Molecular Biology: DNA Replication and Gene Transcription
DNA Replication: The Process of Duplication
DNA replication is the process by which a DNA macromolecule produces two identical copies of the original.
Key Steps and Enzymes in DNA Replication
Arthur Kornberg studied the DNA replication process in 1956. In bacteria, there is typically a single origin of replication.
Initiation and Strand Separation
The process starts with an enzyme called Helicase. This enzyme breaks the hydrogen bonds (H-bonds) between the chains, allowing their separation. As the two
Read MoreCommon Medical Conditions: Definitions by Body System
Medical Conditions: Definitions by Body System
Respiratory System Infections and Disorders
The following infectious diseases have a variety of names depending on the location of the infection within the respiratory tract:
- Nasal Catarrh
- Pharyngitis
- Tonsillitis
- Bronchitis
- Pneumonia
- Laryngitis
- Bronchiolitis
- Tracheolitis
Flu (Influenza): A widespread viral disease that often causes a winter pandemic every ten or fifteen years.
Aphonia: Difficulty emitting sounds due to the inflammation of the vocal cords.
Sinusitis:
Read MoreHuman Body Tissues, Cells, and Common Health Conditions
Connective Tissues
Connective tissues are crucial for linking different organs and tissues. They are characterized by their extracellular matrix.
Conjunctive Tissue
- Joins organs and tissues.
- Contains fibroblasts.
Adipose Tissue
- Designed to store energy in the form of lipids.
- Protects organs from impacts.
- Composed of adipose cells.
Cartilaginous Tissue
- Composed of chondrocytes.
- Lines joints, forming cartilage.
Bone Tissue
- Composed of osteocytes.
Blood Tissue
- Consists of plasma and red blood cells (which lack a
Genetic Mechanisms of Sex Determination: Chromosomes, Syndromes, and Environmental Factors
Genetic Mechanisms of Sex Determination
Meiosis ensures the genetic constancy of a species.
Heteromorphic Chromosomes and Sexual Differentiation
Heteromorphic chromosomes are dissimilar chromosomes, such as the XY pair in mammals. They characterize one sex or the other in many species. While some sex determination is decided by genes on these sex chromosomes, others are located on autosomes.
Life Cycles and Sexual Dimorphism
Life cycles depend on sexual differentiation. Sexual dimorphism refers to the
Read MoreMedical Pathology: Disease Factors & Specific Conditions
Factors Contributing to Disease
Immunologic Agents
Immunologic agents protect the host against various injurious agents but may also turn lethal and cause cell injury. Examples include:
- Hypersensitivity reactions
- Anaphylactic reactions
- Autoimmune diseases
Nutritional Derangements
A deficiency or an excess of nutrients may result in nutritional imbalances.
Nutritional deficiency diseases may be due to an overall deficiency of nutrients (e.g., starvation), of protein-calorie (e.g., marasmus, kwashiorkor),
Read MoreHuman Nutrition: Needs, Diets, and Health
Food and Nutrition Fundamentals
Nutrients are biomolecules that make up our body and are often called proximate principles. Vitamins are essential organic nutrients that need to be part of our diet.
- Carbohydrates: Found in bread, cereals, pasta, etc.
- Proteins: Found in animal products and pulses.
- Mineral Salts: All foods contain mineral salts in varying amounts.
- Lipids: Found in oil, butter, bacon, etc.
- Water: We take in water when we drink and also when we consume food.
- Vitamins: Abundant in vegetables