Eukaryotic Cell Organelles: Nucleus, Mitochondria, Chloroplasts
Core: The Cell’s Control Center
The core, or nucleus, is the main organelle in eukaryotic cells (both animal and plant). It houses the cell’s genome, where DNA replication and RNA synthesis occur. Most cells have a single nucleus, although some, like mammalian erythrocytes, lack nuclei, while others, like hepatocytes, can have two, and osteoclasts can be multinucleated.
Interphase Nucleus
In animal cells, the resting nucleus usually occupies a central position, while in plant cells, it’s often eccentric
Read MoreBlood Groups, STIs, and Eruptive Diseases
Blood groups: A, B, AB, and O. In group O, no A or B antigens are present on the red blood cells, and the plasma contains both anti-A and anti-B antibodies. In group A, antigen A is found on red blood cells, and the plasma contains anti-B antibodies. In group B, antigen B is found on red blood cells, and the plasma contains anti-A antibodies. This explains transfusion reactions: group O blood can be donated to all groups but can only receive from group O (universal donor). Group A can donate to
Read MoreCell Nucleus and Cycle
Interphase Nucleus
The interphase nucleus, ranging from 5 to 10 nm, houses the genetic information. This corresponds to the state of the nucleus when the cell is not dividing, a phase occurring in all eukaryotic cells.
Cell Size and Position
Cell size is related to the cytoplasm, which directly influences cell position. This position, often central, can vary depending on cell type and form, constantly changing and adapting to the cell’s configuration. In isodiametric cells, the nucleus is typically
Read MoreEndomembrane System in Eukaryotic Cells
Introduction
Eukaryotic cells, unlike prokaryotic cells, possess a complex network of internal membranes called the endomembrane system. This system includes various organelles such as the endoplasmic reticulum (ER), Golgi apparatus, lysosomes, peroxisomes, and vacuoles. These organelles play crucial roles in cellular function.
Endoplasmic Reticulum (ER)
The ER is a network of interconnected tubules and sacs extending throughout the cytoplasm. It exists in two forms: rough ER (RER) and smooth ER (
Read MoreBiotechnology: Applications, Ethics, and Advancements
Applications of Biotechnology in Agriculture
DNA technology has been implemented in numerous plants, resulting in varieties with new features:
- Pest Protection: Production of proteins or substances that protect against pests.
- Herbicide Resistance: Crops remain unaffected by herbicides.
- Enhanced Food Production: Examples like golden rice, enriched with vitamin A, can address nutritional deficiencies.
- Tolerance to Adverse Conditions: Development of plants that thrive in harsh environments.
- Emerging Applications:
How Your Body Fights Infection
Nonspecific Defenses
These defenses act rapidly and comprise four types:
1. Inflammation
If passive barriers are breached, inflammation occurs, activating other responses like pain, warmth, and swelling in the affected area. The process is as follows:
- Entrance of a stimulus
- Affected cells release inflammatory mediators (histamine, bradykinin, prostaglandins, etc.)
- These mediators act on the affected tissue, causing increased white blood cell count, vasodilation, increased capillary permeability, and activation