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Define active transport? Discuss with suitable examples

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Cells continuously exchange materials with their environment to maintain  homeostasis  and perform essential functions. This movement of substances across the cell membrane occurs through: Passive transport  (which does not require energy) Active transport  (which requires energy) Active Transport Active transport is a biological process in which molecules or ions move across the cell membrane  against their concentration gradient  (from a lower concentration to a higher concentration). Unlike  passive transport,  which relies on natural diffusion, active transport requires energy in the form of  ATP  (adenosine triphosphate) to drive molecules across the membrane. This energy-driven transport is essential for maintaining cellular functions, such as nutrient uptake, waste removal, nerve impulse transmission and maintaining ion balance. Active transport is crucial for cells because it allows them to maintain an internal environment that d...

Explain what are the checkpoints and its regulation?

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The cell cycle is a precisely controlled process that ensures cells grow, replicate their DNA and divide accurately. To maintain genetic integrity, cells have built-in  checkpoints  that function as surveillance systems, monitoring progress and detecting abnormalities at critical stages. These checkpoints play an essential role in preventing errors that could lead to uncontrolled cell growth, mutations, or diseases like cancer. Checkpoints ensure that each stage of the cell cycle is completed correctly before the cell progresses to the next phase. If a problem is detected, the checkpoint  pauses the cycle,  allowing time for repairs. If the damage is irreparable, the checkpoint can activate  apoptosis (programmed cell death)  to prevent the spread of defective cells. Types of Cell Cycle Checkpoints There are three major checkpoints in the cell cycle: G1 Checkpoint (Restriction Point) –  Occurs at the end of G1 phase and ensures conditions are favorable...

Describe the role of ubiquitin in protein turnover

Protein turnover is a fundamental process in cells that ensures proteins are continuously synthesized and degraded to maintain cellular function and homeostasis. This process is necessary for removing damaged, misfolded or unnecessary proteins while allowing the cell to regulate its proteome in response to environmental changes. The ubiquitin-proteasome system (UPS) plays a crucial role in protein degradation by marking specific proteins for destruction and ensuring their controlled breakdown. Ubiquitin is a small regulatory protein that serves as a  molecular tag  for protein degradation. It is covalently attached to target proteins through a process called  ubiquitination,  which involves a cascade of enzymatic reactions. Proteins that receive specific ubiquitin modifications are directed to the proteasome, a large proteolytic complex, where they are degraded into small peptides and amino acids. This targeted degradation process is essential for cellular homeostasi...

PYQ – MZOE-001: Parasitology (Solved Q&A) | MZOE-001 | MSCZOO | M.Sc.Zoology | IGNOU | December 2024

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M.Sc. (Zoology) (MSCZOO) Term-End Examination December, 2024 MZOE-001 : PARASITOLOGY Time : 2 Hours| Maximum Marks : 50 Note: (i)  Attempt any five questions.            (ii) All questions carry equal marks. 1. (a) What are endoparasites? Give any two examples. (2 Marks) Endoparasites are parasites that live inside the body of their host. They usually infect internal organs like the intestine, liver, lungs, or blood. These parasites depend on the host for nutrients and often cause harm by damaging tissues, stealing nutrients, or releasing toxins. They are commonly found in vertebrates, including humans and may be transmitted through contaminated food, water, or direct contact. Examples: 1. Taenia solium (pork tapeworm) – It lives in the human intestine and causes taeniasis. 2. Plasmodium vivax – A blood parasite that causes malaria in humans, transmitted by female Anopheles mosquitoes. (b) What is the difference between mechanical vector and biologic...

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