DNA Replication and Operons: Mechanisms in Prokaryotes and Eukaryotes
DNA Replication in Prokaryotes: Initiation and Elongation
Initiation Phase: In prokaryotes, DNA replication begins with the initiation phase.
Elongation Phase: This phase involves the synthesis of a new DNA strand. Several DNA polymerase enzymes are involved, primarily DNA polymerase I, II, and III. These enzymes have a dual function:
- Polymerase Activity (5′-3′): Nucleotides bind to the DNA, recognizing the template strand and selecting complementary deoxyribonucleotides. The energy for forming new
Protozoa, Algae, Monera, and Viruses: Characteristics & Types
Protozoa: Characteristics and Types
- Features:
- Unicellular organisms capable of performing all vital functions.
- Heterotrophic: They feed on bacteria, organic debris, and other organic matter.
- Live in aquatic environments, both freshwater and saltwater; most are free-living.
- Types:
- Flagellates: Move by flagella. Some are free-living, and others are parasites. Trypanosoma causes sleeping sickness.
- Ciliates: Move by cilia. Free-living and parasitic. The Paramecium has two nuclei and is slipper-shaped.
- Rhizopods:
Infectious Diseases: Pathogens, Spread, and Immunity
Epidemics and Pandemics
Epidemic: An infectious disease outbreak that spreads quickly, affecting many people within the same region.
Pandemic: An epidemic that affects multiple countries or continents.
Emerging and Re-emerging Diseases
Emerging Diseases: Diseases caused by previously unknown germs.
Re-emerging Diseases: Diseases that reappear after a significant decline. Examples include:
- Polio
- Tuberculosis
- Dengue
- Malaria
Germ Theory
The theory that each infectious disease is caused by a specific microorganism,
Read MoreEcology: Organism-Environment Relationships & Key Concepts
What is Ecology?
Ecology is the scientific study of the relationships between organisms and their environment. The environment includes the physical and chemical conditions as well as the biological or living components of an organism’s surroundings. Relationships include interactions with the physical world as well as with members of the same and other species.
Historical Roots of Ecology
Ecology has its origins in natural history and plant geography. Over the past century, it has developed into a
Read MoreHuman Arteries and Veins Anatomy Quiz
Artery and Vein Anatomy Questions
- Regarding Veins (Choose the Incorrect Statement):
c) Veins have three fundamental layers: intima, media, and adventitia.
- Regarding the Aorta (Choose the Correct Alternative):
- Originates at the level of the 3rd costal cartilage.
- The aortic arch is located in the superior mediastinum.
- Regarding Coronary Arteries (Choose the Correct Statement):
- Supply areas other than the head and neck.
- Vary in length and origin.
- Regarding the External Carotid Artery (Choose the Exception):
Voice Production Anatomy: Larynx, Vocal Cords & Respiration
The Diaphragm
- A large, dome-shaped muscle located below the lungs.
- Essential for the process of breathing.
The Trachea (Windpipe)
A tube providing passage for air between the larynx and the bronchi.
- Provides protection for the respiratory system.
- Composed of C-shaped cartilaginous rings that keep the airway open.
The Larynx
Also known as the voice box, it is composed of several cartilages:
- V-shaped structures composed of muscles and ligament membranes.
- Positioned horizontally within the larynx.
- Joined at