apoptotic factors.

• Endoplasmic reticulum (ER): The ER plays a role in protein and lipid synthesis and calcium storage. It can influence apoptosis under stress conditions (such as in the case of the unfolded protein response) but does not directly release pro-apoptotic factors like mitochondria do.

• The mitochondria's role in apoptosis is critical for maintaining cellular homeostasis, and their dysfunction can lead to various diseases, including cancer and neurodegenerative disorders. The other organelles, while essential for various cellular functions, do not participate in the direct initiation of apoptosis through the release of pro-apoptotic factors.

The correct option is: 4 

Explanation:

• Presence of plasmids: Plasmids are small, circular, extrachromosomal DNA molecules most commonly found in prokaryotic cells. While plasmids are rare in eukaryotes, they are not a defining feature of eukaryotic cells and thus do not align with their typical characteristics.
• The other options correctly describe eukaryotic cell characteristics:
  • Membrane-bound organelles: Eukaryotic cells contain specialized structures called organelles, each enclosed by a membrane and performing distinct functions. Examples include mitochondria (for ATP production), the endoplasmic reticulum (for protein and lipid synthesis), and lysosomes (for intracellular digestion). These organelles are essential for compartmentalizing cellular processes, a feature absent in prokaryotic cells.
  • Linear DNA: Eukaryotes have linear DNA molecules organized into chromosomes within the nucleus. This DNA is associated with histone proteins, forming chromatin, which helps in efficiently packaging DNA and regulating gene expression. This complex structure is essential for eukaryotic cell division and gene regulation.
  • Nucleus: A defining feature of eukaryotic cells, the nucleus is a membrane-bound structure that protects and organizes the cell’s genetic material. The nuclear membrane encloses the DNA, separating it from the cytoplasm and allowing for controlled gene expression and DNA replication.

The correct option is: 2

Explanation:

• Ribosomes are primarily involved in protein synthesis, not lipid synthesis. Ribosomes facilitate the translation of mRNA into polypeptide chains, which then fold to form functional proteins.
• Lipid synthesis occurs in the smooth endoplasmic reticulum (ER), particularly in eukaryotic cells, where lipids and steroids are produced and modified.
• The remaining options accurately match each organelle with its function:
  • Golgi apparatus modifies, sorts, and packages proteins and lipids for secretion or use within the cell.
  • Lysosomes contain enzymes that break down macromolecules, aiding in intracellular digestion and recycling of cellular components.
  • Mitochondria are responsible for ATP production through cellular respiration, providing energy for the cell’s metabolic activities.

The correct option is: 2

Explanation:

• The lysosome is an organelle found in eukaryotic cells that contains enzymes responsible for digesting and breaking down macromolecules, such as proteins, lipids, nucleic acids, and carbohydrates.
• These enzymes can degrade complex molecules into simpler forms, allowing the cell to either recycle the components or expel waste.
• Lysosomes are also involved in the process of autophagy, where they digest damaged cellular components, recycling the materials to maintain cellular health.
• Peroxisome: Peroxisomes contain enzymes, primarily oxidases and catalases, which break down fatty acids and detoxify harmful substances. They play a key role in cellular metabolism by reducing reactive oxygen species (ROS) and producing hydrogen peroxide as a byproduct.
• Mitochondrion: Known as the "powerhouse of the cell," mitochondria generate adenosine triphosphate (ATP) through oxidative phosphorylation, a process critical for energy production. Mitochondria are also involved in metabolic pathways and play a role in cell signaling and apoptosis.
• Endoplasmic Reticulum: The endoplasmic reticulum (ER) has two forms: rough ER (with ribosomes) and smooth ER (without ribosomes). The rough ER is involved in protein synthesis, while the smooth ER synthesizes lipids and detoxifies certain chemicals within the cell.

The correct answer is: Pasteur effect

Explanation:

• Hatch and Slack effect:

  • Refers to the C4 pathway of photosynthesis, where CO₂ fixation occurs via phosphoenolpyruvate carboxylase (PEPCase), producing a four-carbon compound.
  • Named after Marshall Hatch and C.R. Slack, it is not related to glucose consumption in yeast or anaerobic vs. aerobic conditions.
  • ❌ Incorrect, as it is associated with photosynthesis in C4 plants, not yeast metabolism.

• Emerson enhancement effect:

  • Describes the increased rate of photosynthesis when plants are exposed to light of two different wavelengths simultaneously (red and far-red light).
  • It demonstrates the cooperation of Photosystem I and Photosystem II in photosynthesis, unrelated to yeast metabolism.
  • ❌ Incorrect, as it is specific to photosynthesis and has no connection to glucose consumption in yeast.

• Warburg effect:

  • Refers to increased glucose uptake and lactate production in cancer cells, even in the presence of oxygen (aerobic glycolysis).
  • This effect is primarily observed in cancer biology, highlighting altered metabolism in tumor cells, not yeast.
  • ❌ Incorrect, as it is specific to cancer cells and does not explain yeast behavior under anaerobic conditions.

• Pasteur effect:

  • Refers to the phenomenon where yeast and other facultative anaerobes consume more glucose under anaerobic conditions compared to aerobic conditions.
  • Under aerobic conditions, yeast primarily undergoes aerobic respiration, yielding more ATP per glucose molecule (~36-38 ATP), resulting in lower glucose consumption.
  • Under anaerobic conditions, yeast switches to fermentation, producing ethanol and CO₂, but yielding only 2 ATP per glucose molecule, hence the increased glucose consumption to meet energy demands.
  • ✅ Correct Answer, as it precisely explains the increased glucose consumption by yeast in anaerobic conditions.

Key Points

• Biochemical Basis of the Pasteur Effect:

  • During aerobic respiration, glucose is fully oxidized through glycolysis, Krebs cycle, and oxidative phosphorylation, providing high ATP yield.
  • In anaerobic fermentation, pyruvate is converted to ethanol (in yeast) or lactic acid (in muscles), yielding low ATP.
  • To compensate for the low energy output, yeast must increase glucose uptake.

• Practical Implication:

  • The Pasteur effect is important in industrial fermentation processes, such as bread making, brewing, and bioethanol production, where anaerobic fermentation by yeast is deliberately induced to maximize ethanol output.