Understanding Infectious Diseases and DNA Structure
Phases of Infectious Diseases
Every disease can be divided into three phases:
- Incubation Period: The time elapsed between the entry of bacteria and the onset of the first symptoms.
- Prodromal Period: Characterized by the appearance of nonspecific, general signs that occur in a large number of processes. The pathogen has not yet acted on the body in a way that will cause specific infection.
- Clinical Period: The onset of symptoms and signs indicating the disease. These, along with analytical data, allow
Meiosis: Cellular Processes and Life Cycles
Cellular Process
Overview of meiosis. The interphase is duplicated genetic material, and the phenomenon of recombination (represented by red and blue chromosomes). In meiosis I, the homologous chromosomes are divided into two daughter cells. In meiosis II, as in mitosis, each chromatid migrates to one pole. The result is four haploid daughter cells (n).
The preparatory steps that lead to meiosis are identical in pattern and name to the interphase of the mitotic cell cycle. The interphase is divided
Read MoreDNA, Genetic Engineering, Cloning, and Bioethics
DNA and Genetic Engineering
1. DNA: A molecule that carries genetic information from generation to generation. It is part of the nucleic acids, which consist of repeating units called nucleotides.
- Gene: A unit of hereditary information that instructs the cell how to make proteins.
2. Genetic Engineering: A set of techniques for manipulating genes in a living being. It’s a double-edged sword because the same techniques can be used to improve health or to cause harm.
Applications of Genetic Engineering:
Read MoreMonera, Algae, Fungi, Plants, and Animals: Key Traits
Monera
Monera are bacteria. They have naked DNA, no defined nucleus or cell organelles, and a complex cell wall. They occupy all kinds of habitats.
Morphology of Bacteria:
- Cocci: These bacteria have a spherical morphology. They may appear singly or grouped in pairs, or in the form of linear or branched chains.
- Bacilli: These bacteria have an elongated morphology. They can appear isolated or in associated chains.
- Curved Bacteria: These bacteria are curved and can be of three types:
- Vibrios: if they have
The Respiratory System: How We Breathe and Exchange Gases
The Human Respiratory System: An Overview
The respiratory system is responsible for gas exchange. It captures oxygen from the air and transports it via blood to the body’s cells. It also collects carbon dioxide from the blood to expel it. The airways, which conduct air containing oxygen, include the nostrils, pharynx, larynx, trachea, bronchi, and bronchioles. The lungs facilitate gas exchange between blood and air.
Air Transport and Preparation
Before air reaches the lungs, it must be clean, moist,
Read MoreUnderstanding the Heart: Anatomy, Function, and Circulation
The heart is the engine that drives the blood. It is a hollow, tapered organ located in the thoracic cavity between the lungs. The heart is wrapped by a membrane called the pericardium, and its walls are formed by the heart muscle, or myocardium, which enables the heart to contract and relax.
Heart Structure
The heart is divided into two halves, separated by a partition. Each half has two chambers: an atrium and a ventricle. Each atrium communicates only with its corresponding ventricle. The mitral
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