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
Embryonic Development: From Zygote to Organism
Development: Zygote to Adult Organism
Development refers to the transformation of the zygote into an adult organism.
Segmentation
Segmentation is the set of cell divisions where a single cell or multicellular body produces a blastula. Initially, the zygote divides through mitosis, forming a compact mass of undifferentiated cells called blastomeres, known as a morula.
Cells reorganize, placing blastomeres around a central cavity called the blastocoel. This structure is the blastula stage of cell cleavage.
Read MoreAnimal Organization: From Cells to Systems
Animal Organization Hierarchy
All animal cells originate from a zygote, the result of fertilization between an ovum and a spermatozoon. Fertilization triggers changes in the zygote, preparing it for segmentation, DNA and protein synthesis, and cytoplasmic reorganization during embryonic development. The zygote undergoes a series of mitotic divisions. This development is characterized by the formation of infrastructure and the determination of different cell functions. Cells specialize into tissues,
Read MoreOral Microbiology: Bacteria, Protozoa, Fungi & Clinical Relevance
Bacterial Cell Wall Differences: Gram-Positive vs. Gram-Negative
Gram-positive bacteria have a thick murein layer, varying among species. They possess teichoic acids and a low protein content. Gram-negative bacteria have a single murein layer and lack teichoic acids. Both types share a peptidoglycan cell wall for shape and protection.
Bacterial Grouping and Staining
Bacteria group as diplococci (pairs), streptococci (chains), or staphylococci (clusters). Gram staining uses gentian violet, iodine, alcohol,
Read MoreInnate Immune System: Functions and Cells
Innate Immune System Overview
The innate immune system provides a non-specific defense against infections. Unlike the adaptive immune system, it doesn’t confer long-term immunity. Found in all plants and animals, it’s considered an ancient defense strategy.
Major Functions in Vertebrates
- Recruitment of immune cells via cytokines.
- Activation of the complement cascade to eliminate pathogens and dead cells.
- Removal of foreign substances by leukocytes.
- Activation of the adaptive immune system through antigen