Cell Cycle: Phases, Significance, and Genetic Control
Cell Cycle: Interphase and Mitosis
The cell cycle is the ordered set of events from one cell division to another, comprising interphase and mitosis.
Interphase
The cell does not divide, but genetic material duplicates, and cell growth occurs. It’s divided into:
- G1 Phase: Cell growth, doubling of organelles, and cytoplasmic structures. Some cells enter a resting phase.
- S Phase: DNA replication and centriole duplication. Errors can lead to mutations.
- G2 Phase: Preparation for mitosis, cell size increases,
Chromosomal and Sex-Linked Genetic Disorders
Altered Heterochromosome Numbers
Several changes can occur in the number of heterochromosomes, ranging from the duplication of X and Y chromosomes to the presence of four X chromosomes in both women and men. The main heterochromosomal aberrations are:
Turner Syndrome
Only occurs in women. It results from changes in the number of X heterochromosomes, originating from the union of a gamete carrying an X chromosome with a gamete lacking it. This monosomy causes: cardiovascular disease, moderate mental
Read MoreAnimalia: Characteristics, Functions, and Classification
In the scientific classification of living beings, the kingdom Animalia (animals) or Metazoa (metazoans) is a broad group of eukaryotic, heterotrophic, multicellular, and tissue-based organisms. They are characterized by their capacity for locomotion, the absence of chlorophyll and cell walls, and their embryonic development, passing through a blastula stage and determining a fixed body plan (although many species can subsequently undergo metamorphosis). Animals are a natural group closely related
Read MoreBiodiversity and Classification of Living Things
Biodiversity
What is Biodiversity?
It is the totality of species and ecosystems of a region, including the entire gene pool.
Morphological Adaptations
These are anatomical structures that ensure an organism’s harmonious relationship with its environment.
Physiological Adaptations and Types
These are changes in individual organ function, enabling better environmental adaptation. Types include body temperature regulation and fruit ripening.
Convergent Evolution
Different groups of animals or plants develop
Read MoreStem Cell Research and Cloning: Advancements and Applications
Stem Cells and Cloning
What are Totipotent Cells?
Totipotent cells have the remarkable ability to differentiate into any cell type, including embryonic tissues. Stem cells, on the other hand, can self-renew through mitotic divisions and differentiate into specific mature tissues. They vary in potency, ranging from totipotent to unipotent.
Embryo Formation
The journey begins when an egg leaves the ovary and travels to the fallopian tube. Fertilization creates a zygote, which divides into four cells within
Read MoreNervous and Endocrine Systems in Vertebrates
Nervous System
The nervous system collects various stimuli from both inside and outside the body through specialized neurons organized in receptors. External stimuli are detected by exteroceptors, while internal stimuli are detected by interoceptors. This information is transmitted to the central nervous system (CNS), which processes the information and generates a response. Organs that execute commands from the CNS are called effectors.
Invertebrate Nervous Systems
- Nerve Net: Found in primitive animals