Genetics and Heredity: Understanding Meiosis, Mitosis, and Mendel’s Laws
Meiosis
Meiosis is the cell division process in sex cells where one mother cell produces four daughter cells, each genetically distinct from the mother and containing half the number of chromosomes.
In the first division, the chromosome number is halved, and genetic recombination can occur. The second division resembles normal mitosis.
Phases of Meiosis
- Prophase 1: Centrioles replicate, chromosomes become visible, and the nuclear membrane disappears.
- Metaphase 1: Chromosomes align in the center and may
Introduction to Molecular Biology and Genetics
DNA: Deoxyribonucleic Acid
Structure and Function
DNA carries hereditary information, making it the genetic material of life. It is composed of nucleotides, each containing a sugar, a nitrogenous base, and a phosphate group. The core structure of DNA is a double helix.
Nitrogenous Bases
The nitrogenous bases in DNA are Adenine, Guanine, Cytosine, and Thymine.
RNA: Ribonucleic Acid
Structure and Function
RNA is found in the nucleus and cytoplasm. It carries the genetic message from DNA and aids in its decoding.
Read MoreGenetics: Inheritance and DNA
Types of Objects and Evolution
The world contains two main types of objects: living organisms and inert matter. A key difference is the ability of living organisms, such as human beings, to reproduce. These copies are not identical, creating diversity that allows adaptation to different environments and drives the evolution of species.
Darwin proposed that competition for resources among species influences the selection of characteristics. He initially believed in blended inheritance, where offspring
Read MoreThe Rise of Etiopathology: Understanding Disease Causation
The Rise of the Etiopathological Mentality
Understanding Disease Causation
The etiopathological mentality attributes illness to an external cause, asserting that the same cause will always produce the same effect on the body (cause-effect). This concept emerged at the beginning of the 20th century, building upon observations and research from the late 19th century.
Background
Ancient World
Galen, a prominent physician of the Roman Empire, described three potential causes of disease:
- Procatarctic Cause
Human Biology: Nervous System, Senses, and Reproduction
1. Organization of the Nervous System
1.1 Central Nervous System
- Brain:
- Cerebrum (Cerebral Cortex and Limbic System)
- Cerebellum
- Brainstem
- Hypothalamus
- Epithalamus
- Thalamus
- Spinal Cord
1.2 Peripheral Nervous System
- Autonomic Nervous System:
- Sympathetic
- Parasympathetic
- Somatic Nervous System:
- Sensory Nerves
- Motor Nerves
2. Nerve Impulse
2.1 Along a Neuron
The nerve impulse travels in the form of an electric current from the dendrite to the soma (cell body) to the axon.
2.2 Neuron to Neuron
Transmission occurs via connections
Read MoreDigestive & Respiratory Systems: Anatomy, Functions & Diseases
Digestive System
Gastrointestinal Tract
The gastrointestinal tract is a long tube that extends from the mouth to the anus. It’s responsible for the digestion and absorption of food.
Parts of the Digestive System:
Oral Cavity (Mouth)
- Salivation: Saliva contains amylase (breaks down complex carbohydrates), lysozyme (kills bacteria), and mucin (lubricates food).
- Chewing: Mechanically breaks down food into smaller pieces.
- Swallowing: Chewed food mixed with saliva (bolus) is pushed by the tongue to the pharynx