Key Concepts in Earth’s History and Microbiology
Earth’s Ancient History and Life’s Emergence
Major Evolutionary Milestones
- Solar System Forms: Approximately 14 billion years ago (bya)
- Earth Forms: Approximately 4.6 bya
- Formation of Planet Earth: 4.5 bya
- Prokaryotes First Appear: 3.5 bya
- Eukaryotes First Appear: 1.8 bya
- Multicellular Organisms Appear: 1.5 bya
- Animals Appear in Fossil Record: 600 million years ago (mya)
- Fungi and Plants Colonize Land: 490 mya
- Early Humans Appear (Not Modern Man): 2.5 mya
Early Earth Conditions
- Initially fiery and chaotic.
- Atmosphere
Cell Division Fundamentals: Mitosis, Meiosis, and Genetic Principles
Essential Genetic Definitions
Understanding cell division begins with key genetic terms:
- Zygote: A fertilized egg.
- Genome: A cell’s complete set of DNA, packaged as a double-stranded molecule.
- Prokaryotic Genome: Typically a single, double-stranded DNA molecule forming a loop or circle within the nucleoid region.
- Plasmids: Found in prokaryotes, these are small, non-essential DNA molecules. Bacteria can exchange plasmids to acquire new genes, potentially leading to traits like antibiotic resistance.
- Eukaryotic
Life’s Fundamental Principles: Characteristics and Evolutionary Theories
Characteristics of Living Organisms
Living organisms perform vital functions. They are able to:
- Exchange matter and energy with their environment, processed and transformed by processes called metabolism. To maintain life activity, nutrition is essential.
- Create replicas or copies of themselves through the function of reproduction. This function requires the duplication of genetic information.
- Receive and respond to environmental information, a function of relation.
Living things are composed of molecules
Read MoreDNA, Cell Division, and Reproduction: Core Biological Processes
Understanding DNA: The Molecule of Life
DNA is the biomolecule that contains the genetic information for making proteins in the cell. This fundamental molecule dictates the characteristics and functions of all living organisms.
Chromosomes and Chromatin Structure
The genetic material within a cell is organized into structures called chromosomes. These are formed from a complex material known as chromatin, which is an association of DNA and proteins.
- When the cell is at rest, the chromatin is dispersed
Human Body Systems: Nerves, Senses, and Hormones
The Nervous System and Environmental Interaction
The nervous system interacts with both internal and external environments. This interaction allows the body to detect changes and provides appropriate responses to them. Sensory receptors are specialized cells that detect these changes. A detectable change is known as a stimulus.
The Path of a Nerve Impulse
The journey of a nerve impulse from stimulus to response follows a specific sequence:
- A stimulus occurs.
- Sensory receptors detect the stimulus.
- Sensory
Human Respiratory and Digestive Systems & Illnesses
Human Respiratory and Digestive Systems
The respiratory system exchanges gases with the external environment. It takes oxygen (O₂) from the air and transfers it to the bloodstream, while taking carbon dioxide (CO₂) from the blood and expelling it from the body.
The Respiratory System
Components of the Respiratory Tract
- Nasal passages
- Pharynx
- Larynx
- Trachea
- Bronchi
- Bronchioles
These tubes carry air from outside the body into the lungs and vice versa.
The Lungs
Spongy organs located in the rib cage and separated
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