Prokaryotic & Eukaryotic Cells: Structure, Metabolism & Division
Prokaryotic Cell Structure
Prokaryotic cells are characterized by their smaller size compared to eukaryotic cells. Their DNA is not enclosed within a nuclear membrane but dispersed in the cytoplasm, typically as a double-stranded chain. Prokaryotes possess ribosomes, mesosomes (cell membrane folds involved in respiration), and a cell wall with a composition distinct from plants and animals, sometimes featuring multiple layers for enhanced protection.
The kingdom Monera comprises prokaryotic organisms,
Read MoreDigestive System Medications: Protecting and Regulating
Digestive System Medications
Mucosal Protective Agents
- Sulcralfate: Forms a protective film on the stomach lining, preventing erosion and promoting healing.
- Carbenoxolone: Derived from licorice, stimulates mucus secretion for stomach wall protection. Caution in hypertensive patients due to potential fluid retention.
Secretion Inhibitors
- H2 Antihistamines (cimetidine, ranitidine, famotidine): Inhibit hydrochloric acid (HCl) secretion, used for gastric/duodenal ulcers and esophagitis. Possible side effects
Human Cell Organelles, Digestion, Respiration & Nervous System
Human Cell Organelles
Organelle from a human cell:
Mitochondria: Oval-shaped with a double membrane, providing energy.
Vacuoles: Membranous vesicles containing water, waste, and reserves.
Lysosomes: Transform complex substances into simpler ones.
Cytoskeleton: Filaments forming a network for cell structure and movement.
Centrioles: Hollow cylinders directing cytoskeleton movement.
Endoplasmic Reticulum: Sacs and canals for substance manufacturing.
- Smooth: No ribosomes.
- Rough: Ribosomes attached for protein
Understanding Skin and Nail Conditions: A Comprehensive Overview
1. Melanocytes:
• Originate from the neural crest.
• Found in the basal layer of keratinocytes.
• Large clear cytoplasm.
• Dendritic processes reaching the basal layer, spinous, and granulocytes.
• Melanosomes: melanin.
• Melanoepidermic unit: 1 melanocyte to 36 keratinocytes.
• Number is constant, independent of race or gender, but varies by body areas.
• Pigmentation depends on the size and distribution of melanin granules in keratinocytes.
• Affects skin, hair, and eyes.
•
Exploring the World of Cells
1. Cell Theory
– A cell is the structural unit of living things.
– A cell is the functional unit of living things. It performs all metabolic processes.
– Every cell comes from an existing one.
– A cell is the genetic unit of all living beings. It contains the hereditary material.
2. Types of Cellular Organization
– Prokaryotic cells: lack a nucleus. The genetic material is dispersed in the cytoplasm. Ex: bacteria.
– Eukaryotic cells: possess a nucleus containing the genetic material. Plants and animals
Read MoreUnderstanding Vertebrates: From Fish to Mammals
Vertebrates
Vertebrates have bilateral symmetry and are equipped with a skull that protects the brain and a cartilaginous or bony skeleton, including a vertebral column. The typical vertebra has the body clearly divided into three regions: head, trunk, and tail.
Chordata
Deuterostomia, bilateral symmetry, segmented body, triploblasty (three germ layers), well-developed coelom (lost in some groups).
Features:
- They have a hollow, tubular nerve cord, dorsal to the gut (epineurium). From this ridge, in more