Essential Concepts in Biology: From Cells to Ecosystems
Biology
The science of living organisms and their interactions.
Growth and Development
Organisms grow according to DNA instructions.
Molecule
The smallest unit of life, such as DNA.
Cell
The basic unit of structure and function in organisms.
Organism
An individual living entity capable of life processes.
Population
A group of the same species in a specific area.
DNA
Carries genetic information in a double-helix structure.
Natural Selection
A mechanism where favorable traits enhance survival.
Ecosystems
Living organisms
Read MoreHuman Evolution: From Primates to Modern Humans
Key Figures and Theories in Evolutionary Biology
1. Linnaeus (18th Century): Proposed the binomial nomenclature (genus and species) and taxonomy (classification of living forms). Classified humans as Homo sapiens. This was an extrascientific theory, as he believed God created all beings.
2. Lamarck (19th Century): An evolutionist who posited that living things adapt by modifying their bodies in response to the environment through effort. He believed these changes were inherited by offspring, producing
Read MoreHuman Health: Factors, Diseases, and Defense Mechanisms
Health: A Holistic State
Health is a state of complete physical, mental, and social well-being, not merely the absence of disease.
Parameters of Health in a Population
Health, Social, and Economic Development
Poverty and ill health form a positive feedback loop: people get sick, and because they are poor, they get poorer because they are sick, and sicker because they are poorer. Health programs contribute to the economic welfare of countries. The levels of investment in health of a country influence
Read MoreUnderstanding Genetic Mutations: Types and Causes
Mutations
Mutation refers to the sudden changes that appear in individuals of a plant species. Derived from an alteration that occurs in the sequence of nitrogenous bases of DNA, a sequence change in the amino acid is the corresponding protein. The protein encoded by that DNA can change its biological function or act inappropriately. We are now fully aware of the role that mutations play in numerous biological processes, from species evolution to the development of cancer.
Mutations can be classified
Read MoreLiver Cirrhosis, Hypertension, COPD, Hepatitis, Hemostasis: Causes & Symptoms
Cirrhosis
Cirrhosis is a chronic disease characterized by nodules and fibrosis in the liver.
Phases:
- Ascites
- Hepatic encephalopathy
- Hemorrhage
- Jaundice
Glisson’s capsule covers the liver. The cells that defend the liver are Kupffer cells. Initially, there is hepatomegaly and then the size of the liver reduces.
Symptoms:
- Vomiting
- Anorexia
- Abdominal pain (right upper quadrant) – Glisson’s capsule becomes inflamed
Signs:
- Clubbing (fingers with enlarged tips)
- Dupuytren’s contracture
- Growth of the parotid gland
- Peripheral
Cell Division, Biodiversity, and Supporting Tissues in Plants
Mitosis
Mitosis is the division of the nucleus. Before starting, the DNA is duplicated to have two identical copies of genetic information. Mitosis seeks to ensure each new nucleus receives a copy of this information.
Phases:
- Prophase: The DNA condenses and forms chromosomes. The cytoplasm is organized in a system of protein tubules, which are the spindle. At the end of prophase, the nuclear membrane disappears and the chromosomes are free in the cytoplasm. The nucleolus also disappears.
- Metaphase: